青藏高原地表位涡密度强迫对2008年1月中国南方降水过程的影响Ⅰ:资料分析  

Impacts of surface potential vorticity density forcing over the Tibetan Plateau on the evolution of precipitation over southern China in January 2008.PartⅠ:Data analysis

作　　者：马婷婷[1,2] 吴国雄 刘屹岷 江志红[1] 于佳卉[1,2] MA Tingting;WU Guoxiong;LIU Yimin;JIANG Zhihong;YU Jiahu(Key Laboratory of Meteorological Disaster of Miniistry of Education (KLME) , College of Atmospheric Science -, Na?ijing XJniversity of Information Scie?me and Technology , Nanjjing 210044, China;State Key Laboratory of Numerical Modelling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG) 9 Institute of Atmospheric PhysicM (IAP) , Chinese Academy of Sciences (CAS) : Beijing 100029 , China;College of Earth Science , University of Chinese Academy of Sciences , Beijing 100049,China)

机构地区：[1]南京信息工程大学气象灾害教育部重点实验室(KLME)，南京 210044 [2]中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室(LASG)，北京 100029 [3]中国科学院大学地球科学学院，北京 100049

出　　处：《气象学报》2018年第6期870-886,共17页Acta Meteorologica Sinica

基　　金：第三次青藏高原大气科学试验--边界层与对流层观测项目(GYHY201406001);中国科学院前沿科学重点研究项目(QYZDY-SSW-DQC018);国家自然科学基金项目(41730963;91437219;91637312);NSFC-广东联合基金(第二期)超级计算科学应用研究专项资助;国家超级计算广州中心(U1501501);江苏省普通高校研究生科研创新计划项目(KYZZ_0245)

摘　　要：位涡外部源汇是驱动大气环流的原动力。文中详细介绍了地表位涡制造和位涡密度强迫的联系,讨论了不同坐标系中位涡密度方程的特点及其在应用中应当注意的问题。还以2008年初南方低温雨雪冰冻灾害为例,探讨了青藏高原地表位涡密度强迫及东传对下游地区对流性天气发生的影响,拟由此揭示青藏高原位涡密度强迫激发中国东部激烈天气发生的一种新机制。伴随着青藏高原地表正位涡密度的东传,下游地区对流层中高层出现纬向正绝对涡度平流,气旋性环流增强,从而促使低空南风发展,为南方地区提供充沛的水汽条件。另外,南风的增强有利于低空经向负绝对涡度平流的加强,从而使南方地区高、低空形成绝对涡度平流随高度增大的大尺度环流背景,有利于上升运动的发展。上升运动的加强又促进低空南风气流的增强,使高、低空绝对涡度平流随高度增大的环流背景进一步增强,最终导致降水的产生。The external source/sink of potential vorticity(PV) is the original driving force for atmospheric circulation. The relationship between surface PV generation and surface PV density(PVD) forcing is discussed in details, as well as the characteristics and application of the PVD equation in different coordinate systems. In addition, by taking the extremely low temperature and icy weather over southern China in January 2008 as an example, a new mechanism concerning the influence of surface PVD forcing over the eastern flank of the Tibetan Plateau on precipitation over southern China is investigated. The generated surface PVD forcing propagated eastward in the middle troposphere, and the associated positive zonal absolute vorticity advection resulted in the increase of cyclonic relative vorticity downstream. Therefore, ascending air flow and convergence in the lower troposphere developed, which resulted in the development of the southerly winds. The development of the southerly winds favored the increase of the negative meridional absolute vorticity advection, which led to the large circulation background over southern China that the absolute vorticity advection increased with the increasing height. Then, the ascending air flow enhanced, which strengthened the southerly winds and the vertical gradient of the absolute vorticity advection between the lower and middle troposphere in turn. Therefore, the development of the ascending motion, together with the abundant water vapor transported by the southerly winds, led to the formation of the severe precipitation over southern China.

关 键 词：位涡密度 绝对涡度平流 青藏高原 降水 

分 类 号：P433[天文地球—大气科学及气象学]