A Model For The Thicknesses Of The Sea Surface Skin Layers And Its Application

Sea surface skin layer is an important component of the air-sea interface boundary layer and the upper boundary of the profiles of temperature, salinity, and gas concentration in the sea. It is also a possible error source for remote sensing of sea surface temperature (SST) and sea surface salinity (SSS). The research on sea surface skin layer is a crucial subject for the research on air-sea interaction and would be meaningful to enhance the accuracy of sea surface remote sensing.By introducing Batchelor micro-scale, a unified thickness model for skin layers is developed to determine the depths of various ocean skin layers with same model parameters. In this model, the thickness would response to the both sea surface wind speeds and heat fluxes. The thickness ratio of each skin layers is the square root of the ratio of their diffusion rates. The cool skin and haline skin layer effects can be quantified reasonably and more accord with observed data. Based on this unified thickness model, air-sea gas transfer velocity is a function of both wind speeds and heat flux under low winds.Global distributions of haline skin layer and cool skin layer are then simulated, using surface forcing data mainly from OAFlux project and ISCCP. It is shown that, without solar radiation at night, the global average thickness of temperature and haline skin layers are respectively65μm and lmm. Global average temperature difference through cool skin layer is approximately0.2℃, while salinity difference through salinity layer is approximately0.09psu. The microwave remote sensing error caused by the haline skin layer effect is estimated to be only0.02psu.It is shown that forced convections due to sea surface wind stress are dominant over free convections driven by surface cooling in most regions of oceans. The free convection instability is largely controlled by cool skin effect for the thermal microlayer is much thicker and becomes unstable much earlier than the haline microlayer. The similarity of the global distributions of temperature difference and salinity difference across cool and haline skin layers is investigated by comparing their forcing fields of heat fluxes.The vertical water temperature and salinity profiles in the upper few meters of the ocean are essential for calibrating the sea surface temperature (SST) and salinity (SSS) from remotely sensed surface radiation fields. A reliable way to predict the SST and SSS profiles is necessary for many oceanographic applications, since high temporal and spatial coverage of surface profile observations are impractical. Based on several full sets of meteorological data and observed near-surface ocean temperature, measured in the Gulf of California during the Marine Optical Characterization Experiment (MOCE-5), a numerical model is made to simulate the vertical temperature and salinity profiles for the upper20meters of the ocean, considering both the sun’s radiation and the skin effects. The simulated cool skin thickness can refine meshes near sea surface, because of which, the model can better estimate the sea surface cooling effect, thus better simulate the temperature profile near sea surface. The computation results are in reasonable agreement with the observed vertical temperature profiles in the ocean. Possible causes for difference between model results and observations are also discussed.