西江流域汛期暴雨与500hPa关键区准双周振荡的关系  

VARIATIONS OF TORRENTIAL RAIN DURING FLOOD SEASON IN XIJIANG RIVER REGION AND THEIR RELATIONSHIPS WITH THE BIWEEKLY OSCILLATION OF 500 HPA KEY REGION

作　　者：纪忠萍[1] 吴秀兰[1] 刘燕[1] 梁健[1] 项颂翔[1] 谢炯光[1] 

机构地区：[1]广州中心气象台,广东广州510080

出　　处：《热带气象学报》2012年第4期497-505,共9页Journal of Tropical Meteorology

基　　金：广东省科技计划项目(2006B37202004);公益性行业(气象)专项(GYHY201006018)共同资助

摘　　要：采用小波分析、相关分析、功率谱分析、Lanczos滤波等方法探讨了近48年西江流域汛期（4—9月）暴雨的变化特征及其与影响西江流域汛期降水的500hPa关键区准双周振荡的关系。结果表明，西江流域4—9月暴雨日数呈单峰分布，5月开始显著增加，6月暴雨日数达到最高；西江流域4—9月暴雨总日数具有准4年与准22年左右的周期振荡。1960年代后期-1980年代初期及1990年代中期-2000年初期暴雨日数以偏多为主，1960年代前期、1980年代中期-1990年代初期及2005--2008年则以偏少为主。定义西江流域4～9月逐日降水与500hPa高度场上显著的负相关区（22．5～27．5°N，102．5～112．5°E）为影响西江流域汛期降水的500hPa关键区。西江流域汛期降水与500hPa关键区均以准单周、10-30天的准双周振荡为主，而30～60天的季节内振荡不显著，二者在准双周振荡尺度上关系最密切。统计近48年4-9月、6—8月500hPa关键区准双周振荡波谷附近前后3天（个别4天）西江流域暴雨出现的平均几率分别为72．5％、76．4％，因此500hPa关键区准双周振荡的低频波谷对西江流域暴雨的中期预报有较好的参考作用。Using the methods of wavelet analysis, correlation analysis, power spectrum analysis and Lanczos filter, the variation characteristics of the torrential rain during the flood season （from April to September） in the Xijiang River region and their relationships with biweekly oscillations of a key region at the geopotential height of 500 hPa are investigated. The results show that the number of torrential rainfall days in the season has a single-peak distribution, which begins to increase significantly in May and reaches the peak in June. The total number of torrential rain days exhibits significant quasi-periodic oscillations of 4 years and 22 years. It is more from the end of the 1960s to the start of the 1980s and from the mid-1990s to the start of 2000s, and less during the remaining period. The area （22.5-27.5 °N, 102.5-112.5 °E） in the 500 hPa geopotential height is in significantly negative correlation with the daily precipitation in the season in the Xijiang River region, named as the ＂500 hPa key region＂. The daily precipitation during the season in the Xijiang river region and ＂500 hPa key-area＂ exhibit significant quasi-weekly （6-9 day） and quasi-bi-weekly （10-30 day） oscillations, but less significant 30-60 day oscillations. They have the closest relation on the quasi-biweekly timescale. For April to September and June to August over the 48 years, the probability is 72.5% and 76.4% respectively for torrential rain to occur within three or four （in fewer cases） days before or after the valleys of the quasi-biweekly oscillations in the 500 hPa key region. Therefore, it can be used as reference for medium-term forecast of torrential rain in the Xijinag River region.

关 键 词：西江流域 500 hPa关键区 准双周振荡 

分 类 号：P426.616[天文地球—大气科学及气象学]