Application of Regional Climate Model-RegCM4 in the Analysis of Synoptic Structure of July 2000 Heat Wave in Khuzestan Province

Synoptic analysis of the structure of heat waves in Khuzestan province is the main purpose of the present study. Statistical and synoptic analysis and dynamic downscaling technique were used to identify the atmospheric circulation structure in the time of the emergence of a heat wave in the area. To this end, daily maximum temperature during the warm period (June to September) for 13 synoptic stations in the southwest of Iran with different statistical length were taken from the Iran Meteorological Organization.
Based on the statistical analysis results, 1 July 2000 was identified as the hottest day in the selected hottest heat wave in the period of study, and therefore this day was selected for exact investigation and dynamic downscaling.
The results of synoptic analysis showed that the intense subsidence heating that occurred in the selected day had two causes: At the surface of the earth, a low pressure situation with the origin in thermal low pressures of the Gange, Arabian Peninsula and Persian Gulf and West Asians independent subtropical high pressure at 500 hpa level; and warm air advection fluxes to the study area, both in low latitudes and Iran dry areas. The RegCM4 dynamic downscaling results indicated that at the earth surface, there is a strong low pressure on the Zagros and there exists a strong typical ridge at upper levels. This strong typical ridge caused dry adiabatic subsidence and created intense heating. This study revealed that the Zagros high Pressure (ridge) has obvious role in the emergence of heat waves and intensification in Khuzestan.