江南南部初夏汛期降水特征Ⅱ:雨季指数与影响雨季的大气环流关键区
投稿时间:2012-07-03  修订日期:2013-04-22  点此下载全文
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苗长明 南京信息工程大学 气象灾害预报预警与评估协同创新中心, 江苏 南京 210044
杭州市气象局, 浙江 杭州 310051 
mcm0571@sohu.com 
郭品文 南京信息工程大学 气象灾害预报预警与评估协同创新中心, 江苏 南京 210044  
丁一汇 国家气候中心, 北京 100081  
周娟 杭州市气象局, 浙江 杭州 310051  
毛裕定 浙江省气候中心, 浙江 杭州 310002  
基金项目:浙江省社会发展项目(2009C33053)
中文摘要:借鉴梅雨指数的定义,选取贵溪、德兴、玉山、衢州、龙泉为5个代表站,建立了江南南部初夏雨季指数。近50 a来,江南南部初夏雨季平均开始日和结束日分别是6月10日和7月1日,比江淮梅雨早约8 d左右;雨季平均长度为20.5 d,雨季内雨日数平均为15.5 d;江南南部初夏雨季开始日经历了一个显著的“V型”变化过程,结束日呈“纺锤型”振荡变化;雨季的长度和雨日数没有明显的线性趋势变化,但20世纪80年代期间的雨季长度和雨日数年际变化大,旱涝频率高、强度强;20世纪60年代和21世纪以后雨季偏弱年较多。影响江南南部初夏雨季开始早晚的大气环流关键区主要在乌拉尔山附近,若乌拉尔山附近为阻高型(低槽型),则雨季开始早(晚);中高纬系统、太平洋副高和南亚高压也都有影响。影响雨季强度的大气环流关键区分别在东半球的北极区、中低纬度西北太平洋和鄂霍次克海附近上空。
中文关键词:江南南部  初夏  雨季指数  大气环流
 
Characteristics of precipitation in the southern part of the south of Yangtze River Valley in early summer rainy seasonⅡ:Rainy season indexes and effective general circulations
Abstract:By referring to the Meiyu indexes and taking Guixi,Dexing,Yushan Quzhou and Longquan as representative stations,ESRS(the early summer rainy season) indexes have been set.From 1961 to 2010,the general beginning and ending days were 10 June and 1 July respectively,about 8 days before the Meiyu period in the Yangtze-Huaihe River basin.The average duration of ESRS was 20.5 days and there were 15.5 rainy days in this period.The beginning days experienced a "V" pattern variation while the ending days presented a "spindle" oscillation process,and there were no obvious increase or decrease tendencies for the durations of ESRS and the number of rainy days in the last 50 years.Nevertheless,there were apparent variations in the annual durations of ESRS and the number of rainy days during 1980s,and ESRS was relatively weak during 1960s and after 2000.Besides the general circulations over West Pacific and Tibet Plateau,that over the Ural region was the most important factor affecting the starting time of ESRS.The general circulations over the Arctic Pole in the Eastern Hemisphere,West Pacific at low and middle latitudes,and Okhotsk Sea affect the intensity of ESRS obviously.
keywords:southern part of the south of Yangtze River Valley  early summer  rainy season index  general circulation
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