海雾的准周期振荡特征  

CHARACTERISTICS OF QUASI-PERIODIC OSCILLATIONS (QPOS) IN SEA FOG

作　　者：沈忱[1] 黄健[2] 刘寿东[1] 

机构地区：[1]南京信息工程大学应用气象学院,江苏南京210044 [2]中国气象局广州热带海洋气象研究所,广东广州510080

出　　处：《热带气象学报》2010年第1期71-78,共8页Journal of Tropical Meteorology

基　　金：国家自然科学基金(40675013)资助

摘　　要：根据南海北部海雾外场观测获取的高分辨率液态含水量、长波辐射通量数据,采用小波分析方法分析了2008年3月16—17日和18—19日两次海雾中的液态水含量、净长波辐射通量的变化特征,讨论南海北部海雾发展和维持的冷却机制。结果显示:(1)无论在有云或无云条件下,海雾都可发展和维持;但前者的液态含水量明显小于后者,而风速大于后者;(2)在地面海雾的生成之前和生成初期,净辐射通量都存在准周期振荡现象,无论无云/有云,地面海雾液态水的大幅度发展的阶段都存在含水量的准周期振荡现象;(3)含水量的准周期振荡现象与振荡发生时段的长波辐射通量关系不大,而主要通过湍流对液态水的混合作用与高空海雾液态水大量生成阶段的雾顶长波辐射间接相关。(4)海雾的生成都与雾顶长波辐射冷却密切相关,但发展和维持可通过不同的冷却机制,既可通过海气间湍流热量输送和辐射传输,也可通过雾顶长波辐射冷却。Based on the highly resolution data of liquid water content （LWC） of the sea fog and longwave radiation flux collected in a field experiment in northern South China Sea, the characteristics of the evolution of LWC and net longwave radiation flux （NLRF） in the two sea fog processes of 16^th to 17^th and 18^th to 19^th March were analyzed with the method of wavelet transform. The mechanisms of cooling in the processes of sea fog formation and persistence in northern South China Sea were analyzed preliminarily. The result is shown as follows. Ⅰ ： Sea fog can develop and persist whether it is cloudy or not; but the LWC is less in sea fog under cloudy conditions than that on cloudless days and the wind speed is higher. Ⅱ ： There are QPOs in the NLRF before and in the early stage of sea fog formation. Whether it is cloudless or cloudy, QPOs are present in the LWC of sea fog during the significant development of water content, Ⅲ： Being little related with the longwave radiation flux for the period of oscillation, the phenomenon of QPOs in the LWC is indirectly correlated with fog top longwave radiation during the period of abundant production of sea fog liquid water at upper levels through the mixing effect of turbulence. Ⅳ： Although the sea fog is closely correlated with fog top longwave radiation cooling during the formation, it develops and persists via different mechanisms of cooling by either air-sea transfer of turbulent heat and radiation or fog top longwave radiation cooling.

关 键 词：海雾 液态含水量 净长波辐射通量 小波分析 准周期振荡 

分 类 号：P426.4[天文地球—大气科学及气象学]