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湍流交换是海雾中的关键物理过程,在海雾的热量和水汽平衡过程中起重要作用。本文根据2007年3月24～25日一次海雾的外场观测数据,分析了海雾过程中近海面湍流热量交换特征;并在区分风切变机械湍流与雾顶长波辐射冷却热力湍流的基础上,着重分析了两种不同性质的湍流对海雾发展和维持的作用。结果表明:(1)本次海雾是在西南低压和变性冷高压的控制下,来自南海东部暖水区的空气平流在近岸冷海面上形成的暖海雾;暖海雾中的湍流热量交换过程比冷海雾更为复杂;(2)在暖海雾的形成和消散阶段,风切变机械湍流的热量输送起主要作用;而在发展和维持阶段,既有风切变机械湍流的热量输送作用,也有雾顶长波辐射冷却热力湍流的热量输送作用;(3)风切变机械湍流向冷海面输送热量,对近海面空气起到降温和增湿作用;热力湍流同样向冷海面输送热量,但对雾层起到增温和降湿作用;(4)暖海雾中的湍流热量交换机制与雾层的非充分混合结构有密切关系。
Turbulent exchange is a key physical process in the sea fog and plays an important role in the heat and water vapor balance of sea fog. Based on the data from a field survey of the sea fog on March 24-25, 2007, this paper analyzes the characteristics of turbulent heat exchange in the near-sea surface during the sea fog. On the basis of distinguishing the mechanical turbulence of the wind shear from the long-wave radiation cooling heat turbulence , Focusing on the analysis of the two different types of turbulence on the development and maintenance of the sea fog. The results show that: (1) Under the control of low pressure and denuded cold pressure in the southwest, the sea fog is composed of warm sea fog formed by the advection of air advection in the warm waters of the eastern South China Sea on the coastal sea surface. The turbulent heat The exchange process is more complicated than the cold sea fog. (2) During the formation and dissipation of the warm sea fog, the heat transfer of mechanical turbulence of wind shear plays a major role. In the development and maintenance stage, both the mechanical shear turbulence (3) The mechanical shear turbulence conveys heat to the cold sea surface to cool and humidify the air near the sea surface; the heat turbulence also conveys to the cold sea surface Heat, but the temperature and humidity of the fog layer play a role; (4) The warm sea fog in the turbulent heat exchange mechanism and the fog layer is not fully mixed structure is closely related.