383
Global Precipitation Estimation and Applications
combination of data from the TMPA rain products, NASA Shuttle Radar Topography
Mission, and other global geospatial data sets such as the United Nations Food and
Agriculture Organization soil property, MODIS land use, and land cover types. Shown
in Figure 15.5b is the hydrograph of Nzoia Basin in Kenya for flood monitoring.
15.5 CONCLUSIONS
Over the past half century, rapid development of satellite remote sensing techniques
has provided better precipitation quantification over regions with limited or no
ground measurements. Since the launch of TRMM (http://trmm.gsfc.nasa.gov) in
1997, we have witnessed the unprecedented development of various new satellitederived precipitation products with quasiglobal coverage. TRMM was the first satellite dedicated to rainfall measurement and is the only satellite that carries IR, VIS,
and passive/active MW sensors. Now in its 13th year, the TRMM mission has provided a wealth of knowledge on severe storms and short-duration climate shifts such
as El Niño. Successes of the TRMM warrant a future ambitious GPM mission being
launched in 2013 (http://gpm.gsfc.nasa.gov).
As a prelude to GPM, TRMM has exceeded expectations; however, the mission
has inherent limitations of spatiotemporal coverage and limited sensitivity to frozen
precipitation. A critical element driving the scientific objectives of GPM is to understand which scientific problems TRMM has not been able to address. The GPM
mission is an international space network of satellites designed to provide the nextgeneration precipitation observations from LEO MW sensors every 2–4 h anywhere
in the world. GPM consists of both a defined satellite mission concept and ongoing
scientific collaboration involving the global community. The GPM concept centers
on the deployment of a “core” observatory carrying advanced active and passive
MW sensors in a non-Sun-synchronous orbit to serve as a physics observatory to
gain insights into precipitation systems and as a calibration reference to unify and
refine precipitation estimates from a constellation of research and operational satellites. When multiple spacecraft are used in conjunction with these active and passive
remote sensing instruments, the spatial and temporal coverage of global precipitation observations will be improved in the GPM era. It is also expected that future
GPM algorithms will be able to fully characterize uncertainties at certain space and
time scales, as desired by users. Such a complete error characterization does not currently exist and is undoubtedly the great challenge facing the community.
ACKNOWLEDGMENTS
The authors acknowledge the funding support granted by NASA Headquarters
(Grant NNX08AM57G) and the computational facility provided by the Remote
Sensing Hydrology Laboratory (http://hydro.ou.edu) at the University of Oklahoma.
REFERENCES
Adler, R. F. and Negri, A. J. (1988). A satellite infrared technique to estimate tropical convective and stratiform rainfall. Journal of Applied Meteorology, 27, 30–51.
Global Precipitation Estimation and Applications
combination of data from the TMPA rain products, NASA Shuttle Radar Topography
Mission, and other global geospatial data sets such as the United Nations Food and
Agriculture Organization soil property, MODIS land use, and land cover types. Shown
in Figure 15.5b is the hydrograph of Nzoia Basin in Kenya for flood monitoring.
15.5 CONCLUSIONS
Over the past half century, rapid development of satellite remote sensing techniques
has provided better precipitation quantification over regions with limited or no
ground measurements. Since the launch of TRMM (http://trmm.gsfc.nasa.gov) in
1997, we have witnessed the unprecedented development of various new satellitederived precipitation products with quasiglobal coverage. TRMM was the first satellite dedicated to rainfall measurement and is the only satellite that carries IR, VIS,
and passive/active MW sensors. Now in its 13th year, the TRMM mission has provided a wealth of knowledge on severe storms and short-duration climate shifts such
as El Niño. Successes of the TRMM warrant a future ambitious GPM mission being
launched in 2013 (http://gpm.gsfc.nasa.gov).
As a prelude to GPM, TRMM has exceeded expectations; however, the mission
has inherent limitations of spatiotemporal coverage and limited sensitivity to frozen
precipitation. A critical element driving the scientific objectives of GPM is to understand which scientific problems TRMM has not been able to address. The GPM
mission is an international space network of satellites designed to provide the nextgeneration precipitation observations from LEO MW sensors every 2–4 h anywhere
in the world. GPM consists of both a defined satellite mission concept and ongoing
scientific collaboration involving the global community. The GPM concept centers
on the deployment of a “core” observatory carrying advanced active and passive
MW sensors in a non-Sun-synchronous orbit to serve as a physics observatory to
gain insights into precipitation systems and as a calibration reference to unify and
refine precipitation estimates from a constellation of research and operational satellites. When multiple spacecraft are used in conjunction with these active and passive
remote sensing instruments, the spatial and temporal coverage of global precipitation observations will be improved in the GPM era. It is also expected that future
GPM algorithms will be able to fully characterize uncertainties at certain space and
time scales, as desired by users. Such a complete error characterization does not currently exist and is undoubtedly the great challenge facing the community.
ACKNOWLEDGMENTS
The authors acknowledge the funding support granted by NASA Headquarters
(Grant NNX08AM57G) and the computational facility provided by the Remote
Sensing Hydrology Laboratory (http://hydro.ou.edu) at the University of Oklahoma.
REFERENCES
Adler, R. F. and Negri, A. J. (1988). A satellite infrared technique to estimate tropical convective and stratiform rainfall. Journal of Applied Meteorology, 27, 30–51.