宁夏2017年夏季一次连阴雨天气的人工增雨作业条件分析

Analysis of Artificial Precipitation Conditions in a Continuous Rainy Weather in Summer of 2017 in Ningxia

利用MICAPS4.0高空实况资料、FY-2卫星反演产品、Grapes-cams人影模式产品以及隆德气象站42通道微波辐射计资料对宁夏2017年一次大范围连阴雨过程人工增雨作业条件进行分析。结果表明,(1)该次降水过程开始是由冷暖空气交汇形成的锋区降水,转受南支槽过境配合副热带高压外围暖湿空气形成的连阴雨过程;(2)Grapes-cams预报模式分析云中微物理过程,过冷水为冰相水凝物的生成、生长提供了有利条件,雪、霰在下落过程中融化是低层雨水的主要来源;(3)卫星反演的云参数能够较好地反映出云系的移动发展,且较地面降水的发生具有一定的提前量,可以作为人工增雨作业条件判别的参考依据;(4)地面降水与云液态水含量随时间的分布对应较好,且在地面降水出现前,云液态水含量有跃增现象,利用这种现象可判断此时段云系正处于发展阶段,由此可应用于人工增雨作业条件的判别;(5)在降水开始前的1 h左右,高层温度略有升高,地面温度下降,相对湿度大于90%的湿层厚度明显增加,地面产生降水后近地面空气相对湿度接近过饱和状态,降水结束后空气相对湿度明显减小,相对湿度大于90%的湿层延伸的最大高度明显下降。

Using MICAPS4.0 high-altitude live data,FY-2 satellite products,Grapes-cams figure mode and Lund data of the 42 channel microwave radiometer in Ningxia in 2017,a large range of continuous rain process of artificial precipitation enhancement operation conditions is analyzed.The results show that,(1)The precipitation begins to be caused by the intersection of warm and cold air,and is turned into continuous overhanging and rainy process by the transit of the southern trough and the formation of warm and wet air in the periphery of the subtropical high pressure.(2)The microphysical process in the cloud is analyzed by using the cable-cams prediction model.Supercooled water provides conditions for the formation and growth of water condensate in the ice phase,while snow and graupel melt in the falling process is the main source of rain water in the lower layer.(3)The cloud parameters obtained by satellite inversion can well reflect the mobile development of cloud system,and have a certain amount of advance compared with the occurrence of ground precipitation,which can be used as a reference to determine the operating conditions of artificial precipitation.(4)There is a good correspondence between surface precipitation and the distribution of liquid water content in the cloud.Moreover,before the occurrence of ground precipitation,the content of liquid water in the cloud jumpes,which can be used to judge that the cloud system is in the development stage at this time,which can be applied to the discrimination of artificial precipitation operation conditions.(5)About one hour before the precipitation,the temperature in the upper layer rises slightly,the ground temperature drops,and the thickness of the wet layer with relative humidity greater than 90%increases significantly.After the ground produces precipitation,the relative humidity of the air near the ground is close to supersaturation.However,after the end of precipitation,the relative humidity of the air decreases significantly,and the maximum height of the wet layer extending over 90%of the relative humidity decreases significantly.