高层大气三维热力结构异常及其遥相关特征对江淮流域旱涝的影响

IMPACTS OF THREE-DIMENSIONAL THERMAL STRUCTURE ANOMALY OF UPPER ATMOSPHERE AND ITS TELECONNECTION FEATURE ON FLOOD/DROUGHT IN YANGTZE-HUAIHE RIVER VALLEY

文中分析了江淮流域旱涝过程与南北半球经向波列遥相关特征,结果表明,前期赤道地区高层大气的三维热力结构异常与中国江淮流域夏季旱涝异常存在显著相关。进一步研究发现,江淮流域夏季旱、涝年与前期春季低纬高层大气热力结构呈显著的反位相特征,且两者垂直方向均呈跨越南北半球经向波列结构特征,该波列扰动源可追溯到南极冰盖强信号因子。采用EP通量诊断分析可进一步揭示出与江淮流域旱涝过程相关的经向波列传播及高层大气波射线折射特征。

In this paper, the correlations between summer precipitation of Yangtze - Huaihe River Valley and spring temperature of upper atmosphere, such as 100 hPa, 70 hPa, 50 hPa and 30 hPa, are investigated. As well, the thermal structure anomaly features of upper atmosphere are analyzed during the preceding spring of the flood/drought in Yangtze - Huaihe River Valley by using NCEP/NCAR data. Thus the strong signal key area of upper atmosphere thermal anomaly to flood/drought in Yangtze - Huaihe River Valley can be determined. The results show that the summer rainfall in Yangtze - Huaihe River Valley possesses remote response, to a certain extent, to spring thermal anomaly of different upper atmosphere levels. Namely, the temperature anomaly feature of upper atmosphere can be regarded as a strong signal factor for the forecast of flood/drought in Yangtze -Huaihe River Valley. The thermal structure is anomalous not only in 2 - dimensions but also in 3 - dimensions before flood/ drought of Yangtze - Huaihe River Valley. The vertical sections of the spring and summer temperature anomaly before flood/drought of Yangtze - Huaihe River Valley describe reverse pattern for flood and drought years. Furthermore, the meridional wave train connecting the two hemispheres during flood/drought years in Yangtze - Huaihe River Valley is revealed. This wave train feature may be related to some external forcing sources from underlying surface, for example, the sea -ice anomaly of the Antarctic region. This conclusion is further verified through the relevant diagnostic analysis on vertical E-P flux divergence.