Sensitivity of WRF model simulations to physical parameterization over the Persian Gulf and Oman Sea during summer monsoon

The proper parameterizations of exchange processes between air and sea are critically important in better predictions of the atmosphere and ocean characteristics using numerical simulations. These exchanges mainly include sensible, latent and momentum fluxes between the two media. Using numerical weather prediction models is a common way to prepare input data for the numerical ocean models. The meteorological data obtained by this method are often used as forcing for the ocean models. For semi-enclosed seas like the Persian Gulf, using meso-scale numerical weather prediction models are preferred. The Weather and Research Forecasting (WRF) model is one of the most popular scientific and operational numerical weather prediction models that has been widely used in many studies and projects. In the present work, sensitivity to the choice of different physical parameterizations in WRF model simulations have been studied over the Persian Gulf and Oman Sea for the period of 2011 summer monsoon. Monsoon is the most important phenomena that affects the meteorology of the Oman Sea and the Persian Gulf.
The main domain of the model is selected from Arvandrood in the northern Persian Gulf, to the northern part of the Indian Ocean. To provide the initial and boundary data for the WRF model simulations, the FNL data from NCEP are used. The Simulations are carried out for a period starting from the beginning to the end of summer monsoon of the Indian Ocean in 2011. To run the model for a given period of time, namely 7 days, the time period is divided into daily periods. Then, the model is run for every 1.25 days (30 hours) with 6 hours of spin up. When the daily (1.25 days) simulations are done, the first 6 hours of individual simulations are discarded and the resulting daily simulations are concatenated to form a pseudo-continuous dataset. Different choices of physical parameterizations are used to create nine WRF model configurations. The parameters simulated include temperature, humidity and wind velocity for nine different configurations of parameterization schemes. Then the results are compared with the meteorological observations of the coastal and island synoptic stations of I.R. of Iran Meteorological Organization (including Abumoosa, Bushehr, Jask, Qeshm, Khark, and Chabahar), Chabahar buoy and WINDSAT satellite data. To compare results of the model with the satellite data, six points (three in Persian Gulf and three in Oman Sea) are selected. The time interval between two successive observations is three hours for the synoptic stations, one hour for the Chabahar Buoy, and the satellite data are gathered two times per day. The amount of absolute, relative and “root mean square errors” (RMSE) of wind speed at 10 m height, the dry bulb and dew point temperatures at 2 m height are calculated. The results show that configuration No. 3 including Lin microphysics, MRF planetary boundary layer, Kain–Fritsch cumulus convection, RRTM longwave radiation, Goddard shortwave radiation, Revised-MM5 surface layer and NOAH land surface produce less error for temperature and humidity parameters, and configuration No. 2 including Lin microphysics, ACM2 planetary boundary layer, Kain–Fritsch cumulus convection, RRTM longwave radiation, Goddard shortwave radiation, Pleim–Xiu surface layer and land surface had the least error for simulation of surface wind speeds.