基于TRMM卫星的亚洲穿透性对流及其对ENSO事件响应的研究

发布时间：2018-01-11 09:40

本文关键词：基于TRMM卫星的亚洲穿透性对流及其对ENSO事件响应的研究　出处：《兰州大学》2014年硕士论文　论文类型：学位论文

【摘要】：穿透性对流(Overshooting Convections,简称OCs)不但常常伴随暴雨、冰雹、大风、龙卷和闪电等灾害性天气事件,而且在对流层和平流层物质交换过程中也具有重要的作用。本论文利用TRMM卫星的多传感器观测资料研究了亚洲地区OCs的时空分布和强度(雷达反射率、微波亮温和闪电)特征及其对ENSO事件的响应,同时结合欧洲中心再分析资料(ERA-Interinn)分析了相应的环境气象场分布特征,主要研究结果如下： 1.亚洲地区OCs占冷云系统(云顶红外亮温小于235K)总量的2.6%,其中陆地和海洋上分别占2.2%和3.0%。OCs主要分布在150N以南的热带地区,约50%的OCs发生在夏季,其中八月最为活跃,儿乎每月海洋上OCs数目都高于陆地上,并且洋面上OCs的体积降水率和面积均高于陆地。无论是陆地和海洋,OCs的体积降水率均比非穿透性对流(NOCs)高一个数量级。对闪电频数、微波亮温和雷达回波顶高的分析表明,OCs的对流强度明显比非穿透性对流(NOCs)强,其中陆地OCs强度又强于海洋。强OCs主要集中在青藏高原南麓、中国中东部和东南亚地区,同时这些地区OCs的发生概率也很高。 2.OCs的空间分布规律与热力、动力因子和水汽条件的分布呈现较好的对应关系。热带地区CAPE和比湿分别比副热带高约400J/kg和11g/kg、而垂直风切变比副热带约小15m/s(不包括青藏高原),为OCs的发生提供了适宜的环境条件；夏季青藏高原南麓地区CAPE和比湿都很高(CAPE大于500J/kg,比湿大于15g/kg),垂直风切变在3m/s左右,非常有利于强对流的发生和发展；中国中东部地区的OCs数目少但强度大,该区域夏季的比湿和CAPE比其他季节大、垂直风切变小(约5m/s),为强OCs的形成提供了有利的环境条件。 3. ENSO期间,绝大部分地方OCs的频数变化与强度变化呈负相关关系。海洋性大陆和西北太平洋上OCs频数变化最为显著,表现为El Nino时期频数减小,而La Nina时期频数增大(除冬季西北太平洋)。OCs强度变化最明显的区域发生在青藏高原及其南麓地区,表现为El Ninno时期强度增强,La Ninna时期强度减弱。中国中东部除了La Nina夏季OCs频数有所增大外,其他季节的频数变化均不明显,但强度变化比较显著。El Nino时期,OCs的频数变化与比湿和CAPE的变化相一致,但与垂直风切变的变化相反；La Nina时期除冬季外,OCs的频数变化与环境场的对应关系均与El Nino时期相同。
[Abstract]:Penetrating convection overshooting Contractions (OCs) is often accompanied not only by heavy rain, hail, gale, tornado and lightning, but also by disastrous weather events. It also plays an important role in the process of material exchange between troposphere and stratosphere. In this paper, the temporal and spatial distribution and intensity of OCs in Asia are studied by using the multi-sensor observation data of TRMM satellite. Radar reflectivity. The characteristics of microwave light and lightning and its response to ENSO events are analyzed. The distribution characteristics of the corresponding environmental meteorological field are also analyzed by using ERA-Interinn reanalysis data from the European Center. The main findings are as follows: 1. OCs in Asia accounts for 2.6% of the total cold cloud system (the infrared bright temperature of the cloud top is less than 235K). Among them, 2.2% on land and 3.0 on ocean are mainly distributed in tropical areas south of 150N, about 50%% of OCs occur in summer, and most active in August. The number of OCs in the ocean is higher than that on land, and the volume precipitation rate and area of OCs on the ocean surface are higher than those on land, whether on land or sea. The volume precipitation rate of OCs is one order of magnitude higher than that of NOCs. The convection intensity of OCs is stronger than that of non-penetrating convection (NOCs), and the OCs intensity of land is stronger than that of ocean. The strong OCs is mainly concentrated in the southern foot of Qinghai-Xizang Plateau, central and eastern China and Southeast Asia. At the same time, the probability of occurrence of OCs in these areas is also very high. 2. The spatial distribution and thermal properties of OCs. The distribution of dynamic factors and water vapor conditions showed a good correspondence. The CAPE and specific humidity of tropical areas were about 400J / kg and 11g / kg higher than those of subtropics, respectively. The vertical wind shear is about 15m / s smaller than that of the subtropics (excluding the Qinghai-Tibet Plateau), which provides suitable environmental conditions for the occurrence of OCs. In summer, the CAPE and specific humidity in the southern foot of Qinghai-Xizang Plateau are very high, the Cape is more than 500J / kg, the specific humidity is more than 15g / kg / kg, and the vertical wind shear is about 3 m / s. It is very conducive to the occurrence and development of strong convection; In eastern and central China, where OCs is small but intense, summer specific humidity and CAPE are larger than other seasons and vertical windshear is smaller (about 5 m / s). It provides favorable environmental conditions for the formation of strong OCs. 3. During ENSO, there was a negative correlation between the frequency change of OCs and the intensity change in most places, and the OCs frequency in the oceanic continent and the Northwest Pacific Ocean was the most significant. The results show that the frequency of El Nino decreases, while the frequency of La Nina increases (except in winter, the most obvious change of intensity in the Northwest Pacific Ocean) occurs in the Qinghai-Xizang Plateau and its southern foothills. The intensity increases in El Ninno period and weakens in La Ninna period, except for the increase of OCs frequency in La Nina summer in the central and eastern part of China. The frequency change of other seasons is not obvious, but the intensity change is obvious. The frequency change of Nino is consistent with the change of specific humidity and CAPE, but the change of intensity is opposite to that of vertical wind shear. The corresponding relationship between the frequency variation and environmental field in La Nina period is the same as that in El Nino period except in winter.
【学位授予单位】：兰州大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：P732;P412.27

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