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投稿时间：2015-05-07 修订日期：2016-01-18
投稿时间：2015-05-07 修订日期：2016-01-18
中文摘要: 利用西沙永兴岛、珊瑚岛的日降水量资料、欧洲中期数值预报中心再分析资料，以及热带气旋最佳路径资料，统计分析了西沙地区降水的气候特征，并用REOF和K means聚类相结合的合成分析方法，对9—10月该地区非台强降水过程的环流形势进行分类。结果表明：（1）西沙地区在12月到次年4月降水少而在5—11月降水多，降水量最多为9和10月；（2）9—10月西沙地区非台强降水过程的环流形势可分为西南季风槽型、季风槽与冷空气结合型和强冷空气型等三类，其中西南季风槽型主要出现在20世纪90年代的9月，强冷空气型主要出现在10月并在90年代以后明显增多，这主要与南海季风槽在90年代偏活跃，冷空气活动在90年代以后偏强有关。
中文关键词: 非台强降水，REOF，K means聚类分析，环流分型
Abstract:Using daily rainfall data of Xisha Islands, reanalysis data of European Centre for Medium Range Weather Forecasts (ECMWF), typhoon data of Shanghai Typhoon Institute, the present study investigates the rainfall climatology of Xisha, and classifies its synoptic situation associated with the non TC heavy precipitation for September-October. The method used is a new composite method, which combines REOF and K means clustering. It is found that Xisha is dry from December to April of the following year, and wet from May to November. Monthly rainfall peaks at September and October. Three optimal categories are obtained, featuring southwest monsoon trough, the combined effect of the monsoon trough and cold, strong cold air, respectively. Among the three categories, the first one occurred mainly in September of the 1990s, while the third one, which appears mainly in October, has increased significantly since 1990s. Preliminary analysis shows that the monsoon trough was more active in 1990s and the cold air activities have become stronger since 1990s. This may be the major reason for the increasing of the total amount of the non TC heavy rainfall.
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基金项目:国家自然科学基金项目（41365004），海南省气象局科技创新项目（HN2013MS01），海南省南海气象防灾减灾重点实验开放基金课题（SCSF201404）和中国气象局行业专项（gyhy201406010）共同资助
引用文本：
李玉梅,李勋,冯文,陈有龙,2016.秋季西沙非台风强降水天气形势分析[J].气象,42(8):934-943.
LI Yumei,LI Xun,FENG Wen,CHEN Youlong,2016.Investigation of the Synoptic Situation Associated with Autumnal Non TC Heavy Precipitation in Xisha[J].Meteor Mon,42(8):934-943.
李玉梅,李勋,冯文,陈有龙,2016.秋季西沙非台风强降水天气形势分析[J].气象,42(8):934-943.
LI Yumei,LI Xun,FENG Wen,CHEN Youlong,2016.Investigation of the Synoptic Situation Associated with Autumnal Non TC Heavy Precipitation in Xisha[J].Meteor Mon,42(8):934-943.