Detecting and Simulating Urban Modifications on Rainfall Using Satellite Observations and NCAR CAM/CLM2

Menglin Jin

Background and Rational

Understanding of urban effects on rainfall is far from complete. First, most of the previous research used the ground observations to study one or few selected cities. However, urban effects vary with the micro-scale features of individual city. Globally studying urban climate is necessary in order to generalize the most important characters of urban effects. Second, previous studies, via different approaches, reached rather controversial understanding on urban-rainfall relations. It is reported that urban reduces rainfall due to cloud microphysics (Rathemanthen et al. 2001), although other studies showed that urban enhances the intensity of storm significantly and increases downward rainfall (Huff and V ogel 1978, Changnon 1978, Shepherd et. al. 2002). Third, urban simulation is one of the weakest parts of current land surface modeling (Bonan, 2002 personal communication). As one extreme example of land cover and land use changes due to human activities, urban climate must be precisely understood and predicted (Changnon 1992, IPCC 2001).