一次冬季层状云的人工催化效果响应分析

A Response Effectiveness Evaluation for an Artificial Seeding Case of Winter Stratiform Clouds

2018年1月22日在邢台市区倒槽天气系统在低空形成的层状云中利用空中国王飞机搭载的粒子测量系统对水云进行催化作业探测资料,通过催化前后不同尺度的云粒子微物理变化和卫星监测结果,研究人工催化后效果响应,人工催化后目标云效果响应是降水量增加与催化作业之间证据链的重要一环,为增水效果分析提供坚实基础。结果表明,冬季冷云发展过程中,当云凝结核较为同一、且云被限制在某一层内,形成浅薄云层时,云粒子均质增长形成直径为4~6μm过冷水滴组成的水云,最大含水量为0.2 g·m^-3;催化作业后,人工冰核消耗丰富的过冷水迅速增长形成冰晶及冰晶聚合体,催化使云粒子浓度200 cm^-3迅速降到15 cm^-3,100~1000μm冰晶和雪晶浓度增长到150 L^-1,1000μm以上降水粒子浓度增长到70 L^-1,出现直径达6000μm雪花,表明催化促进降雪形成;催化影响区形成无云或少云云区,葵花8卫星云图上沿催化轨迹呈现为深色云带,表明此次催化作业效果显著。

On January 22,2018,an inverted trough was passing through the urban area in Xingtai where strati‐form clouds were developed in low altitude.A particle measuring system mounted on King Air was used to com‐plete and track the seeding operation.By comparing the microphysical variation of different-scale cloud particles before and after the seeding with satellite results,the artificial seeding was found successfully effective.After the seeding,the result response of target cloud is the key for the chain of evidence between precipitation augmenta‐tion and cloud seeding.When cloud condensation nuclei were rather uniform and the cloud was considered as one layer that a shallow cloud layer was formed,the cloud particles would grow homogeneously into supercooled wa‐ter droplets with diameter between 4~6μm,which would further form into the water cloud.The maximum liquid content was 0.2 g·m-2.After the seeding,artificial ice nucleus consumed abundant supercooled water and further grew into ice crystals and ice crystal aggregations.The cloud particle concentration dropped from 200 cm^-3 into 15 cm^-3 because of the seeding,while for the same reason,the concentration of 100~1000μm ice and snow crys‐tals as well as the concentration of precipitation particles over 1000μm increased to 150 L^-1 and 70 L^-1 respective‐ly.Also,the presence of snowflakes with a diameter of 6000μm showed the evidence of positive effect in facili‐tating snowing.Since the seeding area was targeting at cloudless or partly cloudy area,the dark cloud band was found in the Himawari-8 satellite cloud pictures along the seeding trajectory clearly proved the seeding operation with significantly effective results.