A mixed‐layer study of the formation of Levantine intermediate water

Abstract

A mixed‐layer model is used to investigate the formation of Levantine Intermediate Water (LIW) over the Eastern Mediterranean. The one‐dimensional model is initialized with climatological hydrography and integrated over the Levantine basin with forcing by climatological surface fluxes. Realistic and repeated seasonal mixed‐layer cycles are obtained if the annual surface heat input and water loss are offset by a parameterized horizontal advection. The model integrations show that LIW is formed during winter in the mixed layer of the Northwestern Levantine. The preferred formation region for LIW is found through idealized experiments to be controlled by the preconditioning of the hydrography, especially that of the cold, cyclonic Rhodes gyre, rather than by the pattern of the climatological fluxes. The annual‐mean formation rate of LIW is estimated to be 1.0 Sv using the climatological surface fluxes. The magnitude of the annual surface fluxes alters the formation rate and modifies the formation region. An additional annual heat flux reduces the formation rate of LIW, whereas an extra cooling enhances it, as well as forming waters denser than LIW in the center of the Rhodes gyre.