Analyzing the Role of Polar Vortex on Daily Extreme Precipitation in the Northwest of Iran

The polar vortex oscillation is one of the prominent manifestations of troposphere and stratosphere interaction, which plays an important role on the climate extremes. Therefore, in the present study, the concept of linking the daily extreme precipitation with the polar vortex and its control effect on synoptic systems was analyzed in the temporal-spatial analysis of the polar vortex at north-west stations of Iran. In this study, according to the statistic-synoptic approach, at first, the homogeneity of precipitation data and precipitation trend of all six stations were examined by linear regression test. 6 components explaining 90% of the data variance were identified in order to analyze the companionship and awareness of the trajectory and the effect of polar vortex on the studied stations, the location of the polar vortex investigated by T-type principal component analysis. Then, the position of vortex in each of these patterns was investigated by considering the polar vertex reagent contour in the geo-potential elevation maps of 500 hPa level. 6 general patterns were recognized by analyzing temporal and spatial position of the vertex during the given days in which spatial position, the extension and depth of the ridges were different. The highest positioning of the vertex was seen in the first pattern and the ridges obtained from vertex had the highest depth and expanse on the Black Sea. In all patterns, the daily extreme precipitation was caused by the placement of the receiving vessel from the polar vortex on the required area, which was due to the establishment of the massive Rex and Omega dams on Europe.