Sack Lunch Seminar (SLS) - Leo Middleton (WHOI)

Un-mixing the ocean: Double diffusion and turbulence in polar oceans.

 Double diffusion refers to a variety of turbulent processes in which potential energy is released into kinetic energy, made possible by the difference in molecular diffusivities between salinity and temperature in the ocean. We present a new method for estimating the kinetic energy dissipation rates forced by double-diffusive convection using timescale temperature and salinity data. The method estimates the up-gradient diapycnal buoyancy flux associated with double diffusion, which is hypothesized to balance the dissipation rate. To calculate the temperature and salinity gradients on small scales we apply a canonical scaling for compensated thermohaline variance (or ‘spice’) on sub-measurement scales with a fixed buoyancy gradient. Our predicted dissipation rates compare favorably with microstructure measurements collected in the Chukchi Sea and beneath George VI Ice Shelf.

About this series: The Atmosphere, Ocean and Climate Sack Lunch Seminar Series is an informal seminar series within PAOC that focuses on more specialized topics than the PAOC Colloquium. Seminar topics include all research concerning the science of atmosphere, ocean and climate. The seminars usually take place on Wednesdays from 12-1pm. The presentations are either given by an invited speaker or by a member of PAOC and can focus on new research or discussion of a paper of particular interest. Contact: sacklunch-committee@mit.edu