Operational Testing of Various Precipitation Sensors in Support of the United States Climate Reference Network (USCRN)

The U.S. Climate Reference Network (USCRN) is a NOAA sponsored network which is being implemented to provide climate data for climate monitoring and other applications. Reliable, high quality precipitation data are necessary to detect climate change and to validate climate projections and climate models. Approximately 100 CRN sites are being installed nationwide. NCDC (National Climate Data Center) has conducted field tests of various precipitation gauges and shields in support of the CRN network since November 2003. These tests have been conducted at research sites at Sterling, VA and at Johnstown, PA. Precipitation gauges being evaluated include the GEONOR, Frise, OTT AWPAG, TB3 and non recording 8 inch gauges. The GEONOR and OTT gauges are weighing gauges while the Frise and TB3 are tipping bucket gauges. Various gauge shields are evaluated including the Alter, Double Alter, Tretyakov and SDFIR (Small Double Fence Inter-Comparison Reference). Results of gauge and gauge/shield comparisons are shown. Results differentiated by temperature and other parameters are also included. Comparisons for 5 minute and 60 minute maxima are presented. The performance of the GEONOR gauge, selected as the primary CRN gauge, is of particular interest. Site layouts are included and a summary of gauge shield effectiveness is also included.