The general circulation of the Gulf of Aqaba (Gulf of Eilat) revisited: The interplay between the exchange flow through the Straits of Tiran and surface fluxes

Abstract

[1] The Gulf of Aqaba (Gulf of Eilat) is a terminal elongated basin that exchanges water with the northern Red Sea via the Straits of Tiran. The gulf's hydrography exhibits strong seasonal variability, with deep mixing during February-March and stable stratification afterward. We use an oceanic model to investigate the annual cycle of the general circulation and hydrographic conditions in the gulf. We demonstrate that on a subannual time scale, the general circulation deviates from the standard depiction of inverse estuarine circulation. During the restratification season (April-August), the exchange flux with the northern Red Sea is maximal and is driven by density differences between the basins, while atmospheric fluxes actually counteract this exchange flow. The observed warming of the surface layer is mainly due to advection of warm water from the northern Red Sea, with a smaller contribution from surface heating. During the mixing season (September-March), the exchange flux and the advection of heat are minimal and atmospheric fluxes drive convection rather than the exchange flow. We estimate the seasonality of the exchange flow through the Straits of Tiran. The seasonal variability in the exchange flow is large and ranges from 0.04 Sv during early spring to 0.005 Sv during early winter.Citation: Biton, E., and H. Gildor (2011), The general circulation of the Gulf of Aqaba (Gulf of Eilat) revisited: The interplay between the exchange flow through the Straits of Tiran and surface fluxes,

Biogeochemical evidence of heterotrophic N<sub>2</sub> fixation in the Gulf of Aqaba (Israel), Red Sea

“…Comparison of the 5 simulated vertical structure with and without nudging shows that this correction has negligible effects on deep waters, where the effects of N 2 fixation are the most relevant. This is consistent with the existing literature about circulation of the Gulf of Aqaba, which describes how geomorphology and bathymetry limit water exchange between the Gulf of Aqaba and the Red Sea to the upper 300 m (Wolf-Vecht et al, 1992;Biton and Gildor, 2011). It is, therefore, unlikely that horizontal transport could explain the observed accumulation of deep NO 3 .…”

“…During winter 25 (December to March), convective vertical mixing usually extends to depths >300 m (Labiosa et al, 2003), and even reaches the bottom (~700-800 m bottom depth) in some extreme years (Figure 2-3). From April to September, the water column is thermally stratified, and inflowing warm surface waters from outside the Gulf occupy the layer above the thermocline (Genin and Paldor, 1998;Berman et al, 2000;Biton and Gildor 2011). During fall (October to December), surface cooling and high evaporation rates erode the seasonal stratification and re-establish a well-mixed water column (Berman et al, 2003;30 Biogeosciences Discuss., https://doi.org /10.5194/bg-2017-550 Manuscript under review for journal Biogeosciences Discussion started: 19 January 2018 c Author(s) 2018.…”

Biophysical Simulations Support Schooling Behavior of Fish Larvae Throughout Ontogeny

“…The GoA circulation is characterized by deep mixing during winter (Feb-March), and stratification during the rest of the year, with a strong density-driven exchange flow with the Red sea during April-August (Biton and Gildor, 2011). The GoA circulation is also dominated by a chain of several sub-meso-scale eddies along its main axis (Biton and Gildor, 2011).…”

“…The resolution of the MITgcm data was of 1 h (temporal), 300 m (horizontal), and 32 depth layers most of which were concentrated in the upper 300 m (Biton and Gildor, 2011;Berenshtein et al, 2017). The temporal resolution of the particle tracking model was of 10 min (time-step length), with a spatial resolution of centimeters due to a continuous 3D grid, and spatial interpolation of larval positions.…”

Buoyancy-driven circulation in the Red Sea

“…However, these data were collected over a short time period and therefore may not be representative of the annual mean. Biton and Gildor (2011) Protocol. A small fraction of atmospheric CFCs enters the ocean through air-sea gas exchange at the ocean surface.…”