Comparison of the Results of Two Limited-Area Models (Eta and MM5) for the Case Study Over Iran

This paper presents preliminary results of the numerical simulation of weather systems over Iran using the mesoscale model of Eta and compares the results with that of MM5 modeling system. It is to be mentioned and stressed that the comparison made here is in no way comprehensive and does not show anything about the weaknesses or strengths of any of the two mentioned models. The experiments were designed to see the consistency of the Eta model outputs over Iran being compared with that of MM5 and the experiment was based upon using an almost arbitrary and already set up configuration of the models. In this case study, a very active weather system, which occurred over Iran and affected the region from 25 to 28 March 2003 was selected for simulation. Main outputs of the two models including mean sea level pressure, geopotential heights at 500 and 850 hPa levels and cumulative precipitation were both examined with a verifying analysis. In general a fairly good agreement and consistency of the Eta model results were seen. Results of simulations made by the two models for geopotential height at 850 hPa level showed a reasonable agreement among themselves and also with the verifying analysis. A 24-hour forecasts of precipitation with MM5 showed a fairly good agreement with the corresponding observation but in case of Eta a slight under prediction in the west and over prediction in the North of Iran is quite evident.