湛江东海岛一次春季海雾的宏微观结构及边界层演变特征  

Evolution characteristics of the macro-/micro- structure and the boundary layer during a spring heavy sea fog episode in Donghai Island in Zhanjiang

作　　者：吕晶晶[1] 牛生杰[1] 张羽 徐峰[3] 

机构地区：[1]中国气象局气溶胶与云降水重点开放实验室,南京信息工程大学,大气物理学院,南京210044 [2]湛江气象局,湛江524001 [3]广东海洋大学海洋与气象学院,湛江524088

出　　处：《气象学报》2014年第2期350-365,共16页Acta Meteorologica Sinica

基　　金：国家自然科学基金项目(41275151);中国气象局气象行业专项(GYHY(QX)2007-6-26);江苏省青蓝工程"云雾降水与气溶胶研究创新团队"资助项目;江苏高校优势学科建设工程资助项目PAPD;高等学校博士学科点专项科研基金(20133228120002);南京信息工程大学科研基金(20110436)

摘　　要：2011年2—3月利用雾滴谱仪、能见度仪、风廓线雷达及100 m边界层气象要素梯度观测塔在湛江东海岛开展海雾综合观测试验。选取2011年2月23—24日一次约15 h的浓雾过程,从宏微观角度着重分析了其间近地层风、温、湿结构和热、动力演变,微物理过程和爆发性增长特征,及湍流通量输送。结果表明:来自南海暖海面的偏东南暖湿气流平流至广东省沿岸冷海面,发生冷却并达到饱和形成海雾。偏东南暖湿气流为浓雾的酝酿、生成及成熟提供了充沛水汽和稳定的逆温层结条件,逆温强度与暧湿气流强度关系密切。海雾多发生在270 m以下,当630—870 m高度层存在明显的下沉运动时,150—390 m高度层则可保持近似等温和弱逆温层,阻止了下层(270 m以下)水汽与其上层(390 m以上)干冷空气交换,导致下层大气持续髙湿稳定状态。整个过程中,雾滴数浓度(/V)、含水量(W)、平均直径(DnvJ、谱宽(Dmax)和有效半径的平均值分别为248 cm 3,0.102 g/cm3、5.2 pm、36.0和7.0/im。雾滴数浓度(iV)与平均直径(CU)在雾发展初期(生成、发展)和末期(消散)多成正相关趋势,而在成熟阶段两者多成反相关趋势。雾前4小时稳定层结及偏东南暖湿气流持续增湿可认为是雾层爆发性增长的酝酿阶段,雾滴谱拓宽是经过活跃一稳定一爆发的3阶段完成,湍流混合对其影响不大;浓雾快速消散是雾滴蒸发、重力碰并沉降、湍流碰并沉降等共同作用造成的,其中直径大于21 Mm液滴的大量耗散是消散的重要阶段。雾前,湍流由强转弱。雾发生后,湍流持续较弱。由于东南急流引发的风切变导致湍流增强,感热通量出现向上强输送,这与冷海雾维持阶段高层热量交换过程类似。雾消散时,湍流逐渐转强。平均动能在雾前和雾中的两次跃增与偏东南暖湿气流显著增强有关,而雾成熟期湍流动能大幅跃增主要是由雾顶辐射冷却产生的�A comprehensive sea fog experiment was carried out in Donghai Island in Zhanjiang from February to March of 2011, with observational instruments including fog droplet spectrometers,visibility meters,wind profilers equipped with RASS,and the 100 m height observational tower.A 15 h heavy sea fog case during 23-24 February 2011 was chosen to understand the e-volution of meteorological elements including temperature,humidity and wind fields,as well as dynamic and thermodynamic structures of the boundary layer.Furthermore,the characteristics of microphysical processes in relation to burst reinforcement features and turbulent fluxes exchange were analyzed.The main results are as follow：The observed sea fog occurred when the warm and moist southeast airflows from the South China Sea met the cold water zones near the coast of Guangdong Province. The southeast airflows supplied abundant water vapor and built stable temperature inversion layers for preparation,formation and mature of the heavy fog,with a close relationship between temperature inversion intensity and southeast airflows strength. The fog mostly occurred below 270 m.The approximate isothermal and weak temperature inversion layers existed in the heights from 150 m to 390 m due to an obvious downward airflows from 630 m to 870 m height layers,which prevented the lower layer （below 270 m height）water vapor from mixing with the upper layer （above 390 m height）dry and cool air masses, resulting in a stable and high humidity situation for the fog layer.The average values of fog droplets number concentration （N ）,liquid water content （W ）,average diameter （D ave ）,maximum diameter （D max ）and effective radius （R ef ）were 248 cm-3 ,0.102 g/cm3 ,5.2 μm,36.0 μm and 7.0 μm,respectively.The fog droplets number concentration （N ）was posi-tively correlated with average diameter （D ave ）during the fog initial （i.e.the formation and development phases）and ending （i. e.the dissipation phase）stages,and,besides,a negative correla

关 键 词：海雾 微物理参量 热力和动力结构 湍流通量 垂直结构 

分 类 号：P426[天文地球—大气科学及气象学]