南海热带对流季节内振荡对江淮流域旱涝影响的初步分析

THE PRELIMINARY ANALYSIS FOR THE IMPACT OF INTRASEASONAL OSCILLATION OF THE TROPICAL CONVECTION OVER SOUTH CHINA SEA ON THE DROUGHTS AND FLOODS OF CHANGJIANG AND HUAIHE RIVER BASIN

使用TBB17年逐月、候平均资料和欧亚500hPa候平均高度距平场,计算了南海地区逐月TBB的标准差,分析其时空分布特征。采用带通滤波方法,分析了江淮流域旱(1985年)、涝(1991、1998年)年南海地区TBB季节内振荡及其经向传播特征。结果表明,江淮流域涝年,南海地区TBB30～60d和10～20d振荡十分活跃,向北传播非常明显。当TBB强对流位相传播到30°N附近的副热带地区时,激发其对流扰动加强,造成江淮流域集中暴雨。而旱年则相反。南海和30°N地区对流活动的强弱差异与500hPa候平均高度距平场的遥相关揭示出江淮流域旱涝年波列结构有很大的不同。

Based on the monthly and pentad average TBB data of 17 years, and the data of 500 hPa height departure fields averaged by pentad in Eurasia, the standard deviation of TBB was calculated month by month over South China Sea, and its spatial-temporal distribution feature was analyzed. Meanwhile, the characteristics of TBB intraseasonal oscillation and its Longitudinal propagation feature was analyzed by means of the band-pass filter over South China Sea in the drought year （ 1985 ） and flood years （ 199 l, 1998 ） in Changjiang and Huaihe River basins. The results indicate that the oscillation of TBB 30～60 d and 10～20 d over South China Sea is very active in the flood years in Changjiang and Huaihe River basin, and the northward propagation is very clear. When the strong convection phase of TBB is propagated to the subtropical zone around 30 °N, it strengthens the convection disturbance in the subtropical zone, and leads to a period of intensive rainstorm. It is contrary in the drought years. Finally it was revealed that the structure of the wave train is of great difference in the drought years from the flood years in Changjiang and Huaihe River basins by the teleconnection between the convective activity over the South China Sea as well as 30 °N district and the 500 hPa height departure fields averaged by pentad.