长江上游旱涝指标及其变化特征分析

利用长江上游流域51个气象观测站1961～2009年降水资料，计算了各站逐年、四季〖WTBX〗Z〖WTBZ〗指数及区域旱涝指数，在此基础上分析了单站〖WTBX〗Z〖WTBZ〗指数旱涝等级划分的合理性，区域旱涝指数的年代际变化趋势，并对区域典型旱涝年的确定及旱涝成因进行了探讨。结果表明：（1）〖WTBX〗Z〖WTBZ〗指数及以此为基础构建的区域旱涝指数能较好地反映长江上游流域年及四季旱涝变化，作为长江上游流域旱涝指标比较合理；（2）长江上游流域年及四季旱涝有明显的年代际变化特征，年及四季的干旱指数与雨涝指数基本呈反位相特征；（3）长江上游流域四季旱涝与500 hPa高度场分布形势有密切关系，除冬季旱涝与海温场关系较弱外，春、夏、秋季旱涝均与海温场关系密切。研究结论对长江上游流域可持续发展及三峡水库科学运营有一定参考意义

INDICES AND CHARACTERISTIC OF DROUGHT AND FLOOD IN THE UPPER BASIN OF THE CHANGJIANG RIVER

Using the precipitation data of 51 meteorological stations in the upper basin of the Changiiang River from 1961 to 2009,the Z index of years and four seasons were computed and inspected.Based on defining the regional drought and flood indices,the characteristic of drought and flood indices were analyzed during the past 48 years,and then the method of choosing typical drought or flood years was discussed.The study showed that the Z index and regional flood and drought indices depicted obviously the variation features of flood and drought of years and four seasons in the upper basin of the Changjiang River.The drought/flood variation was characterized by obvious interdecadal changes in the upper basin of the Changjiang River.The drought index and the flood index time series have almost anti-phase variations on the annual and seasonal time scales.Drought and flood in four seasons had close relationship with 500 hPa circulation pattern at same time.Except winter,dought and flood in other seasons were related with SSTA Field.The conclusion is useful to the development of the upper basin of the Changjiang River;it will provide technical support to scientific management of the Three Gorges Reservoir.