云南汛期旱涝特征及成因分析  

Characteristic and Formation Cause of Drought and Flood in Yunnan Province Rainy Season

作　　者：段长春[1] 朱勇[2] 尤卫红[3] 

机构地区：[1]云南省气象科学研究所,云南昆明650034 [2]云南省气候中心,云南昆明650034 [3]云南大学资源环境与地球科学学院,云南昆明650091

出　　处：《高原气象》2007年第2期402-408,共7页Plateau Meteorology

基　　金：国家自然科学基金项目(40475040);云南省自然科学基金项目(2004D0005M;2001D0002Z)共同资助

摘　　要：通过Z指数和旋转经验正交函数（REOF）分析等对云南省汛期（5～10月）降水作旱涝等级划分、型态分布和旱涝时空分布特征研究，发现云南省各地汛期降水具有一致性，1980年代以来，汛期旱涝有更频繁发生的趋势，东、西部和东南部地区为云南省全省旱涝多发区。对比分析了云南旱涝年的大气环流特征，发现两者显著差异：涝年500hPa位势高度距平亚洲区域自西向东为“-＋-”波列结构,云南北部低槽活跃，反映出有强冷空气活动的环流背景，伊朗高压及青藏高压活跃，利于与副热带高压形成“两高辐合”的强降水形势；低层850hPa水汽输送和OLR场特征揭示出低纬度热带海洋具有强烈的水汽输送机制；旱年则反之。并讨论了导致云南汛期旱涝的热带强迫源区主要位于孟加拉湾、南海一西太平洋，可能机制是热带强迫所激发的大尺度准定常波列的传播。The grades of drought and flood, the distribution characteristics of precipitation and the temporal and spatial distribution characteristics of drought and flood in the rainy seasons （from May to October） of Yunnan Province were studied with the methods of Z index and empirical orthogonal function （EOF and REOF）. The results indicate that the precipitation of rainy season in Yunnan Province is consistent, and after 1980＇s, the drought and flood frequently take place in some regions of the west-and eastparts of Yunnan Province. And the utilizing composition analysis, the charactistics of 500 hPa heights and 850 hPa wind anomalies in the Northern Hemisphere, convergence and divergence on the levels of 200 hPa and 925 hPa were studied. The results show that stronger Iran-Qingzang highs and northward location of subtropical high and Indian low, and stronger upward stream over tropical areas, weaker Yunnan and northward location of Yunnan height, are likely to lead to more rain in Yunnan Province in the rainy seasons. There is a teleconnection relation between Yunnan summer rainfall and convective activities happening in tropical areas in spring and summer accomplished by the teleconnection wavetrain. During the flood years in Yunnan, the convective activities happening in the Ba Walker circulation are much stronger than that during the droug pening in tropical east Pacific are weaker than those during the y of Bengal and tropical west Pacific and ht years, but the convective activities hapdrought years.

关 键 词：云南省 汛期旱涝 EOF及合成分析 OLR 影响机制 

分 类 号：P426.616[天文地球—大气科学及气象学]