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.