WMO Field Intercomparison of Thermometer Screens/Shields and Humidity Measuring Instruments: Ghardaïa, Algeria, November 2008 – October 2009
The WMO Combined Intercomparison of Temperature Screens/Shields in Conjunction with Humidity Measuring Instruments was carried out in Ghardaïa, Algeria from November 2008 to October 2009, at the kind invitation of the Algerian Meteorological Service and under the leadership of CIMO. This intercomparison allowed testing the performance of the instruments in desert conditions, in a dry, hot and dusty environment. It was planned to carry out a follow-up intercomparison of similar instruments in an arctic environment at a later stage. The main objectives of this intercomparison were to gain knowledge on the performance characteristics and operational factors of radiation screens/shields and humidity sensors. This included especially the reliability, accuracy and long-term stability of tested humidity sensors and the estimation of impact of radiation, wind speed, precipitation on humidity measurements inside the different screens/shields. An International Organizing Committee was set up to determine and agree on the rules of the intercomparison and to support its preparation and execution. The IOC was also tasked to agree on the procedures used for the evaluation of the results and to review and agree on their presentation in the final report of the intercomparison. This report presents in a detailed manner the procedures followed for the data acquisition and the analysis and a comparison of the performance of the instruments relative to the reference. It also contains datasheets for each of the participating instruments, which provide exhaustive information on their performances throughout the intercomparison period, and as a function of different parameters. A number of recommendations were drawn from the results and are directed to users (such as the type of shields to be preferred in desert conditions), to manufacturers, as well as to CIMO for its future activities and conduction of the follow-up intercomparison in arctic environment.
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