Effect of spatial resolution on the simulation of regional precipitation in China in a global climate model.

摘要

In order to evaluate the consequences of climate change for agriculture and the economy we need to develop climate models capable of correctly simulating regional precipitation patterns. The deficiency of global climate models in the simulation of orographic precipitation may be related to the crudeness of model topography. Inadequacies in the parameterizations of physical processes cause additional errors in the calculation of orographic as well as frontal precipitation. In this study, we have investigated the role of model resolution in simulating the geographical distribution of precipitation over China. Comparisons are made between observations and the calculated precipitation fields in a seasonal run with climatological sea surface temperatures. This study describes results for June and July from 12 month simulations of the ECMWF model at the following four resolutions: T21 (5(times)5 degree), T42 (3(times)3 degree), T63 (2(times)2 degree) and T106 (1(times)1 degree). A description of this model is given by Simmons et. al. (1988). The various resolutions of the ECMWF model are virtually identical with the exception of the gravity wave drag (Palmer et al. 1986), vertical diffusion coefficients and orography. The T21 resolution lacks gravity wave drag completely.