北京奥运会期间极端天气的气候统计分析

Climatic and Statistical Analysis on Extreme Weather Events During Beijing Olympic Games

利用1971—2007年观象台、海淀、丰台、朝阳和顺义的气象要素资料,对北京奥运期间8月8—24日的极端天气事件进行了统计分析,结果表明:观象台极端最高气温为37.3℃,年Tmax>36.0℃的出现概率为5%,呈明显的上升趋势,上升率为0.69℃/10年,目前处在偏高期。城郊5站Tmax≥33℃的平均日数为2.8天,变化趋势基本一致,目前处在日数偏多期,每年平均高温闷热(Tmax≥32℃且平均相对湿度≥55%)天气日数为4.7天。观象台日最大降雨量中出现雨量≥25mm·d-1的概率高达68%,城郊5站雨量≥25mm的平均降雨日为1.1天,观象台日最大降雨强度的最大值为156.2mm·d-1。城郊5站平均雷暴日数为3.7天,上述三要素均处在低值期。10分钟平均风速≥7m.s-1以上的大风日数城郊5站为1.2天,目前处在风速较小期。城郊5站平均大雾日数为0.7天,观象台低能见度≤2000m的日数从1990年代平均3.9天降到2000-2007年的1.5天,目前处在日数较少期。

Beijing 2008 Olympic Games will be held on 8 - 24 August. The extreme weather events in this period were analyzed by using the data of Beijing Observatory, Chaoyang, Fengtai Shunyi Meteorological Stations from August 8 - 24 （1971 - 2007）, and Haidian Meteorological Station（1975- 2007）. The results show that the maximum high temperature （Tmax） at Beijing Observatory was 37.3℃ and the occurrence probability of annual Tmax〉36.0℃ is 5 %. The annual variation of Tmax obviously appears an ascending trend with the rate of 0.69℃/10a. It means that the temperature nowadays is in a relatively higher period, the annual mean days of Tmax≥33℃ at five stations is 2.8 with same increasing trend. The annual mean muggy days （Tmax≥32.0℃ with the relative humidity ≥55%） is 4.7. The occurrence probability of daily rainfall （R≥ 25mm） at Beijing Observatory can reach to as high as 68%, the mean number of raining days （R ≥25mm） for five stations is 1.1. The maximum daily precipitation intensity is 156.2mm/d. The mean day of thunderstorm is 3.7. These three factors mentioned above are in a lower- value periods. The mean day of strong wind （averaged wind speed ≥7m/s in 10 min） at five stations is 1.2, and is also in a slower - speed period. The foggy day is 0.7. The day of low visibility ≤ 2000m at Beijing Observatory goes down from 3.9（ 1990- 1999） to 1.5（2000- 2007）, also in a feweroccurrence period.