Structural analysis and environmental factors affecting the formation of the Siberian high-pressure core in the Baikal and Balkhash lakes

The Siberian high-pressure system is one of the components of atmospheric circulation affecting the climate of Iran, especially in the cold season of the year. In this research, the place of the initial formation of this system and its synoptic features have been investigated. For this purpose, the lower tropospheric levels of atmospheric data for the three months December to February data from NCEP / NCAR were received for 22 years. Systems with thermal characteristics were isolated. Then, the central core of this system was determined daily for all months and their geographical coordinates were calculated. The results show that in the vast majority of the months from December to February, the main Siberian high-pressure core is located in the lower atmosphere of the Altai Mountains. The study also found that more than half of the days of Siberian high-pressure had two central nuclei. Thus, contrary to popular belief, the Siberian high-pressure core forms not on the low Siberian plains but the high altitudes of the Altai and Sayan Mountains. Adaptation of isothermal, isobaric, and height maps also showed that the core of the cold in the cold three months was generally on the north or northeast of the Siberian desert. However, the high-pressure core was located on these two high mountains for almost a day. Therefore, in addition to cold, the topographic factor (northwest-southeast extension) plays a very important role in the formation of the high-pressure core. According to the general results of research, this high pressure, directly or indirectly, is the cause of colds and cold waves in the cold period of the year, as well as early and late waves in the country.