PRODUCT USER MANUAL Global Ocean OSTIA Sea …cmems-resources.cls.fr/documents/PUM/CMEMS-OSI-PUM-010-011.pdf · PUM for Global Ocean OSTIA Sea Surface Temperature Reprocessing SST-GLO-SST-L4-REP-OBSERVATIONS-010-011

PRODUCT USER MANUAL

Global Ocean OSTIA Sea Surface Temperature Reprocessing

SST-GLO-SST-L4-REP-OBSERVATIONS-010-011

Issue: 3.5

Contributors: M. Martin, A. McLaren, J. Roberts-Jones, E. Fiedler, Met Office, UK.

CMEMS version scope : Version 1.0

Approval Date : October 22 2015

PUM for Global Ocean OSTIA Sea Surface Temperature Reprocessing


Ref: CMEMS-OSI-PUM-010-011

Date : October 22 2015

Issue : 3.5

© EU Copernicus Marine Service – Public Page 2/ 29

CHANGE RECORD

Issue Date § Description of Change Author Validated By

DRAFT 2 June 2011

All

First draft version, based on L3EUR PUM draft by Francoise Orain. Provided for the preparation of the POR for MyOcean V1

Matthew Martin

V2.0 9 november 2011

Use of latest template L. Crosnier

3.0 13 February 2013

All Dissemination changes for MyOcean V3, and update to latest template

A Sellar, N McConnell 3.0

3.1 14 November 2013

Updating to include the additional production of monthly and seasonal means

A. McLaren L. Crosnier

3.2 31 March 2014

Updating reference details, plus minor corrections


3.3 November 5 2014

Add Table1 describing datasets






Issue : 3.5


3.4 May 1 2015

all Change format to fit CMEMS graphical rules

L. Crosnier

3.5 22 October 2015

All Change MyOcean references to CMEMS

S. Good





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TABLE OF CONTENTS

I INTRODUCTION ......................................................................................................................................... 6

I.1 Scope of this document ............................................................................................................................... 6

I.2 The CMEMS project ................................................................................................................................... 6

I.3 Short introduction to the product .............................................................................................................. 6

I.4 History of the latest updates of the product .............................................................................................. 6

II Reference documents..................................................................................................................................... 7

III SST Level 4 rePROCESSING Processing Chain and Algorithms .......................................................... 8

III.1 Collection of inputs .................................................................................................................................. 8

IV Algorithms for L4 rePROCESSING production ........................................................................................ 10

IV.1.1 Quality control and pre-processing of input data ........................................................................ 10

IV.1.2 Bias correction of input satellite data .......................................................................................... 10

IV.1.3 Creation of the L4 analysis and error estimate ............................................................................ 11

IV.1.4 Creation of the anomaly field ..................................................................................................... 12

IV.1.5 Creation of the monthly and seasonal mean fields ...................................................................... 12

V Graphical examples of the L4 and anomaly products ................................................................................ 13

V.1.1 L4 products : SST, sea-ice concentration and error estimate ...................................................... 13

V.1.2 Anomaly product ........................................................................................................................ 15

VI Products Description ................................................................................................................................... 16

VI.1 Common characteristics ........................................................................................................................ 16

VI.2 L4 reprocessing products ....................................................................................................................... 17

VI.3 Anomaly reprocessing products ............................................................................................................ 17

VI.4 Monthly and seasonal products ............................................................................................................. 17

VII PRODUCT distribution ........................................................................................................................... 18

VII.1 Which Download mechanism is available for this product? ............................................................. 18

VII.2 Download a product through the CMEMS Web Portal Subsetter Service ..................................... 18

VII.3 Download a product through the CMEMS FTP Service .................................................................. 18

VIII NOMENCLATURE OF FILES ............................................................................................................. 19

VIII.1 Nomenclature of files when downloaded through the CMEMS Web Portal Subsetter Service ... 19

VIII.2 Nomenclature of files when downloaded through the CMEMS FTP Service ................................ 19

IX Annex 1 : description of file formats .......................................................................................................... 20

IX.1 Example header of a high resolution L4 reprocessing file .................................................................. 20

IX.2 Example header of an anomaly file ....................................................................................................... 22

IX.3 Example header of a monthly file ......................................................................................................... 25

IX.4 Example header of a seasonal file ......................................................................................................... 27





Issue : 3.5


GLOSSARY AND ABBREVIATIONS

CMEMS Copernicus Marine Environment Monitoring Service

MFC Monitoring and Forecasting Centre

Med Mediterranean

NetCDF Network Common Data Form

CF Climate Forecast (convention for NetCDF)

SSS Sea surface salinity.

SSC Sea surface currents

SSH Sea surface height

RMS Root mean square

SDN SeaDataNet (climatology)

CHL Chlorophyll

SLA Sea Level Anomalies

PC Production Center

PU Production Unit

Meridional Velocity West to East component of the horizontal velocity vector

Zonal Velocity South to North component of the horizontal velocity vector

ftp Protocol to download files

OpenDAP Open-Source Project for a Network Data Access Protocol. Protocol to download subset of data from a n-dimensional gridded dataset (ie: 4 dimensions: lon-lat,depth,time)

Subsetter CMEMS service tool to download a NetCDF file of a selected geographical box using values of longitude an latitude, and time range

PUM for OSTIA Level 4 SST reprocessing products over the global ocean


Ref: MYO-SST-PUM-010-011

Date : 31 March 2014

Issue : 3.2


I INTRODUCTION

I.1 Scope of this document

This is the Product User Manual describing the CMEMS SST reprocessed analysis (level 4) product over the global ocean (SST-GLO-SST-L4-REP-OBSERVATIONS-010-011) [RD.9], which was processed at the Met Office (UK). The manual covers: how it was created, its content, and which data

services are available to access it.

I.2 The CMEMS project

The main objective of the CMEMS project is to deliver and operate a rigorous, robust and sustainable Ocean Monitoring and Forecasting system to users for all marine applications: maritime safety, marine resources, marine and coastal environment and climate, seasonal and weather forecasting.

I.3 Short introduction to the product

The CMEMS OSTIA reprocessed analysis product is a satellite and in-situ foundation SST analysis created by the OSTIA (Operational SST and Ice Analysis) system using re-processed ATSR data, AVHRR Pathfinder data and in-situ data from ICOADS. The product is available from 1st January 1985 to 31st December 2007 on a global regular grid at 0.05° resolution. The CMEMS OSTIA reprocessed analysis product provides an estimate of the foundation SST which is the SST free of diurnal variability.

Additional information on the CMEMS OSTIA reprocessed analysis product is contained in [RD.9].

I.4 History of the latest updates of the product

11th November 2013:

Monthly and seasonal mean files of the reprocessed OSTIA SST analysis data have been produced and are available to users.





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II REFERENCE DOCUMENTS

Ref. Document Name

Document Reference

Issue

Date

[RD.3] The Recommended GHRSST-PP Data

Processing Specification

GDS (Version 1 revision 1.6)

http://www.ghrsst.org/files/download.php?

m=documents&f=GDS-v1.0-rev1.7.pdf

GHRSST/17 GDSv1 Revision 1.6

April 2005

[RD.9] Roberts-Jones, J., E. K. Fiedler, and M. J. Martin, 2012: Daily, Global, High-Resolution SST and Sea Ice Reanalysis for 1985-2007 Using the OSTIA System. J. Climate, 25, 6215-6232. doi: http://dx.doi.org/10.1175/JCLI-D-11-00648.1

Roberts-Jones et al., 2012.

n/a 2012





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III SST LEVEL 4 REPROCESSING PROCESSING CHAIN AND ALGORITHMS

Figure III.1 Schematic diagram of the OSTIA reprocessing processing chain at the UK Met Office.

The Operational Sea surface Temperature and Ice Analysis (OSTIA) reprocessing system has been run at the UK Met Office. Figure III.1 shows the different steps for the creation of the OSTIA reprocessing products. Each step of this processing is described below.

III.1 Collection of inputs

The following inputs are collected for input to the OSTIA reprocessing:

SST satellite data: A collection of the L2P data from a re-processed (A)ATSR series data-set, and L3 data from the PATHFINDER data-set are collected.

Satellite SST data sources ((A)ATSR, Pathfinder)

In situ SST data (ICOADS)

Sea-ice data (EUMETSAT OSI-SAF)

On-line storage and archive

Observations extraction, processing and QC

Satellite data bias correction

Objective analysis and error estimation

Previous day’s analysis with relaxation to climatology

Dissemination of GHRSST format L4 files and anomaly files.





Issue : 3.5


The (A)ATSR data are provided with Sensor Specific Error Statistics (SSES_bias and SSES_std variables) that give an estimate of the systematic and random errors at pixel level, and quality level flags. The Pathfinder data are provided with an estimate of the standard deviation within each pixel, and quality flags.

In situ SST data from ships, drifting and moored buoys are obtained from the ICOADS data-set.

Sea-ice concentration data, re-processed by the EUMETSAT OSI-SAF are used in the OSTIA reprocessing.

Climatologies: the SST climatologies used have been derived from the PATHFINDER SST 5-daily climatology produced by Casey and Cornillon (1999).

Figure III.2 Timeline of observational datasets used in the OSTIA reprocessing.





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IV ALGORITHMS FOR L4 REPROCESSING PRODUCTION

IV.1.1 Quality control and pre-processing of input data

All satellite and in situ SST data valid for a particular day, with a 24-hour overlap on the days either side, are extracted from the observation data-sets. The input SST data undergo various QC and processing steps:

Pathfinder data which have a quality flag of 4 and higher are accepted

ATSR-1 data with flags of 3, 4 and 5 are accepted. ATSR-2 and AATSR data with flag 5 are accepted.

ICOADS data which passed all their QC checks are accepted.

a diurnal check is carried out for (A)ATSR and ICOADS data whereby day-time data (determined using a solar zenith angle calculation) with a wind-speed of less than 6m/s are rejected.

the SSES biases supplied with the (A)ATSR data are removed from each pixel and the SSES standard deviation values are passed on to the next steps in the analysis chain.

for the AATSR data, a skin-to-bulk correction factor is applied.

IV.1.2 Bias correction of input satellite data

Satellite data can be biased for several reasons, including: atmospheric water vapour; atmospheric aerosol (dust); surface changes (e.g. extreme roughness); instrument calibration problems. These biases can lead to biases in the analysis if they are not treated in some way. OSTIA uses a bias correction system based on match-up statistics between satellite and reference measurements (which are assumed to be unbiased). The reference data-set is specified to be all in situ data and the ATSR-2/AATSR data. Bias corrections are carried out on the Pathfinder AVHRR data and the ATSR-1 data.

For each satellite observation type to be calibrated:

match-ups are calculated between each reference data point and the satellite data-set (valid on the same day) with a spatial radius of 25km.

A large scale objective analysis is calculated for each satellite observation type using the match-ups as pseudo-observations of the bias, and a background from the previous day’s bias analysis. The horizontal correlation scales are set to be 700km for this bias analysis.

The bias analysis field is interpolated back to the satellite observation locations, and the bias subtracted from the satellite observation.

The outcome of this process is a new version of the satellite data, which have been bias-corrected.





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IV.1.3 Creation of the L4 analysis and error estimate

The main SST analysis uses a persistence based approach based on the use of the previous

analysis field as a background with a relaxation to climatology. The background field ,

b

i kx at

grid point i and time k is defined as

, , , 1 , 1 ,( )b a c c

i k i k i k i k i kx x x x (1)

where ,i k is a scalar less than 1, , 1

a

i kx is the previous analysis, and ,

c

i kx is a reference

climatology valid for the same time of year as time k . For each grid point and at each

analysis time, a relaxation time scale is derived in order to determine ,i k . For ice-free areas

this time scale is 30 days. SSTs under ice with a concentration greater than 50% are relaxed toward 271.35 K with a shorter time scale. The time scale varies from ~17.5 days to ~5 days linearly with ice concentration from 50% to 100%. A digital Gaussian filter with a half-width of 4.7 km is applied to the background field to remove small scale noise.

The background field calculated using equation (1) and the bias corrected measurements (described previously) are then used to produce an analysis using a multi-scale Optimal Interpolation (OI) type scheme. An iterative procedure is used to calculate the OI solution that is both efficient and flexible when processing large numbers of observations. The system uses 10 iterations.

The background error covariance matrix used in the OI scheme is split into two components, one of which has spatial correlation scales specified as 10km and the other of which has spatial correlation scales of 100km. Both components of the error have spatially varying variances.

The observation error covariance matrix is assumed to be a diagonal matrix (observation errors are uncorrelated with each other). The diagonal elements are specified using the SSES standard deviation values supplied with the GHRSST data.

The observation operator is used to transform from the analysis grid to observation space. A number of different observation operators have been developed for use in OSTIA in order to represent the full range of satellite observation footprints. In the case of microwave data for instance, the observation footprint is larger than the model grid, and the background gridded values which fall within the observation footprint are used to estimate the model equivalent of the observation.

Each SST analysis value is accompanied by an uncertainty estimate. Various methods of approximating analysis error exist. The OSTIA system uses an analysis quality (AQ) optimal interpolation approach to produce this estimate. In this scheme, a second optimal interpolation analysis is performed that is identical to the main SST analysis except that all observations are given a value of 1.0, the background field is set to zero. The error estimates used in the main analysis (background and measurements) are preserved. This field is then combined with the background error variance estimates described above to produce an analysis error estimate at each grid point.





Issue : 3.5


IV.1.4 Creation of the anomaly field

The SST analysis field described in the previous section is interpolated to a ¼ degree latitude/longitude grid. The Pathfinder climatology for the relevant date (described in the “Inputs” section above) is then subtracted to produce an anomaly field.

IV.1.5 Creation of the monthly and seasonal mean fields

Monthly and seasonal means of the L4 analyses are produced by averaging the relevant daily data. Seasons are defined as: December-February; March-May; June-August; September-November. The daily SST analyses are first interpolated to a ¼ degree latitude/longitude grid and then the mean values are calculated. The standard deviation of the daily SST analyses over the month or season is also calculated and provided in the mean files. Additionally, the monthly mean and standard deviation of the daily sea ice concentration fields are also calculated.





Issue : 3.5


V GRAPHICAL EXAMPLES OF THE L4 AND ANOMALY PRODUCTS

V.1.1 L4 products : SST, sea-ice concentration and error estimate





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Figure V.1 Examples of outputs from the high resolution L4 OSTIA reprocessing product on 1st January 2000 (from top to bottom: analysed SST, sea-ice concentration, analysis error).





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V.1.2 Anomaly product

Figure V.2 Example of the ¼ degree resolution SST anomaly product on 1st January 2000.





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VI PRODUCTS DESCRIPTION

VI.1 Common characteristics

The format of SST files within CMEMS follows that defined by the GHRSST project. The GHRSST format specification, GDS 1.0, is used for the reprocessed files. Examples are shown in Annex 1.

The high resolution L4 and lower resolution anomaly products are delivered on a regular lat/lon grid, from 180 W to 180 E and 90 S to 90 N (at a 0.05° horizontal resolution for the high resolution product, and at 0.25° horizontal resolution for the anomaly product), in netCDF format. The files are available covering the period 1st January 1985 to 31st December 2007. The monthly and seasonal mean products are delivered on the same lower resolution grid as the anomaly product.

Dataset Name Description Standard name Unit Dimensions

METOFFICE-GLO-SST-L4-RAN-OBS-

SST

(High resolution, daily analysis)

analysed_sst analysed sea surface temperature sea_surface_foundation_temperature

kelvin (time, lat, lon)

sea_ice_fraction sea ice area fraction sea_ice_area_fraction 1 (time, lat, lon)

analysis_error estimated error standard deviation of analysed_sst sea_surface_temperature_error kelvin (time, lat, lon)

mask land sea ice lake bit mask (time, lat, lon)


ANOM

(Low resolution, daily anomalies)

sst_anomaly sea surface temperature anomaly from Pathfinder climatology - kelvin (time, lat, lon)




SST-MON

(Low resolution, monthly mean

analysis)



standard_deviation_sst standard deviation of analysed sea surface temperature standard_deviation_sea_surface_temperature


sea_ice_fraction sea ice area fraction sea_ice_area_fraction 1 (time, lat, lon)

standard_deviation_ice standard deviation of sea ice fraction standard_deviation_sea_ice_fraction

1 (time, lat, lon)

mask land sea ice lake bit mask (time, lat, lon)


SST-SEAS

(Low resolution, seasonal mean

analysis)



standard_deviation_sst standard deviation of analysed sea surface temperature standard_deviation_sea_surface_temperature


Table1: description of each dataset in product SST_GLO_SST_L4_REP_OBSERVATIONS_010_011.

http://www.ghrsst.org/files/download.php?m=documents&f=GDS2.0_TechnicalSpecifications_v2.0.pdf





Issue : 3.5


VI.2 L4 reprocessing products

The L4 product format specification is described in detail in the GHRSST format specification: GDS 1.0 (rev1.6). Annex 1 provides an example of the netCDF file header.

VI.3 Anomaly reprocessing products

The format for the anomaly product follows as much as possible the specification of the L4 products in [RD.3]. The attributes are the same as those for the L4 product. The changes are that an SST anomaly field is provided, and no error or sea-ice information is provided. Annex 1 provides an example of the netCDF file header.

VI.4 Monthly and seasonal products

The format for the monthly and seasonal products follows as much as possible the specification of the L4 products in [RD.3]. The attributes are the same as those for the L4 product. The changes are that a SST standard deviation is additionally provided, and no error is provided. There is also no sea ice information or mask data provided in the seasonal files. Annex 1 provides an example of the netCDF file header.

http://www.ghrsst.org/files/download.php?m=documents&f=GDS-v1.0-rev1.6.pdf

http://www.ghrsst.org/files/download.php?m=documents&f=GDS-v1.0-rev1.6.pdf





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VII PRODUCT DISTRIBUTION

VII.1 Which Download mechanism is available for this product?

The download mechanisms available for this product are:

Subsetter

Authenticated FTP

VII.2 Download a product through the CMEMS Web Portal Subsetter Service

You first need to register. Please find below the registration steps: http://marine.copernicus.eu/web/34-products-and-services-faq.php#1

Once registered, the CMEMS FAQ http://marine.copernicus.eu/web/34-products-and-services-faq.php will guide you on How to download a product through the CMEMS Web Portal Subsetter Service.

VII.3 Download a product through the CMEMS FTP Service

You first need to register. Please find below the registration steps: http://marine.copernicus.eu/web/34-products-and-services-faq.php#1

The ftp site is accessed using your CMEMS user name and password and the files are located in the

directory called SST-GLO-SST-L4-REP-OBSERVATIONS-010-011.

http://marine.copernicus.eu/web/34-products-and-services-faq.php#1

http://marine.copernicus.eu/web/34-products-and-services-faq.php

http://marine.copernicus.eu/web/34-products-and-services-faq.php

http://marine.copernicus.eu/web/34-products-and-services-faq.php#1





Issue : 3.5


VIII NOMENCLATURE OF FILES

The nomenclature of the downloaded files differs on the basis of the chosen download mechanism Subsetter or FTP service.

VIII.1 Nomenclature of files when downloaded through the CMEMS Web Portal Subsetter Service

Files nomenclature when downloaded through the CMEMS Web Portal Subsetter is based on product dataset name and a numerical reference related to the request date on the MIS.

The scheme is: datasetname-nnnnnnnnnnnnn.nc

where :

.datasetname is a character string within one of the following:

METOFFICE-GLO-SST-L4-RAN-OBS-SST

METOFFICE-GLO-SST-L4-RAN-OBS-ANOM

METOFFICE-GLO-SST-L4-RAN-OBS-SST-MON

METOFFICE-GLO-SST-L4-RAN-OBS- SST-SEAS

. nnnnnnnnnnnnn: 13 digit integer corresponding to the current time (download time) in milliseconds

since January 1, 1970 midnight UTC.

.nc: standard NetCDF filename extension.

Example:

METOFFICE-GLO-SST-L4-RAN-OBS-ANOM_1303461772348.nc

VIII.2 Nomenclature of files when downloaded through the CMEMS FTP Service

Files nomenclature when downloaded through the CMEMS FTP is based as follows:

20111108-UKMO-L4HRfnd-GLOB-v01-fv02-OSTIA.nc.bz2





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IX ANNEX 1 : DESCRIPTION OF FILE FORMATS

IX.1 Example header of a high resolution L4 reprocessing file

An example header of a high resolution L4 netCDF file (generated using ncdump) is given below. netcdf 20000101-UKMO-L4HRfnd-GLOB-v01-fv02-OSTIARAN {

dimensions:

lon = 7200 ;

lat = 3600 ;

time = 1 ;

variables:

int time(time) ;

time:long_name = "reference time of sst field" ;

time:standard_name = "time" ;

time:axis = "T" ;

time:calendar = "Gregorian" ;

time:units = "seconds since 1981-01-01 00:00:00" ;

float lat(lat) ;

lat:long_name = "latitude" ;

lat:standard_name = "latitude" ;

lat:axis = "Y" ;

lat:units = "degrees_north" ;

float lon(lon) ;

lon:long_name = "longitude" ;

lon:standard_name = "longitude" ;

lon:axis = "X" ;

lon:units = "degrees_east" ;

short analysed_sst(time, lat, lon) ;

analysed_sst:long_name = "analysed sea surface temperature"

;

analysed_sst:standard_name = "sea_surface_temperature" ;

analysed_sst:type = "foundation" ;

analysed_sst:units = "kelvin" ;

analysed_sst:_FillValue = -32768s ;

analysed_sst:add_offset = 273.15f ;

analysed_sst:scale_factor = 0.01f ;

analysed_sst:valid_min = -300s ;

analysed_sst:valid_max = 4500s ;

short analysis_error(time, lat, lon) ;

analysis_error:long_name = "estimated error standard

deviation of analysed_sst" ;

analysis_error:units = "kelvin" ;

analysis_error:_FillValue = -32768s ;

analysis_error:add_offset = 0.f ;

analysis_error:scale_factor = 0.01f ;

analysis_error:valid_min = 0s ;

analysis_error:valid_max = 32767s ;

byte sea_ice_fraction(time, lat, lon) ;





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sea_ice_fraction:long_name = "sea ice fraction" ;

sea_ice_fraction:standard_name = "sea_ice_area_fraction" ;

sea_ice_fraction:units = "1" ;

sea_ice_fraction:_FillValue = -128b ;

sea_ice_fraction:add_offset = 0.f ;

sea_ice_fraction:scale_factor = 0.01f ;

sea_ice_fraction:valid_min = 0b ;

sea_ice_fraction:valid_max = 100b ;

sea_ice_fraction:source = "EUMETSAT OSI-SAF" ;

byte mask(time, lat, lon) ;

mask:long_name = "sea/land/lake/ice field composite mask" ;

mask:_FillValue = -128b ;

mask:flag_values = 1b, 2b, 4b, 8b ;

mask:flag_meanings = "sea land lake ice" ;

mask:comment = "b0: 1=grid cell is open sea water\n",

"b1: 1=land is present in this grid cell\n",

"b2: 1=lake surface is present in this grid

cell\n",

"b3: 1=sea ice is present in this grid cell\n",

"b4-b7: reserved for future grid mask data" ;

// global attributes:

:Conventions = "CF-1.0" ;

:title = "OSTIA Sea Surface Temperature and Sea Ice

Analysis" ;

:DSD_entry_id = "UKMO-L4HRfnd-GLOB-OSTIARAN" ;

:references = "None" ;

:institution = "UK Met Office" ;

:contact = "[email protected]" ;

:GDS_version_id = "v1.0-rev1.7" ;

:netcdf_version_id = "3.6.0-p1 of May 24 2005 12:38:59 $" ;

:creation_date = "2010-11-07 UTC" ;

:product_version = "0.1" ;

:history = "Created from sst:temperature from

/data/nwp/ofrd/share/OSTIA/reanalysis/run/sguqe/STORE_20000101/20000101_sst

.nc; error:/data/nw

p/ofrd/share/OSTIA/reanalysis/run/sguqe/opdaily/datawg6/20000101-UKMO-

L4HRfnd-GLOB-v01-fv02-OSTIARAN_err.nc; sea

ice:/data/nwp/ofrd/share/OSTIA/reanalysis/r

un/sguqe/STORE_20000101/20000101_seaice.nc" ;

:spatial_resolution = "6 km" ;

:source_data = "Pathfinder AVHRR version 5, Reprocessed

(A)ATSR, ICOADS in situ" ;

:comment = "IMPORTANT usage statement.\n",

"Unless otherwise agreed in writing, these data may

be used for pure academic \n",

"research only, with no commercial or other

application and all usage must meet \n",

"the Met Office Standard Terms and Conditions,

which may be found here : \n",

"http://www.metoffice.gov.uk/corporate/legal/tandc.html . The data may be

used \n",





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"for a maximum period of 5 years. Reproduction of

the data is permitted provided \n",

"the following copyright statement is included:

\n",

"(C) Crown Copyright 2010, published by the Met

Office. \n",

"You must submit a completed reproduction license

application form (here \n",

"http://www.metoffice.gov.uk/corporate/legal/repro_licence.html ) before

using \n",

"the data. This only needs to be completed once for

each user.\n",

"WARNING Some applications are unable to properly

handle signed byte values. If values are encountered > 127, please subtract

256 fr

om this reported value" ;

:start_date = "2000-01-01 UTC" ;

:start_time = "00:00:00 UTC" ;

:stop_date = "2000-01-02 UTC" ;

:stop_time = "00:00:00 UTC" ;

:southernmost_latitude = -90.f ;

:northernmost_latitude = 90.f ;

:westernmost_longitude = -180.f ;

:easternmost_longitude = 180.f ;

:file_quality_index = 0 ;

IX.2 Example header of an anomaly file

An example header of an anomaly netCDF file (generated using ncdump) is given below.

netcdf 20000101-UKMO-L4LRfnd-GLOB-v01-fv02-OSTIARANanom {

dimensions:

time = UNLIMITED ; // (1 currently)

lat = 720 ;

lon = 1440 ;

variables:

short sst_anomaly(time, lat, lon) ;

sst_anomaly:_FillValue = -32768s ;

sst_anomaly:long_name = "sea surface temperature anomaly

from pathfinder climatology" ;

sst_anomaly:standard_name =

"sea_surface_temperature_anomaly" ;

sst_anomaly:type = "foundation" ;

sst_anomaly:units = "kelvin" ;

sst_anomaly:scale_factor = 0.01f ;

sst_anomaly:add_offset = 0.f ;

sst_anomaly:valid_min = -5000s ;

sst_anomaly:valid_max = 5000s ;







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analysed_sst:long_name = "analysed sea surface temperature"

;








int time(time) ;


time:units = "seconds since 1981-01-01 00:00:00" ;


time:axis = "T" ;


float lat(lat) ;




lat:axis = "Y" ;

float lon(lon) ;




lon:axis = "X" ;





sea_ice_fraction:units = "fraction" ;

sea_ice_fraction:scale_factor = 0.01 ;


sea_ice_fraction:standard_name = "sea_ice_fraction" ;



:title = "Low resolution regrid of OSTIA sst analysis" ;

:DSD_entry_id = "UKMO-L4LRfnd-GLOB-OSTIARANanom" ;






:creation_date = "2010-11-07\000 UTC" ;


:history = "Created from sst:temperature regridded with

area avg. to grid of temperature on new grid. analysed_sst from regridded

area avera

ge of the OSTIA analysis. OSTIA sst_anomaly from NODC/RSMAS AVHRR

Pathfinder Verison 5.0 Climatology regridded with area avg. \n",

"sea_ice_fraction interpolated data from EUMETSAT

OSI-SAF." ;

:grid_resolution = " 0.25000 degree" ;






Issue : 3.5


"Unless otherwise agreed in writing, these data may

be used for pure academic \n",

"research only, with no commercial or other

application and all usage must meet \n",

"the Met Office Standard Terms and Conditions,

which may be found here : \n",

"http://www.metoffice.gov.uk/corporate/legal/tandc.html . The data may be

used \n",

"for a maximum period of 5 years. Reproduction of

the data is permitted provided \n",

"the following copyright statement is included:

\n",

"(C) Crown Copyright 2009, published by the Met

Office. \n",



"http://www.metoffice.gov.uk/corporate/legal/repro_licence.html ) before

using \n",

"the data. This only needs to be completed once for

each user.\n",

"WARNING Some applications are unable to properly

handle signed byte values. If values are encountered > 127, please subtract

256 fr

om this reported value" ;

:start_date = "2000-01-01 UTC" ;


:stop_date = "2000-01-02 UTC" ;

:stop_time = "00:00:00 UTC" ;



:westernmost_longitude = 0.f ;







Issue : 3.5


IX.3 Example header of a monthly file

An example header of a monthly netCDF file (generated using ncdump) is given below.

netcdf \198601-UKMO-L4LRfnd-GLOB-v01-fv02-OSTIARANmonthly {

dimensions:

lon = 1440 ;

lat = 720 ;

time = 1 ;

variables:

int time(time) ;



time:axis = "T" ;


time:units = "seconds since 1981-01-01 00:00:00UTC" ;

float lat(lat) ;



lat:axis = "Y" ;


float lon(lon) ;



lon:axis = "X" ;



analysed_sst:long_name = "analysed sea surface temperature" ;









short standard_deviation_sst(time, lat, lon) ;

standard_deviation_sst:long_name = "standard deviation of

analysed sea surface temperature" ;

standard_deviation_sst:standard_name =

"standard_deviation_sea_surface_temperature" ;

standard_deviation_sst:units = "kelvin" ;

standard_deviation_sst:_FillValue = -32768s ;

standard_deviation_sst:add_offset = 0.f ;

standard_deviation_sst:scale_factor = 0.01f ;

standard_deviation_sst:valid_min = 0s ;

standard_deviation_sst:valid_max = 4500s ;







Issue : 3.5


sea_ice_fraction:standard_name = "sea_ice_fraction" ;

sea_ice_fraction:units = "fraction" ;


sea_ice_fraction:add_offset = 0.f ;

sea_ice_fraction:scale_factor = 0.01f ;



sea_ice_fraction:source = "EUMETSAT OSI-SAF" ;

byte standard_deviation_ice(time, lat, lon) ;

standard_deviation_ice:long_name = "standard deviation of sea

ice fraction" ;

standard_deviation_ice:standard_name =

"standard_deviation_sea_ice_fraction" ;

standard_deviation_ice:units = "fraction" ;

standard_deviation_ice:_FillValue = -128b ;

standard_deviation_ice:add_offset = 0.f ;

standard_deviation_ice:scale_factor = 0.01f ;

standard_deviation_ice:valid_min = 0b ;

standard_deviation_ice:valid_max = 100b ;

standard_deviation_ice:source = "EUMETSAT OSI-SAF" ;

byte mask(time, lat, lon) ;

mask:long_name = "sea/land/lake/ice field composite mask" ;

mask:_FillValue = -128b ;

mask:flag_values = 1b, 2b, 4b, 8b ;

mask:flag_meanings = "sea land lake ice" ;

mask:comment = "b0: 1=grid cell is open sea water\n",

"b1: 1=land is present in this grid cell\n",

"b2: 1=lake surface is present in this grid cell\n",

"b3: 1=sea ice is present in this grid cell\n",

"b4-b7: reserved for future grid mask data" ;



:title = "OSTIA Reanalysis Sea Surface Temperature and Sea Ice

Analysis" ;

:DSD_entry_id = "UKMO-L4LRfnd-GLOB-OSTIARANmonthly" ;








:spatial_resolution = "0.25 degree" ;

:source_data = "Pathfinder AVHRR version 5, Reprocessed multi-

mission (A)ATSR , ICOADS in-situ, Global sea ice concentration reanalysis

EUMETSAT OSI-SAF" ;


"Unless otherwise agreed in writing, these data may be

used for pure academic \n",

"research only, with no commercial or other application

and all usage must meet \n",





Issue : 3.5


"the Met Office Standard Terms and Conditions, which may

be found here : \n",

"http://www.metoffice.gov.uk/corporate/legal/tandc.html .

The data may be used \n",

"for a maximum period of 5 years. Reproduction of the

data is permitted provided \n",

"the following copyright statement is included: \n",

"(C) Crown Copyright 2011, published by the Met Office.

\n",



"http://www.metoffice.gov.uk/corporate/legal/repro_licence.html )

before using \n",

"the data. This only needs to be completed once for each

user.\n",

"WARNING Some applications are unable to properly handle

signed byte values. If values are encountered > 127, please subtract 256

from this reported value" ;

:start_date = "1986-01-01 UTC" ;


:stop_date = "1986-01-31 UTC" ;

:stop_time = "23:59:59 UTC" ;






}

IX.4 Example header of a seasonal file

An example header of a seasonal netCDF file (generated using ncdump) is given below.

netcdf \1985_JJA-UKMO-L4LRfnd-GLOB-v01-fv02-OSTIARANseason {

dimensions:

lon = 1440 ;

lat = 720 ;

time = 1 ;

variables:

int time(time) ;



time:axis = "T" ;


time:units = "seconds since 1981-01-01 00:00:00UTC" ;

float lat(lat) ;



lat:axis = "Y" ;


float lon(lon) ;





Issue : 3.5




lon:axis = "X" ;



analysed_sst:long_name = "analysed sea surface temperature" ;









short standard_deviation_sst(time, lat, lon) ;

standard_deviation_sst:long_name = "standard deviation of

analysed sea surface temperature" ;

standard_deviation_sst:standard_name =

"standard_deviation_sea_surface_temperature" ;

standard_deviation_sst:units = "kelvin" ;

standard_deviation_sst:_FillValue = -32768s ;

standard_deviation_sst:add_offset = 0.f ;

standard_deviation_sst:scale_factor = 0.01f ;

standard_deviation_sst:valid_min = 0s ;

standard_deviation_sst:valid_max = 4500s ;



:title = "OSTIA Seasonal Sea Surface Temperature" ;

:DSD_entry_id = "UKMO-L4LRfnd-GLOB-OSTIAseason" ;








:spatial_resolution = "0.25 degree" ;

:source_data = "OSTIA analysis files" ;


"Unless otherwise agreed in writing, these data may be

used for pure academic \n",

"research only, with no commercial or other application

and all usage must meet \n",

"the Met Office Standard Terms and Conditions, which may

be found here : \n",

"http://www.metoffice.gov.uk/corporate/legal/tandc.html .

The data may be used \n",

"for a maximum period of 5 years. Reproduction of the

data is permitted provided \n",

"the following copyright statement is included: \n",





Issue : 3.5


"(C) Crown Copyright 2013, published by the Met Office.

\n",



"http://www.metoffice.gov.uk/corporate/legal/repro_licence.html )

before using \n",

"the data. This only needs to be completed once for each

user.\n",

"WARNING Some applications are unable to properly handle

signed byte values. If values are encountered > 127, please subtract 256

from this reported value" ;

:start_date = "1985-06-01 UTC" ;


:stop_date = "1985-08-31 UTC" ;

:stop_time = "23:59:59 UTC" ;





:file_quality_index = 0 ;}

Documents

PRODUCT USER MANUAL Global Ocean OSTIA Sea …cmems-resources.cls.fr/documents/PUM/CMEMS-OSI-PUM-010-011.pdf · PUM for Global Ocean OSTIA Sea Surface Temperature Reprocessing SST-GLO-SST-L4-REP-OBSERVATIONS-010-011