兰州大学机构库 >大气科学学院
夏季风活动对大气边界层结构的影响及非季风区超厚大气边界层发展的能量机制分析
Alternative TitleThe Effect of Summer Monsoon Activities on the Atmospheric Boundary Layer Structure and Energy Mechanism of the Development of Super-thick Atmospheric Boundary Layer in Non-Monsoon Region
乔梁
Thesis Advisor张强
2019-05-01
Degree Grantor兰州大学
Place of Conferral兰州
Degree Name硕士
Degree Discipline气象学
Keyword大气边界层厚度 季风影响过渡区 超厚对流边界层 大气边界层结构
Abstract大气边界层是大气中最靠近地表的对流层底部的大气层区域,地表与大气之间几乎所有的热量、动量、水汽、气溶胶、微量气体和大气污染物的交换都是通过陆面过程和大气边界层过程来实现,因此无论是气候变化还是大气环流的调整都与大气边界层过程的贡献密不可分。在大气边界层特征物理参数中,大气边界层厚度是其最为重要的参数之一,它不仅决定着一个地区的大气环境容量,而且还强烈影响着云和对流发展及演变过程,同时也是空气质量监测和天气预报中最为重要的物理参数之一,是数值天气预报模式初始化十分关键的因素。季风系统既是全球大气环流系统的重要角色,也是全球大气能量和水汽输送的主要机制。按照受夏季风的影响程度,可将中国气候区域划分为季风影响区、非季风影响区以及季风影响过渡区。由于各区域受夏季风降水影响程度的不同,导致其陆面特性空间差异明显,大气边界层厚度从西北向东南急剧降低。本文利用分布于季风影响区、季风影响过渡区及非季风影响区的探空站高空观测数据、NASA的MERRA2再分析资料,实现从非季风影响区向季风影响区过渡过程中的大气边界层结构特征的空间变化对比分析,并对大气边界层厚度对夏季风活动的响应进行探讨,同时对非季风影响区出现的超厚对流大气边界层现象通过大气边界层发展的能量机制进行分析说明。最终得出以下主要结论:(1)大气边界层厚度从非季风影响区、季风影响过渡区至季风影响区出现阶梯性大幅降低。非季风影响区出现超厚对流大气边界层,通过季风影响过渡区大气边界层厚度从非季风影响区向季风影响区出现陡峭的递减,当到达季风影响区后,大气边界层厚度达到正常认知的大气边界层厚度。稳定边界层厚度、残余层顶高度和对流边界层厚度按照非季风影响区、季风影响过渡区、季风影响区的顺序依次降低,稳定边界层厚度、残余层顶高度和对流边界层厚度从非季风影响区到季风影响过渡区分别降低了58.3%、28.5%和25.6%,从季风影响过渡区至季风影响区分别降低了41.8%、75.5%和81.8%。(2)夏季风活动对大气边界层厚度的影响十分显著。随着夏季风的爆发,夏季风推进线向西北方向推进,受季风影响的区域大气边界层厚度随之出现降低,而伴随着夏季风的减弱撤退,夏季风推进线向东南方向回退,原先受夏季风控制的区域大气边界层厚度也随之出现了升高。而非季风影响区因不受夏季风的影响,大气边界层厚度在夏季依然以增高为主,在秋季开始降低。(3)季风影响区大气边界层厚度主要受潜热通量的影响,非季风影响区则主要受到夹卷热扩散率和感热通量的影响,而季风影响过渡区则受潜热通量、夹卷热扩散率、感热通量这三个因素的共同影响,过渡区大气边界层厚度的影响机制更为复杂。夹卷热扩散率与大气边界层厚度的小波交叉分析及相关性在非季风影响区和季风影响过渡区的各时期都表现很好,尤其在非季风影响区效果更为明显。潜热通量对非季风影响区的大气边界层影响很小,仅在盛夏季节(6-7月)出现小部分高能量共振区,且两者相关性很低;而对季风影响区和季风影响过渡区则影响范围较大,在春夏季(4-9月)都存在高能量共振区并保持着较高的相关性。感热通量则对季风影响区影响较小,对非季风影响区和季风影响过渡区影响较大,感热通量在非季风影响区和季风影响过渡区区的春夏季都存在着高能量共振区且相关性较好。(5)残余层夹卷能量是非季风影响区超厚大气边界层形成的关键因素。在非季风影响区深厚的近中性残余层背景在超厚对流边界层发展过程中发挥了重要作用,通过夹卷过程从深厚残余层进入到对流边界层的夹卷能量是对流边界层逐日持续发展的关键能量补充,夹卷能量与地表感热能量之和也正好与超厚对流边界层发展所需要吸收的能量相吻合。在夏季每个连续晴空期,对流边界层与残余层之间会形成逐日循环增长机制。正是这种以地表强感热加热为触发机制的对流边界层与残余层之间的正反馈循环增长过程,才会使干旱地区夏季发展出在其它地区很少见的超厚对流大气边界层结构。
Other AbstractThe atmospheric boundary layer is the atmospheric region at the bottom of the troposphere closest to the surface of the atmosphere. Almost all the exchanges of heat, momentum, water vapor, aerosols, trace gases and atmospheric pollutants between the Earth and the atmosphere are achieved through atmospheric boundary layer processes. Therefore, both climate change and atmospheric circulation adjustment are closely related to the contribution of atmospheric boundary layer processes. Among the characteristic physical parameters of the atmospheric boundary layer, the thickness of the atmospheric boundary layer is one of the most important parameters. The atmospheric boundary layer not only determines the atmospheric environmental capacity of a region, but also strongly influences the development and evolution of cloud and convection. It is also one of the most important physical parameters in air quality monitoring and weather prediction, and is a key factor in initialization of numerical weather prediction model. The monsoon system is not only an important role of the global atmospheric circulation system, but also the main mechanism of global atmospheric energy and water vapor transport. According to the influence degree of summer monsoon, China's climate region can be divided into monsoon region, non-monsoon region and transition monsoon region affected by summer monsoon. Because of the different degree of influence of summer monsoon precipitation in each region, the spatial difference of land surface characteristics is obvious, and the thickness of atmospheric boundary layer decreases sharply from northwest to southeast. In this paper, the structure and thickness of atmospheric boundary layer during the transition monsoon region from non-monsoon region to monsoon region are compared and analyzed by using the sounding station altitude observation data distributed in the affected region of summer monsoon, the transition monsoon region of summer monsoon and the non-monsoon region, and the MERRA2 reanalysis data of NASA. The response mechanism of atmospheric boundary layer thickness to the advance and retreat of summer monsoon is discussed. The phenomenon of super-thick convective atmospheric boundary layer in non-monsoon arid area is analyzed and explained through the energy mechanism of atmospheric boundary layer development. The main conclusions are as follows:(1) The thickness of the stable boundary layer, the height of the residual layer top and the thickness of the convective boundary layer decrease in the order of the non-monsoon region, the transition monsoon region affected by the summer monsoon and the monsoon region. The thickness of the stable boundary layer, the height of the residual layer top and the thickness of the convective boundary layer decreased by 58.3%, 28.5% and 25.6% respectively from the non-monsoon region to the transition monsoon region of the influence of the summer monsoon. From the transition monsoon region affected by the summer monsoon to the monsoon region, it decreased by 41.8%, 75.5% and 81.8% respectively. The thickness of atmospheric boundary layer decreases stepwise from non-monsoon region, transition monsoon region of summer monsoon influence to monsoon region.(2) Besides the seasonal variation of atmospheric boundary layer thickness, the influence of summer monsoon is also very important to the variation of boundary layer thickness. With the onset of the summer monsoon, the northwest coast of the summer monsoon pushes forward, and the atmospheric boundary layer thickness affected by the summer monsoon decreases accordingly. With the weakening and retreating of the summer monsoon, the north edge of the summer monsoon retreats to the southeast, and the thickness of the atmospheric boundary layer in the area previously controlled by the summer monsoon also increases. Because the non-monsoon region is not affected by the summer monsoon, the thickness of atmospheric boundary layer still increases in summer and decreases in autumn.(3) The correlation between entrainment thermal diffusivity and atmospheric boundary layer thickness is very well in non-monsoon and transition monsoon regions, especially in non-monsoon region. The thickness of atmospheric boundary layer in non-monsoon region and transition monsoon region is generally much thicker than that in monsoon region. Thicker atmospheric boundary layer will produce thicker residual layer. The entrainment of residual layer in daytime is the main process of entrainment, which makes the entrainment thermal diffusivity in non-monsoon and monsoon regions have a good correlation with the thickness of atmospheric boundary layer.(4) Wavelet Cross-analysis of Meteorological Elements and Atmospheric Boundary Layer Thickness. The latent heat flux has little effect on the atmospheric boundary layer in the non-monsoon region, and only a small part of the high energy resonance region appears in the midsummer season (June-July). However, the monsoon and transition monsoon region have a larger impact, and they exist in spring and summer (April-September). The sensible heat flux and net radiation have less influence on the monsoon region, but more influence on the non-monsoon region and the monsoon region. Especially during the monsoon prevailing period in the monsoon region, there is no high energy resonance region in sensible heat flux and atmospheric boundary layer thickness.(5) The deep background of near-neutral residual layer plays an important role in the development of super-thick convective boundary layer in non-monsoon arid areas. Entrainment energy from deep residual layer to convective boundary layer through entrainment process is the key energy supplement for the continuous development of convective boundary layer. The sum of entrainment energy and surface sensible heat energy coincides with the energy absorbed for the development of super-thick convective boundary layer. During each continuous clear-sky period in summer, a daily cyclic growth mechanism is formed between the convective boundary layer and the residual layer. It is this positive feedback cycle growth process between the convective boundary layer and the residual layer triggered by strong sensible surface heating. Only in this way can the super-thick convective atmospheric boundary layer structure, which is rare in other regions, be developed in the arid region in summer.
Pages64
URL查看原文
Language中文
Document Type学位论文
Identifierhttp://ir.lzu.edu.cn/handle/262010/338314
Collection大气科学学院
Affiliation大气科学学院
First Author AffilicationCollege of Atmospheric Sciences
Recommended Citation
GB/T 7714
乔梁. 夏季风活动对大气边界层结构的影响及非季风区超厚大气边界层发展的能量机制分析[D]. 兰州. 兰州大学,2019.
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