doi:  10.3878/j.issn.1006-9895.1804.17294
春季影响江淮地区的天气尺度气旋活动与同期降水的联系

The significant relationship between the springtime synoptic scale cyclone activities and precipitation anomalies over the Changjiang River–Huaihe River Valleys
摘要点击 880  全文点击 139  投稿时间:2017-12-04  修订日期:2018-04-11
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基金:  国家自然科学基金,省自然科学基金,江苏高校优势学科建设工程资助项目
中文关键词:  天气尺度气旋  自动识别  降水异常  江淮地区
英文关键词:  synoptic  scale cyclone, automatic  identification, precipitation  anomaly, Changjiang  River–Huaihe  River Valleys
        
作者中文名作者英文名单位
周洁雯Zhou Jiewen南京信息工程大学大气科学学院
卢楚翰Lu Chuhan南京信息工程大学大气科学学院
胡叶Hu Ye南京信息工程大学大气科学学院
引用:周洁雯,卢楚翰,胡叶.2018.春季影响江淮地区的天气尺度气旋活动与同期降水的联系[J].大气科学
Citation:Zhou Jiewen,Lu Chuhan,Hu Ye.2018.The significant relationship between the springtime synoptic scale cyclone activities and precipitation anomalies over the Changjiang River–Huaihe River Valleys[J].Chinese Journal of Atmospheric Sciences (in Chinese)
中文摘要:
      本文基于1979-2013年ERA-Interim每日4次的850hPa位势高度场,利用气旋最外围闭合等值线自动识别方法得到春季影响江淮地区的二维气旋集,依据水平尺度划分了天气尺度气旋并分析该区域气旋强度的时空分布特征,研究了气旋活动与站点降水异常的关系,结果表明:天气尺度气旋活动与江淮地区降水异常、强降水事件发生频次均存在显著的正相关关系。气旋活动高-低年份差值分析发现,随着气旋活动增强,对应东北亚地区对流层中上层增温减弱引起的异常高压中心,促使其南部南北经向温度梯度以及高空西风急流偏弱。这有利于江淮区域北部异常正涡度平流输入,同时江淮区域南部及其上游地区对流层中下层出现异常西南气流,从而在江淮地区形成横槽型环流,有利于江淮区域涡度增大,相应的低空辐合、高空辐散垂直结构,为天气尺度气旋发展与维持提供了有利的动力抬升条件。同时,横槽型异常环流配置有利于江淮区域南部的西南暖湿气流和北部的异常西向/西北向水汽输入和堆积,导致区域云量以及降水异常的增多。
Abstract:
      Based on the data 6-hourly 850 hPa geopotential height field from ERA-Interim 1979-2013, extratropical cyclones that occur during spring in Changjiang River–Huaihe River Valleys (CHV) were detected by using 2D cyclone area objective identification method under the recognition of the framework of the outermost closed contours of cyclones.The spatial-temporal characteristics of synoptic scale cyclone activities and their relationship with regional precipitation anomalies during spring over CHV was investigated. The results show that the inter-annual variations of synoptic scale cyclone activity display significant positive correlation with the precipitation anomalies and the occurrence of frequency of heavy precipitation events over CHV. The composite differences between strong and weak cyclone year show that as cyclone activity intensifying, a significant quasi-barotropic high-pressure center exhibits in northeast Asia, which is mainly induced by the upper troposphere warming that weakens the meridional temperature gradient over the south of Japan. The circulation configuration is conducive to a decrease upper westerly jet and a positive vorticity advection in the northern part of CHV accompanied by an anomalous southwesterlies in the middle-low troposphere in the south of CHV. The horizontal trough cyclonic circulation anomalies in CHV results in an increase of the vorticity in this area. The associated low-level convergence and high-level divergence provide favorable dynamic lifting conditions for the development and maintenance of synoptic scale cyclone in CHV. The abnormal circulation configuration of the lower level horizontal trough is favorable to the intensified of southwest warm-wet air flow in the south China and the anomalous easterlies/southeasterlies of water flux in northern CHV, and thus leading to the increase of the regional cloud cover and precipitation anomalies.
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