Sensitivity Analysis of Different Convection Schemes and Domain Centers For Numerical Simulation of Winter Precipitation Over Iran

This paper qualifies the impact of different convection schemes and domaincenters on the simulation of two dry and wet winter precipitations of 1997 and2000 over iran using regcm3 numerical climate model. the model uses acompressible, finite difference with hydrostatic equilibrium in sigma coordinateand a semi-implicit algorithm for reduction of horizontal diffzlsion. in thisst>ndy, sensitwity of the regcm3 regional climate model has been analyzedusing different convection schemes, including greli-a's, grell- fc, emanueland k uo schemes and different domain center locations including himalaya,mediterranean sea, han and indian ocean (near pakistan southern border).nnrpj data with a 5-degree resoluiion.os well as glcc and gtopo datasetare used as initial and boundary conditions. land use and topography data,respectively.we found that the perjorttuince of the model strongly depends on thelocation of the domain center, for example when the center of the domainis located over himalaya then the results for the precipitation are reasonobls;better especially when a siberian high pressure develops over iran. withk1w scheme.the minimum of bias and mae are -0.7mm and 0.6mm for dryyear of 2000, but with grell scheme the error is found to be a minimumcompared to other configurations of the model both in dry and wet seasons. inall experiments the precipitation amounts arc underestimated when comparedto corresponding observations. the largest difference occurred in himolau«experiment. moreovcr, we found that there is an eastward shift in caspian seaprecipitation patt.ern. in all experiments.it is also found that cru reanalysis data cannot be considered as areference for calibration of regcm3 over iran.