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Interannual Variability of Tropical Precipitation: How Well Do Climate Models Agree With Current Satellite Estimates?Since the beginning of the World Climate Research Program's Global Precipitation Climatology Project (GPCP) satellite remote sensing of precipitation has made dramatic improvements, particularly for tropical regions. Data from microwave and infrared sensors now form the most critical input to precipitation data sets and can be calibrated with surface gauges to so that the strengths of each data source can be maximized in some statistically optimal sense. Recent availability of the TRMM (Tropical Rainfall Measuring Mission) has further aided in narrowing uncertainties in rainfall over die tropics and subtropics. Although climate modeling efforts have long relied on space-based precipitation estimates for validation, we now are in a position to make more quantitative assessments of model performance, particularly in tropical regions. An integration of the CCM3 using observed SSTs as a lower boundary condition is used to examine how well this model responds to ENSO forcing in terms of anomalous precipitation. An integration of the NCEP spectral model used for the Reanalysis-H effort is also examined. This integration is run with specified SSTs, but with no data assimilation. Our analysis focuses on two aspects of inter-annual variability. First are the spatial anomalies that are indicative of dislocations in Hadley and Walker circulations. Second, we consider the ability of models to replicate observed increases in oceanic precipitation that are noted in satellite observations for large ENSO events. Finally, we consider a slab ocean version of the CCM3 model with prescribed ocean beat transports that mimic upwelling anomalies, but which still allows the surface energy balance to be predicted. This less restrictive experiment is used to understand why model experiments with specified SSTs seem to have noticeably less interannual variability in precipitation than do the satellite observations.
Document ID
20010020945
Acquisition Source
Marshall Space Flight Center
Document Type
Preprint (Draft being sent to journal)
Authors
Robertson, Franklin R.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Marshall, Susan
Roads, John
Oglesby, Robert J.
Fitzjarrald, Dan
Goodman, H. Michael
Date Acquired
August 20, 2013
Publication Date
January 1, 2001
Subject Category
Environment Pollution
Meeting Information
Meeting: Global Change and Climate Variations
Location: Albuquerque, NM
Country: United States
Start Date: January 15, 2001
End Date: January 19, 2001
Sponsors: American Meteorological Society
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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