Vaisala news 147

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vaisalanews_147_1998 Vaisala's customer magazine. Vaisala News discusses applications where Vaisala's products, solutions and services are in use. It also contains scientific articles written by external experts and other current news items

Text of Vaisala news 147

  • To maintain its high safety standards, Volvohas extensive facilities for testing new models.Vaisalas weather monitoring equipmentinforms test drivers about the ambient weath-er conditions.

    Three new AUTOSONDEs were installedin Australia last year; one of them is situatedin the desert-like Cobar region.

    Using informationprovided by VaisalasIceCast ice predictionsystem and extensiveThermal Mapping,the BirminghamAirport takes preven-tive action to avoidice formation on criti-cal runway surfaces.

    2 147/19982

    Contents3 Presidents Column

    4 New Calibration ProcedureOptimizes RS90 RadiosondePerformance

    7 CAL4 Ensures Accurate RadiosondeCalibration

    8 Promising Pilot Test Results of theNew RS90 Radiosonde in Vienna

    11 New AUTOSONDE Installations inAustralia

    12 JMA Upgrades Three ASAPSounding Systems

    13 MAWS Automatic WeatherStations

    15 Important Step Towards OpenCommunication

    16 Ambitious Upgrading Project inHungary

    20 Volvos Proving Ground: Safety on the Tracks

    22 MILOS 500 Data Collection SystemSupports Marine Research

    23 A Vital Tool for Fire and RescueOperations

    Cover photo:Lehtikuva/Sipa Image

    Editor-in-Chief:Marit Finne

    Publisher:Vaisala Oyj, P.O. Box 26FI-00421 Helsinki,FINLAND

    Phone (int.):(+358 9) 894 91

    Telefax:(+358 9) 894 9227


    Design and Artwork:Non-Stop Studiot Oy

    Editors:Axioma Oy

    Printed in Finland bySvypaino, Finland

    ISSN 1238-2388

    Vaisala in Brief

    We develop, manufacture and marketproducts and services for environmentaland similar industrial measurements. Purpose of those measurements is to pro-vide basis for better quality of life, cost sav-ings, protection of environment, improvedsafety and performance.

    25 AW11 Provides Olympic WeatherReporting

    25 Sustainable Development RequiresGreater Understanding of GlobalClimate Systems

    27 The 78th AMS Meeting:Maturing Our Predictive Capability

    29 Vaisalas Global ICE Activities

    30 New Predictive Road ConditionMonitoring for Flanders

    32 Finlands Traffic Management Centre

    34 Ice Warning System Improves TrafficSafety in Moscow

    36 Latvia Expands Its Road WeatherInformation System

    37 Ice and Fog Warning Systems inAustralia

    38 New Ice Prediction System for theBirmingham Airport

    40 The Worlds Southernmost IceCastInstallation

    43 New ICE Customers

    43 Key Personnel in the ICE Group

    We focus on market segments where wecan be world leaders, as the preferred sup-plier. We pay high attention on customersatisfaction. Our main market quality disci-pline is Product Leadership. Competitiveadvantage is enhanced by economies ofscale and scope.

  • 3147/1998

    Presidents Column

    hen people developsomething new either procedures orproducts there are

    usually three common themes:simplification, automation andintegration. The same is truefor weather observations. Vai-sala has always looked boldlyto the future, aiming to createnew products that offer addedvalue to our customers. Insteadof simply comparing one prod-uct to another, we look at mar-ket needs from a wider perspec-tive.

    Today, full automation ofupper air observations is a factof life. As the many operativeAUTOSONDE systems haveproved, our concept is reliableand efficient. This technologyhas set a new standard for ourvision of the observation net-work in the next millennium.

    Radiosonde product genera-tions seldom change. New prod-ucts must represent significantadvances before it is worth-while to verify their perfor-mance. After years of researchand development work, we arenow launching a new-genera-tion RS90 radiosonde. All the

    sensors in the RS90 radiosondeare new. The accuracy of tem-perature measurements hasbeen improved significantly,humidity measurements revivequickly after exposure to icyconditions, and the pressuresensor maintains its accuratecalibration even in harsh envi-ronments. To optimize the per-formance of these sensors andachieve the greatest benefitfrom them, we have integratedcompletely new calibrationequipment in our radiosondeproduction. This was a majorchallenge because we set muchhigher demands than those fortraditional weather chambers.

    Mini Automatic WeatherStations (MAWS) represent anew way of thinking aboutweather station structure. Thecompact design and easy con-figuration of the MAWS arebrand new. Although mostapplications are in the opera-tive weather services field, theMAWS will no doubt findusers in new applications re-quiring real-time weather meas-urements.

    Road and airport runway sys-tems for ice and fog warning

    are now used in many locationsin both the Northern andSouthern hemispheres. The im-plementation of these systemshas created new models forwinter maintenance. Whereverthey are used, these systems seta new standard for operations.

    A new standard is also need-ed for the quality of the globalweather observation network.To improve our understandingof climate variation andchanges, we have to build evenbetter models of climate behav-ior. This requires input fromresearch, and correspondingly,better weather observations interms of geographical coverage,time and measurement param-eters. The financial input need-ed for continuous develop-ment must be impressed on thenational authorities, who shouldalso be involved in the devel-opment of the new standard.

    Pekka KetonenPresident and CEO

    Setting New Standards


  • 4 147/1998

    When development of the new-generation RS90radiosonde began, the decision was made tooptimize the calibration process and equipmentused with it. The goal was to take full advantageof the advanced features of the entirely new pres-sure, temperature and humidity sensor of thenew radiosonde. The following article describesVaisalas state-of-the-art calibration process forradiosonde sensors. It also discusses the factorsaffecting the uncertainty of radiosonde measure-ments. All the information included is based onthe texts cited in the references.

    The CAL4 has four pressurechambers with constant tempera-ture and variable air pressure.The nominal temperatures are+60, +25, -33, and -72 C. TheRS90 pressure sensors are cali-brated at nominal pressure lev-els of 1080, 900, 800, 600, 400,200, 100, 50, 20 and 2 hPa.

    A fifth order polynomial pres-sure calibration curve is fitted toten pressure calibration points at+25 C. The temperature de-pendence is calculated as thedeviation from the +25 C cali-bration.

    The CAL4 has seven cham-bers dedicated to temperaturecalibration. The RS90 tempera-ture sensors are calibrated attemperature levels of -90, -72, -52, -33, -6, +25, and +60 C.The fifth order polynomial is fit-ted to the seven temperature cali-bration points. The RS90 hu-midity sensors are calibrated at atemperature of +25 C in fourchambers at nominal humiditiesof 0, 30, 60 and 90% RH. Thesecond order polynomial is fit-ted through these four measure-ment points. The temperaturedependence correction is doneand checked in a chamber with anominal temperature of -33 C.

    Ari Paukkunen, Ph. Lic. (Phys.)Project ManagerUpper Air DivisionVaisala Helsinki, Finland

    New Calibration Procedure Optimizes RS90 Radiosonde


    aisalas new CAL4radiosonde calibra-tion equipment wasspecifically designed

    for the RS90 radiosonde. Theresult is a state-of-the-art calibra-tion system that meets the high-est performance standards,offering high accuracy with lowshort-term and long-term uncer-tainties. In the developmentprocess, the following require-ments for a good industrial cali-bration system were carefullyconsidered:

    Individual calibration ofeach sensor with sensorelectronics

    Accurate and unbiasedmathematical modeling ofthe sensors

    Stable and well character-ized calibration chambers

    Internationally traceablelow uncertainty workingreferences and instruments

    Computer aided test (CAT)instrument set-up

    High level of automation

    The structure of the CAL4calibration machine.


  • 5147/1998

    Temperature dependence wastested to be unlinear as a func-tion of temperature accuratelyand accurately enough linear as afunction of humidity.

    References forradiosonde calibration

    The quality of CAL4 calibra-tions is controlled by repeatingthe calibration of a test sampleafter one day, and after 1, 2, 4, 6,8, 12, and 24 months.

    In addition, an independentmeasurement system is used tomonitor and specify the calibra-tion uncertainty. The third andmore stringent cross-checkingmethod is a flight simulationtest for a completed radiosonde.This is done in an environmen-tal chamber with variable pres-sure, temperature and humidity.

    Working references forradiosonde calibration with theCAL4

    A complete range of pressuresensors is used as working refer-ences for each pressure cham-ber, while a separate ambientpressure reference is used to meas-ure the stability of these sensorsduring the process. When everthe control limit is exceeded,immediate test actions are done.

    The working references arecalibrated at the MeasurementStandards Laboratory (MSL) atVaisala Finland (ref. 1). The pres-sure range of the working refer-ences is from 0 to 1100 hPa. Thecalibration is repeated every 12months. The ambient pressurereference is calibrated at MSLfrom 950 hPa to 1050 hPa at 6month intervals.

    Each of the seven tempera-ture chambers has nine refer-ence sensors. Each set of ninethermistors is calibrated at 7

    points in the range of 3 Cabout the chamber nominal tem-perature. The thermistors are cali-brated at MSL at 6 month in-tervals.

    A set of dewpoint meters isused as a working reference forhumidity. The dewpoint metersare calibrated at MSL at 12month intervals. The calibration