Ground validation of radar reflectivity and rain rate retrieved by the TRMM precipitation radar Original Research Article

The National Space Development Agency of Japan (NASDA) has calibrated and validated radar reflectivity and rain rate retrieved by the Tropical Rainfall Measurement Mission (TRMM) Precipitation Radar (PR) based on the data of operational meteorological radars and the field campaign. Well-calibrated radars and disdrometers demonstrated good agreement with PR within 1 to 2dBZ accuracy and are quite stable. Some ground-based radars exhibited quantitatively higher values than PR, and others were, lower values. Therefore we could not get as good agreement with ground-based radards as expected. PR-estimated rain rates were compared with ground-based rain-gauge data and radar-based rain data on an instantaneous and a monthly basis. So far, PR estimates are lower than ground-based measurements. There is also a seasonal dependence of rain intensity estimated by PR 2A25. The sampling error may not be as large as it had been feared. It is necessary to take statistics to determine the amounts of sampling errors at various area sizes.