Wallops/RainStat

Radiometer instruments of increasingly sophisticated capability continue to be a primary means for estimating rainfall intensity on a global basis from satellites. The "footprint" of area on the earth's surface observed by these passive space-borne instruments is generally several kilometers across. Within this footprint, rainfall intensity may vary considerably, and the variability leads to significant errors in rainfall estimate retrievals applied to the satellite data. To help assess the magnitude of these errors, NASA has contracted NOAA/ETL to operate its ground-based NOAA/D X-band radar to quantify the small-scale variability of rain. The project is motivated by needs for improved algorithms to analyze data from a new version of the Advanced Microwave Scanning Radiometer (AMSR) that will be flown aboard the international EOS-PM "Aqua" satellite mission to be launched in December 2000. NOAA/ETL conducted initial tests in Colorado in September 1999 to demonstrate the radar's ability to obtain the necessary measurements and to develop analysis techniques for the rainfall statistics. A more extensive follow-on field effort will be conducted in the spring of 2001 using the same radar at Wallops Island, Virginia. In addition to collecting rainfall statistics, the radar's polarization capabilities will be employed to test methods for improving the accuracy of radar estimates of rain intensity, extending the ETL work conducted earlier for TRMM and Rain-X. See the poster for a more detailed description of the polarization technique.