黄东海大气边界层高度季节变化特征及其成因

利用CFSR再分析资料,采用EOF的分析方法统计分析了黄东海边界层高度的季节变化特征,探讨了2个模态的分布型以及与之相联系的下垫面热通量和垂直环流,统计了ICOADS资料中近30a逐月低云发生频率和海雾发生频率,揭示了其与边界层高度分布特征的一致性。结果表明:盛行风的平流作用与下垫面特征相结合造成的低空稳定性的变化是黄东海边界层高度时间上夏季低、冬季高,空间上呈现东高西低、南高北低的重要因素。EOF分析中第一模态表现为整个黄东海区域具有一致性,主要是大尺度环流的影响;第二模态为春秋相反的2个分布型,与海洋锋、冷舌以及暖水团的季节变化有着密切关系。黄东海大气边界层高度的最大值出现时间以及其大小在空间上较为一致,而最小值以黄东海海洋锋为界,向北逐渐减小,以南差异性不大,出现时间上有较大的差异。,这主要由黄东海冷舌、暖水团以及海洋锋的季节变化所引起对边界层经向分布影响较大所引起的。春夏季节,南部(西部)低云发生频率高于北部(东部),海雾发生频率低于北部(东部);海雾高频区对应较低边界层高度,而低云高频区对应相对较高边界层高度。

The Seasonal Variation and Causation of Atmospheric Boundary Layer Height at Yellow-East Sea

In this paper,CFSR data has been used to analyze the seasonal variation of atmospheric boundary layer height(ABLH) at Yellow-East Sea through EOF analyzed method,and discusses the two modes of distribution type.The surface heat flux and vertical circulation have been analyzed to find the causation.The monthly ICOADS data for nearly 30 years has been used to discuss the distribution of the frequencies of low cloud and sea fog,and to reveal the consistency of the ABLH and the frequencies.The results are showed as follows: The prevailing wind advection and the sea surface characteristics cause the changing of low level stability,and then reduced the distribution of ABLH at Yellow-East Sea,which is the eastern higher than the western and the southern higher than northern.Through EOF analysis,it has been found that the first mode has coherence at the entire Yellow-East Sea,mainly caused by large-scale circulation;the second mode performs the opposite distributions between spring and autumn,mainly associated with the seasonal variation of ocean front,cold tongue and warm water mass.The time and value of maximum ABLH have few changes at Yellow-East Sea,while the minimum ABLH gradually decreases from sea front to north and there is little differences at south of sea front,the differences mainly due to the seasonal variation of the cold tongue,warm water mass and ocean front.In spring and summer,the southern(western) low cloud frequency is higher than the northern(eastern),the sea fog frequency is lower than the northern(eastern).When the frequency of sea fog(low cloud) is higher,the ABLH is lower(higher).