信息公告: 《热带气象学报》再次入选“中国科学引文数据库(CSCD)来源期刊”以及连续8次入编《中文核心期刊要目总览》    
引用本文:
【打印本页】   【HTML】   【下载PDF全文】   查看/发表评论  【EndNote】   【RefMan】   【BibTex】
←前一篇|后一篇→ 过刊浏览    高级检索
本文已被:浏览 27次   下载 0 本文二维码信息
码上扫一扫!
分享到: 微信 更多
近40年大气10~20 d准双周振荡对华西秋季涝旱年降水的影响
温雨, 李丽平
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/气象灾害教育部重点实验室/大气科学学院,江苏 南京 210044
摘要:
利用 1980—2021 年格点化数据集(CN05.1)的中国逐日降水资料和 NCEP/NCAR 逐日再分析资料,对比分析了中国华西秋季典型涝旱年低频降水特征及其与不同纬带大气低频环流的关系,并给出前期预报信号。(1) 华西秋季降水在涝旱年存在显著 10~20 d、20~30 d 和 30~60 d低频振荡周期,10~20 d准双周振荡周期(简称为 10~20 d)最重要。(2) 无论涝旱年,欧亚大陆均有两脊两槽低频环流形式,低频巴尔喀什湖-贝加尔湖(简称为“巴-贝湖”)高压脊、东亚大槽、孟加拉湾反气旋和西太平洋副热带高压(华南及沿海反气旋)是影响华西秋雨的关键低频环流系统,但涝年中高纬(低纬)低频环流系统较旱年偏强偏西(偏南),副热带西风急流更强,对流更活跃,导致更丰富的干冷和暖湿气流交绥于华西。(3) 影响涝旱年的低频水汽环流系统主要包括“巴-贝湖”低频反气旋式、华北-日本群岛附近的低频气旋式、孟加拉湾低频反气旋式和南海-西太平洋低频气旋式水汽环流,但涝年来自中高纬偏北干冷、偏东北的湿冷气流较旱年偏西偏南偏强;涝年的干(湿)冷气流源地在新地岛(鄂霍次克海和日本海),旱年的在中西伯利亚(日本群岛以东的西北太平洋)。涝年有较多来自孟加拉湾和热带北太平洋中部及南海暖湿水汽流,旱年暖湿水汽流则主要来自南海,少量来自孟加拉湾和西太平洋。(4) 无论涝旱年,都要关注“巴-贝湖”高压脊、东亚大槽和西太平洋副高的前期低频预测信号。涝年预测信号出现在-10d,信号主要沿西北-东南路径传播,旱年信号出现在-8 d,各个信号传播路径不同且略复杂。
关键词:  华西秋雨  华西旱涝  秋季低频降水  大气低频振荡  延伸期预报信号
DOI:10.16032/j.issn.1004-4965.2024.074
分类号:
基金项目:
Impact of Atmospheric Quasi-periodic Oscillations on Autumn Precipitation in West China During Flood and Drought Years Over the Last 40 Years
WEN Yu, LI Liping
Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters/Key Laboratory of Meteorological Disaster,Ministry of Education/School of Atmospheric Sciences, Nanjing University of Information Science & Technology, Nanjing 210044, China
Abstract:
This study examines the influence of atmospheric quasi-periodic oscillations on autumn precipitation in West China during flood and drought years over the past 40 years. Using the CN05.1 gridded daily precipitation data and NCEP/NCAR daily reanalysis data from 1980 to 2021, we compare and analyze the characteristics of low-frequency precipitation in typical flood and drought years, as well as its relationship with low-frequency atmospheric circulation at different latitudes. Moreover, we provide early forecast signals based on our findings. The results indicate the following: (1) Autumn precipitation in West China during flood and drought years exhibits significant low-frequency oscillation periods of 10-20 days, 20-30 days, and 30-60 days, with the 10-20 day period being the most prominent. (2) Convective development occurs in West China during both flood and drought years. However, in flood years, the subtropical westerly jet over the region is stronger, resulting in more active convection, stronger vertical upward motion, and vertical meridional circulation. (3) Regardless of flood or drought years, the low- frequency circulation pattern over Eurasia consists of two ridges and two troughs. The key low-frequency circulation systems that impact autumn rainfall in West China include the low-frequency Lake Balkhash- Baikal ridge (referred to as“Ba-Bei Lake”), the East Asian trough, the Bay of Bengal anticyclone, and the western Pacific subtropical high (South China and coastal anticyclone). However, these low-frequency circulation systems are stronger and more westward (southward) in flood years compared to drought years, resulting in a convergence of more abundant dry-cold and warm-humid airflows in West China. (4) The low-frequency water vapor circulation systems that influence precipitation during flood and drought years mainly include the mid-high latitude “Ba-Bei Lake” low-frequency anticyclone circulation, the low- frequency cyclone circulation near North China-Japan Islands, the low-frequency anticyclone circulation in the Bay of Bengal, and the low-frequency cyclone circulation in the South China Sea-Western Pacific. In flood years, the dry-cold (wet-cold) airflow from the north (northeast) of the mid-high latitudes is more northward and eastward, originating from Novaya Zemlya (Sea of Okhotsk and Sea of Japan). In drought years, these airflows originate from Central Siberia (the Northwest Pacific Ocean to the east of the Japanese Islands). Furthermore, in flood years, there are more warm and humid water vapor flows from the Bay of Bengal and the tropical North Pacific Central and South China Sea, while in drought years, warm and humid water vapor flows mainly come from the South China Sea, with a smaller proportion from the Bay of Bengal and the Western Pacific. (5) Regardless of flood or drought years, early monitoring of low- frequency forecast signals related to the“Ba-Bei Lake”ridge, the East Asian trough, and the West Pacific subtropical high is crucial. In flood years, these signals appear on the -10th day and primarily propagate along the northwest-southeast path. In drought years, the signals appear on the 8th day, with slightly more complex propagation paths for each signal.
Key words:  autumn precipitation in West China  drought and flooding in West China  low-frequency precipitation in the autumn  atmospheric low-frequency oscillation  extended-range forecast signal
版权所有《热带气象学报》编辑部 您是第8619960位访问者
Tel:020-39456476、39456435 E-mail:LLSH@gd121.cn
技术支持:本系统由北京勤云科技发展有限公司设计