Effect of the Application of the Different Convection Parameterization Schemes and Spatial Resolutions on the Performance of RegCM Model in Simulating Precipitation, Temperature, and Actual Evapotranspiration (Case Study: Lake Urmia Basin)

The regional climate models play an important role in simulating the atmospheric and land surface processes and are considered as an important tool in climatic studies. Aimed at comparing the performance of the different convection parameterization schemes (Emanuel, Tiedtke, Kain-Fritsch, Grell-AS and Grell-FC) in simulating precipitation, temperature and actual evapotranspiration over the Lake Urmia Basin, this study employed the RegCM4.5 model for downscaling the outputs of NNRP1 model for a 5-year period. Moreover, the effect of application of two different spatial resolutions was investigated. The results showed that for the 48 km resolution, the Kain-Fritsch scheme, with a slight difference from the Grell-AS and the Grell-FC, had the highest performance in simulating precipitation and actual evapotranspiration and the Grell-AS scheme had the highest performance in simulating temperature. In the case of 12 km resolution, the difference among stations in terms of the most appropriate convection scheme for simulating precipitation was high; but in the case of temperature, the Kain-Fritsch showed the superiority. Also, the comparison of the results for two spatial resolutions showed that, in most cases, application of the 12 km resolution resulted in no improvement in the simulation performance. Thus, the application of the Kain-Fritsch scheme and the 48 km resolution are recommended for the Lake Urmia Basin.