西吉县秋覆膜期间主要降水天气形势分析

Analysis on the main precipitation situation during autumn mulch in Xiji county

利用地面和高空观测MICAPS资料,对2015年10月22日和2016年10月9日西吉县出现的两次有效降水(5 mm)进行分析。结果表明:500 hPa中高纬欧亚大陆以纬向环流为主,不断有波动从槽底沿平直西风气流影响西吉,提供动力抬升条件,从500~700 hPa均有明显的湿舌存在,整层湿度条件较好。水汽条件和动力条件能够得到满足,有利于降水发生。进一步分析2002—2014年固原地区的降水形势,发现在出现新疆高压脊型、乌拉尔山阻塞高压型、里海高压脊型、贝加尔湖阻塞高压型、蒙古高压脊型、乌山阻塞高压脊型、贝湖冷低压型西吉县容易出现有效降水;当500 hPa高空图高原上暖高压加强东移,贝湖高压,中亚有冷低压发展,500 hPa或700 hPa高空图上西北低压槽、切变线东南移时极易造成西吉县出现有效降水。

Using the ground and upper-air observation micaps data, we analyzed the two effective precipitations（5 mm） that occurred in Xiji county on October 22, 2015 and October 9, 2016.The test results showed that the 500 hPa high latitude Eurasian continent was dominated by latitudinal circulation, and there were constant fluctuations affecting Ningxia from the bottom of the trough along the flat westerly wind, providing conditions for power lifting. There were obvious wet tongues from500 hPa to 700 hPa, and the whole layer had better humidity conditions. Water vapor and dynamic conditions can be satisfied, which was conducive to precipitation. we summarized the precipitation situation during the filming period of autumn mulch in Xiji county from 2002 to 2014 and found that in the presence of Xinjiang high-pressure ridges, Ural obstruction high pressure type, Caspian high-pressure ridge type, Baikal obstruction high pressure type, Mongolia high-pressure ridge type, Ural blocking high-pressure ridge type, and Baikal cold low-pressure type, Xiji was prone to effective precipitation.When the 500 hPa high altitude map was warm and high pressure strengthened eastward, high pressure in Lake Baikal;cold and low pressure developed in Central Asia, and at the 500 hPa or 700 hPa high altitude map, the northwestern low pressure trough and shear line moved southeast;it can easily cause effective precipitation in Xiji county.