Salt fingering in the Cyprus eddy

The Cyprus Eddy, is a warm core eddy wedged between the seasonal and permanent thermoclines. Density Ratio (Rρ) and Turner Angle (Tu) indicate salt-fingering favorable conditions in both thermoclines (Tu > 45°). Buoyancy fluxes due to heat and salt estimation using Kunze's (1987) model for thick interfaces indicate that during summer, the buoyancy fluxes in, the seasonal thermocline are one order of magnitude larger than in the permanent thermocline. During all other seasons when the seasonal thermocline exists the buoyancy flux through it is of the same order of magnitude as that of the permanent thermocline. These fluxes are significant in determining the T and S signals of the eddy. The flux of salt into the eddy by salt fingering through the seasonal thermocline during the 9 summer months accounts for the excess of salt observed in the eddy (0.25-0.35 ptt). These suggested fluxes are further substantiated by the following observed changes in the chemical composition of the water in the eddy. High nitrate and low oxygen (>1.5 μM/kg; <175 mM/kg, respectively) are found in the eddy during winter when the seasonal thermocline dissapears, so the eddy is exposed to the atmosphere its primary source of oxygen and the opposite is expected.This discrepancy can be resolved by assuming a flux of high nitrate/low oxygen water into the eddy from below the permanent thermocline. During summer when the eddy is sealed off from the atmoshere by the seasonal thermocline the appearance of high oxygen and low nitrate (>220 μM/kg; <lμM/kg respectively) in die eddy indicates the exchange of water with the euphotic zone, overlying the seasonal thermocline.