The Status of Satellite-Based Climate Rainfall Observations

Abstract

A number of satellite and merged satellite/in-situ rainfall datasets have been developed extending as far back as 1979. While the availability of global rainfall data covering over two decades and encompassing two major El Niño events is a valuable resource for a variety of climate studies, significant differences exist between many of these products. Unfortunately, issues such as availability often determine the use of a product for a given application instead of an understanding of the relative strengths and weaknesses. Because all satellite rainfall retrieval algorithms make assumptions regarding the cloud structure and microphysical properties, systematic changes in the assumed parameters between regions and/or over time may result in regional and/or temporal biases in the rainfall estimates. These biases tend to be relatively small compared to random errors in the retrieval, however, when random errors are reduced through spatial and temporal averaging, as is the case for climate applications, they become the dominant source of error. To help researchers attempting wade through the vast array of climate rainfall products currently available we have developed a Climate Rainfall Data Center (CRDC). The CRDC web site (rain.atmos.colostate.edu/CRDC) provides climate researchers information on the various rainfall datasets available as well as access to experts in the field of satellite rainfall retrievals to assist them in the appropriate selection and use of these products.