Observations of the summer Red Sea circulation

Abstract

[1] Aiming at exploring and understanding the summer circulation in the Red Sea, a cruise was conducted in the basin during the summer of 2001 involving hydrographic, meteorological, and direct current observations. The most prominent feature, characteristic of the summer circulation and exchange with the Indian Ocean, is a temperature, salinity, and oxygen minimum located around a depth of 75 m at the southern end of the basin, associated with Gulf of Aden Intermediate Water inflowing from the Gulf of Aden during the summer season as an intruding subsurface layer. Stirring and mixing with ambient waters lead to marked increases in temperature (from 16.5 to almost 33°C) and salinity (from 35.7 to more than 38 psu) in this layer by the time it reaches midbasin. The observed circulation presents a very vigorous pattern with strong variability and intense features that extend the width of the basin. A permanent cyclone, detected in the northern Red Sea, verifies previous observations and modeling studies, while in the central sector of the basin a series of very strong anticyclones were observed with maximum velocities exceeding 1 m/s. The three-layer flow pattern, representative of the summer exchange between the Red Sea and the Gulf of Aden, is observed in the strait of Bab el Mandeb. In the southern part of the basin the layer flow is characterized by strong banking of the inflows and outflows against the coasts. Both surface and intermediate water masses involved in the summer Red Sea circulation present prominent spatial variability in their characteristics, indicating that the eddy field and mixing processes play an important role in the summer Red Sea circulation.

In-situ observation of deep water corals in the northern Red Sea waters of Saudi Arabia

“…The deeper part of the Red Sea basin is ventilated by slope convection fed by the outflow from the Gulf of Suez and the Gulf of Aqaba (Quadfasel and Baunder, 1993;Quadfasel, 2001). Due to the large water reservoir of the Gulf of Aqaba, the latter outflow is steadier and provides a more permanent source for the Red Sea Deep water (Quadfasel, 2001;Sofianos and Johns, 2007). This leads to a southward flow that merges with the southward flow of the lower thermocline in the interior of the basin to make up the outflow of Red Sea Water through Bab El Mandeb.…”

The response of the Red Sea to a strong wind jet near the Tokar Gap in summer

“…Their results show that the ocean color data can provide information about the surface circulation in the Red Sea, and the circulation can influence the distribution of chlorophyll-a. Sofianos and Johns (2007) demonstrate by using shipboard ADCP data from an along-axis cruise track that there is a strong dipole near 19 o N with a cyclone in the north and an anticyclone in the south.…”

Synergistic Use of Remote Sensing and Modeling to Assess an Anomalously High Chlorophyll-a Event during Summer 2015 in the South Central Red Sea

“…Salinity increases from 36.5% in the far southern region to 40-41% towards the northern part [7]. It is noteworthy that below the pycnocline (205-300 m), the entire Red Sea basin has water with extremely uniform temperature and salinity, with values of 21.6 and 40.6 practical salinity units (psu) ‰, respectively [8][9][10].…”