Impact of resolution on regional climate modeling in the source region of Yellow River with complex terrain using RegCM3

Abstract

This paper presents results from a 20-year (1990–2009) simulation by RegCM3 with both 45- and 15-km horizontal resolutions. The research focuses on the source region of Yellow River and its surrounding area, which is located on the northeast edge of the Tibetan Plateau with its very complex topography. Driven by the ECMWF ERA-interim reanalysis data, RegCM3 displays reasonable ability to reproduce the spatial patterns, annual cycles, and the interannual variabilities of regional surface climate, though the model shows wet and cold bias. The model’s performance is more close to observation for the source region of Yellow River than the other part of the analysis region, and the application of high resolution of 15 km demonstrates better skill with less bias for mean climate and larger correlation coefficients for interannual variability at most stations. However, the high-resolution simulation shows little advantage for reproducing the variations of precipitation and surface air temperature with altitude. The RegCM3 model also generally reproduces the probability distribution functions (PDFs) of surface climate and, consequently, the occurrence of climatic extremes and extreme indices. The simulation with high resolution again proves to be more reliable to generate climatic extremes over complex terrain of the source region of the Yellow River, related to its better representation of complex terrain and local processes.