于佳卉,刘屹岷,马婷婷,吴国雄. 2018. 青藏高原地表位涡密度强迫影响我国2008年1月南方雨雪天气的一种新机制-Ⅱ数值模拟[J]. 气象学报, (0):-, doi:10.11676/qxxb2018.043
青藏高原地表位涡密度强迫影响我国2008年1月南方雨雪天气的一种新机制-Ⅱ数值模拟
A new mechanism on the Influence of Surface Potential Vorticity Density Forcing over the Tibetan Plateau on the icy weather over southern China in January 2008. Ⅱ Numerical Simulation
投稿时间:2018-03-05  修订日期:2018-04-29
DOI:10.11676/qxxb2018.043
中文关键词:  极端天气,青藏高原,位涡密度W,地表W强迫,数值模拟
英文关键词:Extreme weather event, Tibetan Plateau, Potential vorticity density (PVD), Surface PVD forcing, Numerical Simulation
基金项目:第三次青藏高原科学试验_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(批准号:41730963,91437219,91637312)、和“NSFC-广东联合基金(第二期)超级计算科学应用研究专项资助”和“国家超级计算广州中心”(项目号U1501501)的联合支持
作者单位E-mail
于佳卉 南京信息工程大学气象灾害教育部重点实验室 vivian@lasg.iap.ac.cn 
刘屹岷 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) lym@lasg.iap.ac.cn 
马婷婷 南京信息工程大学气象灾害教育部重点实验室 matingting@lasg.iap.ac.cn 
吴国雄 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) gxwu@lasg.iap.ac.cn 
摘要点击次数: 522
全文下载次数: 406
中文摘要:
      青藏高原东坡近地表的辐合能够增加地表的位涡密度(PVD)。高耸的青藏高原与等熵面相切,其东坡近地表增加的位涡密度成为等熵面边界上的位涡密度强迫源。利用IAP/LASG FAMIL全球大气环流模式[目的]探究青藏高原地表PVD增长对2008年初我国华南地区雨雪灾害天气形成的影响。首先与观测资料对比发现,通过张弛逼近(nudging)动力初始化,在背景试验(CON)中,模式能够比较合理的再现青藏高原东部的地表PVD增长和1月24到1月27日期间我国华南的大气环流场及降水场。而在高原的地表PVD增长减弱的敏感性试验中高原下游区域特别是华南沿海,广西到山东一带的降水明显减小甚至消失。对结果的分析表明:青藏高原区域的地表PVD增长在低空能够增强我国华南沿海地区的南风和水汽输送以及负的绝对涡度平流输送;在高空,高原上产生的正的位涡密度沿西风环流向下游输送,形成高层正的绝对涡度平流。从而在高原下游形成绝对涡度平流随高度增加的大尺度环流背景,有利于上升运动发展。同时,高原地表PVD增长在低空所激发的气旋式环流增加了华南的水汽输送,最终激发了华南极端降水的产生。该个例模拟的结果从而证实了青藏高原东部的地表位涡密度强迫激发其下游极端天气发生的一种新机制。
英文摘要:
      The surface air convergence on the eastern flank of the Tibetan Plateau (TP) can increase the in situ surface potential vorticity density (PVD). Since the elevated TP intersects with the isentropic surfaces in the lower troposphere, the increased PVD on its eastern flank thus forms a PVD forcing source of the intersected isentropic surface at the boundary. The influence of surface PVD forcing over the TP region on the extreme winter storm over southeast China in 2008 is investigated by using numerical experiments based on the atmospheric circulation model FAMIL. Compared with observations, the simulation results show that, by using a nudging method for assimilating observation data in the initial flow, this model can reasonably reproduce the distribution of precipitation, atmospheric circulation and PVD propagation over the TP region during the winter storm period. In order to investigate the impact of the increased surface PVD over the TP region on the extreme precipitation in southeast China, a sensitivity experiment has been designed by reducing the surface PVD over the TP region. By comparing the results with those counterparts in the control experiment, sensitivity experiment shows that the precipitation over the downstream area was reduced, especially in southeast China. The rain band from Guangxi province to Shandong province was almost disappeared. It is demonstrated that in the lower troposphere, the increase of surface PVD over the TP region can generate anomalous cyclonic circulation over southern China which plays an important role in increasing southerly winds and the water vapor transport in the area; it also increases the northward negative absolute vorticity advection. In the upper layers, the surface PVD which is generated on the eastern TP region can propagate on isentropic surface along westerly wind and results in positive absolute vorticity advection in the downstream places. Consequently, due to the development of both ascending motion and water vapor transport downstream of the TP, the extreme precipitation event occurred over southern China. Thereby, a new mechanism concerning the influence of the increased surface PVD over the eastern TP slopes on the extreme weather event occurring over eastern China is revealed.
查看全文   查看/发表评论  下载PDF阅读器
分享按钮