一次对流云人工消减雨作业云条件预报和作业预案合理性分析

为做好固定目标时段和区域的人工消减雨作业,利用云降水显式预报系统(CPEFS_v1.0)对云系性质和结构、移速移向及演变、降水机制等云条件进行预报.预报结果显示,2017年8月8日影响呼和浩特的云系性质为分散性对流云,具有冷暖混合云结构,云中上升气流强,对流单体水平尺度约为几十千米,生命史约为1.5～3 h,云顶高度约...

Forecast on Convective Cloud Condition and Analysis on Seeding Plan of an Artificial Rainfall Mitigation Case

In order to do well artificial rainfall mitigation on specific target period and area,cloud seeding condition such as cloud properties and structure,moving speed and direction,cloud evolution,precipitation mechanism and so on was forecast by using Cloud Precipitation Explicit Forecast System(CPEFS).The results showed that on 8 August 2017 in Hohhot there were scattering convective clouds,with cold-warm mixed vertical structure and strong updrafts.Horizontal scale of single convective cloud was about tens of kilometers,and lifetime was about 1.5-3.0 hours.Cloud top(bottom)height of 10(3)km,and 0℃layer height of 4.3 km.Cloud microphysics aspects were with high content of snow and graupel,low cloud water content in warm regions,maximum content of supercooled water of 0.7 g·kg^-1,less ice crystals in areas with rich supercooled water, mainly with cold precipitation mechanism. Convective clouds first appeared inthe northwest direction of the core zone in Hohhot, rapidly developing and moving eastward and southwardgradually to the core zone at the speed about 30-40 km·h ^-1 . Satellite and radar observations also showed there wereconvective clouds. The forecasted generation time of convective clouds was 1-2 hours later than observation, butmoving direction was consistent with observation. Moving speed was 10-20 km·h ^-1 slower. The maximum liquidwater content was 0.6 g·m ^-3 at the 5 400 m height (-8℃) by airborne cloud physical detection. The forecasted cloudwater content was consistent with detection. The seeding plan was made based on cloud condition forecast. The area30-50 km northwest of the core zone was chosen as key defense zone. AgI over-seeding would be suitable to beimplemented in the 5.1- 7.0 km height. In the morning of 8 August the aircraft would carry out detection in weakecho areas of the first defense line. Ground operations would focus on the implementation of over-seeding in theinitial stage of convective clouds in the third defense line to achieve the goal of rainfall mitigation. Based on theplan, additional five sets of ground mobile seeding equipment were added to reinforce the capability of rainfallmitigation ahead of 24 hours of target time. Rainfall mitigation was carried out with the 5 sets equipment. Insummary, the cloud seeding condition forecast was proper, and the seeding plan was reasonable, which providedstrong support for field rainfall mitigation action.