Skill of ECHAM4.5 and Regional Spectral Model In Capturing the Circulation Pattern and Seasonal Rainfall over Sudan

Abstract

In this study, the general circulation model ECHAM4.5 out put data has been evaluated to see whether the model is capable for simulating Sudan’s seasonal rainfall and the circulation patterns. Here we have compared ECHAM4.5 circulation pattern with the National Centers for Environmental Prediction (NCEP) reanalysis data. The simulated seasonal rainfall is compared with CRU rain data set and the rain gauges. The Regional Spectral Model (RSM) developed at the National Center for Environmental Prediction (NCEP) has been utilized to generate 10-year (1990-1999) ensembles of ten model hindcast simulations at horizontal spacing of 55 km. The ECHAM4.5 (GCM), at T42 horizontal grid spacing provides lateral boundary forcing to the RSM. The performance of the RSM in capturing Sudan Seasonal rainfall has been evaluated. Precipitation from GCM and RSM are compared with one another and with the station observed data. ECHAM4.5 has shown good skill in simulating the circulation pattern of the main rainy season June –August, especially for the driest and wettest years. RSM has better spatial distribution of the seasonal rainfall, where as ECHAM4.5 has over estimated the seasonal rainfall. RSM has reduced the percentage errors of the simulated seasonal rainfall.