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ARS Home » Pacific West Area » Boise, Idaho » Northwest Watershed Research Center » Research » Publications at this Location » Publication #96710
Title: QUANTIFICATION OF PRECIPITATION MEASUREMENT DISCONTINUITY INDUCED BY WIND SHIELDS ON NATIONAL GAUGES

Author
item YANG, DAQING - INST GLOBAL CHNG RES
item GOODWIN, BARRY - ATMO ENV SER ONTARIO CANA
item Hanson, Clayton

Submitted to: Water Resources Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/18/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: Because of the need for precipitation sets that can be used for hydrological studies that are international in scope, the World Meteorological Organization (WMO) established a study to determine snowfall catch relationships between precipitation gages that are used by several countries. Various combinations of wind shields and national precipitation gauges commonly used in countries of the Northern hemisphere have been studied in this paper, using the combined intercomparison data collected at 14 sites during the WMO Solid Precipitation Measurement Intercomparison Project. One of the test sites was established by the U.S. Department of Agricultural- Agricultural Research Service on the Reynolds Creek Experimental Watershed in southwest Idaho in the fall of 1987 and operated through the spring of 1994. The results show that wind shields improve gauge catch of precipitation particularly for snow. Shielded gauges, on average, measure 20-70% more snow than unshielded gauges. Without a doubt, the use of wind shields on precipitation gauges has introduced a significant discontinuity into precipitation records particularly in cold and windy regions. This discontinuity is not constant and it varies with wind speed, temperature and precipitation type. Adjustment for this discontinuity is necessary to obtain homogenous precipitation data for climate change and hydrological

Technical Abstract: Various combinations of wind shields and national precipitation gauges commonly used in countries of the Northern Hemisphere have been studied using the combined intercomparison data collected at 14 sites during the WMO Solid Precipitation Measurement Intercomparison Project. The results show that wind shields improve gauge catch of precipitation particularly for snow. Shielded gauges, on average, measure 20-70% more snow than unshielded gauges. Without a doubt, the use of wind shields on precipitation gauges has introduced a significant discontinuity into precipitation records particularly in cold and windy regions. This discontinuity is not constant and it varies with wind speed, temperature and precipitation type. Adjustment for this discontinuity is necessary to obtain homogenous precipitation data for climate change and hydrological studies. The relation of the relative catch ratio (RCR, ratio of measurements of shielded gauge to unshielded gauge) versus wind speed and temperature has been developed for Alter and Tretyakov wind shields. Strong linear relations between measurements of shielded gauge and unshielded gauge have also been found for different precipitation types.