平流层爆发性增温期间大气波动及海水表面温度变化的研究

发布时间：2018-06-27 21:25

本文选题：平流层爆发性增温 + 重力波　；参考：《武汉大学》2016年博士论文

【摘要】：平流层爆发性增温(SSW)是一种发生在冬季极区的非常强烈的大气现象。在增温事件发生期间,大气的温度场、风场都受到强烈的影响,并且这种影响是全球性的。平流层爆发性增温会引起全球不同层区的大气耦合,因此研究其效应对于理解大气的动力学过程具有重要的意义。本文的主要工作有三个方面：1)利用COSMIC温度数据和NCEP/NCAR再分析资料,对2008年的极涡位移型增温事件和2009年的极涡破碎型增温事件期间的极区重力波活动的变化特征进行了研究。2)利用ERA-interim再分析资料结合COSMIC数据研究了SSW期间热带背景大气和Kelvin波的变化。3)利用ERA-interim再分析资料的海水表面温度(SST)数据统计了不同ENSO相位的SSW事件期间,海水表面温度异常(SSTA)的变化特征。研究结果表明：1、极区纬向平均的重力波活动在两种类型的增温事件之间均出现增强,这种增强在主增温期间随着纬向风转向由高向低发展。在极涡位移型主增温事件期间,重力波活动在向下发展过程中强度保持稳定,而在极涡破碎型主增温期间,重力波活动在向下发展过程中则出现了明显的减弱。极区重力波活动的空间分布会由于极涡的位置和强度不同呈现地理上的差异。总体而言,极涡边缘区域背景风场相对较强,重力波活动也较强,而在极涡外部及内部,重力波活动较弱。然而重力波振幅最大值并不总与风速最大的区域相对应。这些差异可能是由背景风的选择性传播以及重力波波源的差异造成的。2、在SSW期间,增强的中高纬行星波活动使得经向环流也增强,从而在热带平流层造成上涌,使得平流层温度出现降低。在此期间,平流层的纬向风出现了向东的扰动。Kelvin波活动在SSW期间与热带印度洋-西太平洋局地的对流活动出现明显的耦合。Kelvin波对驱动平流层东向纬向风扰动的贡献也比正常年份大得多。3、统计结果表面,SSW事件的类型与ENSO相位存在着联系,极涡破碎型的SSW事件几乎都发生在拉尼娜相位。SSW事件期间,赤道中东部太平洋的SSTA比SSW发生之前出现增大,而北太平洋的SSTA则出现减小。赤道中东部太平洋SSTA的变化在厄尔尼诺和拉尼娜相位要比ENSO中性相位显著。
[Abstract]:Stratospheric explosive warming (SSW) is a very strong atmospheric phenomenon occurring in winter polar regions. During the warming event, the temperature field and wind field of the atmosphere are strongly affected, and the influence is global. Stratospheric explosive warming can lead to atmospheric coupling in different layers of the world, so it is of great significance to study its effects for understanding the dynamic process of the atmosphere. The main work of this paper has three aspects: 1) using COSMIC temperature data and NCEP / NCAR reanalysis data. The variation characteristics of gravity wave activity in the polar region during the polar-vortex displacement-type warming events in 2008 and the polar vortex-breaking warming events in 2009 are studied. 2) the tropical background during SSW is studied using ERA-interim reanalysis data and COSMIC data. The variation of atmospheric and Kelvin waves. 3) using the sea surface temperature (SST) data of ERA-interim reanalysis data, the SSW events with different ENSO phases are calculated. Characteristics of surface temperature anomalies (SSTA) in seawater. The results show that the zonal mean gravity wave activity in the polar region increases between the two types of warming events, and this enhancement changes from high to low with the zonal wind during the main warming period. During the main warming event of the polar vortex displacement type, the gravity wave activity remains stable in the process of downward development, while the gravity wave activity weakens obviously in the downward development process during the main warming process of the polar vortex breaking type. The spatial distribution of gravity wave activity in polar region is geographically different due to the location and intensity of polar vortex. In general, the background wind field in the edge of the polar vortex is relatively strong, and the gravity wave activity is relatively strong, while the gravity wave activity is relatively weak outside and inside the polar vortex. However, the maximum amplitude of gravity wave does not always correspond to the region with the largest wind speed. These differences may be caused by selective propagation of background winds and differences in gravity wave sources. During SSW, the increased activity of mid-high latitude planetary waves also increases the meridional circulation, resulting in upwelling in the tropical stratosphere. The stratospheric temperature is reduced. In the meantime, The zonal wind in the stratosphere is disturbed eastward. The Kelvin wave activity is obviously coupled with the convective activity in the tropical Indian and western Pacific region during SSW. The contribution of Kelvin wave to driving the eastward zonal wind disturbance in the stratosphere is also more than normal. The year is much larger. 3. The type of SSW event on the surface of the statistical results is related to the ENSO phase. Almost all the SSW events of polar vortex fragmentation occur during the La Nina phase. The SSTA in the central and eastern equatorial Pacific increases than before SSW, while the SSTA in the North Pacific decreases. The variation of SSTA in the central and eastern equatorial Pacific is more significant in the El Nino and La Nina phases than in the ENSO neutral phase.
【学位授予单位】：武汉大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：P421.32;P433;P731.1

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