华北夏季旱涝与同期500hPa高度异常

Contemporaneous Association of Atmospheric Circulation Anomaly at 500 hPa with Summer-time Floods/Droughts over North China

采用中国气象局整编的月降水量、50 0 h Pa月平均高度场资料 ,利用相关、合成和奇异值分解等方法分析了华北夏季旱涝的时空分布特征及其环流异常特征 ,得到了 50 0 h Pa高度场与同期降水的主要耦合模态。结果表明 :华北旱涝年 ,北半球环流从高纬到低纬都存在显著的异常 ,其中显著区域有 4个 :北非到西亚的低纬地区、青藏高原地区、乌拉尔山东北部及加拿大东部。环流的异常变化与华北夏季降水的异常变化趋势较一致。亚洲地区由高纬到低纬 ,涝年环流异常表现为“+ - +”分布 ;旱年为“- + -”分布。

Atmospheric circutation characteristics associated with summer flood/drought,which is graded by a new scheme,over North China are addressed in this papar in terms of the 1951-2000 monthly rainfall and 500 hPa heights from National climate center by using the correlation,composite and singular value decomposition(SVD) methods.Results show that in North China drought/flood years prominent circulation anonmalies occur all over Northern Hemisphere,and the most significant anomalies appear in the low-latitude area from North Africa to West Asia,the Qinghai-Xizang Plaeau region,the northeast of Ural mountains,and the east of Canada.The trend of the circulation anomaly is consistent with that of summer rainfall in North China.The circulation anomalies in Asia display a 'positive-negative-positive' pattern from high-latitudes to low-latitudes in summer flood years and a 'negative-positive-negative' pattern in summer drought years.