Reduction of discontinuity due to the orbit boost in TRMM Precipitation Radar product for climate studies

The Precipitation Radar (PR) on the TRMM satellite has observed tropical rainfall for more than 15 years. The long-term rainfall data from TRMM PR have been very useful for scientific studies. However, several studies have shown that the amount of weak convective rainfall decreased in the PR product due to the TRMM orbit boost from 350 km to 402.5 km in August 2001. In this study, the impact of the sensitivity degradation on the rainfall amounts is estimated by adjusting the pre-boost data with a simulation of reduced sensitivity by the orbit boost. A PR precipitation product with reduced artificial discontinuity at the timing of the orbit boost is produced for climate studies. The result shows that the decrease of the global rainfall amount due to the sensitivity is about 2.1% on average. However, the decreases of rainfall amount due to the sensitivity degradation vary spatially and they are larger, in particular, in subtropical ocean.