Title of Paper: Enabling Technologies for the Global Precipitation Measurement Mission

Principal Author: Mr. Christopher S. Ruf

Abstract: Global Precipitation Measurement (GPM) is an international mission intended to extend and improve on the performance of TRMM. Global, rather than tropical, coverage is provided by a polar orbit inclination. A reduction in temporal sampling from TRMM’s 15 hr to 3 hr will result from an integrated multi-platform approach. With these two improvements in sampling characteristics, GPM will extend the TRMM applications from climate assessment to more fully meet the needs of numerical weather prediction & data assimilation, the study of microphysical processes and mesoscale cloud models, prediction of snow & ice accumulation, and severe storm applications such as hurricanes and floods.

GPM will integrate the precipitation measuring capabilities offered by future AMSR and NPOESS/CMIS radiometers together with its own suite of precipitation-specific sensors. The GPM core spacecraft is an upgraded version of TRMM that will include a multi-channel precipitation radar and radiometer. Smaller constellation satellites will carry radiometer-only payloads at orbits that are specifically phased between AMSR, CMIS and the core platform in order to provide optimal temporal sampling. The Constellation Microwave Radiometers (CMRs) contain only a subset of the channels that are included in the core radiometer and use an electrically scanned synthetic aperture antenna to minimize impact to the spacecraft. The driving design priority with CMR is reduced recurring cost per platform in order to fly as many as possible and drive down the revisit time of the integrated GPM system. To this end, the Instrument Incubator Program has developed critical technologies needed to reduce recurring costs. These include MMIC-based “radiometers on a chip” and custom low power ASIC digital signal processing subsystems. Design and performance details of these technologies will be presented, together with their expected impact on the CMR sensor and the GPM mission as a whole.