Evaluation of the effect of Siberia’s high pressure extension on daily minimum temperature changes in Iran

Abstract

One of the climatic phenomena that affects low temperatures in Iran is the penetration of tongues of high pressures from Siberia during the cold period of the year. Therefore, in order to investigate the effect of Siberia’s high pressure on the occurrence of low temperatures in Iran, air pressure at sea level for the region from 45 to 125°E and 25 to 65°N within the time range of one day and the location range of 2.5°, 561 grids for the month of December from the years 1948 to 2010 was extracted from the NOAA website and evaluated. It is necessary to explain that all pressure data for the studied range were classified into clusters using statistical analysis. Seven of these clusters were chosen as dominant. Of these, three prominent, important patterns, including clusters 3, 4, and 6, together account for 62.26 % our records in during December. In these three patterns, the effect of Siberia’s high pressure on the occurrence of low temperatures in Iran during December is more visible compared to the other patterns. On the other hand, simultaneous with the occurrence of the fourth cluster, with 99 % of Iran’s entire area, the maximum area of the country experiences below-average temperatures, and simultaneous with the occurrence of the second cluster, only 3 % of the entire area of Iran experiences below-average temperatures during December. In addition, we discovered a significant trend of increasing temperatures for most of the clusters in Iran, which can be attributed to global warming.