北京2008年奥运会开幕日云、降水特征及人工影响天气作业分析

Characteristics of Cloud-Precipitation and the Impact of Weather Modification Activities on the Opening Day of the Beijing 2008 Olympics

2008年奥运会开幕日当天北京及周边地区出现了较强对流云团,尤其是西南和东北两个方向云体发展旺盛,并且向北京城区形成"合围"之势,给国家体育场内开幕式活动的顺利进行带来了极大威胁。根据天气实况,北京市有针对性地组织实施了大规模地面火箭人工消减雨作业。利用自动气象站雨量监测、雷达云和降水探测以及卫星资料反演的云特征参量,通过对奥运会开幕式活动期间云、降水主要特征及人工消减雨作业的物理响应分析,结果显示:2008年8月8日傍晚至夜间北京西南和东北部郊区(县)对流发展较强,19时(北京时间,下同)至23时降水集中分布于北京房山区与怀柔区、密云县一带。北部—东北部对流云团和雨带在向东北方向缓慢移出过程中曾出现西伸、南压现象,西南部对流云团在进入房山区后其主体移动缓慢,雨区向东偏北移动并威胁到城区和国家体育场,最后云团沿东南方向逐渐移出北京市。结合地面火箭作业的时间、空间分布,通过对目标区内自动气象站雨量、雷达回波探测和卫星资料反演的云、降水宏微观特征参量变化分析均表明,大规模和高强度的火箭引晶作业对抑制云、降水的形成和发展起到了一定作用。

Strong convective clouds existed in Beijing and its surrounding areas during the opening ceremony of the 2008 Olympic Games.Clouds developed vigorously especially in the directions of southwest and northeast.They moved towards Beijing city zone and an encirclement trend was formed.Such impending clouds and precipitation posed a significant threat to the ongoing ceremony activities at the National Stadium.According to the actual weather condition,weather modification organizations implemented cloud seeding operations by firing lots of special rockets to mitigate or suppress precipitation.Using the rainfall data of automatic weather stations,radar detection of clouds and precipitation,and two cloud parameters retrieved from satellite data,the authors analyzed the main cha-racteristics of cloud-precipitation together with some physical evidence from weather modification activities during the period of the opening ceremony.The results displayed that strong convection developed in the southwest and northeast outskirts of Beijing in the evening and night on 8 Aug 2008.From 1900 LST to 2300 LST,precipitation was concentrated in Fangshan district and Huairou,Miyun county of Beijing.Strong convective clouds and the followed rainfall distribution in the north and northeast mainly moved slowly towards northeast.There also occurred a bit extending to the west and south.In the southwest,convective clouds stepped slowly after they entered into Fangshan district.The rainfall distribution moved toward northeast and posed a serious threat to the city zone and the National Stadium.Then the main body of it moved slowly toward southeast and finally away from Beijing.Combining with the sites distribution of ground-based rocket launchers and the operation time of cloud seeding,some changes of the macro-micro characteristics of cloud and precipitation derived from automatic weather stations＇ rainfall,radar detection,and satellite data retrieval showed that the intense large scale firing rockets and seeding clouds with AgI had played a certain role in inhibiting the formation and development of cloud and precipitation in the target area.