Analyzing the Long-Term Changes in the Mediterranean-Red Sea Hybrid System

Different pressure centers and synoptic systems affect Iran's climate, and their changes can have significant climatic consequences. In this research, the trend of long-term changes in the number of coupled low-pressure of Mediterranean -Red Sea, as coupled low-pressure centers effective on Iran's rainy climate, was investigated. For this purpose, the geopotential height data of 1000 hp for the 40-year statistical period from 1987 to 2018 was extracted from the European Medium-Term Weather Forecast Center (ECMWF). In total, during this period, 97 low-pressure centers of the Mediterranean-Red Sea circulation were formed over the region. Based on the non-parametric method of chi-square test (chi-score), the trend of cyclone frequency changes was investigated. The results showed that during the investigated period, the number of coupled low-pressure of Mediterranean -Red Sea did not experience statistically significant changes in terms of decades and two semi-statistics. In examining changes on a smaller scale, cross-sectional changes were observed in four-year and two-year periods.