Abstract:

To fully understand the mechanism of strong winter cooling in Chongqing, this paper used the weather dynamic diagnosis method to analyze the weather system evolution characteristics, dynamic structural characteristics and water vapor conditions of a strong cooling weather process from January 22 to 29, 2018 in Chongqing, based on the conventional ground observation data, sounding data and the numerical model data. The results showed that: (1) from January 22 to 29, the cold air invaded Chongqing from the northeast path, and the daily average temperature generally decreased by at least 6℃ within 72 h; compared with the western region, the northeastern region with generally higher altitude was affected by the cold air earlier, so it had a large-scale temperature dropping earlier and the lowest temperature was generally lower than that of the western region, with rainy and snowy weather coming later; under the dynamic functions of high and low level jet stream and low vortex-shear line, a large-scale rain firstly appeared in eastern region with sufficient water vapor conditions; when the cold air returned to the western region, it caused continuous strong cooling and rain; (2) the low-pressure system and cold center in the west of Lake Baikal, the northeast cold vortex, high and low level jet stream and the middle-low level vortex-shear line were the key points to forecast the affected time and area for Chongqing strong cooling with rainy (snowy) weather.

Key words: Chongqing, strong cooling, weather system, dynamic structure