An explanation in the outflows from the semi-enclosed seas (Persian Gulf)

Semi-enclosed and marginal seas as the Red Sea and the Persian Gulf as a result of excessive evaporation turn into an "inverse estuary" like flow that produce strong plumes which from outflows as they inter the open ocean. Red Sea and the Persian Gulf outflow extend to the depths of 800 and 500 m respectively (Bower et al 2000) and a layered structure with vertical scales (depths) of 50 to 100 m as well as with layers with finer scales (25m) . As the intrusive outflow have inversion in vertical temperature and salinity profiles they are pron to double diffusive convection which can produce layers that are 20 to 30 m rhich according to the existing laboratory observations (Ruddich and Turner, 1979). But thicher layers have been attributed to processes such as tidal pulsations or outflow separation due to bottom topography or source variability etc. (Fedorov 1978, Bower et al 2000). However laboratory simulation of plumes in enclosed stratified environment shows that the low frequency internal waves exited by the plum outflow can produce horizontal counter flowing shear (Wong et al 2000) that may break up intrusive fronts and form layers. The scales of such layers are determined by the flow structure of the internal wave modes.Using the available data from the outflows (specially the one from the Persian Gulf to Oman Sea) and ambient water properties we estimate the vertical scales and number of coarse layers (in salinity and temperature profiles) of internal waves as they may be responsible in floding up the outflow front. The estimated scales are compared with the observations although we have to remember that the these outflows occur in open sea and with other effects such as Coriolis, tidal effects..