南方城市降雪概率分析——以绍兴市越城区2022年1—2月降雪天气为例

Probability in Southern Cities—Taking Snowfall Weather in Yuecheng District of Shaoxing City from January to February 2022 as An Example

利用MICAPS 4等分析资料,分析了2022年1—2月发生在绍兴市的5次降雪天气过程,从环流背景、风场、探空、温度场、动力热力等方面总结增大城区降雪天气概率的有利环境特征,结果表明:(1)形势场配置上,北方存在冷高压,东亚槽后冷空气渗透南下,高空位于南支槽前,提供较好的水汽输送条件,700 hPa存在急流,850 hPa低涡切变,低层具有明显的动力强迫作用。(2)温度形势上,冷空气势力偏强,-4℃线压至浙中以南地区。(3)700~850hPa存在较明显逆温层,零度层高度低(<200 m),近地面温度低(2℃左右)。(4)从降雪来看,尤其是积雪情况,高海拔山区降雪概率更大,积雪也一般比城区偏大2~5cm。

Using MICAPS 4 and other analysis data,the five snowfall weather processes in Shaoxing from January to February 2022 were analyzed,and the favorable environmental characteristics for increasing the probability of snowfall weather in urban areas were summarized from the aspects of circulation background,wind field,sounding,temperature field,dynamic heat and so on.The results showed that:(1)in the configuration of the shape field,there was a cold high pressure in the north,the cold air behind the East Asian trough penetrated the south,and the high altitude was located in front of the south branch trough,providing better water vapor transport conditions,There is jet at 700 hPa,low vortex shear at 850 hPa,and obvious dynamic forcing at the lower layer.(2)In the temperature situation,the cold air force is relatively strong,and the-4℃line presses to the south of central Zhejiang.(3)There is a relatively obvious inversion layer at 700~850 hPa,with low height of zero layer(<200 m)and low temperature near the ground(about 2℃).(4)In terms of snowfall,especially snow cover,the probability of snowfall in high altitude mountainous areas is higher,and the snow cover is generally 2~5 cm larger than that in urban areas.