我国东南部夏季干旱指数研究

STUDY ON DROUGHT INDEX OVER THE SOUTHEASTERN CHINA IN SUMMER

根据中国东南部夏季降水与气温显著负相关的特点 ,选用合适的干旱指数分析了旱涝的时空变率 .得到的 4个空间型较之降水分型结构简单 ,又综合反映气候异常状态 .时间演变没有显著的长期倾向 .干旱指数场与 850 h Pa U、V等场奇异值分解 ( SVD)分析得到 ,南海至菲律宾西风偏强 ,中国东部南风分量偏强 ,副高南 (北 )侧东 (西 )风偏强时 ,长江中下游偏旱 ,反之则偏涝 .

WT5BZ]On the basis of the fact that there exists significant negative correlation between temperature and precipitation over the southeastern China in summer, a drought index is appropriately chosen to investigate the spatial and temporal variability of summer drought/flood while no long lerm trend is found in the time evolution of drought/flood, structures of four spatial patterns based on the index are more signatures of similarity than precipitation patterns, and reflect the climate anomaly. In addition, singular value decomposition (SVD) is applied to analyze the index dataset and 850 hPa U , V components and some other fields, respectively. It turns out that drought likely occurs in the middle and lower reaches of the Yangtze River when westerly over the South China Sea and the Philippines, southerly over eastern China, and westerly (easterly) over the north (south) of subtropical high increase. On the contrary, flood likely occurs.[WT5BZ] [WT5HZ]