| 广东省前汛期暴雨与500 hPa关键区准双周振荡 |
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| 引用本文： | 纪忠萍,谷德军,吴乃庚,谢炯光.广东省前汛期暴雨与500 hPa关键区准双周振荡[J].应用气象学报,2010,21(6):671-684. |
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| 作者姓名： | 纪忠萍 谷德军 吴乃庚 谢炯光 |
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| 作者单位： | 1.广州中心气象台, 广州 510080 |
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| 基金项目： | 中国气象局气象新技术推广预报员专项(CMATG2007Y04)、公益性行业（气象）专项（CTHY20100618）、广东省科技厅项目(2006B37202004)、〖JP〗广东省气象局项目(2008A02)和中国气象局气候变化专项（CCSF0903）共同资助。 |
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| 摘 要： | 采用小波分析、功率谱和交叉谱分析、Lanczos滤波等方法探讨了1961—2008年广东省前汛期暴雨的变化及与影响广东省前汛期降水的500 hPa关键区准双周振荡的关系。结果表明:20世纪90年代以来,广东省6月发生暴雨的日数明显增多,强度增强;但90年代后期以来,前汛期暴雨的总日数却减少;前汛期暴雨总日数具有较明显的准6～7年周期振荡。广东省前汛期暴雨量占总降水量的37.7%,它与总降水量呈显著正相关。广东省前汛期降水与500 hPa关键区在大多数年份均存在显著的准单周、准双周振荡。虽然它们也存在30～60 d振荡,但不显著。500 hPa关键区与广东省前汛期降水在准双周振荡尺度上关系最密切,振荡超前或滞后的时间差在2 d之内。统计近48年4—6月500 hPa关键区准双周振荡波谷前后3 d(个别4 d)广东省暴雨出现的概率为79%。采用典型个例的合成分析,得到500 hPa关键区准双周振荡波谷附近有、无暴雨出现的大气环流场演变具有明显差异,可为广东省前汛期暴雨的中期预报提供参考。
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| 关 键 词： | 前汛期暴雨 500 hPa关键区 准双周振荡 中期预报 |
| 收稿时间： | 2009-12-03 |
Variations of Torrential Rain in First Rainy Season in Guangdong Province and Its Relationships with the Biweekly Oscillation of 500 hPa Key Region |
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| Ji Zhongping,Gu Dejun,Wu Naigeng and Xie Jiongguang.Variations of Torrential Rain in First Rainy Season in Guangdong Province and Its Relationships with the Biweekly Oscillation of 500 hPa Key Region[J].Quarterly Journal of Applied Meteorology,2010,21(6):671-684. |
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| Authors: | Ji Zhongping Gu Dejun Wu Naigeng and Xie Jiongguang |
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| Affiliation: | 1.Guangzhou Central Weather Observatory, Guangzhou 5100802.State Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences, Beijing 1000813.Guangzhou Institute of Tropical and Marine Meteorology, Key Open Laboratory for Tropical Monsoon, China Meteorological Administration, Guangzhou 510080 |
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| Abstract: | In order to improve medium range prediction of torrential rain in Guangdong Province, the variation characteristics of the torrential rain in first rainy season and their relationships with biweekly oscillation of a key region at 500 hPa geopotential height are investigated with wavelet analysis, power spectrum analysis, cross spectrum analysis and Lanczos filter using the daily precipitation data of 86 stations and rainfall regimes, and NCEP/NCAR daily data for the last 48 years of 1961-2008. The results show that torrential rain during June has increased in both the number of days and intensity since the 1990s, but the total number of torrential rain days for the season has decreased since the end of the 1990s, exhibiting significant quasi periodic oscillations of 6—7 years. The storm rainfall accounts for 37.7% of total rainfall during Guangdong first rainy season, and is significantly positive correlated to the total rainfall. The area (20°-30°N, 102.5°-120°E) with 500 hPa geopotential height is significantly negative correlated with the daily precipitation during April-June in Guangdong, named as the 500 hPa key region. The daily precipitation during April-June in Guangdong and 500 hPa key region exhibit significant quasi weekly (5—9 days) and quasi bi weekly (10-20 days) oscillations but less significant 30—60 days oscillations. The relation between 500 hPa key region and the daily precipitation during April—June in Guangdong Province in the quasi biweekly oscillation scale is most close connected, and the lead or lag time of oscillation is within 2 days. From April to June over the 48 years, the probability of torrential rain is 79% within three or four days (in fewer cases) before or after the valleys of the quasi biweekly oscillations in the 500 hPa key region. The characteristics of atmospheric circulation with or without torrential rain in Guangdong Province for quasi biweekly oscillatory valleys of 500 hPa key region are analyzed with the composite analysis of typical examples. When the torrential rain happens near the valleys, the cold air moves southward by significantly enhanced trough over East Asian, meanwhile, trough over the Bay of Bengal significantly deepens and widens, and torrential rain in Guangdong Province are caused by the interaction between north cold air and southwest warm and moist air brought by strong southwest flow from the Bay of Bengal. When no torrential rain happens near the valleys, the cold air acts northward, no significantly transfer of water vapor moisture transport from the Bay of Bengal, Guangdong Province is controlled by strong southwesterly at the verge of subtropical high and is located in the divergent region of moisture flux, the rainfall is weaker. All these are not conducive to the occurrence of rainfall, especially torrential rain. Therefore, the significant difference between the circulation fields can be used as reference for medium range forecast of torrential rain in Guangdong Province. |
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| Keywords: | torrential rain in first rainy season 500 hPa key region biweekly oscillation medium range forecast |
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