WMO Solid Precipitation Measurement Intercomparison- …

1 W O R L D M E T E O R O L O G I C A L O R G A N I Z A T I O NINSTRUMENTS AND OBSERVING METHODSR E P O R T No. 67 WMO/TD - No. 8721998 WMO Solid Precipitation MEASUREMENTINTERCOMPARISONFINAL Goodison and Louie (both Canada)and D. Yang (China)NOTEThe designations employed and the presentation of material in this publication do not imply the expression of anyopinion whatsoever on the part of the Secretariat of the World Meteorological Organization concerning the legal statusof any country, territory, city or area, or of its authorities, or concerning the delimitation of its frontiers or report has been produced without editorial revision by the WMO Secretariat. It is not an official WMO publicationand its distribution in this form does not imply endorsement by the Organization of the ideas WMO Solid Precipitation Measurement Intercomparison was started in the northern hemispherewinter of 1986/87.

2 The field work was carried out in 13 Member countries for seven years. TheIntercomparison was the result of Recommendation 17 of the ninth session of the Commission forInstruments and Methods of Observation (CIMO-IX).As in previous WMO intercomparisons of rain gauges, the main objective of this test was to assessnational methods of measuring Solid Precipitation against methods whose accuracy and reliability wereknown. It included past and current procedures, automated systems and new methods of observation. Theexperiment was designed to determine especially wind related errors, and wetting and evaporative losses innational methods of measuring Solid Precipitation . The aim was to derive standard methods for adjusting solidprecipitation measurements and to introduce a reference method of Solid Precipitation Measurement forgeneral use to calibrate any type of Precipitation report is a consolidation of data and information from the most challenging intercomparisonorganized by WMO so far to determine the in situ performance characteristics of instruments.

3 Various typesof national gauges were compared at 26 test sites in different climatic regions during at least 5 winterseasons against a commonly agreed reference design which was not previously used to the goal of the test, the magnitude of the systematic errors in the Measurement of solidprecipitation is now clearly documented. This is very important for research in the field of climate , methods for adjusting current and historical archive data have been derived which Memberscan test and, if needed, adapt to their own equipment and conditions. Although this intercomparison providesvaluable information on how best to improve the measurements of not only Solid Precipitation but also of rain,one must continue to address the problem of determining the required algorithm for correcting datacontaining systematic errors to which all measurements may be subject.

4 Specific attention should be given toidentification of problems in measuring Precipitation with automatic should like to place on record the gratitude of CIMO to the managements, the national ProjectLeaders, the numerous scientists, and the operational staffs of all participating Members which were activelyinvolved in this lntercomparison. The contributors came not only from the national services but also fromother institutions that operated some of the test also should like to acknowledge the significant work done by the members of the InternationalOrganizing Committee (IOC) responsible for the preparation and proper conduct of the trial as well as fordetermining the best procedures for evaluation of the results and their presentation.

5 Finally, I express mygreat appreciation to Dr. Goodison (Atmospheric Environment Service of Canada), the Chairman of theIOC and the Project Leader of the whole Intercomparison for his dedicated work and his efforts in bringingtogether all the national data needed for this report and for ensuring that they be evaluated and presented inthe very clear manner that can be seen in this comprehensive report. In addition to this I would like to thankthe staff of AES involved in this work for the significant support they provided in the evaluation of national testresults and for the preparation of this am confident that Members of WMO and others will find this report very useful, especially forimproving the Measurement of Solid Precipitation .

6 It should contribute to the homogeneity of national datasets so that a better regional and global compatibility of the long-term data series might be achieved. (Dr. J. Kruus) President of the Commision forInstruments and Methods Observation(B L A N K P A G E)TABLE OF CONTENTSPAGEACKNOWLEDGEMENTSEXECUTIVE SUMMARYiCHAPTER 1 OF Precipitation Measurement OF WORKING NETWORK REFERENCE 2 OF THE COLLECTION AND OBSERVATION ANALYSIS12 CHAPTER 3 SUMMARY DESCRIPTION OF SITES, INSTRUMENTSAND DATA OF SITE DESCRIPTIONS AND OF DATA ARCHIVE17 CHAPTER 4 RESULTS AND AND DATA OF DATA TRETYAKOV Precipitation NIPHER SNOW 8 STANDARD NON-RECORDING 5 AUTOMATION OF WINTER 6 CONCLUSIONS AND 7 DEMONSTRATION AND IMPLEMENTATIONS OF : ADJUSTMENT OF Precipitation ARCHIVE FOR THENORTHWEST TERRITORIES (NWT) : AN OPERATIONAL SYSTEM FOR CORRECTINGPRECIPITATION FOR THE AERODYNAMIC.

7 APPLICATION OF Precipitation CORRECTION,GERMAN METEOROLOGICAL SERVICE, BUSINESS : OPERATIONAL CORRECTION OF : APPLICATIONS OF THE WIND-BIAS ASSESSMENTS TOPRECIPITATION DATA IN USA AND GLOBAL ARCHIVES73 REFERENCES77 BIBLIOGRAPHY83 GLOSSARY87 ANNEXESACKNOWLEDGEMENTSThe WMO Solid Precipitation Measurement Intercomparison has been successfully completed through thecontribution, dedication and commitment of many individuals and agencies. The Intercomparison was unique,with 16 countries participating at over 25 sites. The tireless work of participants who established andoperated sites over a number of years, analyzed the data and contributed to writing reports and papers isgratefully acknowledged. The people who had direct contact with the Organizing Committee are listed addition, there were numerous observers at the experimental sites whose dedication to acquiring qualitydata was essential for the success of the Intercomparison.

8 Thanks is extended to the agencies whichprovided staff to work on this study and who funded the establishment and operation of sites. I extend specialthanks to my own agency, the Atmospheric Environment Service, Canada, for its support of thisIntercomparison, especially for the special funding required to establish the digital data base for the are due to John Metcalfe for overseeing the preparation of this data support of the President, Executive and members of CIMO throughout this Intercomparison is acknowl-edged. We would not have succeeded without their on-going guidance, questions and suggestions. Thanksto my colleagues on the International Organizing Committee of the Intercomparison: Boris Sevruk, ValentinGolubev, and Thilo G nther for their on-going support.

9 The preparation of the report has been a majorundertaking; it would not have been possible without the dedicated work of Paul Louie and Daqing Yang. Itrust that it meets Members' , I wish to extend special thanks to the WMO Secretariat who made sure that we stayed on course andaddressed the issues. Klaus Schulze, and his predecessor Stephan Klemm, ensured our meetings werefocussed and relevant; they brought their own special expertise to the problems being discussed; they madesure that all countries concerns were considered. The Intercomparison would not have succeeded withouttheir guidance. Thank GoodisonChairman, International Organizing CommitteeWMO Solid Precipitation Measurement of ParticipantsCanadaBarry GoodisonPaul LouieJohn MetcalfeRon HopkinsonChinaDaqing YangErsi KangYafen ShiCroatiaJanja MilkovicDenmarkHenning MadsenFlemming VejenPeter AllerupFinlandEsko ElomaaReijo HyvonenBengt TammelinAsko TuominenS.

10 HuovilaIndiaN. Mohan RaoB. BandyopadhyayVirendra KumarCol AgarwalGermanyThilo G ntherJapanMasanori ShirakiHiroyuki OhnoKotaro YokoyamaYasuhiro KominamiSatoshi InoueNorwayEirik F rlandRomaniaViolete CopaciuRussian FederationValentin GolubevA. SimonenkoSlovakiaMiland LapinSwedenBengt DahlstromSwitzerlandBoris SevrukFelix BlumerVladislav Ne porUKJ. FullwoodR. JohnsonUSARoy BatesTimothy PangburnH. GreenanGeorge LeavesleyLarry BeaverClayton HansonAlbert RangoDouglas EmersonDavid LegatesP. GroismanWMOK laus SchulzeStephan Klemm102(B L A N K P A G E)iEXECUTIVE SUMMARYI ntroductionIn the spring of 1985, the International Workshop on Correction of Precipitation Measurement was held inZurich, Switzerland. One of the conclusions was a recommendation to the WMO to organize a SolidPrecipitation Measurement Intercomparison.