摘要
选取中国西北东部1960—2004年33个台站夏季(6—8月)逐日降水资料和北半球NECP/NCAR500hPa高度场再分析资料,首先统计了中国西北东部逐年夏季总降水量和无雨日数,并根据它们呈显著负相关的特点,定义了无雨日数-降水均一化干湿指数,然后对干湿指数场进行了EOF分解,探讨了西北东部夏季干湿异常的演变特征,同时对干湿异常年份进行了500hPa高度距平场合成分析。结果发现:一致性异常特征是西北东部夏季干湿指数的最主要的空间异常模态;西北东部近45年来的变干趋势是明显的;新疆脊偏弱、东亚大槽偏浅是西北东部夏季湿年同期500hPa高度场特征,而新疆脊偏强、东亚大槽偏深是干年同期500hPa高度场特征;乌拉尔山脊线偏西、东亚大槽偏浅是湿年前期12月高度场特征;乌拉尔山脊线偏东、东亚大槽偏深是干年前期12月高度场特征。冬季12月500hPa高度场环流特征是预测下年夏季干湿特征不容忽视的指标。
By using the daily summer （JJA） precipitation data from 33 observational stations in the east of Northwest China from 1960 to 2004, and the reanalysis data of 500hPa height field from NCEP/NACAR, the total precipitation and rainless days are first calculated. According to their features of significant negative correlation, a homogeneous dry-moist index is defined, and then by EOF analysis, the anomaly evolution feature of drought-moist index fields is studied, in addition, the 500hPa height anomaly field compound analysis in drought and moist anomaly is conducted, and the results show that consistent anomaly feature is the main pattern of summer drought-moist index in the east of Northwest China. Drying tendency is significant in the east of Northwest China in recent 45a. In moist years, the main feature of synochronized 500hPa height field is that Xinjiang ridge is weak and East Asia trough is shallow, but in drought years its feature is reverse. The main feature of prophase （December） 500hPa height field is that Ural ridge line is lean to west and East Asia trough is shallow in moist years, it is also reverse in drought years. The prophase （December） 500hPa height field feature cannot be neglected to forecast drought and moist features of next summer in the east of Northwest China.
出处
《气象》
CSCD
北大核心
2006年第10期94-101,共8页
Meteorological Monthly
基金
科技部科研院所社会公益研究专项"中国干旱气象灾害监测预警方法研究"(编号:2004DIB5J192)资助
关键词
干湿特征
降水量
无雨日数
EOF分解
drought and moist feature precipitation rainless days EOF
