| 摘要: |
| 为探究冬季不同背景风场下黑潮锋影响边界层云的机理,采用高分辨率卫星数据和再分析数据,研究了冬季海面背景风为垂直(西北风)和平行(东北风)东海黑潮海表面温度锋(黑潮锋)条件下,边界层云对黑潮锋的响应。结果表明:背景风垂直黑潮锋情况下,黑潮锋强迫的边界层内次级环流明显,黑潮锋暖水侧海面冷平流强,海气温差增大,海气界面潜热感热通量增大,海气界面不稳定性增大,产生上升运动,云底高度抬升。上升运动在边界层底向南北两侧辐散,在冷水侧产生下沉运动与500 hPa高压下沉叠加,使局地云量明显减少,形成晴空少云区(云洞)。在暖水侧以南的下沉支叠加云顶上的下沉运动和边界层退耦效应共同作用,产生另一个云洞。气压调整机制为次级环流产生的主要原因。背景风平行黑潮锋情况下,海面空气温度平流作用小,暖水侧海气温差较小,虽然海洋仍然加热大气,但海气界面不稳定较弱,湍流增强使云底高度抬升,垂直混合机制为该湍流增强的主要原因。 |
| 关键词: 层积云 海气边界层 黑潮海洋锋 响应机制 |
| DOI：10.11693/hyhz20211100303 |
| 分类号:P421 |
| 基金项目:国家重点研发计划2019YFC号,1510102号;国家自然科学基金,41876130号;国家自然科学基金,41975024号。 |
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| RESPONSE OF BOUNDARY LAYER CLOUDS TO THE EAST CHINA SEA KUROSHIO FRONT UNDER DIFFERENT BACKGROUND WINDS IN WINTER |
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GAO Chang1, ZHANG Su-Ping1,2, YI Li1,2, ZHANG Yin-Yi3
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1.College of Oceanography and Atmospheric Sciences, Ocean University of China, Qingdao 266100, China;2.Key Laboratory of Physical Oceanography, Ocean University of China, Qingdao 266100, China;3.Lianyungang Meteorological Observatory, Lianyungang 222006, China
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| Abstract: |
| High-resolution satellite data and reanalysis data were used to study the response of boundary layer clouds to the Kuroshio front when the winter sea surface background wind is perpendicular (northwest) or parallel (northeast) to the Kuroshio front. The results show that when the background wind is perpendicular to the black tide front, the secondary circulation in the boundary layer forced by the black tide front is obvious, the cold advection on the warm water side of the black tide front is strong, the sea-air temperature difference increases, the latent and sensible heat flux at the sea-air interface increases, the instability at the sea-air interface increases, and the cloud base height rises. The upward movement diverges from the bottom of the boundary layer to the north and south sides, resulting in the subsidence movement on the cold water side and the superposition of 500hPa high pressure subsidence, which significantly reduces the local cloud cover and forms a clear sky with few clouds (cloud hole). In the south of the warm water side, another cloud hole is generated by the combination of the descending support and the descending motion of the cloud top and the decoupling effect of the boundary layer. The barometric adjustment mechanism is the main cause of secondary circulation. When the background wind is parallel to the Kuroshio front, the advection effect of sea surface air temperature is small, and the temperature difference between sea and air on the warm water side is small. Although the ocean still heats the atmosphere, the instability of the sea-air interface is weak, and the enhanced turbulence increases the height of cloud base. The vertical mixing mechanism is the main reason for the enhanced turbulence. |
| Key words: stratocumulus marine atmospheric boundary layer Kuroshio front responding mechanism |
