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.
出处
《南京气象学院学报》
CSCD
北大核心
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 ( )
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
the Middle and Low reaches of the Yangtze River
East Asian monsoon
low frequency oscillation
