【作者】 陈斌；

【导师】 徐祥德；

【作者基本信息】 中国气象科学研究院 ， 气象学， 2009， 博士

【摘要】 上对流层-下平流层(UT/LS)水汽分布和变化过程对全球地气系统的辐射能量平衡有重要的影响。发生在UT/LS区域的水汽输送过程是影响该区域水汽组成的重要物理过程,对未来的全球气候变化具有很好的指示意义。亚洲季风区作为夏季北半球对流层向下平流层水汽输送和交换的"窗口",虽然引起了研究者的强烈兴趣,但至今为止其研究仍然薄弱。为此,本文以卫星反演产品综合分析为基础,结合相关观测资料、NCEP再分析数据等,借助基于拉格朗日方法求解方案的大气模式(FLEXPART),采用诊断分析和数值模拟相结合的途径,对亚洲季风区夏季UT/LS水汽分布、输送过程及其相关机理进行了研究。主要结论如下:(1)多年的再分析资料表明,北半球夏季青藏高原及其周边区域上空为强大的南亚高压所控制,该区域具有全球最高的对流层顶高度,夏季往往小于100hPa。UT/LS区域大气温度波动垂直方向呈现出“正-负-正”的变化,UT区域的加热可以通过温度波动的向上传播到下平流层中。南亚高压主体的东南侧为强的上升运动区,此大气流场的气候态特征为对流层向平流层水汽输送提供了有利的环流背景条件。(2)利用最新的卫星资料,对亚洲季风区夏季UT/LS大气水汽及其他大气痕量成分季节内变化特征进行分析,发现上对流层主要存在两个振荡周期,即10-20天和30-60天,而下平流层主要表现为30-60天的季节内周期振荡,这两个周期振荡分别和青藏高原及其南部区域的夏季对流加热以及南亚高压的位置变化具有同位相特征,说明青藏高原及其周边区域的夏季对流抬升和南亚高压闭合环流的共同作用是影响该区域水汽及其大气痕量成分分布、变化的主要动力过程。(3)通过对流层-平流层交换诊断分析发现,发现夏季向上穿越对流层顶的对流层向平流层质量和水汽输送(TST)主要发生在青藏高原东南侧及其临近的UT/LS区域的上空。穿越对流层顶气块4天前后的轨迹分析表明,向上穿越对流层顶以后,可以向热带地区继续输送,表明青藏高原上空以南亚高压为主要环流特征的UT/LS区域水汽输送对全球平流层水汽平衡具有重要的影响。(4)初步探讨了南亚高压在亚洲季风区夏季UT/LS输送过程及水汽等异常分布形成中的动力作用。理想的集合数值模拟实验研究表明,南亚高压水平方向上的动力屏障作用主要表现在14～16km高度。一般而言,而水平方向上,近地层大气在南亚高压闭合环流内滞留时间甚至可超过一个月,这也是亚洲季风区上空夏季水汽等异常和维持形成的原因之一。(5)通过高分辨的拉格朗日输送模式,诊断了进入亚洲季风区夏季平流层水汽的主要对流源区。研究表明,亚洲季风区夏季对流层向对流层向平流层质量输送的主要源区主要分布在热带西太平洋的中国南海、孟加拉湾、印度半岛东及其青藏高原区域。而对流层向平流层水汽输送的近地层对流源区主要为青藏高原及其周边区域,该区域贡献了整个亚洲季风区的进入平流层水汽的三分之一多。青藏高原及其周边区域的对流加热和较高的对流层顶温度是青藏高原地区成为夏季UT/LS水汽输送主要对流源区的可能原因。(6)结合中尺度气象模式和拉格朗日输送模式对南亚高压内水汽进入平流层的一次天气尺度输送过程和机理进行了分析。对流抬升作用下,湿空气可向上输送到位温320-340K高度,然后在南亚反气旋大尺度平流作用下,在反气旋的西侧向北输送。而在反气旋的东部及南侧经过对流层的冷点,进入到平流层中。南亚高压系统内辐射加热引起的大尺度的输送过程是亚洲季风区反气旋内部水汽进入平流层且水汽异常中心得以维持的主要原因,而对流加湿的作用较小。更多还原

【Abstract】 The distributions and variations of atomosphere water vapor in upper troposphere– lower stratosphere (UT/LS) play an important role in the radiation energy balance of global earth-atmosphere, therefore exert an greatly affect on global climate changes. Asian monsoon region is a“window”of water vapor transport and exchange between troposphere and stratosphere in Northern Hemisphere in summer. As an important physical process to affect water vapor and other trace gases of UT/LS, the mass transport and exchange over this area has been focused on, but till now the research is at its early stage.Therefore, in this paper, based on the synthesis analysis of updata satellite products, related observation and re-analysis data, etc., and by utilizing lagrangian FLEXPART model, the method of combining diagnostic analysis with numerical simulation, the process to transport water vapor transport from troposphere to stratosphere and associated possible mechanism in summer over Asian monsoon region are studied. Several conclusions are listed as followings:(1)Multiyear re-analysis data show that, Tibetan plateau and its peripheral areas in Northern Hemisphere is controlled by strong south asian high in summer season. The air temperature wave pattern in UT/LS area show that the temperature changed can transfer from UT to LS verticaly. Compare to the same latitudeal areas, this region has the highest tropopause height, which is often lower than 100 hPa in summer. The strongest ascent motion is located at the southeast side of the south asian high. The climatology feature of atmospheric stream field provides favorable circumfluence background condition for TST. (2)The intra-seasonal oscillation characteristics of UT/LS atmosphere components in asian monsoon in summer are analyzed by utilizing the tested reversion data collected from Microsoft Limb Sound(MLS) and Atmospheric Infrade Sounder (AIRS). It is found that two osillation periods role for UT atmosphere components changes, i.e., 10-20 dyas and 30-60 days, while the intra-seasonal oscillation period for LS is 30-60 days. These two periodic oscillations are in phase with the convective heating above Tibetan plateau and its southern area in summer, and the location changes of south asian high, respectively. It indicates that, the convection over Tibetan plateau and its surrounding regions in summer, and the south asian high are two main dynamical processes to affect the TST transport of UT/LS atmosphere.(3)The diagnostic analysis of troposphere stratosphere mass exchange(STE) shows that TST mainly presents in the southeast side of Tibetan plateau, and its surrounding UT/LS height. Satellite products also indicate the areas controled by south Asian high is the mainly transport pathway of TST. By computing the residence time of air particles, two sinks of TST transport across the tropopause are found: one is tropical, the other is high-latitude region. It illuminates that the TST process in UT/LS region above Tibetan plateau where the south asian high is the main atmosphere circulation feature has great influence on global STE.(4)In this paper, the effect of south asian high in the UT/LS trace distribution and transportation also be studied. Idealized ensemble numerical simulation illuminates the influence of south asian high on the anomaly distribution of trace gases mostly in the height between 14km and 16km. It takes about 3-6 days to transport air contamination from near-surface layer upwards to the lower troposphere near south asian high region vertically. While in horizontal direction, the close circumfluence of south asian high makes near-surface-layer air contamination stay inside the anticyclone about more than one month. It indicates that short-lifecycle photochemical reaction process of air contamination may also affect the lower-troposphere atmosphere components. This may be one of the explanaitons for which the low-value center of ozone and anomaly distribution characteristics of other atmosphere components present above Tibetan plateau in summer. (5)Back trajectories driven by large-scale analyzed wind fields are used to investigate the mainly water vapor convective soure which can contribute to the water balance in asian summer monsoon UT/LS region, as well as the air mass sources for tropospher to stratospher mass transport (TSMT), defined in terms of the locations where each trajectory last left the atmospheric boundary layer. Results show us that the mainly mass source is different from of the water vapor. The tropical western Pacific Ocean, the bengal bay, India areas, the south of Tibetan plateau and its adjoints are the main mass convective sources, which is consistent with the horizontal distribution of near-surface-layer summer convection. While the Tibetan plateau and its surrounding areas is the most important water vapor source for LS. Streathen convection over this area and the more warm tropoapause temperature can be used to explain this phenomena.(6) By combined the meso-scale weather forcast model and the lagrangian transport model, this paper presented a study on the process and possible mechanism of the vapor transport from near PBL to LS in the south Asian monsoon anticycloon. The mositened air can be lifted to the 320-340K potential temperater levels firstly, and then transport toward North-West conved by largen scale advection. The air parcels experienced their cold point temperature at the east and south part of the anticycloon and then be transported into strotospher. The maxmium water vapor in UTcan be exist and transported into stratosphere mainly due to not the convection moisten but the anticycloon large scale advection.更多还原