李驰钦,左群杰,高守亭,鲁蓉. 2018. 青藏高原上空一次重力波过程的识别与天气影响分析[J]. 气象学报, 76(6):904-919, doi:10.11676/qxxb2018.026
青藏高原上空一次重力波过程的识别与天气影响分析
Identification of a gravity wave process over the Tibetan Plateau and its impact on the weather
投稿时间:2017-12-13  修订日期:2018-04-04
DOI:10.11676/qxxb2018.026
中文关键词:  重力波  WRF模式  青藏高原  冬季降雪  对流
英文关键词:Gravity wave  WRF model  Tibetan Plateau  Winter snowfall  Convection
基金项目:第三次青藏高原大气科学试验——边界层与对流层观测(GYHY201406001)、国家基金委重大研究计划项目(91437215)。
作者单位E-mail
李驰钦 中国科学院大气物理研究所云降水物理与强风暴重点实验室, 北京, 100029
中国科学院大学, 北京, 100049 
 
左群杰 中国科学院大气物理研究所云降水物理与强风暴重点实验室, 北京, 100029 zqj@mail.iap.ac.cn 
高守亭 中国科学院大气物理研究所云降水物理与强风暴重点实验室, 北京, 100029
中国气象科学研究院灾害天气国家重点实验室, 北京, 100081 
 
鲁蓉 中国科学院大气物理研究所云降水物理与强风暴重点实验室, 北京, 100029
中国科学院大学, 北京, 100049 
 
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中文摘要:
      应用再分析资料、多套卫星反演资料和WRF中尺度数值模拟资料,识别了2005年1月10日青藏高原上空一次重力波过程,以及重力波对青藏高原西部降雪的影响。结果表明,此次重力波位于急流出口区的左方,以西南-东北走向覆盖青藏高原大部分地区。大尺度的冷暖平流相间分布和不断增强的非平衡流为重力波的形成提供了有利背景场。小波交叉谱分析显示垂直涡度与水平散度在对流层中层满足重力波的极化性质,在青藏高原西部的上升支对应有降雪过程发生。WRF可以较好地再现这一过程,并且能够模拟出再分析资料中无法分辨的中尺度重力波。数值模拟表明,青藏高原近地面强烈非绝热加热使得低层大气静力不稳定,在近地面暖区触发对流后引起高层凝结释放潜热,低层融化冷却,有利于激发重力波,并在其上升支产生固态凝结物,随后到来的冷气团提供了有利的水汽输送条件,大范围的弱抬升运动取代了原间隔进入降雪区的强对流上升支,使得固态凝结物得以落至地面,最终在青藏高原西部形成本次降雪过程。
英文摘要:
      Based on reanalysis data, multiple sets of satellite retrieval data and the WRF model simulation data, a gravity wave process on 10 January 2005 is identified over the Tibetan Plateau. The impact of the gravity wave on snowfall over the western Tibetan Plateau is also studied. It is found that the gravity wave was located to the left of jet stream exit, and covered most part of the Plateau from southwest to northeast. The wave-like temperature advection pattern and the strengthening of unbalanced flow provided environmental condition favorable for the development of gravity wave. Wavelet cross spectrum analysis shows that vertical vorticity and horizontal divergence in the middle troposphere were consistent with the polarization state of gravity waves. Snowfall was detected over the updraft region in the western Tibetan Plateau, which can be well simulated by WRF. Simulation can also reproduce the mesoscale gravity wave that can hardly be identified in reanalysis data. Numerical simulation shows that the strong diabatic heating near the surface resulted in static instability. Convections were thus easily triggered over the warmer region, which led to latent heat release by condensation over high altitudes. The melting-induced cooling near the ground associated with convection forced the gravity wave development. The formation of solid hydrometers took place over updraft regions, and the subsequent arrival of cold air provided favorable condition for water vapor transport. Weak large-scale ascending motion later replaced the strong updrafts that entered the snow region intermittently. Solid hydrometers then fell onto the ground and precipitation eventually occurred over the western Tibetan Plateau.
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