THE USE OF TRMM PR DATA TO ESTIMATE BIAS OF OPERATIONAL RADAR DATA AND TEMPORAL FLUCTUATION OF BIAS

Abstract

The interest of this study is to estimate bias error of operational ground-based radar (GR) data by comparison with coincident data from Precipitation Radar (PR) onboard the Tropical Rainfall Measuring Mission (TRMM) satellite. The methodology of comparison is presented. Three-dimensional distribution of reflectivity factor on the Cartesian grid system is constructed by transformation and interpolation of volume scanning GRdata. The interpolation uses both horizontal and vertical effective radius. The interpolated data yieldsvalues of reflectivity factor at PR-based grid points under the assumption that observations by the TRMM PR are vertical pointing. Such a procedure gives a chance for comparison between data from two separate plathomes. Analysis indicates that the GR used in this study tends to observe less reflectivity factor than the TRMM PR. This tendency is not height-dependent. However, the temporal fluctuation of bias is also found from analysis for 13 rain events occurred during about a year. This is an auxiliary result, which demonstrates the stability of the calibration of the GR system for each short period.