System concept for the next-generation spaceborne precipitation radars

The 13.8-GHz Precipitation Radar (PR) aboard the US/Japan Tropical Rainfall Measuring Mission (TRMM) satellite is the first rain profiling radar ever launched into space. A TRMM follow-on mission, called the Global Precipitation Mission (GPM), is currently planned to extend and to improve the TRMM acquired rainfall data set. One of the key components of the GPM science instrumentation is an advanced, dual-frequency rain mapping radar. In this paper, we present a system concept for this second-generation spaceborne precipitation radar (PR-2) for the GPM. The key PR-2 system consists of: (1) a 13.6/35 GHz dual frequency radar electronics that has Doppler and dual-polarization capabilities; (2) a large but lightweight, dual-frequency, wide-swath scanning, deployable antenna; (3) digital chirp generation and the corresponding on-board pulse compression scheme to allow a significant improvement on rain signal detection without using the traditional, high-peak-power transmitters and without sacrificing the range resolution; (4) an approach to adaptively scan the antenna so that more time can be spent to observe rain rather than clear air; and (5) the built-in flexibility on the radar parameters and timing control such that the same radar can be used by different future rain missions.