兰州大学机构库 >大气科学学院
两类ENSO事件对我国极端降水的影响研究
Alternative TitleThe Influence of Two Types of ENSO Events on Extreme Precipitation in China
李馨雨
Thesis Advisor李艳
2019-05-23
Degree Grantor兰州大学
Place of Conferral兰州
Degree Name学士
Degree Discipline大气科学
Keyword两类ENSO 夏季极端降水 衰退期 大气环流
Abstract为了探究两类ENSO事件对我国极端降水的影响,为中国极端降水日数以及强度的预测提供更为坚实的物理基础,利用1981-2010年中国逐日降水格点资料、Met Office Hadley Centre逐月海表温度资料以及美国国家环境预报中心/大气研究中心(NCEP/NCAR)再分析月平均资料,将El Niño事件分为东部型和中部型两类,采用合成差值分析方法研究了两类事件在发展期、成熟期以及衰退期三个阶段对我国极端降水日数以及强度的影响差异,并选取衰退期夏季为个例,探讨这种差异的形成机制,得到以下结论:(1)东部型El Niño事件的发展期夏季,除华南沿海以及西南地区外,全国大部分区域极端降水日数比中部型El Niño年偏少1~3日;成熟期,两类El Niño年极端降水日数的分布几乎相同;衰退期夏季,除黄河中游地区外,全国大部分区域极端降水日数偏多1~5日,最为明显的是长江流域、东北地区以及西北地区;(2)两类El Niño事件对极端降水强度的影响差异被一条“东北-西南”走向的分界线大致划为两个区域,向北差异不大,向南差异复杂,而且分界线随时间发生阶段性的南北振荡;(3)衰减期夏季,东部型El Niño年的南亚高压比中部型El Niño年偏强,高层辐散加强。6月,东部型El Niño年西太副高偏西偏强、孟加拉湾低槽加深,大量暖湿空气被输送到我国长江流域;7月,副高偏强,西南急流偏强,长江流域极端降水事件偏多;8月,东北地区相对湿度偏高,500hPa有一浅槽,低层风场辐合,利于发生极端降水事件。
Other AbstractTo explore the effects of two types of ENSO events on extreme precipitation in China and provide a more solid physical basis for the prediction of extreme precipitation days and intensity in China, the daily precipitation grid data of China from 1981 to 2010, the monthly sea surface temperature data of Met Office Hadley Center and National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis of monthly mean data are used to divide El Niño events into eastern and central types. The effects of two types of events on the number and intensity of extreme precipitation in China during the three stages of development, maturity and recession are studied by using synthetic analysis method, and the formation mechanism of these differences is discussed by taking the summer of recession as an example, and we get the following conclusions:(1) In the summer of the development period of the eastern El Niño event, except for the coastal areas of South China and southwest China, the days of extreme precipitation in most regions of the country are 1-3 days less than those in the central El Niño year; in the mature period, there is little difference between them; in the summer of recession, except in the middle reaches of the Yellow River, the days of extreme precipitation in most regions of the country are 1-5 days more, the most obvious being the Yangtze River Basin and Northeast China. And Northwest China.(2) The difference of the influence of two types of El Niño Events on extreme precipitation intensity is roughly divided into two regions by a "northeast-southwest" strike boundary, which has little difference to the north and complex difference to the south, and the boundary oscillates periodically from north to south over time. (3) In summer of attenuation period, the South Asian high in eastern El Niño year was stronger than that in central El Niño year, so the upper level divergence was strengthened. In June, the eastern El Niño subtropical high was stronger to the west, the Bay of Bengal trough deepened and the 850hPa low-level jet was stronger. A large amount of warm and humid air was transported to the Yangtze River basin, which made the Yangtze River basin prone to extreme precipitation events. In August, the relative humidity in Northeast China is relatively high, there is a shallow trough in 500hPa, and the low-level wind field converges, so extreme precipitation events occur frequently.
Pages30
URL查看原文
Language中文
Document Type学位论文
Identifierhttp://ir.lzu.edu.cn/handle/262010/338349
Collection大气科学学院
Affiliation大气科学学院
Recommended Citation
GB/T 7714
李馨雨. 两类ENSO事件对我国极端降水的影响研究[D]. 兰州. 兰州大学,2019.
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