Air-sea interactions in stable atmospheric conditions: Lessons from the desert semi-enclosed Gulf of Eilat (Aqaba)
Abstract. Accurately quantifying air-sea heat and gas exchange is crucial for comprehending thermoregulation processes and modeling ocean dynamics; these models incorporate bulk formulae for air-sea exchange derived in unstable atmospheric conditions. Therefore, their applicability in stable atmospheric conditions, such as desert-enclosed basins in the Gulf of Eilat/Aqaba (coral refugium), Red Sea, and Persian Gulf, is unclear. We present 2-year Eddy Covariance results from the Gulf of Eilat, a natural laboratory for studying air-sea interactions in stable atmospheric conditions which are directly related to ocean dynamics.
The measured mean evaporation, 3.22 m year-1, approximately double than previously estimated by bulk formulae, is exceeding the heat flux provided by radiation. Notably, in arid environments wind speed seasonal trend is compelling maximum evaporation in summer, with minimum winter rate. The higher evaporation rate appears when elevated wind, particularly in the afternoon, coincide with an increase in vapor pressure difference. The bulk formulae approach inability to capture the seasonal (opposite from our measurements) and annual trend of evaporation is linked to errors in quantifying of the atmospheric boundary layer stability parameter.
Most of the year, there is a net cooling effect of surface water (-79 W m-2), primarily through evaporation. The substantial heat deficit is compensated by the advection of heat via northbound currents from the Red Sea, which we indirectly quantify from energy balance considerations. Cold and dry synoptic-scale winds induce extreme heat loss through air-sea fluxes, and are correlated with destabilizing of the water column during winter and initiating vertical water column mixing.
Status: open (until 04 Mar 2024)
2 years Eddy Covariance measurements over the Gulf of Eilat (Aqaba), V1 [Dataset] https://doi.org/10.17632/wmtdmjgsfp.1
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