Comparison of Rain Gauge Measurements in Mid-Atlantic Region

As part of the NASA Tropical Rainfall Measuring Mission ground validation program, a mid-latitude coastal ground validation site has been operating in the Mid-Atlantic region for over a year. The site includes 20 tipping bucket rain gauge stations within 15-150 km of National Weather Service (NWS) S-band Doppler radar (KAKQ), located at Wakefield, Virginia. With the guidance of the NWS Wakefield Office, the gauge stations were collocated with seven Automated Surface Observing Systems (ASOS) and six co-op sites. In addition, we had four gauge stations near state agency weather stations, one at a municipal airport weather station, and one at a newly developed Climate Reference Network (CRN) site. We deployed triple gauges at each site except at ASOS sites where dual gauge platforms were situated. Operational NWS and other agencies weather station gauges are often employed in validating radar rainfall estimation and hydrological studies. The accuracy of operational gauge measurements was determined by applying a statistical package to daily and monthly gauge rainfall measurements. Our results showed that co-op gauges have a high percent of error on both daily and monthly scale, while the error margins of ASOS gauges had a wide range depending on the site. An independent study of tipping bucket performance was conducted at NASA Wallops Island, Virginia where dual tipping bucket gauges from three different vendors were operated about three months. The low cost and high performance of Met One gauges seems to be the best choice for long-term operation at remote sites.