重庆地区一次冬季强降温过程诊断分析

为了更全面地认识重庆地区冬季强降温发生机制,文章利用常规地面观测资料、探空资料及数值模式资料,采用天气动力学诊断方法,对重庆地区2018年1月22日-29日强降温天气过程的天气系统演变特征、动力结构特征及水汽条件进行分析。结果表明：(1)1月22日-29日冷空气由东北路径侵入重庆地区,72h内日平均温度普遍下降6℃及以上,东北部地区由于先受冷空气影响且海拔普遍偏高,较西部地区先出现大范围降温且最低温度普遍低于西部地区,出现雨雪天气；西部地区在高、低空急流及川东低涡切变线的动力作用下,配合充足的水汽条件较东部地区先出现大范围降雨,东北路冷空气回流至西部地区,并持续低温阴雨天气。(2)贝加尔湖以西的低压系统、冷中心及东北冷涡、高低空急流、中低层低涡切变线是预报重庆地区此次强降温伴随雨(雪)天气的出现时间及影响区域的重要预报着眼点。

Precipitation Distribution in the Complex Terrainsin the Tibet Plateau Southeast Margin

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°C 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.