Raffaele Ferrari, MIT, Earth, Atmospheric and Planetary Sciences, USA


A new theory of the abyssal ocean circulation


It has been long been recognized that the large-scale circulation of the abyssal ocean is enabled by small-scale turbulent mixing. Theories developed in the fifties and sixties posited that the diapycnal mixing drives widespread upwelling of abyssal waters and broad poleward meridional flows. We will argue that these predictions need to be revised in view of recent observations showing that mixing is strongly enhanced close the ocean seafloor, where the breaking of internal tides and lee waves is most vigorous. The bottom-intensified mixing induces a pattern of near-bottom up- and downwelling along ridges and seamounts that is quite different from the traditionally-assumed widespread upwelling. These along-boundary flows drive a horizontal circulation characterized by zonal flows in the ocean interior and meridional flows along the ocean’s western boundaries. The along-boundary flows further set the overall abyssal ocean stratification. We conclude by discussing the implications of this new emerging theory of the abyssal ocean circulation and stratification for climate studies.


Tuesday November 19, 11:15


Rossbysalen C609, Arrhenius laboratory, Svante Arrhenius väg 16C, 6th floor