2015年夏季东亚和南亚降水异常与热带太平洋海温异常的联系及机理
投稿时间:2019-03-22  修订日期:2019-04-27  点此下载全文
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作者单位E-mail
张梦珂 南京信息工程大学大气科学学院 zhangmk_06@163.com 
金大超 南京信息工程大学气象灾害教育部重点实验室/气候与环境变化国际合作联合实验室/气象灾害预报预警与评估协同创新中心 jindc@nuist.edu.cn 
中文摘要:2015年我国东部夏季降水呈现南北反位相的空间分布,河套地区降水异常偏少、长江中下游地区降水异常偏多,同期印度中部地区降水负异常,上述三个区域2015年夏季降水距平百分率绝对值极大值均超过55%。东亚和南亚地区2015年夏季降水异常的形成机理主要是由于该年夏季处于El Ni?o事件的发展位相,菲律宾群岛及临近区域反气旋环流异常,江淮地区至日本列岛气旋式环流异常,对流层低层位势高度场和整层水汽异常输送场亦存在相一致的空间分布,表现为负位相的EAP/PJ型遥相关,有利于河套地区降水偏少和长江流域降水偏多。热带太平洋海温异常引起热带地区Walker环流负异常,热带西太平洋地区上空受异常下沉气流控制,热带印度洋区域对流层盛行东风异常,减弱了印度夏季风,并造成了印度中部地区夏季降水偏少。另一方面,印度上空对流层低层受异常反气旋控制,该异常反气旋北侧的西风异常沿着青藏高原南麓向东运动,增强了和EAP/PJ遥相关相联系的异常水汽输送,有利于维持和增强河套地区降水负异常和长江中下游地区的降水正异常。
中文关键词:2015年夏季降水异常  中国东部  印度中部  El Ni?o  EAP/PJ型遥相关
 
Mechanisms in the relationship of East and South Asia summer precipitation with tropical Pacific SSTA during 2015
Abstract:The spatial distribution of summer precipitation in the eastern China exhibits an out-of-phase relationship between Hetao region (HT) and the middle and lower reaches of Yangtze River Valley (YRV) in 2015. The precipitation in HT and central India (CI) is below-normal, while in YRV is above-normal. The absolute maximum of the anomalous precipitation percentage in the above three regions is more than 55 % in 2015. The formation mechanism of precipitation anomaly in East and South Asia during boreal summer in 2015 is mainly due to the development phase of El Ni?o events at the same time. An anomalous anticyclone circulation is located in the Philippines and adjacent regions with a cyclone detected from the Yangtze-Huaihe river basin to Japan. There is a consistent spatial distribution of the anomalous geopotential height field in the lower tropospheric and water vapor integrated vertically from Earth’s surface up to 300-hPa, which reveals the spatial distribution of the negative phase of EAP (East Asian-Pacific)/PJ (Pacific-Japan) teleconnection. It is beneficial to the negative precipitation anomaly in HT and the positive precipitation anomaly in YRV. The tropical Pacific SSTA weakens the Walker circulation in the tropical region, which contributes to the descenting motion over the western tropical Pacific. The abnormal easterly wind prevails in the tropical Indian Ocean, which weakens the Indian summer monsoon and results in below-normal precipitation in CI during boreal summer. The lower troposphere over India is controlled by an anomalous anticyclone. Meanwhile, the abnormal westerly wind on the northern side of the anticyclone moves eastward along the southern edge of the Tibetan Plateau, which enhances the anomalous water vapor transport associated with EAP/PJ teleconnection. Therefore, it is conducive to maintaining and enhancing the below-normal precipitation in HT and the above-normal precipitation in YRV.
keywords:summer precipitation anomaly in 2015  Eastern China  central India  El Ni?o  East Asia-Pacific/Pacific-Japan teleconnection
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