广东汛期开始日期的年际和年代际变化研究

A Study of Interannual and Interdecadal Variations of the Rain Season Onset Dates in Guangdong Province

用小波分析和相关统计等方法 ,对近 5 0多年来广东开汛的年际和年代际变化及与副高、PDO指数的关系进行了研究 ,同时也研究了它与后期天气、前期 5 0 0hPa环流场和海温场的关系。结果表明 ,近 5 0年来广东开汛呈偏早的趋势 ,具有明显的 2～ 7年左右的年际和 34年左右的年代际周期振荡 ;开汛的年代际振荡与副高、PDO指数是一致的 ,并与它们存在反向的关系 ,且突变的时间也均发生在 2 0世纪 70年代中后期 ;广东开汛与后期天气的相关分析表明 ,它与广东 4月降水的相关最好 ,与 5 ,6月的相关则差 ;与广东降水集中期初日只有在 1986年以后至今才具有显著的正相关 ,而与降水集中期次数却在 1977年之前就具有显著的负相关 ;广东开汛的早晚与前冬 5 0 0hPa高度场存在几个显著的相关中心 ,与前秋北太平洋西风漂流区的海温异常也有明显的相关。

On the basis of wavelet and correlation analysis,the interannual and interdecadal variations of the Rain Season Onset Dates (RSOD) in Guangdong Province in the past 52 years (from 1951 to 2002) are studied,and its relation to the index of the Northwest Pacific subtropical high intensity and Pacific interdecadal Oscillation (PDO) in March-May,the subsequent weather in April-June and the 500 hPa circulation in the preceding winter and Sea Surface Temperature Anomaly (SSTA) in the North Pacific Ocean in the preceding autumn is also investigated.The main results show that RSOD has an earlier tendency in the past 52 years and has the main oscillation periods of quasi-2-7 years and quasi-34 years; the subtropical high and PDO also have the main oscillation periods of quasi-34 years,show an opposite phase relation to the RSOD in decadal variations,and have an abrupt climatic jump in the middle and late period of the 1970s with RSOD; there exists a better correlation between RSOD and rainfall amount in April than in May or June; there also exists a pronounced positive correlation to the first date of concentrated rainstorm period in Guangdong Province in April-June after 1986,but a negative correlation to the frequency of concentrated rainstorm period before 1977; the relation between RSOD and 500 hPa circulation and SSTA in the North Pacific Ocean shows that there exists several high correlation centers to 500 hPa geopotential height,and one high correlation center to SSTA near (40°N,175°W-160°W) in the North Pacific,which has important implication for the prediction on rain season onset dates.