Sensitivity of the Regional Climate Models: The Role of the Convection Schemes

The objective of this paper is to study the sensitivity of the regional climate models to the utilized convection schemes when it is used to simulate the rainfall over a certain domain, Regional Climate Model (RegCM3), which has the advantages that the interactions at different scales can be well simulated and, has been employed to investigate the autumn 1994 rainfall over Egypt and more emphasis on the flash flood that hit Egypt on the late night of 31 of October to the 2nd of November 1994. The simulation period is from the 1st of August 1994 to the end of November 1994. Several model runs have been carried out using different convection schemes in an effort to investigate their performance in simulating the rainfall over the entire domai, in general, and more focusing over Egypt. The validation of the simulation output indicated that the RegCM3 is capable of simulating both the spatial patterns and magnitude of the rainfall over Egypt to some extent, and showed that the results were sensitive to the cumulus parameterization scheme choice. The model with the Grell cumulus parameterization scheme with Fritsch Chappell assumption simulated the process of the heavy rains case well; however, there are still some discrepancies between the simulations and observations. For example, the model cannot completely simulate the intensity, the location and the onset time of the rainfall