2014年夏季长江流域持续性低温的大尺度环流异常
投稿时间: 2018-03-20  最后修改时间: 2018-04-30  点此下载全文
引用本文:
摘要点击次数: 347
全文下载次数: 
作者单位E-mail
杜雪婷 南京信息工程大学大气科学学院 dudu2557@126.com 
陆尔 南京信息工程大学大气科学学院 elu@nuist.edu.cn 
赵玮 南京信息工程大学大气科学学院  
基金项目:公益性行业(气象)科研专项(重大专项)(GYHY501506001-1)、国家自然科学基金项目(41275092)
中文摘要:变暖背景下,伴随着高温事件的频繁发生,低温事件也不时出现,2014年夏季的持续低温是近年来的一个重要个例。观测表明,2014年的低温异常不只是区域性地出现在长江流域的陆地上;近地面的低温异常是大尺度的,呈一带状,从陆地延伸到海洋上。这种带状异常不只出现在近地面,在大气各层(925hPa—500hPa)都有。分析表明,大气中的这个低温带主要是由高纬环流的异常造成的。在位势高度场上,最重要的异常出现在高纬,在60癗有呈带状的位势高度正距平,它引导(距平意义上的)偏北气流从正北和东北偏东方向侵入,由此在紧邻其南侧的区域形成一同样也为带状的偏低温区。大气各层都呈现出这种在高纬有位势高度的正距平,相应地在稍南的低纬(40癗)有位势高度负距平,在它们之间即为低温区。这种配置型式在大气各层都有,从低层往上,它们整体地表现出由南往北的倾斜,其垂直剖面呈现为距平意义上的大尺度的、类似于锋面的倾斜结构。文中用简单的概念模型对此进行了理解,认为这样的结构是由大气动力异常和热力异常相互影响、共同作用而形成的。
中文关键词:大气异常、低温事件、垂直结构
 
The Large-Scale Anomalous Circulation Responsible for the Persistent Low Temperature over the Yangtze River Basin in Summer 2014
Abstract:While high temperature events occur frequently in the warming climate, low temperature events also appear from time to time. The persistent low temperature in summer 2014 is a typical case in recent years. Observations show that the low temperature abnormality in the near surface layer is not just regionally over the land, but can also extend to the ocean, in a pattern of a large-scale belt. Such abnormality belt appears not only in the near surface, but also in all the atmospheric levels (925hPa-500hPa). Analysis shows that the low temperature in the atmosphere is mainly caused by the anomalous systems in the high latitudes. In the geopotential height field, the belt-like positive anomalies at 60癗 may lead to the intrusions of the colder-than-normal air from the north or the northeast, and thus the formation of the low temperature belt in its southern region. The positive anomalies of the geopotential height are shown in all levels. Correspondingly, there are negative anomalies of geopotential height at low latitudes (40癗). The low temperature region is between them. This distribution pattern exists in all levels. From the near surface to the upper levels, these systems display an overall tilt from the south to the north, thus the vertical cross-section is in a large-scale front-like structure. This is understood with a simple conceptual model. The vertical structure may be maintained by the interaction of the dynamical and therm-dynamical anomalies in the atmosphere.
keywords:atmospheric anomalies, low temperature events, vertical structure
查看全文  查看/发表评论  下载PDF阅读器