Atmospheric Circulation and Water Vapor Characteristics of Snowstorm Anomalies in Northern Xinjiang

The snowstorm in northern Xinjiang was extremely excessive in 2010, the snowfall and snow depth were exceed historical maximum and huge economic losses were made. The snowstorms in northern Xinjiang are divided into cold front snowstorm and warm sector snowstorm. Based on analysis of time and space distribution of the snowstorm in northern Xinjiang, using the NCEP/NCAR2.5°×2.5°reanalysis data, the circulation and water vapor transfer features in snowstorm were analyzed. The results show that: the snowstorm in northern Xinjiang often occur in mountain area and windward slope, and geomorphic effect can’t be ignored. The snowstorm in northern Xinjiang is closely related to the location and intensity of Polar front jet and Subtropical jet, and the overlying and confluence of two frontal zone is major large-scale circulation background of cold front snowstorm, and polar front jet is dominant during warm sector snowstorm. The cause of cold front snowstorm is confluence of the north cold air and the southwest warm moist air flow, and if warm sector snowstorm occur, the colder north cold air southward is the cause. The cold front snowstorm occurs in strong cold frontal zone, and the ground cold high pressure exhibits northeast southwest. When the ground cold high pressure exhibits northwest southeast, the warm front ahead of cold front trigger warm snowstorm. The water vapor of the snowstorm in northern Xinjiang is transfer in a relay, and the location and intensity of the Iran subtropical high is crucial for water vapor transfer of snowstorm.