1991年夏季长江中下游降水和风场的低频振荡特征分析  

Characteristics of Low Frequency Oscillation of Precipitation and Wind Field in the Middle and Low Reaches of the Yangtze River in Summer 1991

作　　者：张秀丽[1] 郭品文[1] 何金海[1] 

机构地区：[1]南京气象学院大气科学系,江苏南京210044

出　　处：《南京气象学院学报》2002年第3期388-394,共7页Journal of Nanjing Institute of Meteorology

基　　金：国家重点基础研究发展规划项目 G1 9980 4 0 90 0 ( )

摘　　要：对 1 991长江中下游地区夏季降水和风场进行 Morlet小波分析 ,结果表明 :这些要素有明显的低频特征 ,其变化具有阶段性的特点。 6月中旬之前主要表现为准双周振荡 ,6月中旬之后 3 0～ 60 d振荡逐渐明显 ;低频西风峰值超前降水峰值 2～ 4d。通过对散度场及流场的分析发现 ,7月份以后 ,低纬低频系统北传 ,同时中纬 40～50°N低频系统南传 ,两者交汇在 3 0～ 3 5°N。The analysis of wavelet of wind field and rainfall in the Middle and Low reaches of the Yangtze River in summer 1991 shows that these elements exhibit a significant low frequency character and periodic change:quasi-two week oscillation before mid-June 30～60d oscillation after mid-June,and the time of peak value of low frequency u wind being 2～4d prior to the that of rainfall peak. Based on the study on divergence and wind fields, it is found that after July the low frequency vortex in low-latitude moves northward while the vortex in mid-latitude moves southward.As a result,the two meet between 30～35°N,which is the major cause of two heavy rainfall in the Middle and Low reaches of the Yangtze River.

关 键 词：1991年 夏季 长江 降水 风场 低频振荡特征分析 东来季风 

分 类 号：P426.6[天文地球—大气科学及气象学]