2004年夏季的天气及预测试验

Weather System Analysis and Its Real-Time Prediction in Summer 2004

简要介绍了2004年夏季的主要天气过程和中国科学院大气物理研究所2004年汛期预测的结果.总体上看,2004年夏季江淮流域的降雨分布较均匀,没有造成大江大河及大范围的洪涝,中高纬度典型的梅雨环流形势没有完全建立,西风槽活动频繁.夏季最强的一次降雨过程(7月15～20日)是高空低压槽前的持续性暴雨.2004年夏季华北大部分地区降雨偏多,多为低槽冷锋造成;影响我国的热带气旋明显偏多,8月登陆浙江、福建的2个台风破坏力较大;江南和西北都出现了较强的高温天气,江南和新疆的高温分别为副高和大陆高压造成;9月2～5日川东和重庆的降雨与低涡在该地区的稳定维持有关.从汛期实时降水预测结果看,预测系统对6～8月江淮雨带及其暴雨中心的预测较为准确,对大范围的雨带无漏报和空报.而对华北地区降雨而言,预测评分要低于江淮梅雨,这可能是因为模式中的物理过程,特别是降水的物理过程未能完全准确反映华北地区的情况.要提高华北地区降雨的预测水平,今后应继续开展深入的研究.

The main weather systems and prediction results in rainy season 2004 in Institute Atmospheric Physics/Chinese Academy of Sciences(IAP/CAS) are introduced in this paper. The typical Meiyu over Yangtze River and Huaihe River basins during the summer 2004 pattern did not form, whereas the active troughs in westerlies at middle latitude occurred dispersedly, hereby, no severe flooding appeared over there. The most severe successively heavy rainfall event in the summer 2004 was caused by upper-level trough on 15—20 July. The precipitation amount over most part of North China was above the normal, and most of them produced by trough and cold front. The tropical cyclones in western Pacific Ocean were obviously more than normal, two typhoons landing on Zhejiang and Fujian provinces in August resulted in serious disasters. The hot wave occurred in southern and northwestern China in the summer 2004, which was associated with subtropical high of West Pacific and continental high, respectively. The heavy rainfall in eastern Sichuan and Chongqing related to the stabilization of southwest vortex during 2—5 September. The real time prediction for rainy season (June, July and August) shows that the prediction for the rain belts and severe heavy rainfall over Huaihe River and Yangtze River basins is relatively better than that over North China. Therefore, it has been supposed further researches should be done to improve the prediction of rainfall over North China, especially, the study of physical processes which are very important to predict rainfall accurately over North China.