Examining the Consistency of Precipitation Rate Estimates between the TRMM and GPM Ku-Band Radars

For over 20 years, precipitation measurement has continued with spaceborne radars including the Precipitation Radar (PR) operating at 13.8 GHz on the Tropical Rainfall Measuring Mission and the Ku-band Precipitation Radar (KuPR) operating at 13.6 GHz on the Global Precipitation Measurement mission core satellite. PR and KuPR have essentially the same hardware designs and the same algorithm to make standard products (PRV8 and KuPRV06, respectively). The surface precipitation rate estimates (R) and related variables are statistically compared between PR and KuPR for a common observation area (within 35 degrees N and 35 degrees S) and period (April to September 2014). Due to the difference in sensitivity, the total precipitation amount recorded by KuPR is larger than recorded by PR by approximately 1.3%. For heavy precipitation, PR shows a smaller measured radar reflectivity factor (Z(m)) and a larger R than KuPR. Z(m) is affected by the attenuation and it is smaller for PR than KuPR, as the frequency is slightly higher. The attenuation corrected radar reflectivity factor is almost the same for PR and KuPR. However, the adjustment factor is larger for PR, which results in a larger R. Direct comparison between PR and KuPR during matchup cases demonstrates similar results.

Automated summary

The study compares the estimation of precipitation and related variables between PR and KuPR for a common observation area and period. It is found that KuPR records a larger total precipitation amount than PR due to differences in sensitivity, and for heavy precipitation, PR shows a smaller radar reflectivity factor and a larger precipitation estimate.