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SHIP WEATHER CODES
C O N T E N T S
1 INTRODUCTION 1
1.1 Types of Surface Synoptic Sea Stations 1
1.2 Recruitment of Voluntary Observing Ships/Fleet 4
1.3 Criteria for Recruitment 4
1.4 Programme for Surface Observations on Board Ships 5
1.5 Special Observations 6
1.6 Coding of Observations 7
1.7 Automation of Observations on Board Ship 7
1.8 Meteorological Instrumentation on Board Ships 8
1.8.1 Instruments Measuring Atmospheric Pressure 8
1.8.2 Instruments Measuring Wind Speed and Direction 9
1.8.3 Instruments Measuring Temperature and Humidity 10
1.8.4 Instruments Measuring Sea Temperature 10
1.9 Transmission of Ship’s Observations to The Shore 11
1.9.1 INMARSAT 11
1.9.2 Coastal Radio Stations (CRS) 11
1.9.3 Global Maritime Distress Safety System (GMDSS) 12
1.9.4 Marine Pollution Emergency Response Support 13
System (MPERSS)
1.10 Meteorological Logbooks for Ships 14
1.10.1 Layout of Ship Weather Logbooks 14
1.10.2 Scrutiny of Entries 14
i
1.11 Port Meteorological Office 15
1.12 Incentive Programme for Voluntary Observing Ships (VOS) 17
1.13 VOSClim Project (Voluntary Observing Ships Climate 17
Programme)
2 THE SHIP CODE 19
3 WMO CODE FM 13-XI SHIP CODE EXPLANATION 23
4 DRIFTING BUOY COOPERATION PANEL(DBCP) 47
4.1 National Data Buoy Programme (NDBP) 47
4.2 Format for Buoy Data Exchange. 48
4.3 FM 18-X Buoy – Report of Buoy Observation 49
4.4 Regulations for Buoy Observation Reporting 50
4.4.1 General 50
4.4.2 Section 0 50
4.4.3 Section 1 51
4.4.4 Section 2 52
4.4.5 Section 3 52
4.4.6 Section 4 52
5 GENERAL INFORMATION 54
5.1 Cloud Cover and Height of Lowest Cloud 54
5.2 Wind Direction Estimated 55
5.3 Wind Speed Estimated 55
5.4 Beaufort Scale 56
5.5 Additional VOSClim Data (for VOSClim Participants only)
Information 57
ii
5.6 Visibility 58
5.7 Temperatures 58
5.8 Air Pressure 58
5.8.1 Air Pressure Reading 58
5.8.2 Amount of Pressure Tendency 59
5.8.3 Barometer Check 59
5.9 Weather 59
5.10 SST Basic Requirements 60
5.11 SST Instrument Exposure 60
5.11.1 SST Methods of Observation 60
5.11.2 Sea Buckets 60
5.11.3 Intake and Tank Thermometers 61
5.11.4 Hull Attached Thermometers 61
5.12 Waves 62
5.12.1 Definition of Wind Wave 62
5.12.2 Definition of Swell Wave 62
5.12.3 Wave Direction 62
5.12.4 Wave Period 62
5.12.5 Wave Height 63 5.13 Cloud Information 64
5.14 Icing 67
5.14.1 Meteorological Factors Related to Icing 67
5.14.2 Types of Icing at Sea 67
6 TABLES FOR REDUCTION AND CONVERSION 68
6.1 Temperature Correction of the Kew Pattern Mercury 68
Barometer (Old Convention)
iii
6.2 Temperature Correction of the Kew Pattern Mercury 70
Barometer (Hectopascal Scale – New Convention)
6.3 Correction of Mercury Barometer (Hectopascal Scale) to 72
Standard Gravity In Latitude 45 O
C (Old Convection)
6.4 Correction of Mercury Barometer (Hectopascal Scale) to 73
Standard Gravity I.E 980.665 Cm/Sec 2
(New Convention)
6.5 Reduction of Pressure in Hectopascal to Mean Sea Level 75
(Temperatures In 0
F)
6.6 Reduction of Pressure in Hectopascal to Mean Sea Level 77
(Temperatures in 0
C)
6.7 Table for Finding the Dew Point 78
6.8 Conversion of Temperature Readings on the Fahrenheit 82
Scale to the Celsius (Formerly Centigrade) and Absolute
Scales
6.9 Conversion of Nautical Miles to Statute Miles and 84
Kilometers
6.10 Conversion of Feet to Meters 84
7 REFERENCES 85
8 APPENDIX 86
8.1 Fig 4 : Layout of Ship Weather Logbook 86
8.2 Meteorological regions and zones for transmission of 90
ships’ weather messages.
iv
v
SHIP WEATHER CODES
F O R E W O R D
A publication entitled “Code for Radio Weather Messages from ships” was issued by
the India Meteorological Department in 1914 for reporting of weather observations made by
the merchant ships from the Bay of Bengal and Arabian Sea. In 1931 this was replaced by
the “Indian Ships Weather Code”.
A common universal code for use by ships at sea was adopted by the International
Meteorological Organisation in 1947 and accordingly. “Ships weather Code – 1949” came
into force from 1st
January 1949. This code was further revised and “Ships Weather Code
1968” came into use from 1st
January 1968.
The World Meteorological Organisation has further modified the code for reporting
weather messages from ships and adopted a new code which will be brought into effect from
1st
January 1982. The same had been published as “Ships Weather Code 1982”.
Important changes that were introduced in the “Ships Weather Code 1982” were: (i)
The code was arranged in different sections on the basis of dissemination of the data
globally, regionally and nationally (ii) Individual groups were provided for reporting the
different temperature data, rainfall, weather, clouds etc., and identified by indicator figures so
that when these data are not available or are not significant, such groups may be dropped
out (iii) Temperature to be reported correct to a tenth of a degree Celsius (iv) only thousands
digit of pressure to be omitted.
In the current edition the following additions are made:
(i) BUOY code and
(ii) Information of VOSCLIM Project.
The present code replaces all previous “Ships Weather Codes”.
N. Jayanthi
Meteorological Office, Pune-5, Deputy Director General of
August 2005. Meteorology (Weather Forecasting)
1 INTRODUCTION
The international scheme by which ships plying the various oceans and seas of the world
are recruited for taking and transmitting meteorological observations is called the "WMO Voluntary
Observing Ships‟ Scheme". The forerunner of the scheme dates back as far as 1853. These
delegates of 10 maritime countries came together, to discuss the establishment of a uniform
system for the collection of meteorological and oceanographic data from the oceans and the use
of these data for the benefit of shipping in return. In the twentieth century, the system was
recognized in the International Convention for the Safety of Life at Sea. The convention is "the
Contracting Governments undertake to encourage the collection of meteorological data by ships at
sea and to arrange for their examination, dissemination and exchange in the manner most suitable
for the purpose of aiding navigation".
Voluntary observing ships make a highly important contribution to the Global Observing
System of the World Weather Watch. Although new technological means, such as satellites and
automated buoys, are used to gather data from the oceans, the voluntary observing ships
continue to be the main source of oceanic meteorological information.
From the beginning shipping has assisted in the scientific exploration of the oceans and
also in the development of suitable measuring techniques for use by ship borne observers.
Nowadays, the co-operation of voluntary observing ships is sought in each of the large-scale
scientific experiments conducted by special research vessels to furnish the additional data needed for
complete analyses of environmental conditions. In addition, the participation of these ships is
regularly requested in technical studies and investigations concerning observing methods, such as
the measurement of sea-surface temperature, precipitation, wind, etc.
1.1 Types of surface synoptic sea stations
Meteorological observing stations include surface synoptic sea stations of different types.
There are three types of mobile ship stations engaged in the WMO Voluntary Observing Ships‟
Scheme, namely:
1
No
. o
f S
hip
s
1990
1
991
1
992
1
993
1
994
1
995
1
996
1997
1
998
1
999
2
000
2
001
2002
2
003
2
004
2
005
(a) Selected ship stations;
(b) Supplementary ship stations;
(c) Auxiliary ship stations.
Selected ships
A selected ship station is a mobile ship station, which is equipped with sufficient certified
meteorological instruments for making observations, transmits regular weather reports and enters
the observations in meteorological logbooks. A selected ship should have at least a barometer
(mercury or aneroid), a thermometer to measure sea-surface temperature (either by the bucket
method or by other means), a psychrometer (for air temperature and humidity), a barograph, and
possibly, an anemometer.
Selected ships constitute the large majority of voluntary observing ships. Fig 1 depicts the
strength of selected ships year after year.
Strength of Indian Voluntary Ships
Selected Ships
20
15
10
5
0
Years
Fig 1
Supplementary ships
A supplementary ship station is a mobile ship station equipped with a limited number of
certified meteorological instruments for making observations transmits regular weather reports and
2
No
. o
f S
hip
s
No
. o
f S
hip
s
19
90
19
91
1990
1
991
1992
1993
1
994
1995
1996
1
997
1998
1999
2
000
2001
2002
2
003
2004
2005
19
92
19
93
1
99
4
19
95
1
99
6
19
97
19
98
19
99
20
00
20
01
20
02
2
00
3
20
04
2
00
5
enters the observations in meteorological logbooks. Fig 2 depicts the strength of supplementary
ships year after year
Strength of Indian Voluntary Ships
Supplementary Ships
200
150
100
50
0
Years
Fig 2
Auxiliary ships
Beyond the shipping lanes normally used by selected or supplementary ships very few
observations are available. Ships in these data-sparse areas, although not equipped with certified
instruments, may be asked to make and transmit weather reports. They are classified as „auxiliary
ships‟. An auxiliary ship station is a mobile ship station, normally without certified meteorological
instruments, which transmits reports in a reduced code form or in plain language, either as a
routine or on request, in certain areas or under certain conditions. Fig 3 depicts the strength of
Auxiliary ships year after year
Strength of Indian Voluntary Ships
Auxilliary Ships
50
40
30
20
10
0
Years
Fig 3
3
1.2 Recruitment of Voluntary Observing Ships / fleet
Requirement to recruit ships
According to the Manual on the Global Observing System, each Member shall arrange for
the recruitment of ships that are on the national register of that Member as mobile sea stations. In
fulfilling this obligation, each Member contributes to the common objective of obtaining sufficient
coverage of meteorological observations over the sea. While a uniform coverage of the oceans is
desirable, this is difficult to achieve in view of the large differences in the density of shipping traffic.
This traffic is comparatively dense in the Northern Hemisphere, but this is not the case in the
tropics or in the Southern Hemisphere. Consequently, greater attention should be given to the
recruitment of voluntary observing ships in these areas.
Meteorological Services in many countries are required to provide more detailed
information of the weather and sea conditions in coastal areas. Some Services have successfully
recruited ships of local companies to make and transmit observations during their voyage from
harbour to harbour along the coast. Such ships may be recruited as supplementary or as auxiliary
ships. Their observations have everywhere been found to be of great value.
1.3 Criteria for recruitment
Several criteria can be used in deciding whether a particular ship should be recruited as a
selected, supplementary or auxiliary ship, to satisfy both national and international needs.
Questions, which should be examined, are whether all the necessary instruments can be installed,
whether the ship's officers will have the time available for recording and transmitting the
observations and whether the necessary regular contact can be established for the receipt of
meteorological logbooks. Generally ship owners and masters are very cooperative in these
matters; however, it is advisable that these questions be thoroughly discussed at the recruiting
stage.
Countries may recruit ships of foreign registry, which visit the ports of the recruiting country
sufficiently often to permit regular contact. This recruitment is sometimes done by arrangement
between the Meteorological Services of two countries concerned. In order to avoid the entry of
duplicate data into the international archiving system, meteorological logbooks from ships of
foreign registry should be procured and stored through appropriate arrangements with the
4
Meteorological Service of the country of registry. When a ship of foreign registry is recruited, the
Member in whose country the ship is registered should be notified.
For the recruitment of an auxiliary ship, no prior arrangements are required with the
Meteorological Service of the country of registry. Members should establish a suitable
organizational unit for the recruitment of voluntary observing ships. This unit should contact
shipping agencies to enlist their cooperation, arrange for the provision of instruments, instructive
material and other necessary documents to ships, arrange for the collection and examination of
the ships‟ meteorological logbooks, arrange for visits to ships, and to look after the various
financial questions involved. Port meteorological officers can play a large role in the recruitment of
ships.
1.4 Programme for surface observations on board ships
Synoptic observations should be made at the main standard times: 0000, 0600, 1200 and
1800 UTC. When additional observations are required, they should be made at one or more of the
intermediate standard times: 0300, 0900, 1500 and 2100 UTC. The observer is requested to
record at least four observations per day
a. While taking observations, atmospheric pressure should be read at the exact standard
time, the observation of other elements being made within the ten minutes preceding
the standard time.
b. When operational difficulties on board ship make it impracticable to make the synoptic
observation at a main standard time, the actual time of observation should be as near
as possible to the main standard times. In special cases, the observations may even be
taken one full hour earlier than the main standard time i.e. at 2300, 0500, 1100 and
1700 UTC. In these cases the actual time of observation should be indicated; however,
these departures should be regarded only as exceptions.
c. When sudden or dangerous weather developments are encountered, observations
should be made for immediate transmission without regard to the standard times of
observation.
d. Observations should be made more frequently than at the main standard times
whenever storm conditions threaten or prevail. Meteorological Services may request
more frequent observations for storm warnings, particularly for tropical cyclones.
Special observations may also be requested for search and rescue or other safety
reasons.
5
e. Supplementary observations when required for scientific studies should be made at
intermediate standard times, subject to non-interference with navigation duties.
f. When an observation is made at 0300, 0900, 1500 or 2100 UTC in order to ensure its
transmission to a coastal radio station, it is desirable that the observation at the next
main standard time should be made for climatological purposes, and if possible
transmitted in accordance with normal procedures.
g. Ships‟ officers should be encouraged to continue taking and reporting observations
while the ships are in coastal waters, provided it does not interfere with their duties for
the safety of navigation.
h. Transmission of ships‟ observations by INMARSAT is not constrained by the watch
keeping hours of radio officers aboard ship; transmission can be made at any time.
The distinction between two separate wave trains, and, in particular, the distinction
between sea and swell, can be difficult for an inexperienced observer. Sea waves are systems of
waves observed at a point, which lies within the wind field producing the waves. Swell waves are
systems of waves observed at a point remote from the wind field, which produced the waves, or
observed when the wind field, which generated the waves no longer, exists.
The distinction between sea and swell can be made from the following criteria.
Wave direction: If the mean direction of all waves of more or less similar characteristics differs 300
or more from the mean direction of waves of different appearance, then the two sets of waves
should be considered to belong to separate wave systems.
Appearance and period When typical swell waves, characterized by their regular
appearance and long-crestedness, arrive approximately, i.e. within 20°, from the direction of the
wind, they should be considered as a separate wave system if their period is at least four seconds
greater than the period of the larger waves of the existing sea.
1.5 Special observations
In relation to international programs of scientific or economic significance, observations of a
special nature are needed from ships at sea and WMO is requested to assist through its
Voluntary Observing Ships‟ Scheme. One such example is the request for observations on
locust swarms in the seas around Africa, Arabia, Pakistan and India. This program is of great
importance to the agricultural economy in these countries concerned.
6
Another example is the logbook report of freak waves. A freak wave is defined as a wave
of very considerable height ahead of which there is a deep trough. It is the unusual steepness of
the wave, which makes it dangerous to shipping. Favourable conditions for the development of
freak waves seem to be strong current flows in the opposite direction to a heavy sea and
especially when this occurs near the edge of the continental shelf. The reports may contribute to a
mapping of these particularly dangerous areas and to a better understanding of the phenomenon.
1.6 Coding of observations
Ships‟ observations are coded in the international meteorological codes published in the
Manual on Codes, Volume I (WMO -No. 306). The various code forms are given code names,
which are sometimes included in the heading of the ship's report. In all cases, however, a 4-letter
identification group is used. The details of coding of ship observation are given in Chapter 2
1.7 Automation of observations on board ship
Automation of shipboard observations has been advanced by the advent of personal
computers and satellite communications. In one form the observations are taken manually in the
traditional way and then entered into a personal computer, which may be in the form of a laptop or
notebook. The computer programme recommended by WMO and developed by KNMI,
Netherlands, viz., “TURBOWIN 3.0” is also available on Internet, at following address.
http://www.knmi.nl/onderzk/applied/turbowin/turbowin.html.
The computer programme then:
(a) Provides screen prompts to assist with data entry.
(b) Calculates the true wind, MSL pressure and dew point.
(c) Checks validity of some data, e.g. month in range 1–12
(d) Stores the observation in SHIP code on disc and prints it out for transmission.
(e) Formats the observation in International Marine Meteorological Tape (IMMT) format and
stores it on disc or transmits the data to a shore station via a satellite system.
If the ship is equipped with International Maritime Satellite (INMARSAT-C), the computer
diskette can be placed in the INMARSAT terminal and transmitted without rekeying. In addition to
7
filling in a meteorological logbook the diskette of observations in IMMT format is sent periodically
to the Meteorological Office.
Another form of automation is the Marine Data Collection Platform (MDCP), which consists
of a hand-held computer, air temperature and air pressure sensor, transmitter and antenna. The
coded SHIP observations are entered into the computer and collected by Service Argos satellite.
In this case the meteorological logbook still has to be entered manually and returned to the
Meteorological Office in the traditional way.
Completely automated shipboard weather stations present difficulties. Proper locations for
sensors are not easy to find, particularly for wind and dew point, while equipment for automated
measurement of visibility, weather, clouds and wave height cannot be accommodated in the
confined space of a ship.
1.8 Meteorological Instrumentation on Board Ships
General
Full guidance upon the basic meteorological instruments suitable for use on board ships
making observations under the Voluntary Observing Ships Scheme, together with advice on
methods of observations, is provided in the Guide to Meteorological Instruments and Methods of
Observation (WMO-No. 8) Part II, Chapter 4, Marine observations.
Experience over several years has indicated that certain features of the present
instrumentation fitted to ships require constant attention. The following comments emphasize
those aspects to which special care should be given and are fully complimentary to the general
guidance in the above-mentioned Guide.
1.8.1 Instruments measuring atmospheric pressure
In practice the proper installation and operation of mercury barometers at sea has proved
very difficult, and mercury barometers are now rarely installed on board ships. The use of
precision aneroid barometers on the other hand does not give rise to similar problems. However,
because of the zero drift to which these instruments are liable, frequent checking against standing
barometers is necessary in order to ensure proper continuous operation. The zero drift of aneroid
8
currently in use is seldom continuous, the instrument correction remaining stable for a rather long
period of time, and then suddenly dropping to another level. Checking procedures should
therefore continue routinely even if the correction has remained stable for some time. This
checking should be carried out by a PMO whenever possible, preferably at intervals not exceeding
three months. A permanent record of all such checks should be attached to the instrument and
should include information on the date of the check and the temperature and pressure at which
the check was made.
On board small vessels the reduction of the pressure reading to MSL may be carried out
by the addition of a given reduction constant, or simply by correcting the reading of the scale to
give pressure at MSL directly. When the elevation of the barometer varies significantly with the
loading of the ship, the use of different reduction constants has to be considered. The draught of
very large tankers can vary between a sea-going ballast condition and a fully loaded condition by
as much as 10 metres. If the barometer elevation is great, air temperature may also have to be
taken into consideration when preparing reduction tables. At all times the limit of accuracy of the
applied reduction should be kept within 0.2 hPa.
Barographs used on board ships should be supplied with an efficient built-in damping
device and the instrument should be mounted on shock-absorbing material in a position where it is
least likely to be affected by concussion, vibration or movement of the ship. The best results are
generally obtained from a position as close as possible to the centre of flotation. The barograph
should be installed with the pen arm oriented athwart-ship to minimize the risk of its swinging off
the chart
1.8.2 Instruments measuring wind speed and direction
In order that wind reports from ships equipped with instruments are comparable with
estimated winds and wind reports from land stations, anemometer readings should be averaged
over 10 minutes. It is difficult to estimate 10-minute means by watching the dial of an anemometer.
Overestimations of more than 10% are not uncommon. It is therefore preferable that the
instrument readout used for reporting wind velocities be automatically averaged over 10 minutes.
If such readouts are not available, careful instructions should be given in order to avoid
overestimation.
9
Due to the flow distortion caused by superstructure, masts and spars, the site of the
anemometer sensor has to be carefully selected, preferably as far forward and as high as
possible. The wind speed needs to be corrected for effective height.
Any anemometer mounted on a ship, measures the movement of air relative to the ship;
and it is essential that the true wind be computed from the relative wind and the ship‟s velocity. A
simple vector diagram may be used, although in practice this can be a frequent source of error.
Special slide rules and hand computers are available and programs can be installed on small
digital computers.
1.8.3 Instruments measuring temperature and humidity
Temperature and humidity observations should be made by means of a psychrometer with
good ventilation, exposed in the fresh air stream on the windward side of the bridge. The use of a
louvered screen is not as satisfactory. If it is used, two should be provided, one secured on each
side of the vessel, so that the observation can be made on the windward side. The muslin and
wick fitted to a wet-bulb thermometer in a louvered screen should be changed at least once a
week, and more often in stormy weather.
Automated or distant-reading thermometers and hygrometers should be sited in a well-
ventilated screen with good radiation protection and placed as far away from any artificial source
of heat as practicable. It is advisable to compare the readings with standard psychrometer
observations at the windward side of the bridge at regular intervals, particularly when new types of
equipment are introduced.
1.8.4 Instruments measuring sea temperature
It is important that the temperature of the uppermost thin film of water (measured by infra-
red radiometers) should be distinguished from the temperature of the underlying mixed layer. It is
the representative temperature of the mixed layer, which should be reported by voluntary
observing ships.
10
The "bucket" instrument method is the simplest and probably the most effective method of
sampling this mixed layer, but unfortunately the method can only be used on board small vessels
moving slowly.
Other methods are:
(a) Intake and tank thermometers, preferably with distant reading display and used only
when the ship is moving;
(b) Hull-attached thermometers located forward of all discharges;
(c) Trailing thermometers; and
(d) Infra-red radiometers.
These instruments are described in Part II, Chapter 4 of the Guide to Meteorological
Instrument and Observing Practices (WMO-No. 8).
1.9 Transmission of ship‟s observations to the shore
1.9.1 INMARSAT
Ship reports can be transmitted readily to a Coast Earth Station (CES) / Land Earth Station
(LES) , which has been authorised to accept these reports at no cost to the ship. The national
Meteorological Service of the country operating the CES pays the cost, which is usually less than
the cost of a report received via coastal radio. There are a number of such CESs in each satellite
footprint and they are listed, together with the area from which they will accept reports, in WMO-
No. 9, volume D, Part B. Code 41 is the INMARSAT address which automatically routes the report
to the Meteorological Service concerned. To place a limit on the costs incurred by a national
Meteorological Service, a CES may be authorised to accept reports only from ships within a
designated area of ocean. These limits should be drawn to the attention of the relevant ship‟s
officers when recruiting a ship under the Voluntary Observing Ships Scheme. A radio operator is
not needed to transmit the report, and hence transmission is not restricted to the operator‟s hours
of duty.
1.9.2 Coastal Radio Stations(CRS)
Ship reports can be transmitted by radiotelegraphy to a coastal radio station, which has
been authorised to accept these reports at no cost to the ship. (The costs are met by the country
11
operating the coastal radio station, in many cases by the national Meteorological
Service). Weather reports from mobile ship stations should (without special request) be transmitted
from the ship to the nearest coastal radio station situated in the zone in which the ship is
navigating. If it is difficult, due to radio propagation conditions or other circumstances, to
contact promptly the nearest radio station in the zone in which the ship is navigating.
Members may issue instructions to their mobile ship stations to the effect that their weather
reports may be transmitted via one of their home coastal radio stations designated for the
collection of reports.
The ship weather report must be addressed to the telegraphic address of the relevant
National Meteorological Centre. The address should be preceded by the abbreviation "OBS" to
ensure appropriate handling of the message at the coastal radio station. The coastal radio station
must forward the report to the National Meteorological Centre with minimum delay. At present two
Coastal Radio Stations in India viz. Chennai on East coast and Kochi on West cost are
functioning.
1.9.3 Global Maritime Distress Safety System (GMDSS)
This is a new WMO System for the preparation and dissemination of Meteorological
forecasts and Warning to the Shipping on high seas under the Global Maritime Distress and
Safety System (GMDSS). The implementation date for the GMDSS was fixed on 1st February
1992, with phased implementation over seven years period to 1 Feb. l999. The broadcasts are
made through both GMDSS and existing conventional systems during the transit period.
India (IMD) has accepted the responsibility of 'Issuing Service' i.e. for composing a
complete broadcast bulletin on the basis of information input from the relevant preparation
services. Under the WMO programme on GMDSS Broadcast Safety Net System, India has started
issuing operation service bulletins with effect from 1st June 1996 for the METAREA VIII N North of
equator The bulletin contains Meteorological warnings, synoptic features and forecasts (Part I, II
and III) for METAREA VIII N and would be broadcast once everyday at 0900 UTC.and 1800
UTC. Responsibility of India Meteorological Department for issue of GMDSS bulletin is given in
Fig 5.
Fig 5 - Safetynet Metarea VIII (N) India : Forecast Areas
The area of the Indian Ocean enclosed by lines from the Indo-Pakistan frontier in 23°45'N 68°E to 12°N 63°E, thence to Cape Gardafui; the east African coast
south to the Equator, thence to 95°E, to 6°N, thence NE'wards to the Myanmar / Thailand frontier in 10°N 98°30'E.
1.9.4 Marine Pollution Emergency Response Support System (MPERSS)
The system ensures that in the event of major Marine Pollution incident on the high sea
requiring clean up or other marine response operations, the necessary
meteorological/oceanographic support can be provided to the relevant authorities in an efficient,
timely and co-ordinated manner. For this purpose the oceans and seas are divided into areas for
which National Meteorological Services assumes responsibilities. These areas are Marine
Pollution Incident (MPI) areas and are the same areas as the Marine Safety Information (MSI)
areas of GMDSS.
The India (IMD) has accepted the responsibility to participate on trial basis as an Area
Meteorological Co-ordinator (AMC), in the WMO Marine Pollution Emergency Response Support
System (MPERSS) from the month of July 1996.
13
In the event of major Marine pollution emergency incident on high sea, India (IMD) will
provide the necessary meteorological support for Met. Area VIII N i.e. Bay of Bengal, Arabian Sea
and North of equator. NHAC, New Delhi is designated as Area Meteorological co-ordinator. The
advisories / bulletins are issued by ACWC Mumbai, Calcutta and INOSHAC, Pune. Indian Coast
Guard has national and international responsibilities to take care of marine oil pollution. India
meteorological Department provides the wind data and currents.
1.10 Meteorological Logbooks for Ships
1.10.1 Layout of Ship Weather Logbooks
The recording of observations in permanent form is obligatory for selected and
supplementary ships and recommended for auxiliary ships. On ships where the observations are
entered on a personal computer a diskette will be likely to serve as the means of record.
Otherwise the observations are recorded in a meteorological logbook. The layout of logbooks is a
national responsibility. Generally, the order of parameters recorded in the logbook follows the
order of elements in the SHIP code form. Thus the logbook can be used both for recording the
synoptic weather report which is to be transmitted and to include in the same format additional
information required for climatological purposes. For the latter use, the entries are subsequently
transferred on to IMMT format. The layout of Meteorological logbook (IMD) is shown in fig. 4.
(given at end).
Logbooks should be returned with information regarding the ship, the instruments used
and other details of a general nature, and space should be provided for these entries. The name of
the master, the observers and the radio officer should also be included, particularly if an
incentive programme exists in the country where the ship has been recruited.
1.10.2 Scrutiny of entries
There is always a possibility of errors occurring in the entries in a logbook however clear
the instructions might be and despite the care taken by the observer in his work. Completed
logbooks must therefore be scrutinised upon receipt and obvious errors corrected. It is of
14
great importance that the types of errors, which are made frequently, be brought to the attention of
the observers concerned so that any misinterpretation of the instructions or erroneous practices in
reading instruments or making entries can be corrected. When the logbooks are received by the
port meteorological officer, or section of the national Meteorological Service dealing with voluntary
observing ships, a first check should be made as soon as possible to permit a personal
conversation with the appropriate ship‟s officers. Such conversations or written responses
commenting on logbooks that have been received constitute an important element of the
continuous training of ship borne observers. Without this feedback information the officers would
soon become uncertain as to the quality of their work or the implementation of certain observing or
coding procedures and, with an inevitable waning of interest, the quality of their observations may
deteriorate.
Similar scrutiny and personal liaison is especially important in respect of special
observations of freak waves, sea-surface currents. Without the willing cooperation of marine
observers, these non-routine data would not be available.
Ships‟ officers often include questions on coding matters or on any special phenomena
observed by them in the "remarks" column of the logbook. Response to these questions is
important, as this falls within the same spirit of maintaining interest in meteorological work.
1.11 Port Meteorological Offices
In recruiting voluntary observing ships and assisting them in their meteorological work,
direct contact with ships‟ officers is often needed to provide them with instructive material and
other documents, to inspect meteorological instruments on board ships, to collect completed
logbooks of observations and, on an initial check, take such corrective action as is possible by
personal contact. For this purpose, port meteorological officers having maritime experience should
be appointed at main ports.
Port meteorological officers are representatives of the Meteorological Service of the
country as far as the local contact with maritime authorities are concerned. The role of port
meteorological officers is a very important one and the efficiency of the voluntary system of ships'
observations often depends on the initiative displayed by these officers. They are in a good
position to discuss with ships‟ officers any problems they have encountered and offer suggestions,
15
bring to their attention any changes in procedures that may have taken place and give them the
latest information, which they may desire. Opportunity should also be taken to explain various
meteorological and/or oceanographic programmes whenever observations are specially needed
from ships. Meteorological instruments on board ships should be checked and other advice or
assistance in meteorological matters should be given by port meteorological officers upon request
by the master of any ship, irrespective of its State of registry.
The port meteorological officers should also report to the meteorological authorities in their
country if the meteorological work done on board the ship has not been entirely satisfactory.
Members should immediately react to these reports; when they concern the work carried out
under the authority of another Member, the latter should be informed. If action has to be taken
upon complaints this can best be done through the port meteorological officers who can play a
very important role by a tactful approach to the masters and, if constructive criticism is expressed
in positive terms, goodwill can be maintained all round.
The scope of the work of port meteorological officers depends largely on the importance of
the marine traffic in the particular area served. Before deciding to establish a port meteorological
officer in a given port, a study must be made of the various services, which should be provided. As
marine activities develop, a review should be made from time to time to see whether new services
should be provided.
There are six Port Meteorological Offices in India as given below:
Address Telephone Number Working Hours
Port Meteorological Office,
Alibnagar, Malkhana Building,
N. S. Dock, Gate No. 3,
KOLKATA – 700043
+91 033 24793167
0930 - 1800
16
1.12 Incentive Programme for Voluntary Observing Ships (VOS)
In recognition of the valuable work done by ships‟ officers in taking and transmitting
meteorological observations and as an incentive to maintain the high standard of the observations
many maritime countries have established a national award or certificate system. India
Meteorological Department issues Excellent Awards every year on 5th
April, which is celebrated as
National Maritime Day. These awards are given in the form of books, in recognition for the
meteorological work done on board ships. On an average about 15 ships receive Excellent
Awards and about 10 ships receive Certificate of Merit for their quality work.
1.13 Voluntary Observing Ships Climate Programme (VOSCLIM) PROJECT
The main purpose of voluntary ships climate project is to provide a high quality set of
marine met observations. There is a growing need for higher quality data from a sub-set of the
VOS. Improved meta-data (ships dimensions etc) with regard to the ship and observing practices,
and improved quality control of the observations, are the initial priorities for the VOS Climate
17
Port Meteorological Office,
C/o The Director,
Cyclone Warning Centre, Chinna Waltair,
VISAKHAPATNAM-530 017,
ANDHRA PRADESH
+91 0891 2746506
1000 - 1700
Port Meteorological Office,
10th Floor, Cenetenary Building,
Chennai Port Trust, Rajaji Road,
Chennai - 600 001
+91 044 25360187
ext 23
0915 - 1745
Port Meteorological Office,
Cochin Harbour,
North End, Wellingdon Island,
KOCHI - 682 009.
+91 0484 2667042
0900 - 1730
Officer-in-charge,
Port Meteorological Liasion Office,
Sada P.O.., Head Land Sada,
GOA - 403 804
+91 0832 2520012
0900 - 1730
(MONDAY - FRIDAY)
(SATURDAY AND
SUNDAY CLOSED)
Port Meteorological Office,
3rd Floor,
New Labour Hamallage Building,
Yellow Gate, Indira Dock,
FORT, MUMBAI - 400 001
+91 022 22613 733
0930 - 1800
(MONDAY - FRIDAY)
(SATURDAY AND
SUNDAY CLOSED)
project. Other desirable enhancements to the VOS system include increased use of automatic
coding and improved instrumentation and detailed information of how the observations are
collected. Such observations are of great value to operational marine meteorological forecasting.
Climate studies rely on increased accuracy of good observation. The primary objective of the
project is to provide a high-quality subset of marine meteorological data, with extensive associated
metadata, to be available in both real time and delayed mode. Eventually, it is expected that the
project will transform into a long-term, operational program. Specifically, the project gives priority
to the parameters like wind direction and speed, sea level pressure, sea surface temperature, air
temperature and humidity. Data from the project will be used to input directly into air-sea flux
computations, as part of coupled atmosphere-ocean climate models; to provide ground truth for
calibrating satellite observations; and to provide a high-quality reference data set for possible re-
calibration of observations from the entire VOS fleet. VOSCLIM is intended to produce high-quality
data and therefore the selection of ships is a very important part of this project.
18
2 THE SHIP CODES
CODE FORMS AND EXPLANATORY NOTES
FM 13-VII SHIP – Report of surface observation from a sea station.
C O D E F O R M (D. . . D)
SECTION 0 MiMiMjMj ( A1bwnbnbnb) YYGGiw 99LaLaLa
QcLoLoLoLo
SECTION 1 iR iXh VV Nddff 1snTTT 2snTdTdTd 3PoPoPoPo**
4PPPP 5appp 6RRRtR** 7wwW1W2 8NhCLCMCH
9hh//**
SECTION 2 222DsVs (0snTwTwT w) (1PwaPwaHwaHwa)**
(2PwPwHwHw) ((3dw1dw1dw2dw2) (4Pw1Pw1Hw1Hw1)
(5Pw2Pw2Hw2Hw2)) (6IsEsEsRs) (ICE+Plain language
or ciSibiDiZi
SECTION 3 333
(0 . . . . ) (1snTxTxTx) (2snTnTnTn) (3Ej j j) (4E‟sss)
(5j1j2j3j4) (6RRRtR) (7 . . . .) (8NsChshs) **
(9SpSpSpSp) (80000 ) (0 . . . .) (1 .. . .)
SECTION 4 444
SECTION
5
N‟C‟H‟H‟Ct **
555
Groups required as per national practice. *
** Not to be reported by ships
* See remarks against Section 5 on next page.
19
N O T E S :
1. The code form FM 13-VII SHIP is used for reporting surface observations from a sea
station (ship), manned or automatic.
2. i) A SHIP report, or a bulletin of SHIP reports, is identified by the symbolic letters MiMiMjMj =
BBXX
ii) The code name SHIP shall not be included in the report.
iii) The word “section” and section numbers also are not to be included in the report.
3. i) In a bulletin of SHIP reports MiMiMjMj (i.e.BBXX) shall be given only in the first line of the
text of the bulletin and the groups D…D YYGGiw shall be included in every individual
report.
ii) The group A1bwnbnbnb is for identification of buoy and shall not be used by ships.
4. The above-mentioned code form is considered suitable for ships, which report weather
messages in full form (i.e. selected ships). This code form is also used for reporting messages
from Ocean Weather Stations.
5. Report from sea station, not reporting in the abbreviated or reduced form, shall always include
Sections 0,1,and 2 and Section 2 shall always include the possible maximum number of data
groups.
6. The code form is made up of figure groups arranged by sections in ascending order of their
numerical indicators with the exception that all the groups of Section 0, first two groups of
Section 1 and the first group of Section 2 (i.e.222DsVs) are always included in the report.
As a result the following features are achieved:-
a) The loss of information due to the accidental loss of any one of these groups is strictly
limited to the information content of that group:
b) The rules for inclusion or omission of sections or of groups between brackets can be laid
down for each specific case of data requirements.
c) The length of the message can be kept to a strict minimum by dropping out some groups
whenever their information content is considered insignificant or when the information
content is not normally available.
20
The code word ICE of Section 2 plays the role of a numerical indicator for the last data
group of the section or for the equivalent plain language information.
7. The code form is divided into a number of sections as follows:
Section
Number Indicator figures or
Symbolic figure
groups
Contents
0 - Data for reporting identification (type, ship‟s call
sign/buoy identifier, date, time, location) and units of
wind speed used.
1 - Data for international exchange.
2 222 Maritime data pertaining to a sea station
3 333 Data for regional exchange.
4 444 Data for clouds with
base below station
level.
Not for ships
5 555 Data for national exchange.
8. Ships which report in abbreviated form (i.e. Supplementary ships) shall include:
a) Section 0
b) Section 1 restricted to:
iRiXhVV Nddff 1snTTT 4PPPP 7wwW1W2
8NhCLCMCH
c) Section 2 reduced to:
222// (6IsEsEsRs) (ICE + plain language or (ciSibiDizi) )
This abbreviated form is considered suitable for supplementary ships i.e. ships not
supplied with full sets (as the selected ships) but with modified sets of tested instruments.
9. Ships which report their observations in reduced form (i.e. Auxiliary ships) shall include:
a) Section 0
b) Section 1 restricted to:
iRiX/VV Nddff 1snTT/ 4PPP/ 7wwW1W2
21
Where (i) the air temperature shall be expressed in whole degree
0C.
(ii) the mean sea level pressure shall be expressed in whole millibars
(hectopascals)
c) Section 2 restricted to:
222// (6IsEsEsRs) (ICE + plain language or ciSibiDizi )
This reduced form is considered suitable for any ship other than a selected or a
supplementary ship, which is not supplied with tested instruments and may be requested to
report in areas where shipping is relatively sparse, or on request and especially when storm
conditions threaten or prevail. These ships may report in plain language if the use of code is
impracticable.
The / in the group 4PPP/ signifies that the information in the tenths of a hectopascal is not
available owing to lack of accuracy or closeness of scale of the ships barometer.
10. (a) In case of a station located at sea on a drilling rig, the ship‟s call sign shall be
replaced by the identifier RIGG.
(b) In case of a station located at sea an oil or gas production platform the ships call
sign shall be replaced by the identifier PLAT.
(c) In reports of sea stations other than buoys, drilling rigs and oil or gas production
platforms, and in the absence of a ship‟s call sign, the word SHIP shall be used for
D….D.
11. While reporting air temperature, dew-point temperature and sea surface temperature,
when data are not available as a result of a temporary failure of instrument, the groups for
reporting these temperatures may either be omitted or reported as 1////, 2//// and (0////).
22
3 WMO code FM 13-XI SHIP EXPLANATION
The observations are to be formatted according to WMO code FM 13-XI SHIP. This code
form is used for observations from ships and fixed sea stations.
BBXX
Identification letters for a weather report from a ship or fixed sea station
D…D
Ship's call sign (or WMO identification number if fixed sea station)
YY GG iw
YY Day of the month (UTC)
01 First day of the month.
02 Second day of the month …etc.
GG Time of observation. To nearest hour (UTC).
iw- Wind speed indicator
Code Description
0 Wind speed estimated [m/sec]
1 Wind speed from anemometer [m/sec]
3 Wind speed estimated [knots]
4 Wind speed from anemometer [knots]
23
99 LaLaLa
99 Indicator figures for ship report
LaLaLa Latitude, degrees and tenths
Tenths shall be obtained by dividing the minutes by six, disregarding the remainder
Qc LoLoLoLo
Qc Quadrant of the globe
Code Lat. Long.
1 N E
3 S E
5 S W
7 N W
LoLoLoLo Longitude, degrees and tenths
Tenths shall be obtained by dividing the minutes by six, disregarding the remainder
iR iX h VV
iR Indicator for precipitation
Most ships and fixed sea stations should normally enter code figure 4.
Code Precipitation data (Group GRRRtR )
1 Included
2 Included
3 Omitted (precipitation amount = 0
4 Omitted (precipitation amount not available.
24
iX Indicator for weather group
Code Figure Type of station
operation
Group 7wwW 1 W 2
1 Manned Included
2 Manned Omitted (no significant phenomenon to report)
3 Manned Omitted (not observed, data not available)
4 Automatic Included
5 Automatic Omitted (no significant phenomenon to report)
6 Automatic Omitted (not observed, data not available)
Ships and fixed sea stations should normally enter the following code
1 Station manned, group 7wwW1W2 included.
h Height of base of lowest cloud in the sky
If sky is not visible owing to fog, or if height is unknown, then / is reported. If there is fog,
and the sky is visible through it, the cloud is reported as if no fog were present. A height exactly
equal to one of the heights in the table is reported by the higher code figure.
Code Height (ft) Height (m)
0 0 to 150 0 to 50
1 150 to 300 50 to 100
2 300 to 600 100 to 200
3 600 to 1,000 200 to 300
4 1,000 to 2,000 300 to 600
5 2,000 to 3,000 600 to 1,000
6 3,000 to 5,000 1,000 to 1,500
7 5,000 to 6,500 1,500 to 2,000
8 6,500 to 8,000 2,000 to 2,500
9 8,000 or more or no
cloud
2,500 or more or no
25
VV Horizontal visibility.
If visibility varies in different directions then the shorter distance is coded.
Code Visibility (km) Visibility (n mile)
90 <50 m <0.03
91 50 m 0.03
92 0.2 0.1
93 0.5 0.3
94 1 0.5
95 2 1.1
96 4 2.2
97 10 5.5
98 20 11
99 • 50 • 27
N dd ff
N Total amount of cloud
Code Amount of sky covered
0 None (cloudless).
1 One eighth of sky covered or less, but not zero.
2 Two eighths of sky covered.
3 Three eighths of sky covered.
4 Four eighths of sky covered.
5 Five eighths of sky covered.
6 Six eighths of sky covered.
7 Seven eighths of sky covered or more, but not eight eighths.
8 Eight eighths (sky completely covered).
9 Sky obscured by fog or other meteorological phenomena.
/ Cloud cover obscured for other reasons or not observed.
26
Code Direction
07 070 °
08 080 °
09 090 °.etc.
18 180 °etc.
27 270 °etc.
36 360 °
99 Indeterminate
dd Direction of surface wind
True direction from which the wind is blowing, to the nearest ten degrees, given in the
first two figures of the 360° notation, e.g.
Code Direction
00* Calm (no waves)
01 010 °
02 020 °
03 030 °
04 040 °
05 050 °
06 060 °
*NB A northerly wind must always be coded as 36 and never 00.
For intermediate values the higher value is coded.
ff Speed of surface wind in knots or m/s
Wind speed in units indicated by iw, e.g.
Code* Beaufort scale
00 0
01-03 1
04-06 2
07-10 3
11-16 4
(*If iw indicates units in knots)
Note : When the wind speed, in units indicated by iw is 99 units or more, ff above is reported as 99
and the group 00fff is reported immediately after the group Nddff.
27
00 fff
Wind speed, in units indicated by iw, of 99 units or more.
1 Sn TTT
1 Indicator figure for temperature group
Sn Sign of temperature
Code
Description
0 Temperature positive or zero
1 Temperature negative
TTT Air temperature in whole degrees and tenths
2 Sn TdTdTd
2 Indicator figure for dew-point group
Sn Sign of temperature
Code Description
0 Temperature positive or zero
1 Temperature negative
TdTdTd Dew-point temperature in whole degrees and tenths
4 PPPP
4 Indicator figure for pressure group
PPPP Pressure in hPa (millibars) and tenths
Only initial 1 is omitted, e.g. 998.6 is coded as 9986 and 1014.7 is coded 0147.
Note : The hectapascal (hPa) is numerically equivalent to the millibar (mb)
28
5 appp
5 Indicator figure for pressure change group
a Characteristic of barometric tendency in last three hours (for stations with
barographs)
Characteristic of barometric tendency in last three hours (a)
Code Description
0 Rising then falling. [barometer same or higher than 3 hrs ago]
1 Rising then steady; or rising then rising more slowly. [barometer higher than 3
hrs ago]
2 Rising (steadily or unsteadily). [barometer higher than 3 hrs ago]
3 Falling or steady then rising; or rising then rising more rapidly. [barometer
higher than 3 hrs ago]
4 Steady. [barometer same as 3 hrs ago]
5 Falling then rising. [barometer same or lower than 3 hrs ago]
6 Falling then steady; or falling then falling more slowly. [barometer lower than 3
hrs ago]
7 Falling (steadily or unsteadily). [barometer lower than 3 hrs ago]
8 Steady or rising, then falling; or falling, then falling more rapidly. [barometer
lower than 3 hrs ago]
ppp Change of atmospheric pressure in three hours preceding observation in tenths of
hPa
0.1 hPa (mb) is coded as 001
1.0 hPa (mb) is coded as 010
10 hPa (mb) is coded as 100
7 ww W1 W2
7 Indicator for weather group
ww Present Weather
"Present weather" shall describe the weather at time of observation or (where specifically
mentioned) during the period of one hour immediately preceding it. For "Present weather" one
does not take into account meteorological phenomena which has been experienced more than
one hour before the observation
29
Use highest code figure applicable (except that 17 takes preference over 20 to 49 incl.)
00 - 49 No precipitation at ship at time of observation
00 -03 Change of sky in last hour
00 Cloud development not observed or not observable.
01 Clouds dissolving or becoming less developed.
02 State of sky on the whole unchanged.
03 Clouds generally forming or developing
.
04 - 09 Haze, dust, sand or smoke
04 Visibility reduced by smoke, e.g. veldt or forest fire, industrial smoke, volcanic
ash.
05 Haze.
06 Widespread dust in suspension in the air, not raised by wind at or near ship at
time of observation.
07 Visibility reduced by blowing spray.
08 Dust devils within last hour.(not for marine use.)
09 Dust storm or sandstorm within sight at the time of observation or during
preceding hour.
10 -12 Shallow fog or mist
10 Mist (visibility 1,000 meters or more).
11 Shallow fog in patches. [not deeper than 10 m at sea]
12 Shallow fog, more or less continuous. [not deeper than 10 m at sea]
30
13 -16 Phenomena within sight but not at station
13 Lightning visible, no thunder heard.
14 Precipitation not reaching the ground or surface of sea.
15 Precipitation beyond 5 km (2.7 n mile),reaching surface.
16 Precipitation within 5 km (2.7 n mile),reaching surface
17 Thunder audible during the 10 minutes preceding the time of observation,
but no precipitation at time of observation
18 -19 Phenomena within last hour or at time of observation
18 Squall(s) [at or within sight of ship]
19 Funnel cloud(s) (Tornado cloud or waterspout)
[at or within sight of ship]
20 -29 Phenomena within last hour but not at time of observation
20 Drizzle (not freezing) or snow rains. [not falling in showers]
21 Rain (not freezing). [not falling in showers]
22 Snow. [not falling in showers]
23 Rain and snow, or ice pellets. [not falling in showers]
24 Drizzle or rain, freezing. [not falling in showers]
25 Shower(s) of rain.
26 Shower(s) of snow, or of rain and snow.
27 Shower(s) of hail, or of hail and rain.
28 Fog in the past hour but not at present (visibility was less than
1,000 m but is now 1,000 m or more). 29 Thunderstorm (with or without precipitation or lightning). See also
91-
94.
31
30 - 39 Dust storm, sandstorm, drifting or blowing snow
30 Dust storm or sandstorm, falling*,slight or moderate.
31 Dust storm or sandstorm, unchanging*,slight or moderate.
32 Dust storm or sandstorm, rising*,slight or moderate
33 Dust storm or sandstorm, falling*,severe.
34 Dust storm or sandstorm, unchanging*,severe.
35 Dust storm or sandstorm, rising*,severe.
36 Drifting snow, below eye level, slight or moderate.
37 Drifting snow, below eye level, heavy.
38 Blowing snow, above eye level, light or moderate.
39 Blowing snow, above eye level, heavy.
(*These terms refer to development during the preceding hour.)
40 - 49 Fog at time of observation
40 Fog bank at a distance at the time of observation, but not at ship during
last hour, the fog extending to a level above that of the observer.
[visibility 1,000 m or more]
41 Fog in patches. [visibility less than 1,000 m]
42 Fog, thinning in last hour, sky discernible. [visibility less than 1,000 m]
43 Fog, thinning in last hour, sky not discernible. [visibility less than 1,000
m]
44 Fog, unchanging in last hour, sky discernible. [visibility less than 1,000
m]
45 Fog, unchanging in last hour, sky not discernible. [visibility less than
1,000 m]
46 Fog, beginning or thickening in last hour, sky discernible. [visibility less
than 1,000 m]
47 Fog, beginning or thickening in last hour, sky not discernible. [visibility
less than 1,000 m]
48 Fog, depositing rime, sky discernible. [visibility less than 1,000 m]
49 Fog, depositing rime, sky not discernible. [visibility less than 1,000 m]
32
50 - 99 Precipitation at ship at time of observation
(The intensity of the precipitation reported is that at the actual time of observation. The term
'intermittent' indicates that either the precipitation began, or that there were breaks during the
preceding hour, without presenting the character of a shower).
50 -59 Drizzle
50 Slight drizzle. Intermittent.[not freezing]
51 Slight drizzle. Continuous. [not freezing]
52 Moderate drizzle. Intermittent. [not freezing]
53 Moderate drizzle. Continuous. [not freezing]
54 Dense drizzle. Intermittent. [not freezing]
55 Dense drizzle. Continuous. [not freezing]
56 Freezing drizzle. Slight.
57 Freezing drizzle. Moderate or dense.
58 Drizzle and rain. Slight.
59 Drizzle and rain. Moderate or dense.
60 - 69 Rain
60 Slight rain. Intermittent. [not freezing]
61 Slight rain. Continuous. [not freezing]
62 Moderate rain. Intermittent. [not freezing]
63 Moderate rain. Continuous. [not freezing]
64 Heavy rain. Intermittent. [not freezing]
65 Heavy rain. Continuous. [not freezing]
66 Freezing rain. Slight.
67 Freezing rain. Moderate or heavy.
68 Rain or drizzle and snow. Slight.
69 Rain or drizzle and snow. Moderate or heavy.
33
70 - 79 Solid precipitation, not in shower
70 Slight fall of snowflakes. Intermittent.
71 Slight fall of snowflakes. Continuous.
72 Moderate fall of snowflakes. Intermittent.
73 Moderate fall of snowflakes. Continuous.
74 Heavy fall of snowflakes. Intermittent.
75 Heavy fall of snowflakes. Continuous.
76 Ice prisms. [with or without fog]
77 Snow rains. [with or without fog]
78 Isolated star-like snow crystals. [with or without fog]
79 Ice pellets.
80 - 90 Showery precipitation. No thunder at time of observation or during
preceding hour
80 Slight rain shower(s).
81 Moderate or heavy rain shower(s).
82 Violent rain shower(s).
83 Slight shower(s)of rain and snow.
84 Moderate or heavy shower(s)of rain and snow.
85 Slight snow shower(s).
86 Moderate or heavy snow shower(s).
87 Slight showers of snow pellets or small hail*.
88 Moderate or heavy showers of soft or small hail*.
89 Slight showers of hail*. [not associated with tender]
90 Moderate or heavy showers of hail*. [not associated with thunder]
(*The hail may be accompanied by rain, snow, or both.)
91 - 94 Thunderstorm* during the preceding hour but not at the time of
observation
91 Slight rain. [precipitation occurring at time of observation]
92 Moderate or heavy rain. [precipitation occurring at time of observation]
93 Slight snow, or heavy rain and snow, mixed, or hail. [precipitation
occurring at time of observation]
94 Moderate or heavy snow, or rain and snow, mixed, or hail.
[precipitation occurring at time of observation]
95 - 99 Thunderstorm at time of observation
95 Slight or moderate thunderstorm without hail, but with rain and/or
snow [precipitation occurring at time of observation]
96 Slight or moderate thunderstorm with hail. [precipitation occurring at
time of observation]
97 Heavy thunderstorm without hail, but with rain and/or snow.
[precipitation occurring at time of observation]
98 Thunderstorm with dust or sandstorm.
99 Heavy thunderstorm with hail. [precipitation occurring at time of
observation]
(*Thunder heard; lightning may or may not be seen.)
W1W2 Past Weather
The period covered by "Past weather" shall be: Six hours for observations at 0000, 0600,
1200 and 1800 UTC; Three hours for observations at 0300, 0900, 1500 and 2100 UTC; For other
observation hours please consult your PMO, Offshore Adviser or Meteorological Centre
0 Cloud covering half or less of sky throughout appropriate period.
1 Cloud covering half or less of the sky for part of appropriate period
and more than half the sky for part of the period.
2 Cloud covering more than half of sky throughout appropriate period.
3 Sandstorm, dust storm or blowing snow. [visibility less than 1,000
metres]
4 Fog or thick haze. [visibility less than 1,000 metres]
5 Drizzle.
35
6 Rain.
7 Snow, or rain and snow mixed.
8 Shower(s).
9 Thunderstorm(s),with or without precipitation
.
The highest applicable figure should be selected. An exception is made, however, in cases
where the precipitation etc. is confined to the past hour, and is sufficiently well indicated by the ww
code figure. Two code figures are applicable to the weather during the appropriate period, the
highest code figure is recorded under W1 and the next highest is recorded for W2 .If the weather
has been the same throughout the period, the code figures for W1W2 will be the same.
8 Nh CL CM CH
8 Indicator figure, cloud group
Nh Total amount of sky covered by low (or middle , if no low) cloud(see N for
coding details)
CL Cloud types Cu,Cb,Sc,St
Code to be decided by the following order of priority;
/ Cloud Cl not visible owing to darkness, fog, sandstorm, etc.
0 No clouds of type Cl
9 Cb present: the upper part of at least one is clearly fibrous often in the
form of an anvil.
3 Cb present: none of the upper parts is clearly fibrous or in the form of
an anvil.
4 Sc formed from the spreading out of Cu; Cu may also be present.
8 Cu and Sc present, with bases at different levels.
2 Cu of moderate or strong vertical extent is present.
If none of the above cloud types is present choose whichever one of the following
represents the greatest amount of sky cover;
36
1 Cu with little vertical extent and seemingly flattened or ragged Cu, other
than that associated with bad weather.
5 Sc other than that formed by the spreading out of Cu.
6 St in a more-or-less continuous sheet or layer, or in ragged shreds
(other than ragged St of bad weather), or both.
7 Ragged St and/or ragged Cu predominant, both associated with bad
weather, usually below As or Ns.
CM Cloud types Ac,As,Ns
Code to be decided by the following order of priority;
/ Cloud Cm not visible owing to darkness, fog, sandstorm, etc.
0 No clouds of type Cm .
9 Ac present in chaotic sky, generally at several levels.
8 Ac present with sprouting in the form of turrets or battlements, or with
small cumuliform tufts.
7 Ac present with As or Ns.
6 Ac formed by the spreading out of Cu or Cb, with no As or Ns present.
5 Ac progressively invading the sky. No As or Ns present.
4 Ac in patches continually changing in appearance. No As or Ns
present.
7 Ac present at two or more levels. No As or Ns present.
7 or 3 Ac at one level: the greater part is opaque (Cm=7) or is semi-
transparent (Cm=3). No As or Ns present.
2 As mostly opaque, or Ns, but no Ac.
1 As mostly semi-transparent. No Ac or Ns
37
CH Cloud types Ci,Cs,Cc
Code to be decided by the following order of priority;
/ Cloud Ch not visible owing to darkness, fog, sandstorm, etc.
0 No clouds of type Ch .
9 Cc alone or predominantly greater than other Ch clouds combined.
7 Cs covering the whole sky, with or without Ci or Cc.
8 Cs, not increasing, not covering whole sky.
6 Cs progressively invading the sky: the continuous veil extends more
than 45° above horizon, but does not cover whole sky.
5 Cs progressively invading the sky but the continuous veil does not
reach 45° above the horizon.
4 Ci invading the sky. No Cs present.
3 Dense Ci originating from Cb. No Cs present.
2 Ci, dense patches, turrets or tufts, greater than Ci in filaments, strands
or hooks OR
1 Ci, in filaments, strands, or hooks not progressively invading the sky,
greater than Ci in dense patches, turrets or tufts.
222 Ds Vs
222 Section indicator figure
Ds Course made good during last three hours
Code True direction Code True direction
0 Ship stopped 5 SW
1 NE 6 W
2 E 7 NW
3 SE 8 N
4 S 9 No information
38
Code Speed (knots)
5 21 to 25
6 26 to 30
7 31 to 35
8 36 to 40
9 Over 40
Vs Average speed during last three hours
Code Speed (knots)
0 Ship stopped
1 1 to 5
2 6 to 10
3 11 to 15
4 16 to 20
0 Ss TwTwTw
0 Indicator figure, sea temperature group
Ss Sign and type of temperature measurement
Code Sign Type of measurement
0 Positive or 0 Intake
1 Negative Intake
2 Positive or 0 Bucket
3 Negative Bucket
4 Positive or 0 Hull contact sensor
5 Negative Hull contact sensor
6 Positive or 0 Other
7 Negative Other
TwTwTw Sea-surface temperature in degrees and tenths
1 PwaPwa HwaHwa
1 Indicator figure, wave group (obtained by instrumental methods)
PwaPwa Period of wind waves in seconds
HwaHwa Height of waves, obtained by instrumental methods, in units of 1/2 metres
39
2 PwPw HwHw
2 Indicator figure, wave group
PwPw Period of sea waves in seconds
HwHw Height of sea waves in units of 1/2 metres
e.g. 01 = 0.5 m NB Calm is reported as 20000.
3 dw1dw1 dw2dw2
3 Indicator figure, direction of swell waves group
dw1dw1 Direction from which first swell waves are coming in tens of degrees
dw2dw2 Direction from which second swell waves are coming in tens of degrees
Code True direction Code True direction
00 Calm, no waves 36 360°
18 180° 99 Confused, direction indeterminate
4 Pw1Pw1 Hw1Hw1
4 Indicator figure, first swell wave group
Pw1Pw1 Period of first swell waves in seconds
Hw1Hw1 Height of first swell waves in units of 1/2 metres
e.g. 01 = 0.5 m, 02 = 1 m
5 Pw2Pw2 Hw2Hw2
5 Indicator figure, second swell wave group
Pw2Pw2 Period of second swell waves in seconds
Hw2Hw2 Height of second swell waves in units of 1/2 metres
e.g. 01 = 0.5 m, 02 = 1 m
40
6 Is EsEs Rs
6 Indicator figure, ice accretion group
Is Type of ice accretion
Code Description
1 Icing from sea spray.
2 Icing from fog.
3 Icing from rain.
5 Icing from spray and rain.
EsEs Ice thickness in centimeters
Rs Rate of ice accretion
Code Description
0 Ice not building up.
1 Ice building up slowly.
2 Ice building up rapidly.
3 Ice melting or breaking up slowly.
4 Ice melting or breaking up rapidly.
70 HwaHwaHwa
70 Indicator figure, additional wave group (obtained by instrumental methods)
HwaHwaHwa Height of waves, obtained by instrumental methods, in units of 0.1 metre
The group 70HwaHwaHwa shall be reported in addition to the group
1PwaPwaHwaHwa when the station has the capability of accurately measuring
instrumental wave height in units of 0.1 metre.
41
8 Sw TbTbTb
8 Indicator figure, wet-bulb group
Sw Sign and type of wet-bulb temperature
Code Sign Type
0 Positive or zero Measured
1 Negative Measured
2 Iced bulb Measured
5 Positive or zero Computed
6 Negative Computed
7 Iced bulb Computed
TbTbTb Wet-bulb temperature in degrees and tenths
ICE Ci Si bi Di zi
ICE Ice group indicator
Concentration or arrangement of sea ice
Code Description
0 No ice.
1 Ship in open lead more than 1 n mile wide or ship in fast ice with boundary
beyond limit of visibility.
2 - 5 Ice concentration uniform.
2 Open water or very open pack ice,<3/10 concentration.*
3 Open pack ice 4/10 to <6/10 concentration.*
4 Close pack ice 7/10 to <8/10 concentration.*
5 Very close pack ice 9/10 or more, but not 10/10 concentration
42
6 - 9 Ice concentration not uniform.
6 Strips and patches of pack ice with open water between.*
7 Strips and patches of close or very close pack ice with areas of lesser
concentration between.*
8 Fast ice with open water, very open or open pack ice to seaward of
the ice boundary.*
9 Fast ice with close or very close pack ice to seaward of the ice
boundary.*
/ Unable to report, because of darkness, poor visibility or because ship
is more than 0.5 n mile away from ice edge.
(* Ship in ice or within 0.5 n mile of ice)
Si Stage of development
Code
Description
0
New ice only (frazil ice, grease ice, slush, shuga).
1
Nilas or ice rind,<10 cm thick.
2
Young ice (grey ice, grey-white ice) 10 -30 cm thick.
3
Predominantly new and/or young ice with some first-year ice.
4
Predominantly thin first-year ice with some new and/or young ice.
5
All thin first-year ice (30 -70 cm thick).
6
Predominantly medium first-year ice (70 -120 cm thick) and thick first- year
ice (>120 cm thick) and some thinner (younger) first-year ice.
7
All medium and thick first-year ice.
8
Predominantly medium and thick first-year ice with some old ice
(usually more than 2 metres thick).
9
Predominantly old ice.
/ Unable to report, because of darkness, poor visibility or only ice of
land origin visible or ship is more than 0.5 n mile away from ice edge.
ice edge.
than 0.5 n mile away from ice edge.
43
bi Ice of land origin
Code
Description
0
No ice of land origin.
1
1-5 icebergs, no growlers or bergy bits.
2
6-10 icebergs, no growlers or bergy bits.
3
11-20 icebergs, no growlers or bergy bits.
4
Up to and including 10 growlers and bergy bits no icebergs.
5
More than 10 growlers and bergy bits no icebergs.
6
1-5 icebergs with growlers and bergy bits.
7
6-10 icebergs with growlers and bergy bits.
8
11-20 icebergs with growlers and bergy bits.
9
More than 20 icebergs with growlers and bergy bits a major hazard to
navigation.
/
Unable to report because of darkness, poor visibility or only sea ice is
visible.
Di Bearing of principal ice edge
Code Description
0 Ship in shore or flaw lead.
1 Ice edge towards NE.
2 Ice edge towards East.
3 Ice edge towards SE.
4 Ice edge towards South.
5 Ice edge towards SW.
6 Ice edge towards West.
7 Ice edge towards NW.
8 Ice edge towards North.
9 Not determined (ship in ice).
/ Unable to report, because of darkness, poor visibility or only ice of
land origin visible.
44
zi Ice situation and trend over preceding three hours
Code Description
0 Ship in open water with floating ice in sight.
1 Ship in easily penetrable ice; conditions improving.*
2 Ship in easily penetrable ice; conditions not changing.*
3 Ship in easily penetrable ice; conditions worsening.*
4 Ship in ice difficult to penetrate; conditions improving.*
5 Ship in ice difficult to penetrate; conditions not changing.*
6-9 Ice difficult to penetrate, conditions worsening.
6 Ice forming and floes freezing together.*
7 Ice under slight pressure.*
8 Ice under moderate or severe pressure.*
9 Ship beset.*
/ Unable to report, because of darkness or poor visibility.
(* Ship in ice)
555 indicator national groups
following groups determined by national decision
= Observation delimiter (break sign)
Additional groups required for VOSCLIM Project.
HDG
Ship‟s heading the direction to which the bow is pointing. Referenced to true North.
(000-360);e.g. 360 = North 000 = No movement 090 = East
45
COG Ship‟s ground course, the direction the vessel actually moves over the fixed earth and
referenced to True North
SOG Ship‟s ground speed, the speed the vessel actually moves over the fixed earth.
(00-99), Round to nearest whole knot.
SLL
Maximum height in meters of deck cargo above Summer maximum load line.
(00-99) report to nearest whole meter
Sthh
Departure of reference level (Summer maximum load line) from actual sea level. Consider
the difference positive when the summer maximum load line is above the level of the sea and
negative if below the water line.
St sign position. O = positive or zero, 1 = Negative
hh (00-99) is the difference to the nearest whole meter between the summer maximum
load line and the sea level
RWD
Relative wind direction in degrees of the bow
000 – no apparent relative wind speed (calm conditions on deck). Reported direction for relative
wind = 001 – 360 degrees in a clockwise direction off the bow of the ship. When directly on the
bow, RWD = 360
RWS
Relative wind speed reported in units indicated by iw (knots or m/s) in either whole knots or
whole meters per second (e.g. 010 knots or 005 m/s).
46
4 DRIFTING BUOY COOPERATION PANEL (DBCP)
The Drifting Buoy Cooperation Panel (DBCP) is composed of national networks of moored
and drifting buoys. Several of these data buoy networks have been identified as elements of the
Global Ocean Observing System (GOOS), Integrated Observing System. DBCP also encourages,
supports, or initiates development and testing of new observing techniques, quality control
procedures, and new data processing systems. It also encourages impact studies based on buoy
data.
The most important task of the DBCP is to ensure a satisfactory coordination at the
international level of drifting and moored buoy programs to increase the number of buoys
deployed, rationalize spatial distributions for most effective data returns, and continually improve
data quality.
These measurements are obtained as part of an international program designed to make
this data available in an effort to improve climate prediction. Climate prediction models require
accurate estimates of SST to initialize their ocean component. Drifting buoys provide essential
ground truth SST data for this purpose. The models also require validation by comparison with
independent data sets. Surface velocity measurements are used for this validation.
4.1 National Data Buoy Programme
India with a coastline of over 7500 km length and about 2.02 million sq km area within the
Exclusive Economic Zone (EEZ) offers immense scope for exploration and capitalization of marine
resources. With this as a prominent aspect, Department of Ocean Development, Government of
India has established the National Data Buoy Programme (NDBP) in 1997 at the National Institute of
Ocean Technology ( NIOT) Chennai.
47
The Institute is firm to do systematic real-time meteorological and oceanographic
observations that are necessary to improve oceanographic services and predictive capability of
short and long-term climatic changes. Time series observations are vital to improve the
understanding of ocean dynamics and its variability. A network of twelve data buoys have been
deployed both in Arabian Sea and Bay of Bengal during the implementation period of the
programme from 1997 to 2002. The network has been presently increased to twenty.
4.2 Format for Buoy Data Exchange
Mi Mi Mj Mj Y Y M M J G G g g iw
Qc La La La La La Lo Lo Lo Lo
Lo Lo
111 0 d d f f 1 Sn T T T 4 P P P P
222 0 Sn Tw Tw Tw Pwa Pwa Hwa Hwa
EXPLANATION:
Mi Mi Mj Mj Will always by ZZyy as per international practice
YY The day of the year
MM The month of the year
J The unit digit of the year
GGgg Time (UTC) in hours and minutes
iw Indicator group for reporting of wind observation (iw = l in this
case)
Qc Quadrant of the globe (Qc = l in this case)
La La La La La Latitude in thousands of a degree
Lo Lo Lo Lo Lo Lo Longitude in thousands of a degree
ddff Wind direction and speed
Sn Sign of Temperature (0 for +ve, l for –ve (Sn=0 in this case)
TTT Air temperature in tenths of degree
PPPP Pressure at mean sea level in tenths of hPa (Thousand‟s digit is
omitted)
TW TW TW Water temperature in tenths of degree
Pwa Pwa Period of wind wave in seconds
Hwa Hwa Height of wind wave in units of 0.5 metres
48
4.3 FM 18-X BUOY – Report of a buoy observation
CODE FORM:
SECTION 0 MiMiMjMj A1bwnbnbnb YYMMJ GGggiw QcLaLaLaLaLa
LoLoLoLoLoLo (6QiQt//)
SECTION 1 (111QdQx 0ddff 1snTTT 2snTdTdTd
or
29UUU
3PoPoPoPo
4PPPP 5appp)
SECTION 2 (222QdQx 0snTwTwTw 1PwaPwaHwaHwa 20PwaPwaPwa 21HwaHwaHwa)
SECTION 3 (333Qd1Qd2 (8887k2 2z0z0z0z0
2znznznzn
3T0T0T0T0
3TnTnTnTn
4S0S0S0S0
4SnSnSnSn)
(66k69k3 2z0z0z0z0 d0d0c0c0c0
2znznznzn dndncncncn)
SECTION 4 (444 (1QpQ2QtwQ4) (2QnQl//) (QcLaLaLaLaLa LoLoLoLoLoLo)
or
(8ViViViVi) (9idZdZdZd) (YYMMJ
GGgg/)
(7VBVBdBdB)
NOTES:
(1) BUOY is the name of the code for reporting buoy observations.
(2) A BUOY report, or a bulletin of BUOY reports, is identified by the group MiMiMjMj = ZZYY.
(3) The inclusion of the group 9idZdZdZd is strongly recommended for buoys which have been
deployed with drogues.
49
(4) The group 9idZdZdZd should not be used in reports from a buoy on which a drogue has
never been installed.
(5) The code form is divided into five sections, the first beig mandatory in its entirety, except
group 6QiQt//, and the remainder optional as data are available:
Section
number
Symbolic figure
group
Contents
0 -- Identification, time and position data
1 111 Meteorological and other non-marine data
2 222 Surface marine data
3 333 Temperatures; salinity and current (when available) at
selected depths
4 444 Information on engineering and technical parameters,
including quality control data
4.4 Regulations for Buoy Observation Reporting
4.4.1 General
The code name BUOY shall not be included in the report.
4.4..2 Section 0
4.4.2.1 All groups in Section 0 are mandatory, except group 6QiQt//, and shall be included in each
report, even if no other data are reported.
4.4.2.2 Each individual BUOY report, even if included in a bulletin of such report, shall contain as the
first group the identification group MiMiMjMj.
4.4.2.3 Group A1bwnbnbnb
Only buoy numbers (nbnbnb) 001 through 499 are assigned. In the case of a drifting buoy, 500
shall be added to the original nbnbnb number.
50
NOTES:
(1) A1bw normally corresponds to the maritime zone in which the buoy was deployed. The WMO
Secretariat allocates to Members, who request and indicate the maritime zone(s) of interest, a
block or blocks of serial numbers (nbnbnb) to be used by their environmental buoy stations.
(2) The Member concerned registers with the WMO Secretariat the serial numbers actually assigned
to individual stations together with their geographical positions of deployment.
(3) The Secretariat informs all concerned of the allocation of serial numbers and registrations made by
individual Members.
4.4.2.4 Groups QcLaLaLaLaLa LoLoLoLoLoLo
Position shall be reported in tenths, hundredths or thousandths of a degree, depending on the
capability of the positioning system. When the position is in tenths of a degree, the groups shall
be encoded as QcLaLaLa// LoLoLoLo//. When the position is in hundredths of a degree, the
groups shall be encoded as QcLaLaLaLa/ LoLoLoLoLo/.
4.4.2.5 Group (6QiQt//)
QiQt are quality control indicators. Qi applies to position and Qt to time.
4.4.3 Section 1
4.4.3.1 Each of the groups in Section 1 shall be included for all parameters that have been
measured, when data are available.
4.4.3.2 When data are missing for all groups, the entire section shall be omitted from the report.
4.4.3.3 Group 111QdQx
Qd is a quality control indicator for the section. If all data groups have the same quality control
flag value, Qd shall be coded with that value and Qx shall be set to 9. If only one data group
in the section has a quality control flag other than 1, Qd shall be coded with that flag and Qx
shall indicate the position of this group within the section. If more than one data group have a
quality control flag greater than 1, Qd shall be set to the greater flag value and Qx shall be set to
9.
NOTE: When Qx shows the position of the data group, it should be relative to the group containing Qx.
For example, Qx = 1 refers to the data group immediately following.
51
4.4.4 Section 2
4.4.4.1 Each of the groups in Section 2 shall be included for all parameters that have been
measured, when data are available.
4.4.4.2 When data are missing for all groups, the entire section shall be omitted from the report.
4.4.4.3 Group 222QdQx
Regulation 18.3.3 shall apply.
4.4.5 Section 3
4.4.5.1 General
Section 3 is in two parts. The first par, identified by the indicator group 8887k2, shall be
used to report temperatures and/ or salinity at selected depths. The second part, identified
by the indicator group 66k69k3, shall be used to report current at selected depths. Either or
both parts shall be transmitted, depending on the availability of the temperature and/ or
salinity data for the first part and of the current data for the second part.
4.4.5.2 Temperatures shall be reported in hundredths of a degree Celsius. When accuracy is
limited to tenths of a degree, data shall be encoded using the general from 3TnTnTn/.
4.4.5.3 Group 333Qd1Qd2
Qd1Qd2 are two quality control indicators. Qd1 is used to indicate the quality of
the temperature and salinity profile and Qd2 is used to indicate the quality of the current
speed and direction profile.
4.4.6 Section 4
4.4.6.1 General
Additional groups in this section shall be included as data are available or required.
52
4.4.6.2 Group (1QpQ2QtwQ4)
When 1Qp , Q2, Qtw and Q4 = 0, the corresponding group shall not be transmitted.
Its absence thus indicates a satisfactory general operation.
4.4.6.3 Group (2QNQL//)
When QN and QL = 0, the corresponding group shall not be transmitted.
4.4.6.4 Group (QcLaLaLaLa)
This group shall be transmitted only whn QL = 2 (location over one pass only). It gives the
latitude of the second possible solution (symmetrical to the satellite subtrack).
NOTE: Same coding as in Section 0.
4.4.6.5 Group (LoLoLoLoLoLo)
This group shall be transmitted only when QL = 2 and it gives the longitude of the second
possible position, the latitude being indicated by the previous group.
NOTE: Same coding as in Section 0.
4.4.6.6 Group (YYMMJ GGgg/)
The groups YYMMJ GGgg/ give the exact time of the last known position and shall be
transmitted only when QL = 1 together with the following group 7VBVBdBdB.
4.4.6.7 Group (7VBVBdBdB)
This group shall be transmitted only when QL = 1.
Example: At the last location, the true direction of the buoy is 47O
and its speed is 13 cm.
s-1
– the group is coded 71304.
4.4.6.8 Group (8ViViViVi)
The number of groups 8ViViViVi containing information on the engineering status of the
buoy shall not exceed three.
NOTES:
(1) The physical equivalent of the value ViViViVi will be different from one buoy to another.
(2) Interpretation of these groups will not be necessary to permit use of the meteorological
data
53
5 GENERAL INFORMATION
5.1 Cloud cover and Height of lowest cloud
Cloud cover (cloud amount) (N)
The total amount of cloud should be estimated by considering how much of the apparent
area of the sky is covered by cloud. In determining the amount of cloud of a specified form or type
present, the observer should estimate, by taking into consideration the evolution of the sky, the
cloud amounts of each layer or mass at the different levels as if no other clouds were present.
Care should be taken to avoid unconsidered guessing and the best safeguard against this
is a knowledge of the evolution of the clouds under consideration. On occasions of fog which is so
thick as to make it impossible to tell whether there is cloud above or not, the state of sky should be
recorded as sky obscured. If the cloud can be seen through the fog, the cloud amount should be
estimated as well as circumstances permit. If the sun, moon or stars can be seen through the fog
and there is no evidence of cloud above the fog, the state of the sky should be recorded as clear.
At night the observation of total cloud amount is noted by observing which stars are
showing and which are obscured. It is more difficult to differentiate between low, middle and high
clouds and reliable observation depends upon the degree of illumination and the experience of the
observer.
Cloud height estimation (Nh)
In the absence of instrumental aids the cloud-base height must be estimated. In order to
improve their ability to do this, observers should be encouraged to take every opportunity of
checking their estimates against known heights, e.g. when a cloud base is seen to intercept a
mountainous coast. (Although in such circumstances the cloud base may be lower at the mountain
than at sea). At stations where the observer has reports available from aircraft descending or
ascending in the vicinity he can relate these to what he sees and so provide reports sufficiently
reliable for meteorological purposes. At other stations estimates can sometimes be widely in error.
The heights of the bases of the various types may be expected to be between the following
limits, roughly.
54
Low Clouds (Cl)
Stratus: usually below 600 m (2000 ft) and sometimes nearly down to the surface.
Cumulonimbus: 600 - 1500 m (2000 - 5000 ft).
Stratocumulus: 450 - 1350 m (1500 - 4500 ft).
Cumulus: 450 - 1500 m (1500 - 5000 ft).
Middle Clouds (Cm)
Nimbostratus: 150 - 2000 m (500 - 6500 ft), usually below 600 m (2000 ft) in moderate rain or
snow.
Altostratus and Altocumulus: 2000 - 5500 m (6500 - 18000 ft).
High Clouds (Ch)
Usually above 5500 m (18000 ft).
NOTE- These limits tend to be considerably higher in low latitudes; this applies particularly to high
clouds.
5.2 Wind direction estimated (dd)
Visual estimates will normally be based upon the appearance of the surface of the sea.
The wind direction is determined by observing the orientation of the crests of sea waves, i.e. wind-
driven waves and not waves raised by the wind in a distant area, or the direction of streaks of
foam, which are markedly blown in the direction of the wind.
5.3 Wind speed estimated (ff)
Visual estimates will normally be based upon the appearance of the surface of the sea.
The wind speed is obtained by reference to the Beaufort scale and the specifications for each
number. The specifications of the Beaufort scale numbers refer to conditions in the open sea.
NOTE
Factors which in general must be taken into account in estimating wind speeds are the lag
between the wind increasing and the sea getting up, the smoothing or damping down of
wind
55
effects on the sea surface by heavy rain, and the effect of strong surface currents (for
instance, tidal currents) on the appearance of the sea. Sea criteria become less reliable in shallow
water or when close inshore, owing to the effect of tidal currents and the shelter provided by the
land.
5.4 Beaufort Scale
Bf
Wind Speed (Knots)
Specifications For Observation On Board Ship
0 < 1 Sea like a mirror.
1 1- 3 Ripples with the appearance of scales are formed, but without foam crests.
2
4 - 6 Small wavelets, still short but more pronounced: crests have a glassy appearance
and do not break.
3
7 - 10 Large wavelets; crests begin to break; foam of glassy appearance; perhaps
scattered white horses
4 11 - 16 Small waves, becoming longer; fairly frequent white horses.
5
17 - 21 Moderate waves, taking a more pronounced long form; many white horses are
formed (chance of some spray).
6
22 - 27 Large waves begin to form; the white foam crests are more extensive everywhere
(probably some spray).
7
28 - 33 Sea heaps up and white foam from breaking waves begins to be blown in streaks
along the direction of the wind.
8
34 - 40 Moderately high waves of greater length; edges of crests begin to break into the
spindrift; the foam is blown in well- marked streaks along the direction of wind.
9
41 - 47 High waves; dense streaks of foam along the direction of the wind; crests of
waves begin to topple, tumble and roll over; spray may affect visibility
10
48 - 55
Very high waves with long overhanging crests; the resulting foam, in greater
patches, is blown in dense white streaks along the direction of the wind; on the
whole, the surface of the sea takes a white appearance; the tumbling of the sea
becomes heavy and shock-like; visibility affected.
11
56 - 63
Exceptionally high waves (small and medium-sized ships might be for a time lost
to view behind the waves); the sea is completely covered with long white patches
of foam lying along the direction of the wind; everywhere the edges of the wave
crests are blown into froth; visibility affected.
12
> 63 The air is filled with foam and spray; sea completely white with driving spray;
visibility very seriously affected
Wind direction measured
Ship Ships fitted with cup anemometers, wind vanes or anemographs, should report the mean
reading over a ten-minute period or, if the wind changes markedly in the ten-minute period, an
average over the period after the change. When observations are taken from a moving
ship, it is necessary to distinguish between the apparent wind (NO allowance made for ship's
course and sp eed )
56
and the true wind (with respect to True North direction; allowance made for ship's course and
speed). For all meteorological purposes the true wind shall be reported. With this program the
apparent wind will be converted to true wind automatically.
NOTE (SHIPS ONLY)
If the apparent wind direction is used as input: please insert the apparent measured wind
direction as accurate as possible. The computed true wind will be more accurate (e.g. insert 346
instead of the rounded value 350).
NOTE (SHIPS ONLY) Some Meteorological Centres do not allow anemometer, wind vane and
anemograph readings for synoptic reporting purposes, this will be indicated by your PMO or
Meteorological Centre.
Fixed sea station
Fixed sea stations fitted with cup anemometers, wind vanes or anemographs, should report the
mean reading over a ten-minute period or, if the wind changes markedly in the ten-minute period,
an average over the period after the change
Wind direction estimated
Visual estimates will normally be based upon the appearance of the surface of the sea. The wind
direction is determined by observing the orientation of the crests of sea waves, i.e. wind-driven
waves and not waves raised by the wind in a distant area, or the direction of streaks of foam which
are markedly blown in the direction of the wind.
5.5 Additional VOS Clim data (for VOSClim participants only) Information
Max. Height Deck Cargo above summer max. load line
Report to the nearest whole metre
Difference between summer max. load line and water line
Difference to the nearest whole metre between the summer maximum load line and the sea level.
Consider the difference positive when the summer maximum load line is above the level of the sea
and negative if below the water line.
57
NOTES
All wind directions: FROM which the wind is blowing Some Meteorological Centres do not
allow anemometer, wind vane and anemograph readings for synoptic reporting purposes, this will
be indicated by your PMO or Meteorological Centre.
5.6 Visibility (VV)
On a large ship it is possible to make use of objects aboard the ship for estimation when
the visibility is very low, but it should be recognized that these estimates are likely to be in error
since the ship may affect the air. For the higher ranges, the appearance of the land when coasting
is a useful guide, and the distance of landmarks, just as they are appearing or disappearing, may
be measured from the chart. Similarly, in the open sea, when other ships are sighted and their
distances known, e.g. by radar, the visibility can be obtained. In the absence of other objects, the
appearance of the horizon, as observed from different levels, may be used as a basis of the
estimation. Although abnormal refraction may introduce errors into such methods of estimation,
they are the only ones available in some circumstances. At night, the appearance of navigation
lights can give a useful indication of the visibility.
NOTE
When the visibility is not uniform in all directions it should be estimated or measured in the
direction of least visibility (excluding reduction of visibility due to ship's smoke).
5.7 Temperatures (TTT and TdTdTd)
Thermometers should be read to an accuracy of 0.1 °C. Dew-point and relative humidity
can be obtained from the readings of the air temperature (dry-bulb) and wet-bulb. If the wet-bulb
reading is not available, dew-point and wet-bulb temperature can be obtained from the readings of
the air temperature and relative humidity (if available)
5.8 Air pressure (PPPP)
5.8.1 Air pressure reading
The following text is based on an aneroid barometer reading, if the reading is taken from
another kind of barometer please use corrections as advised by your PMO, Offshore Adviser or
Meteorological Centre.
58
In general the aneroid barometer should be set to read the pressure at the level of the
instrument. On board ships and at fixed sea stations however, the instrument may be set to
indicate the pressure at (mean) sea level, provided the difference between the station pressure
and the sea level pressure can be regarded as constant. The reading should be corrected for
instrumental errors.
5.8.2 Amount of pressure tendency (a)
The amount of the pressure tendency in the past three hours is obtained from a marine
barograph, preferably an open-scale instrument graduated in divisions of 1 hPa, or from an
integrated electronic barometer-barograph with a digital output.
5.8.3 Barometer check
Barometers and barographs should be checked as frequently as possible against standard
instruments on shore at least once every three months. A permanent record of all such checks
should, if possible, be attached to the instrument, and should include such information as the date
of the check, temperature and pressure at which the check was made. It is particularly important
that barometers and barographs be checked as frequently as possible, because of possible zero
drift, especially when the instruments are new.
5.9 Weather (ww and W1W2)
"Past weather" shall be selected in such way that "Past weather " and " Present weather"
together give as complete a description as possible of the weather in the time interval concerned.
For example, if the type of weather undergoes a complete change during the time interval
concerned, " Past weather " shall describe the weather prevailing before the type of weather
indicated by " Present weather " began.
59
5.10 SST basic requirements
The temperature to be observed is that of the sea surface representative of conditions in
the near-surface mixing layer underlying the ocean skin.
The sea-surface temperature should be very carefully observed. This is because, amongst other
things, it is used to obtain the difference with air temperature, which provides a measure of the
stratification of temperature and humidity and of other characteristics of the lower layers of
maritime air masses. For these reasons the temperature of a seawater thermometer should be
read to 0.1 °C.
5.11 SST Instrument exposure
5.11.1 SST methods of observation
It has not been possible to adopt a standard device for observing sea-surface
temperatures on account of the great diversity in ship size and speed and of considerations of
cost, ease of operation and maintenance.
The temperature of the sea surface may be observed by:
a) Taking a sample of the sea-surface water with a specially designed sea-bucket.
b) Reading the temperature of the condenser intake water.
c) Exposing an electrical thermometer to the seawater temperature either directly or
trough the hull.
d) Other.
5.11.2 Sea buckets
A sea-bucket is lowered over the side of the ship, a sample of sea-water is hauled on
board and a thermometer is then used to obtain its temperature. The sample should be taken from
the leeward side of the ship, and well forward of all outlets. The thermometer should be read as
soon as possible after it has attained the temperature of the water sample. When not in use the
bucket should be hung in a shady place to drain.
A sea-bucket should be designed to ensure that sea water can circulate through it during
collection and that the heat exchange due to radiation and evaporation is minimum. The
associated thermometer should have a quick response and be easy to read and should preferably
60
be fixed permanently in the bucket. If the thermometer must be withdrawn for reading, it should
have a small heat capacity and be provided with a cistern around the bulb of volume sufficient that
the temperature of the water withdrawn with it does not vary appreciably during the reading. The
Member recruiting the ship for observations should deem the design of bucket adequate for the
purpose.
Sea-buckets of good design (not simple buckets of canvas or other construction) can be
expected to agree well over an extensive rang of conditions. However, they are less convenient to
use than instruments attached to the ship and their use is sometimes restricted by weather
conditions.
5.11.3 Intake and tank thermometers
The thermometer provided within the intake pipe when the ship is built is normally not
suitable for the measurement of sea surface temperature. Thus the Member recruiting the ship
should, with the permission of the shipping company concerned, install a thermometer appropriate
for the purpose. This should preferably be mounted in a special tube providing adequate heat
conductivity between the thermometer bulb and the intake water.
When a direct-reading thermometer is installed in cramped conditions the observer should
be warned of the possibility of error in his readings due to parallax. A distant-reading system with
the display elsewhere (e.g. in the engine room or on the bridge) overcomes this problem. The
observer should also be aware that for ships of deep draught, or when a marked temperature
gradient exists within the sea surface layer, intake temperatures reading usually differ
considerably from those close to the sea surface. Finally, of course, the intake temperature should
not be taken when the ship is stationary, for then the cooling water is not circulating.
5.11.4 Hull attached thermometers
Hull-attached thermometers provide a very convenient and accurate means of measuring
sea-surface temperature. They are necessarily distant-reading devices, the sensor being mounted
either externally in direct contact with the sea using a "through-the-hull” connection, or internally
(the “limpet” type) attached to the inside of the hull. Both types show very good mutual
agreement, with the ”through-the-hull” type showing a slightly quicker response.
61
5.12 Waves
5.12.1 Definition of Wind Wave:
System of waves observed at a point that lies within the wind field producing the waves.
5.12.2 Definition of Swell Wave
System of waves observed at a point remote from the wind field, which produced the
waves, or observed when the wind field, which generated the waves no longer, exists.
5.12.3 Wave direction
The direction from which the waves are coming is most easily found by sighting along the
wave crests and then turning 90° to face the advancing waves. The observer is than facing the
direction from which the waves are coming.
5.12.4 Wave period
The period of the waves is the time between the passage of two successive wave crests
past a fixed point. The average value of the wave period is reported, as obtained from the larger
well-formed waves of the wave system being observed.
This is the only element, which can actually be measured on board moving merchant
ships. If a stopwatch is available, only one observer is necessary; otherwise two observers and a
watch with a second hand are required. The observer notes some small objects floating on the
water at some distance from the ship: if nothing better is available, a distinctive patch of foam can
usually be found which remains identifiable for the few minutes required for the observations. He
starts his watch when the object appears at the crest of the wave. As the crest passes on, the
object disappears into the trough, then reappears on the next crest, etc. The time at which the
object appears to be at the top each crest is noted.
The observations are continued for as long as possible; they will usually terminate when
the object becomes too distant to identify, on account of the ship's motion. Obviously the longest
period of observation will be obtained by choosing an object initially on the bow as far off as it can
be clearly seen.
62
Another method is to observe two or more distinct consecutive periods from an individual
group while the watch is running continuously: with the passage of the last distinct crest of a group
or the anticipated disappearance of the object, the watch is stopped, then restarted with the
passage of the first distinct crest of a new group. The observer keeps count of the total number of
periods until he reaches 15 or 20 at least.
With observations of a period less than five seconds and low wind velocity, the above observation
may not be easily made, but such waves are less interesting than those with longer periods.
5.12.5 Wave height
The average value of the wave height (vertical distance between trough and crest) is
reported, as obtained from the larger well-formed waves of the wave system observed.
The following table shows roughly which height of WIND WAVES (SEA) may be expected
in the OPEN sea, remote from land. In enclosed waters, or when near land with an offshore wind,
wave heights will be smaller and the waves steeper. Furthermore the lag effect between the wind
getting up and the sea increasing should be borne in mind.
Wind force Probable Height Of waves Probable Max. Height of waves
[Beaufort] [metres] [metres]
0 0 0
1 0.1 0.1
2 0.2 0.3
3 0.6 1
4 1 1.5
5 2 2.5
6 3 4
7 4 5.5
8 5.5 7.5
9 7 10
10 9 12.5
11 11.5 16
12 14 -
63
5.13 Cloud Information
Description Altocumulus
White or grey, or both white and grey, patch, sheet or layer of cloud, generally with
shading, composed of laminae, rounded masses, rolls, etc., which are sometimes partly fibrous or
diffuse and which may or may not he merged; most of the regularly arranged small elements
usually have an apparent width between one and five degrees.
Main differences between Altocumulus and similar clouds of other general
a. Cirrus. Altocumulus clouds sometimes produce descending trails of fibrous appearance
(virga). When this is the case, the clouds are regarded as Altocumulus and not as Cirrus,
so long as they have a part without a fibrous appearance or a silky sheen.
b. Cirrocumulus. Altocumulus may sometimes be confused with Cirrocumulus. In case of
doubt, if the clouds have shading, they are by definition Altocumulus, even if their elements
have an apparent width of less than one degree. Clouds without shading are by definition
Altocumulus if most of the regularly arranged elements, when observed at an angle of
more than 30 degrees above the horizon, have an apparent width between one and five
degrees. A corona or irisation is often observed on thin parts of Altocumulus but only
infrequently on Cirrocumulus.
c. Altostratus. An Altocumulus layer may sometimes be confused with Altostratus; in case
of doubt, clouds are called Altocumulus if there is any evidence of the presence of laminae,
rounded masses, rolls, etc.
d. Stratocumulus. Altocumulus, with dark portions, may sometimes be confused with
Stratocumulus. If most of the regularly arranged elements have, when observed at an
angle of more than 30 degrees above the horizon, an apparent width between one and five
degrees, the cloud is Altocumulus.
e. Cumulus. Altocumulus in scattered tufts may be confused with small Cumulus clouds; the
Altocumulus tufts, however, often show fibrous trails (virga) and moreover are, in their
majority, smaller than the Cumulus clouds.
64
Description Altostratus
Altostratus. Greyish or bluish cloud sheet or layer of striated, fibrous or uniform
appearance, totally or partly covering the sky, and having parts thin enough to reveal the sun at
least vaguely, as through ground glass. Altostratus does not show halo phenomena.
Main differences between Altostratus and similar clouds of other genera
(a) Cirrus. Sheets or layers of Altostratus may, on rare occasions, degenerate into patches,
which may be confused with patches of dense Cirrus. Altostratus patches however have a
greater horizontal extent and are predominantly grey.
(b) Cirrostratus. A high and thin layer of Altostratus may he mistaken for a veil of
Cirrostratus. It is sometimes possible to identify the doubtful cloud by remembering that
Altostratus prevents objects on the ground from casting shadows and that it may show a
ground glass effect. If halo phenomena are present, the doubtful cloud is Cirrostratus.
(c) Altocumulus and Stratocumulus Altostratus sometimes has gaps, breaches or rifts;
care should be exercised not to confuse it with an Altocumulus or Stratocumulus sheet or
layer showing the same features. Altostratus is distinguishable from Altocumulus and
Stratocumulus by its more uniform appearance.
(d) Nimbostratus. A low, thick layer of Altostratus may he distinguished from a similar layer
of Nimbostratus by the presence in Altostratus of thinner parts through which the sun is,
or could be, vaguely revealed. Altostratus is also of a lighter grey and its under surface is
usually less uniform than that of Nimbostratus. When, on moonless nights, doubt exists
regarding the choice of the designation Altostratus or Nimbostratus, the layer is by
convention called Altostratus, if no rain or snow is falling.
(e) Stratus Altostratus is distinguishable from Stratus, with which it may be confused, by its
ground glass effect. Furthermore, Altostratus is never white, as thin Stratus may be when
observed more or less towards the sun.
65
Description Nimbostratus
Grey cloud layer, often dark, the appearance of which is rendered diffuse by more or less
continuously falling rain or snow, which in most cases reaches the ground. It is thick enough
throughout to blot out the sun. Low, ragged clouds frequently occur below the layer, with which
they may or may not merge.
Main differences between Nimbostratus and similar clouds of other genera
(a) Altostratus
Thin Nimbostratus may be confused with thick Altostratus. Nimbostratus generally has a
darker grey colour than Altostratus. By definition, Nimbostratus is sufficiently opaque throughout to
hide the sun or moon, whereas Altostratus hides the luminary only when the latter is behind the
thickest parts. If on dark nights, doubt exists regarding the choice of the designation Nimbostratus
or Altostratus, the cloud is by convention called Nimbostratus when rain or snow reaches the
ground.
(b) Altocumulus and Stratocumulus
The lack of clearly defined elements or its lack of a distinct lower surface distinguishes
nimbostratus from a thick layer of Altocumulus or Stratocumulus.
(c) Stratus
Nimbostratus is distinguished from thick Stratus by the fact that it is a dense cloud
producing rain, snow or ice pellets; the precipitation which may fall from Stratus is in the form of
drizzle, ice prisms or snow grains.
(d) Cumulonimbus
When the observer is beneath a cloud having the appearance of a Nimbostratus, but
accompanied by lightning, thunder or hail, the cloud should by convention is called
Cumulonimbus.
66
5.14 Icing
Ice accretion is extremely hazardous in its effects on small ships, particularly on vessels of
less than about 1000 gross tonnage. Even on ships of the order of 10,000 gross tonnage it can
cause radio and radar failures due to the icing of aerials. Visibility from the bridge may also be
affected. Problems have occurred due to icing on the deck cargoes of large container ships. Apart
from its possible effect on stability it may cause difficulty in unloading cargo at the port of
destination when containers and their lashings are frozen solidly to the deck. Fishing vessels are
particularly vulnerable to ice accretion.
5.14.1 Meteorological factors related to icing
The most important meteorological elements governing ice accretion at sea are the wind
speed and the air temperature. The higher the wind speeds relative to the ship and the lower the
air temperature, the greater the rate of ice accretion. There appears to be no limiting air
temperature below, which the icing risk decreases.
5.14.2 Types of icing at sea
There are two main types of icing at sea: icing from seawater and icing from fresh-water.
Icing from seawater may be due either to spray and seawater thrown up by the interaction
between the ship, or installation, and the waves or else to spray blown from the crests of the
waves or both. Icing from fresh-water may be due to freezing rain and/or drizzle, or occasionally
wet snow followed by a drop in temperature, or it may be due to freezing fog. Both types may
occur simultaneously.
67
T A B L E – I
6 TABLES FOR REDUCTION AND CONVERSION
6.1 Temperature Correction of the Kew Pattern Mercury Barometer
(hectopascal Scale – Old convention)
For „Old Convention” barometers, which are calibrated to read correct at 285 o A.
Temperatures used for this correction are to be read from the attached thermometer.
The correction is subtracted if temperature is above 285 o A and added
if temperature is below 285 o
A.
Attached
thermometer (Add correction)
Barometer readings (mb/hPa)
Attached
thermometer (subtract correction
860 880 900 920 940 960 980 1000 1020 1040
Corrections (mb)
284 o
A 0.15 0.15 0.15 0.16 0.16 0.16 0.17 0.17 0.17 0.18 286 o
A
283 0.30 0.30 0.31 0.32 0.32 0.33 0.34 0.34 0.35 0.36 287
282 0.44 0.45 0.46 0.47 0.48 0.49 0.50 0.51 0.52 0.53 288
281 0.59 0.61 0.62 0.63 0.64 0.66 0.67 0.68 0.70 0.71 289
280 0.74 0.76 0.77 0.79 0.81 0.82 0.84 0.86 0.87 0.89 290
279 0.89 0.91 0.93 0.95 0.97 0.99 1.01 1.03 1.05 1.07 291
278 1.04 1.06 1.08 1.11 1.13 1.15 1.17 1.20 1.22 1.24 292
277 1.19 1.21 1.24 1.26 1.29 1.32 1.34 1.37 1.39 1.42 293
276 1.33 1.36 1.39 1.42 1.45 1.48 1.51 1.54 1.57 1.60 294
275 1.48 1.51 1.55 1.58 1.61 1.64 1.68 1.71 1.74 1.78 295
274 1.63 1.66 1.70 1.74 1.77 1.81 1.85 1.88 1.92 1.95 296
273 1.78 1.82 1.86 1.90 1.93 1.97 2.01 2.05 2.09 2.13 297
68
Attached
thermometer (Add correction)
Barometer readings (mb/hPa)
Attached
thermometer (subtract correction
860 880 900 920 940 960 980 1000 1020 1040
Corrections (mb)
272 1.93 1.97 2.01 2.05 2.10 2.14 2.18 2.22 2.27 2.31 298
271 2.08 2.12 2.17 2.21 2.26 2.30 2.35 2.39 2.44 2.49 299
270 2.22 2.27 2.32 2.37 2.42 2.47 2.52 2.57 2.61 2.66 300
269 2.37 2.42 2.48 2.53 2.58 2.63 2.68 2.74 2.79 2.84 301
268 2.52 2.57 2.63 2.69 2.74 2.80 2.85 2.91 2.96 3.02 302
267 2.67 2.73 2.78 2.84 2.90 2.96 3.02 3.08 3.14 3.20 303
266 2.82 2.88 2.94 3.00 3.06 3.13 3.19 3.25 3.31 3.37 304
265 2.97 3.03 3.09 3.16 3.22 3.29 3.35 3.42 3.49 3.55 305
264 3.11 3.18 3.25 3.32 3.39 3.45 3.52 3.59 3.66 3.73 306
263 3.26 3.33 3.40 3.48 3.55 3.62 3.69 3.76 3.83 3.91 307
262 3.41 3.48 3.56 3.63 3.71 3.78 3.86 3.93 4.01 4.08 308
261 3.56 3.63 3.71 3.79 3.87 3.95 4.03 4.10 4.18 4.26 309
260 3.71 3.79 3.87 3.95 4.03 4.11 4.19 4.28 4.36 4.44 310
259 3.86 3.94 4.02 4.11 4.19 4.28 4.36 4.45 4.53 4.62 311
258 4.00 4.09 4.18 4.26 4.35 4.44 4.53 4.62 4.71 4.79 312
257 4.15 4.24 4.33 4.42 4.51 4.61 4.70 4.79 4.88 4.97 313
256 4.30 4.39 4.49 4.58 4.68 4.79 4.86 4.96 5.05 5.15 314
255 4.45 4.54 4.64 4.74 4.84 4.93 5.03 5.13 5.23 5.33 315
69
TABLE - II
6.2 Temperature Correction of the Kew Pattern Mercury Barometer
(hectopascal Scale – NEW CONVENTION)
For “New Convention”, barometers which are calibrated
to read correct at 273 o A (0 o C).
Temperatures used for this correction are to be read from the attached thermometer.
The correction is to be subtracted.
Attached
Thermometer
Barometer Readings (hectopascal)
O A
O C
920 940 960 980 1000 1020 1040
273 0 0.00 0.00 0.00 0.00 0.00 0.00 0.00
274 1 0.16 0.16 0.16 0.17 0.17 0.17 0.18
275 2 0.32 0.32 0.33 0.34 0.34 0.35 0.36
276 3 0.48 0.48 0.49 0.50 0.51 0.52 0.53
277 4 0.63 0.64 0.65 0.67 0.68 0.70 0.71
278 5 0.79 0.80 0.82 0.84 0.85 0.87 0.89
279 6 0.95 0.97 0.99 1.01 1.03 1.05 1.07
280 7 1.11 1.13 1.15 1.18 1.20 1.22 1.25
281 8 1.26 1.29 1.32 1.35 1.38 1.40 1.43
282 9 1.42 1.45 1.48 1.52 1.55 1.57 1.60
283 10 1.58 1.61 1.64 1.68 1.71 1.74 1.77
284 11 1.74 1.77 1.81 1.84 1.88 1.91 1.95
285 12 1.89 1.93 1.97 2.01 2.05 2.09 2.13
286 13 2.05 2.09 2.13 2.18 2.22 2.26 2.30
287 14 2.21 2.25 2.30 2.34 2.39 2.44 2.48
288 15 2.36 2.41 2.46 2.51 2.56 2.61 2.66
289 16 2.52 2.57 2.63 2.68 2.73 2.78 2.83
70
Attached
Thermometer
Barometer Readings (hectopascal)
O A
O C
920 940 960 980 1000 1020 1040
290 17 2.68 2.73 2.79 2.84 2.90 2.96 3.01
291 18 2.84 2.89 2.95 3.01 3.07 3.13 3.19
292 19 2.99 3.05 3.12 3.18 3.24 3.30 3.36
293 20 3.15 3.22 3.28 3.35 3.41 3.48 3.54
294 21 3.31 3.38 3.44 3.51 3.58 3.65 3.72
295 22 3.46 3.54 3.61 3.68 3.75 3.82 3.89
296 23 3.62 3.70 3.77 3.84 3.92 3.99 4.07
297 24 3.78 3.86 3.93 4.01 4.09 4.17 4.25
298 25 3.93 4.02 4.10 4.18 4.26 4.34 4.42
299 26 4.09 4.18 4.26 4.34 4.43 4.51 4.60
300 27 4.25 4.34 4.42 4.51 4.60 4.69 4.77
301 28 4.40 4.49 4.59 4.68 4.77 4.86 4.95
302 29 4.56 4.65 4.75 4.84 4.94 5.03 5.13
303 30 4.72 4.81 4.91 5.01 5.11 5.20 5.30
304 31 4.88 4.97 5.07 5.18 5.28 5.37 5.47
305 32 5.03 5.13 5.24 5.34 5.44 5.55 5.65
306 33 5.19 5.29 5.40 5.51 5.61 5.72 5.82
307 34 5.34 5.45 5.56 5.67 5.78 5.89 6.00
308 35 5.50 5.60 5.72 5.84 5.95 6.06 6.17
309 36 5.65 5.76 5.88 6.00 6.11 6.23 6.35
310 37 5.81 5.92 6.04 6.17 6.28 6.40 6.53
311 38 5.97 6.09 6.21 6.34 6.46 6.58 6.71
312 39 6.13 6.25 6.37 6.51 6.63 6.75 6.88
313 40 6.28 6.41 6.54 6.67 6.80 6.93 7.06
71
TABLE - III
6.3 Correction of Mercury Barometer (hectopascal Scale)
TO STANDARD GRAVITY IN LATITUDE 45 O C
(OLD CONVECTION)
To be used with barometers calibrated according to “Old Convention”
For latitudes 0 o to 44 o, the correction is to be SUBTRACTED,
For latitudes 46 o to 90 o , the correction is to be ADDED.
Latitude Pressure in
hectopascal
Latitude Pressure in
hectopascal Latitude Pressure in
hectopascal
N OR S 950 1000 1050 N OR S 950 1000 1050 N OR S 950 1000 1050
O
ADD O
SUB Corrections
(hectopascal) O
ADD O
SUB Corrections
(hectopascal) O
ADD O
SUB Corrections
(hectopascal)
45 45 .00 .00 .00
44 46 .09 .09 .09 29 61 1.30 1.37 1.44 14 76 2.18 2.29 2.40
43 47 .17 .18 .19 28 62 1.38 1.45 1.52 13 77 2.21 2.33 2.45
42 48 .26 .27 .28 27 63 1.44 1.52 1.60 12 78 2.25 2.37 2.49
41 49 .34 .36 .38 26 64 1.51 1.59 1.67 11 79 2.28 2.40 2.52
40 50 .43 .45 .47 25 65 1.58 1.66 1.74 10 80 2.31 2.43 2.55
39 51 .51 .54 .57 24 66 1.64 1.73 1.82 9 81 2.34 2.46 2.58
38 52 .60 .63 .66 23 67 1.71 1.80 1.89 8 82 2.36 2.49 2.61
37 53 .67 .71 .75 22 68 1.77 1.86 1.95 7 83 2.38 2.51 2.64
36 54 .76 .80 .84 21 69 1.82 1.92 2.02 6 84 2.40 2.53 2.66
35 55 .85 .89 .93 20 70 1.88 1.98 2.08 5 85 2.42 2.55 2.68
34 56 .92 .97 1.02 19 71 1.94 2.04 2.14 4 86 2.43 2.56 2.69
33 57 1.00 1.05 1.10 18 72 2.00 2.10 2.21 3 87 2.44 2.57 2.70
32 58 1.08 1.14 1.20 17 73 2.04 2.15 2.26 2 88 2.45 2.58 2.71
31 59 1.16 1.22 1.28 16 74 2.09 2.20 2.31 1 89 2.46 2.59 2.72
30 60 1.24 1.30 1.37 15 75 2.13 2.24 2.35 0 90 2.46 2.59 2.72
72
TABLE - IV
6.4 Correction of Mercury Barometer (hectopascal Scale)
TO STANDARD GRAVITY i.e 980.665 cm/sec 2
(NEW CONVENTION)
To be used with barometers calibrated according to “New Convention”
Lat. N
or S
Correction
Lat. N
or S
Correction
Lat. N
or S
Correction
At 980 mb/hPa
At 1040 mb/hPa
At 980 mb/hPa
1040 mb/hPa
At 980 mb/hPa
At 1040 mb/hPa
O
mb
mb O
mb
mb O
mb
mb
0
-2.63
-2.79
16
-2.24
-2.37
28
-1.49
-1.58
5
-2.59
-2.75
17
-2.19
-2.32
29
-1.42
-1.50
6
-2.57
-2.73
18
-2.14
-2.27
30
-1.34
-1. 42
7
-2.55
-2.71
19
-2.08
-2.21
31
-1.26
-1.34
8
-2.53
-2.68
20
-2.03
-2.15
32
--1.18
-1.25
9
-2.50
-2.66
21
-1.97
-2.09
33
-1.10
-1.17
10
-2.47
-2.62
22
-1.91
-2.02
34
-1.02
-1.08
11
-2.44
-2.59
23
-1.84
-1.95
35
-0.93
-0.99
12
-2.41
-2.55
24
-1.78
-1.88
36
-0.85
-0.90
13
-2.37
-2.51
25
-1.71
-1.81
37
-0.76
-0.81
14
-2.33
-2.47
26
-1.64
-1.74
38
-0.67
-0.72
15
-2.28
-2.42
27
-1.57
-1.66
39
-0.59
-0.62
73
To be used with barometers calibrated according to “New Convention”
Lat. N or S
Correction
Lat. N or S
Correction
Lat. N or S
Correction
At 980 mb/hPa
At 1040 mb/hPa
At 980 mb/hPa
1040 mb/hPa
At 980 mb/hPa
At 1040 mb/hPa
O
mb
mb O
mb
mb O
mb
mb
40
-0.50
-0.53
56
0.92
0.98
72
2.05
2.17
41
-0.41
-0.43
57
1.00
1.06
73
2.10
2.23
42
-0.32
-0.34
58
1.09
1.15
74
2.15
2.28
43
-0.23
-0.24
59
1.17
1.24
75
2.19
2.33
44
-0.14
-0.15
60
1.24
1.32
76
2.24
2.37
45
-0.05
-0.05
61
+1.32
+1.40
77
2.28
2.42
46
0.04
0.04
62
+1.40
+1.48
78
2.32
2.46
47
0.13
0.14
63
1.47
1.56
79
2.35
2.50
48
0.22
0.23
64
1.54
1.64
80
2.38
2.53
49
0.31
0.33
65
1.61
1.71
81
2.41
2.56
50
0.40
0.42
66
1.68
1.79
82
2.44
2.59
51
0.49
0.52
67
1.75
1.86
83
2.46
2.62
52
0.58
0.61
68
1.81
1.92
84
2.48
2.64
53
0.66
0.70
69
1.87
1.99
85
2.50
+2.66
54
0.75
0.80
70
1.93
2.05
90
+2.54
+2.70
55
0.84
0.89
71
1.99
2.11
74
TABLE - V
6.5 Reduction of Pressure in Hectopascal to Mean Sea Level
These corrections are to be ADDED to the barometer reading
Height Air Temperature (Dry Bulb) O
F
Height
In Feet 0 o
10 o 20
o 30 o 40
o 50 o 60
o 70 o 80
o 90 o
In Feet
5
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
5
10
0.4
0.4
0.4
0.4
0.4
0.4
0.4
0.4
0.3
0.3
10
15
0.6
0.6
0.6
0.6
0.6
0.5
0.5
0.5
0.5
0.5
15
20
0.8
0.8
0.8
0.8
0.8
0.7
0.7
0.7
0.7
0.7
20
25
1.0
1.0
1.0
0.9
0.9
0.9
0.9
0.9
0.9
0.9
25
30
1.2
1.2
1.1
1.1
1.1
1.1
1.1
1.1
1.0
1.0
30
35
1.4
1.4
1.4
1.3
1.3
1.3
1.3
1.3
1.2
1.2
35
40
1.6
1.6
1.6
1.5
1.5
1.4
1.4
1.4
1.4
1.4
40
45
1.8
1.8
1.8
1.7
1.7
1.6
1.6
1.6
1.5
1.5
45
50
2.0
2.0
2.0
1.9
1.9
1.8
1.8
1.8
1.7
1.7
50
55
2.2
2.2
2.2
2.1
2.1
2.0
2.0
1.9
1.9
1.9
55
60
2.4
2.4
2.4
2.3
2.3
2.2
2.2
2.1
2.1
2.0
60
65
2.6
2.6
2.6
2.5
2.5
2.4
2.4
2.3
2.3
2.2
65
70
2.8
2.8
2.8
2.7
2.7
2.6
2.5
2.5
2.4
2.4
70
75
Height Air Temperature (Dry Bulb) O
F
Height
In Feet 0 o
10 o 20
o 30 o 40
o 50 o 60
o 70 o 80
o 90 o
In Feet
75
3.1
3.0
2.9
2.9
2.8
2.8
2.7
2.7
2.6
2.5
75
80
3.3
3.2
3.1
3.0
3.0
2.9
2.9
2.8
2.8
2.7
80
85
3.5
3.4
3.3
3.2
3.2
3.1
3.1
3.0
2.9
2.9
85
90
3.7
3.6
3.5
3.4
3.4
3.3
3.2
3.2
3.1
3.1
90
95
3.9
3.8
3.7
3.6
3.6
3.5
3.4
3.4
3.3
3.3
95
100
4.1
4.0
3.9
3.8
3.8
3.7
3.6
3.5
3.5
3.4
100
Notes:
For mercury barometers Old convention uses all the Tables Nos. I, III and V or VI.
For mercury barometers New Convention use all the tables Nos. II, IV and V or VI
For aneroid barometers use only Table No. V or VI
(In cases where the correction for height above mean sea level is already incorporated in
the index correction given to the ship for aneroid barometers, the correction in tables V or
VI is not to be applied
76
TABLE - VI
6.6 Reduction of Pressure in Hectopascal to Mean Sea Level
N.B. The correction is always additive and holds good strictly for readings
approximating 1,000 hectopascal *
Height in
metres
Temperature of Air o
C Height in
metres
0 o
C 5 o
C 10 o
C 15 o
C 20 o
C 25 o
C 30 o
C 35 o
C
mb. mb. mb. mb. mb. mb. mb. mb.
2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 2
4 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.4 4
6 0.7 0.7 0.7 0.7 0.7 0.7 0.7 0.7 6
8 1.0 1.0 1.0 0.9 0.9 0.9 0.9 0.9 8
10 1.3 1.2 1.2 1.2 1.2 1.1 1.1 1.1 10
12 1.5 1.5 1.4 1.4 1.4 1.4 1.4 1.3 12
14 1.8 1.7 1.7 1.7 1.6 1.6 1.6 1.6 14
16 2.0 2.0 1.9 1.9 1.9 1.8 1.8 1.8 16
18 2.3 2.2 2.2 2.1 2.1 2.1 2.0 2.0 18
20 2.5 2.5 2.4 2.4 2.3 2.3 2.3 2.2 20
22 2.8 2.7 2.7 2.6 2.6 2.5 2.5 2.4 22
24 3.0 2.9 2.9 2.8 2.8 2.8 2.7 2.7 24
26 3.3 3.2 3.1 3.1 3.0 3.0 2.9 2.9 26
28 3.5 3.4 3.4 3.3 3.3 3.2 3.2 3.1 28
30 3.8 3.7 3.6 3.6 3.5 3.4 3.4 3.3 30
32 4.0 3.9 3.9 3.8 3.7 3.7 3.6 3.5 32
* - For other pressures, the corrections to be applied are in proportion.
77
6.7 Table for Finding the Dew Point (Oc) ( T D T D)
(For use with Whirling Psychrometers only)
TABLE – VII
Dry Bulb
Depression of Wet Bulb
00.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
10.0
10.0
9.2
8.1
7.2
6.0
4.9
3.8
2.5
1.2
-0.2
-1.9
-3.3
11.0
11.0
10.2
9.2
8.3
7.2
6.2
4.9
3.8
2.5
+1.2
-0.2
-1.9
12.0
12.0
11.1
10.2
9.4
8.3
7.4
6.2
5.1
3.8
2.5
+1.2
-0.2
13.0
13.0
12.1
11.2
10.3
9.4
8.5
7.4
6.4
5.1
4.0
2.5
+1.2
14.0
14.0
13.2
12.3
11.4
10.5
9.5
8.5
7.6
6.4
5.3
4.0
2.8
15.0
15.0
14.1
13.1
12.5
11.5
10.6
9.7
8.6
7.6
6.6
5.3
4.2
16.0
16.0
15.3
14.4
13.5
12.7
11.8
10.8
9.8
8.8
7.7
6.6
5.6
17.0
17.0
16.2
15.4
14.7
13.8
12.8
12.0
11.1
10.0
9.0
7.9
6.8
18.0
18.0
17.2
16.4
15.6
14.8
14.0
13.1
12.1
11.2
10.3
9.2
8.1
19.0
19.0
18.2
17.5
16.6
15.8
15.0
14.1
13.4
12.4
11.4
10.5
9.5
20.0
20.0
19.2
18.5
17.7
17.0
16.1
15.3
14.4
13.5
12.7
11.7
10.6
21.0
21.0
20.2
19.5
18.7
18.0
17.2
16.4
15.5
14.7
13.8
12.8
12.O
22.0
22.0
21.3
20.6
19.8
19.0
18.2
17.5
16.6
15.8
14.9
14.0
13.1
23.0
23.0
22.3
21.6
20.9
20.2
19.3
18.5
17.7
17.0
16.1
15.3
14.3
78
Dry Bulb
Depression of Wet Bulb
00.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
24.0
24.0
23.3
22.6
21.9
21.1
20.4
19.7
18.8
18.0
17.2
16.4
15.5
25.0
25.0
24.3
23.6
22.9
22.2
21.5
20.7
20.0
19.2
18.3
17.5
16.6
26.0
26.0
25.3
24.7
23.9
23.3
22.6
21.8
21.0
20.2
19.5
18.7
17.8
27.0
27.0
26.3
25.7
25.0
24.3
23.6
22.9
22.1
21.4
20.6
19.8
19.0
28.0
28.0
27.4
26.7
26.0
25.3
24.6
23.9
23.2
22.5
21.7
21.0
20.2
29.0
29.0
28.3
27.7
27.0
26.4
25.7
25.0
24.2
23.6
22.8
22.1
21.3
30.0
30.0
29.4
28.7
28.0
27.4
26.7
26.1
25.3
24.6
23.9
23.2
22.4
31.0
31.0
30.4
29.7
29.1
28.4
27.7
27.1
26.4
25.7
25.0.
24.2
23.5
32.0
32.0
31.4
30.7
30.1
29.4
28.8
28.1
27.4
26.8
26.1
25.4
24.6
33.0
33.0
32.4
31.8
31.1
30.5
29.8
29.1
28.5
27.8
27.1
26.5
25.7
34.0
34.0
33.4
32.7
32.1
31.5
30.1
30.2
29.5
28.9
28.2
27.5
26.8
35.0
35.0
34.4
33.8
33.2
32.5
31.9
31.3
30.6
29.9
29.3
28.6
27.9
36.0
36.0
35.4
34.8
34.2
33.5
32.9
32.3
31.6
31.0
30.3
29.7
29.0
37.0
37.0
36.4
35.8
35.2
34.6
34.0
33.4
32.7
32.0
31.4
30.7
30.0
38.0
38.0
37.4
36.8
36.2
35.6
34.9
34.4
33.7
33.1
32.5
31.8
31.1
39.0
39.0
38.4
37.8
37.2
36.6
36.0
35.4
34.7
34.1
33.5
32.8
32.2
40.0
40.0
39.4
38.8
38.2
37.6
37.0
36.4
35.8
35.2
34.5
33.9
33.3
Note: Dew-point temperatures for intermediate values of dry bulb and/or depression of wet bulb are
to be worked out by interpolation.
79
Table for Finding the Dew Point (O C) ( T D T D)
(For use with Whirling Psychrometers only)
Dry Bulb Depression of Wet Bulb
6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10.0
10.0 -5.3 -7.6 -9.7 -12.9 -16.2 - - - -
11.0 -3.6 -5.3 -7.6 -10.3 -12.9 - - - -
12.0 -1.9 -3.6 -5.7 -7.6 -10.3 -13.7 - - -
13.0 -0.2 -1.9 -3.6 -5.7 -8.1 -10.3 -13.7 - -
14.0 +1.2 -0.2 -1.9 -3.6 -5.7 -8.1 -10.9 -
15.0 2.8 +1.5 -0.2 -1.9 -3.6 -5.7 -8.1 -10.9 -14.5
16.0 4.2 3.0 +1.5 +0.1 -1.9 -3.6 -5.7 -8.1 -10.9
17.0 5.6 4.5 3.0 1.8 +0.1 -1.5 -3.6 -5.7 -8.1
18.0 7.0 5.8 4.5 3.8 1.8 +0.4 -1.5 -3.3 -5.7
19.0 8.8 7.2 6.0 4.7 3.3 2.0 +0.4 -1.2 -3.3
20.0 9.7 8.6 7.4 6.2 4.9 3.5 2.0 +0.6 -1.2
21.0 10.9 9.8 8.8 7.7 6.4 5.1 3.8 2.3 +0.6
22.0 12.1 11.2 10.2 9.0 7.9 6.8 5.3 4.0 2.5
23.0 13.4 12.4 11.4 10.5 9.4 8.1 7.0 5.8 4.2
80
Dry Bulb Depression of Wet Bulb
6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10.0
24.0 14.7 13.6 12.7 11.7 10.6 9.7 8.5 7.2 6.0
25.0 15.8 14.9 14.0 13.0 12.0 10.9 9.8 8.8 7.6
26.0 17.0 16.1 15.3 14.3 13.4 12.3 11.2 10.2 9.0
27.0 18.2 17.3 16.4 15.5 14.7 13.6 12.7 11.5 10.5
28.0 19.3 18.5 17.7 16.8 15.8 14.9 14.0 13.0 12.0
29.0 20.5 19.7 18.8 18.0 17.2 16.2 15.3 14.3 13.4
30.0 21.6 20.9 20.1 19.2 18.3 17.5 16.6 15.6 14.7
31.0 22.8 22.0 21.1 20.4 19.6 18.7 17.8 17.0 16.1
32.0 23.9 23.1 22.4 21.6 20.8 20.0 19.1 18.2 17.3
33.0 25.0 24.2 23.5 22.7 22.0 21.1 20.3 19.5 18.6
34.0 26.1 25.4 24.7 23.9 23.1 22.3 21.6 20.7 19.9
35.0 27.2 26.5 25.8 25.0 24.3 23.5 22.7 21.9 21.1
36.0 28.3 27.6 26.8 26.1 25.5 24.7 23.9 23.1 22.3
37.0 29.4 28.7 28.0 27.3 26.5 25.8 25.1 24.3 23.0
38.0 30.5 29.8 29.1 28.4 27.7 27.0 26.2 25.5 24.7
39.0 31.5 30.8 30.2 29.5 28.8 28.1 27.4 26.7 25.9
40.0 32.6 32.0 31.3 30.6 29.9 29.2 28.5 27.8 27.0
Note: Dew-point temperature for intermediate values of dry bulb and/ or
depression of wet bulb are to be worked out be interpolation.
81
TABLE - VIII
6.8 Conversion of Temperature Readings on the Fahrenheit Scale to the Celsius
(Formerly Centigrade) and Absolute Scales
O F O
C O
A O
F O
C O
A O
F O
C O
A
0
-17.8
255.2
18
-7.8
265.2
36
2.2
275.2
1
-17.2
255.8
19
-7.2
265.8
37
2.8
275.8
2
-16.7
256.3
20
-6.7
266.3
38
3.3
276.3
3
-16.1
256.9
21
-6.1
266.9
39
3.9
276.9
4
-15.6
257.4
22
-5.6
267.4
40
4.4
277.4
5
-15.0
258.0
23
-5.0
268.0
41
5.0
278.0
6
-14.4
258.6
24
-4.4
268.6
42
5.6
278.6
7
-13.9
259.1
25
-3.9
269.1
43
6.1
279.1
8
-13.3
259.7
26
-3.3
269.7
44
6.7
279.7
9
-12.8
260.2
27
-2.8
270.2
45
7.2
280.2
10
-12.2
260.8
28
-2.2
270.8
46
7.8
280.8
11
-11.7
261.3
29
-1.7
271.3
47
8.3
281.3
12
-11.1
261.9
30
-1.1
271.9
48
8.9
281.9
13
-10.6
262.4
31
-0.6
272.4
49
9.4
282.4
14
-10.0
263.0
32
0.0
273.0
50
10.0
283.0
15
-9.4
263.6
33
+0.6
273.6
51
10.6
283.6
16
-8.9
264.1
34
1.1
274.1
52
11.1
284.1
17
-8.3
264.7
35
1.7
274.7
53
11.7
284.7
82
O
F O
C O
A O
F O
C O
A O
F O
C O
A
54
12.2
285.2
77
25.0
298.0
100
37.8
310.8
55
12.8
285.8
78
25.6
298.6
101
38.3
311.3
56
13.3
286.3
79
26.1
299.1
102
38.9
311.9
57
13.9
286.9
80
26.7
299.7
103
39.4
312.4
58
14.4
287.4
81
27.2
300.2
104
40.0
313.0
59
15.0
288.0
82
27.8
300.8
105
40.6
313.6
60
15.6
288.6
83
28.3
301.3
106
41.1
314.1
61
16.1
289.1
84
28.9
301.9
107
41.7
314.7
62
16.7
289.7
85
29.4
302.4
108
42.2
315.2
63
17.2
290.2
86
30.0
303.0
109
42.8
315.8
64
17.8
290.8
87
30.6
303.6
110
43.3
316.3
65
18.3
291.3
88
31.1
304.1
111
43.9
316.9
66
18.9
291.9
89
31.7
304.7
112
44.4
317.4
67
19.4
292.4
90
32.2
305.2
113
45.0
318.9
68
20.0
293.0
91
32.8
305.8
114
45.6
318.6
69
20.6
293.6
92
33.3
306.3
115
46.1
319.1
70
21.1
294.1
93
33.9
306.9
116
46.7
319.7
71
21.7
294.7
94
34.4
307.4
117
47.2
320.2
72
22.2
295.2
95
35.0
308.0
118
47.8
320.8
73
22.8
295.8
96
35.6
308.6
119
48.3
321.3
74
23.3
296.3
97
36.1
309.1
75
23.9
296.9
98
36.7
309.7
76
24.4
297.4
99
37.2
310.2
83
TABLE - IX
6.9 Conversion of Nautical Miles to Statute Miles and Kilometres
Nautical Miles
Statute Miles
Kilometers
Nautical Miles
Statute Miles
Kilometers
1
1.2
1.9
10
11.5
18.5
2
2.3
3.7
20
23.0
37
3.
3.5
5.6
30
34.5
56
4.
4.6
7.4
40
46.1
74
5.
5.8
9.3
50
57.6
93
6.
6.9
11.1
60
69.1
111
7.
8.1
13.0
70
80.6
130
8.
9.2
14.8
80
92.1
148
9.
10.4
16.7
90
103.6
167
100
115.2
185
Based on Nautical Mile of 6, 080 feet.
TABLE - X
6.10 Conversion of Feet to Metres
Feet
Metres
Feet
Metres
Feet
Metres
Feet
Metres
1
0.30
10
3.05
100
30.5
1000
305
2
0.61
20
6.1
200
61
2000
610
3
0.91
30
9.1
300
91
3000
910
4
1.22
40
12.2
400
122
4000
1220
5
1.52
50
15.2
500
152
5000
1520
6
1.83
60
18.3
600
183
6000
1830
7
2.13
70
21.3
700
213
7000
2130
8
2.44
80
24.4
800
244
8000
2440
9
2.74
90
27.4
900
274
9000
2740
10000
3050
84
7 REFERENCES
1. IMD Ship Weather codebook –1982
2. WMO Publication No 306 Volume lI. Manual on codes.
3. Turbowin software 3.0
85
Fig
.
4
86
APPENDIX 1
Fig . 4 (contd)
87
88 Fig . 4 (contd)
Fig . 4 (contd)
89
AP
PE
ND
IX
2
AP
PE
ND
IX 2
Fig 6 - Meteorological regions and zones for transmission of ships‟ weather messages.
90
