Preprints
https://doi.org/10.5194/egusphere-2023-1724
https://doi.org/10.5194/egusphere-2023-1724
22 Jan 2024
 | 22 Jan 2024
Status: this preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).

Air-sea interactions in stable atmospheric conditions: Lessons from the desert semi-enclosed Gulf of Eilat (Aqaba)

Shai Abir, Hamish A. McGowan, Yonatan Shaked, Hezi Gildor, Efrat Morin, and Nadav G. Lensky

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.

Shai Abir, Hamish A. McGowan, Yonatan Shaked, Hezi Gildor, Efrat Morin, and Nadav G. Lensky

Status: open (until 04 Mar 2024)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-1724', Anonymous Referee #2, 29 Jan 2024 reply
    • CC1: 'Reply on RC1', Nadav G. Lensky, 11 Feb 2024 reply
  • RC2: 'Comment on egusphere-2023-1724', Anonymous Referee #1, 05 Feb 2024 reply
    • AC1: 'Reply on RC2', Shai Abir, 09 Feb 2024 reply
Shai Abir, Hamish A. McGowan, Yonatan Shaked, Hezi Gildor, Efrat Morin, and Nadav G. Lensky

Data sets

2 years Eddy Covariance measurements over the Gulf of Eilat (Aqaba), V1 [Dataset] S. Abir et al. https://doi.org/10.17632/wmtdmjgsfp.1

Shai Abir, Hamish A. McGowan, Yonatan Shaked, Hezi Gildor, Efrat Morin, and Nadav G. Lensky

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Short summary
Understanding air-sea heat exchange is vital for studying ocean dynamics. Eddy Covariance measurements over the Gulf of Eilat revealed a 3.22 m year-1 evaporation rate. Inconsistent with bulk formulae estimation in stable atmospheric conditions. Requiring bulk formulae to be revisited in these environments. The surface fluxes have a net cooling effect on the gulf water on an annual mean (-79 W m-2), balanced by a strong exchange flux between the Red Sea and the Gulf of Eilat.