Raffaele Ferrari, a Scripps/UC San Diego alumnus and the Cecil and Ida Green Professor of Oceanography at the Massachusetts Institute of Technology (MIT), will present a technical lecture at Scripps as the recipient of the 2016 Robert L. and Bettie P. Cody Award in Ocean Sciences:
Technical Lecture: “Toward a New Abyssal Recipe”
October 11 at 3 p.m. at the Scripps Seaside Forum (light refreshments precede lecture)
Starting with Walter Munk’s seminal paper on abyssal recipes, it is generally understood that small-scale mixing, such as is caused by breaking internal waves, drives upwelling of the densest ocean waters that sink to the ocean bottom at high latitudes. However, the observational evidence from the last twenty years that the strong turbulent fluxes generated by small-scale mixing in the stratified ocean interior are more vigorous close to the ocean seafloor than above implies that small-scale mixing converts light waters into denser ones, thus driving a net sinking of abyssal waters. Using a combination of theoretical ideas and numerical models, we will argue that abyssal waters upwell along weakly stratified boundary layers, where small-scale mixing of density decreases to zero to satisfy the no density flux condition at the ocean bottom. This new abyssal recipe will be first illustrated with observations from the Drake Passage region in the Southern Ocean. Then we will discuss the implications of the new recipe for the global ocean circulation. We will provide evidence that that the abyssal ocean meridional overturning circulation is the small residual of a large net sinking of waters, driven by small-scale mixing in the stratified interior above the bottom boundary layers, and a slightly larger net upwelling, driven by the decay of small-scale mixing in the boundary layers.
Ferrari will also present a public lecture, “The Role of Ocean Turbulence in Climate,” on October 12. More details about the public lecture here: https://scripps.ucsd.edu/events/cody-award-public-lecture-role-ocean-turbulence-climate