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气象:2014,40(11):1324-1337
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黄渤海一次持续性大雾过程的边界层特征及生消机理分析
(1 国家气象中心,北京 100081;2 中国海洋大学海洋气象学系,青岛 266000;3 中国气象局华风传媒集团,北京 100081)
Mechanism of a Sea Fog Event over Yellow Sea and Bohai Sea
(1 National Meteorological Centre, Beijing 100081;2 Department of Marine Meteorology, Ocean University of China, Qingdao 266000;3 Huafeng Media Group, CMA, Beijing 100081)
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投稿时间:2013-09-18    修订日期:2014-07-14
中文摘要: 利用常规气象观测资料、NCEP的FNL客观再分析资料和L波段雷达探测资料以及采用国家卫星气象中心多通道气象卫星监测数据和定性分析海雾的方法来处理卫星监测的海雾信息,探讨了2010年2月22—25日黄渤海大雾过程的边界层海气要素的特征、大雾成因及生消机理,结果表明:(1)这次大雾是产生在欧亚中高纬平直环流、大气层结稳定的气象条件下。南支槽前的西南气流与副热带高压西北侧及沿海高压脊后部的偏南气流汇合,形成一支跨越中低纬的偏南气流为海雾形成提供有利的水汽条件。(2)大雾的生消与海表温度、气海温差、空气稳定度和风场等气象、水文要素有密切关系;大雾期间,黄渤海气海温差在0~2℃;大气边界层至对流层下部均有逆温层和等温层,逆温层内的温差为6~8℃,垂直温度的变化是上层温度随时间增大高于低层,使逆温层加强并不断抬升,抑制空气垂直对流发展。近地层空气湿度较大,在200 m附近出现一个液态水含量达0.6 g·kg-1大值区;850 hPa以下层均由2~4 m·s-1的东北风随高度顺转成6~8 m·s-1的西南风,为大雾形成和持续发展提供了有利条件。(3)大雾的湍流最大发展高度达到240 m,湍流混合作用可将中上层湿区水汽和雾滴带到近海面层,同时也有利于空气的降温,易达到饱和凝结而形成大雾。中低层持续弱暖平流把暖湿气流输送至冷海面上有利于近海面逆温层的建立和维持,海面辐射冷却作用激发平流形成大雾。
Abstract:Using conventional meteorological observations, NCEP reanalysis data (FNL), L band radar data, and applying the multi channel satellite monitoring data from National Satellite Meteorological Centre and qualitatively analyzing the sea fog, this paper discusses the heavy sea fog event during February 22-25, 2010, including the boundary layer (BL) characteristics, formation and disappearance mechanism. The results show that: (1) The fog happens under straight circulation in the Eurasian high latitudes, with stable atmospheric stratification weather conditions. The southwest flow of southern branch trough converges with the southerly flow in the northwest of subtropical high and behind high pressure ridge, and the corresponding low latitude southerly flow provides a favorable moisture condition for the formation of this event. (2) The process of fog is closely related to sea surface temperature, air sea temperature difference, stability of atmosphere, wind and other meteorological or hydrological factors. During the fog process, air sea temperature difference is 0-2℃, inversion and isothermal layers appear from BL to the lower troposphere. There is a 6-8℃ in inversion layer, and vertical temperature increasing by time is greater in the upper level than in the bottom, which causes the inversion layer to strengthen and continue to uplift or reconstruct, and restrains the vertical convection. Air humidity is comparatively large in the near surface layer with a center of 0.6 g·kg-1 in liquid water content around 200 m. And there is 2-4 m·s-1 northeasterly clockwise turning to 6-8 m·s-1 southwesterly below 850 hPa, which provides favorable conditions for the fog. (3) The developed height of turbulence reaches 240 m. The turbulent mixing brings moisture and droplets from upper layer to the surface layer, and contributes to the cooling, which results in the saturation and condensation for the fog event. The warm air in the lower layer is transported to the cold sea surface by the sustained weak and warm advection, which is conducive to the establishment of the inversion. The radiation cooling triggers this fog event.
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基金项目:公益行业(气象)科研专项(GYHY201206001)资助
引用文本:
黄彬,王皘,陆雪,李靓,张礼春,2014.黄渤海一次持续性大雾过程的边界层特征及生消机理分析[J].气象,40(11):1324-1337.
HUANG Bin,WANG Qian,LU Xue,LI Liang,ZHANG Lichun,2014.Mechanism of a Sea Fog Event over Yellow Sea and Bohai Sea[J].Meteor Mon,40(11):1324-1337.