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Estimating the Uncertainty in Passive-Microwave Rain-RetrievalsCurrent passive-microwave rain-retrieval methods are largely based on databases built off-line using cloud models. The vertical distribution of hydrometeors within the cloud has a large impact on upwelling brightness temperatures ([31,[5]). Thus, a forward radiative transfer model can predict off-line the radiance associated with different rain scenarios. To estimate the rain from measured brightness temperatures, one simply looks for the rain scenario whose associated radiances are closest to the measurements. To understand the uncertainties in this process, we first study the dependence of the simulated brightness temperatures on different hydrometeor size distribution (DSD) models. We then analyze the marginal and joint distributions of the radiances observed by the Tropical Rainfall Measuring Mission satellite and of those in the databases used in the TRMM rain retrievals. We finally calculate the covariances of the rain profiles and brightness temperatures in the TRMM passive-microwave database and derive a simple parametric model for the conditional uncertainty, given measured radiances. These results are used to characterize the uncertainty inherent in the passive-microwave retrieval.
Document ID
20000053111
Acquisition Source
Jet Propulsion Laboratory
Document Type
Other
Authors
Coppens, Dorothee (California Inst. of Tech. Pasadena, CA United States)
Haddad, Ziad (Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA United States)
Im, Eastwood (Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA United States)
Date Acquired
September 7, 2013
Publication Date
January 1, 1997
Subject Category
Meteorology And Climatology
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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