The Dynamics of the Skin Temperature of the Dead Sea

We explored the dynamics of the temperature of the skin layer of the Dead Sea surface by means of in situ meteorological and hydrographic measurements from a buoy located near the center of the lake. The skin temperature is most highly correlated to air temperature (0.93–0.98) in all seasons. The skin temperature is much less correlated to the bulk surface water temperature in the summer (0.80), when the lake is thermally stratified, and uncorrelated in the winter, when the Dead Sea is vertically mixed. Low correlations were found between the skin temperature and the solar radiation and wind speed in all seasons. The skin, with its low thermal inertia, responds immediately to the atmospheric forcing. Heat fluxes across the sea surface are also presented. The high correlation of skin temperature to air temperature with minimal time lag is a result of the nearly immediate response of the thin skin layer to the surface heat fluxes, primarily the sensible heat flux. 1. Introduction Sea surface temperature (SST) is a critically important parameter in the study of ocean-atmosphere interactions. SST has a major role in atmospheric models, weather forecasting, climate change models, and energy balance calculations. SST can be measured from satellites and represents a very thin boundary layer (~10？μm skin layer) between the turbulent ocean and atmospheric layers. At this boundary layer, exchanges of sensible and latent heat occur, and long-wave radiation is emitted and absorbed [1]. Different processes act on the skin layer and on the water body beneath it (bulk layer), resulting in a difference between the skin and bulk temperatures. Saunders [2] presented a simple theory in which the difference between bulk temperature and skin temperature, commonly termed “the skin effect” ( ), is proportional to the heat flux (including sensible, latent, and long wave radiative heat fluxes from ocean to atmosphere) and inversely proportional to the kinematic stress (wind friction); the theory is limited to conditions of negligibly low solar radiation and excludes very low wind intensity. One of the predictions of this model is that the ocean is usually covered with a “cool skin”. The skin effect is estimated using measured in situ bulk temperature and long wave radiation from which the skin temperature is calculated [3]. The effects of wind, waves, and the upper layer mixing on the boundary layer have been investigated [3–5]. These studies have shown that wind mixes the upper layer, cooling the skin layer, and that breaking waves momentarily destroy the skin layer, which