波列和对流活动对2010年6月长江中下游地区梅雨期前后两次强降水过程影响的异同
投稿时间: 2017-03-21  最后修改时间: 2017-04-17  点此下载全文
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作者单位E-mail
李慧 南京信息工程大学 lihui100.com@163.com 
陆尔 南京信息工程大学 elu@nuist.edu.cn 
基金项目:国家自然科学基金项目(面上项目,重点项目,重大项目);国家重点基础研究发展计划(973计划)
中文摘要:基于574气象站的降水资料和NCEP/NCAR再分析资料,对比分析2010年6月7~11日和18~22日发生在长江中下游地区梅雨期前后的两次强降水过程成因。研究揭示,两者的相同点表现在:梅雨前后降水过程期间中高纬度地区都存在Rossby波向下游传播,中纬度地区呈现双阻形式,低纬度地区西太平洋副热带高压(以下简称西太副高)强度偏强、西伸脊点位置偏西。不同之处在于:(1)梅雨期前的第一次降水雨带位置偏北,位于长江流域,呈准纬向分布,降水中心位于114癊附近,受到东北地区上空异常发展的高压系统的影响,水汽主要来源于西北太平洋和西太平洋;Rossby波的波源位于北欧地区附近,向下游频散的波活动通量在乌拉尔山东侧和我国东北地区辐合。而贝加尔湖地区为低槽,使得冷空气南下到36癗左右,同时孟加拉湾活跃的对流系统使西太副高加强西伸到95癊左右,冷暖空气交汇,导致强降水发生;(2)发生在梅雨期的第二次降水过程的主要雨带南压至江南地区,雨带呈带状分布,降水中心位于118癊附近,水汽主要来源与孟加拉湾、南海以及西太副高外围。Rossby波的波源位于北欧地区和中西伯利亚地区附近,向下游频散波活动通量在我国内蒙古和鄂霍茨克海地区辐合。东亚地区的低槽较第一次过程明显加深,有利于冷空气到达长江中下游地区(30癗左右),西太平洋暖池地区活跃的对流系统使得西太副高加强西伸到90癊左右,冷暖空气在长江中下游及其以南地区交汇,导致强降水在该地区发生。可见,即便是月内相邻的两次持续性强降水过程触发机制也是不同的。
中文关键词:持续性降水异常  大气环流  梅雨  波活动通量  对流活动
 
The impact of Rossby waves and convection activities on two precipitation events before and during the June 2010 Meiyu period
Abstract:Using daily data from NCEP/NCAR reanalysis dataset and precipitation observations, defined the amount of precipitation of station is larger than 150mm and the rainfall persistent more than 3 days as a rainfall processes. So, two heavy rainfall processes during 7-11 June and 18-22 June in 2010 in the middle and lower reaches of the Yangtze River (MLRYR) are compared. The results show that these two processes occurred under the same circulation background with a double-block high in the middle latitudes. During these events, the intensity of the western Pacific subtropical high (WPSH) is stronger and the western extension point is more westward than normal in the low latitudes. However, two major differences were observed between the events: (1) the first rain belt during the pre-Meiyu period was located at the north of 114癊 in the Yangtze River basin. Because of the abnormally high-pressure system over the Ural Mountains and a low-pressure trough over the Baikal Lake area, the cold air southward to about 36癗. Meanwhile, the strengthened and westward WPSH located at about 95癊. The water vapor mainly emanated from the northwest Pacific and the western Pacific. The cold and warm air then converged, leading to heavy rainfall. (2) The main rain belt during the Meiyu period was located in JiangNan region and the precipitation center was located at about 118癊. The low-pressure trough in East Asia was more prominent than the first rainfall process, which was favorable for cold air reaching the MLRYR (about 30癗). The westward extension of the WPSH located at about 90癊. The water vapor mainly emanated from the Bay of Bengal, the South China Sea and the edge of WPSH. The cold and warm air converged in the MLRYR as well as its southern area, leading to heavy precipitation in these regions.
keywords:Persistent precipitation anomalies  Atmospheric circulation  Meiyu  Wave activity flux  Convective activity
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