Buoyancy-driven circulation in the Red Sea
Citable URI
https://hdl.handle.net/1912/6752DOI
10.1575/1912/6752Abstract
This thesis explores the buoyancy-driven circulation in the Red Sea, using a combination of
observations, as well as numerical modeling and analytical method.
The first part of the thesis investigates the formation mechanism and spreading of Red Sea
Overflow Water (RSOW) in the Red Sea. The preconditions required for open-ocean convection,
which is suggested to be the formation mechanism of RSOW, are examined. The RSOW is
identified and tracked as a layer with minimum potential vorticity and maximum
chlorofluorocarbon-12. The pathway of the RSOW is also explored using numerical simulation.
If diffusivity is not considered, the production rate of the RSOW is estimated to be 0.63 Sv using
Walin’s method. By comparing this 0.63 Sv to the actual RSOW transport at the Strait of Bab el
Mandeb, it is implied that the vertical diffusivity is about 3.4 x 10-5m2 s-1 .
The second part of the thesis studies buoyancy-forced circulation in an idealized Red Sea.
Buoyancy-loss driven circulation in marginal seas is usually dominated by cyclonic boundary
currents on f-plane, as suggested by previous observations and numerical modeling. This thesis
suggests that by including β-effect and buoyancy loss that increases linearly with latitude, the
resultant mean Red Sea circulation consists of an anticyclonic gyre in the south and a cyclonic
gyre in the north. In mid-basin, the northward surface flow crosses from the western boundary to
the eastern boundary. The observational support is also reviewed. The mechanism that controls
the crossover of boundary currents is further explored using an ad hoc analytical model based on
PV dynamics. This ad hoc analytical model successfully predicts the crossover latitude of
boundary currents. It suggests that the competition between advection of planetary vorticity and
buoyancy-loss related term determines the crossover latitude.
The third part of the thesis investigates three mechanisms that might account for eddy generation
in the Red Sea, by conducting a series of numerical experiments. The three mechanisms are: i)
baroclinic instability; ii) meridional structure of surface buoyancy losses; iii) cross-basin wind
fields.
Description
Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution September 2014
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Suggested Citation
Thesis: Zhai, Ping, "Buoyancy-driven circulation in the Red Sea", 2014-09, DOI:10.1575/1912/6752, https://hdl.handle.net/1912/6752Related items
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