Atmosphere Ocean Science Colloquium

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Diapycnal Mixing in the Ocean Interior: Patterns, Processes and Parameterizations

Speaker: Jen Mackinnon, Scripps

Location: Warren Weaver Hall 102

Date: Friday, May 2, 2014, 11 a.m.

Synopsis:

Here I will present an overview of current research into diapycnal turbulent mixing in the ocean interior. The talk will be loosely structured around ongoing work as part of a NSF and NOAA funded Climate Process Team tasked with improving representations of diapycnal mixing in global ocean models. Though average observed diapycnal mixing rates in the deep ocean are consistent with values required by inverse models, recent focus has been on the dramatic spatial variability of mixing rates in both the upper and deep ocean, which spans several orders of magnitude. Climate models have been shown to be very sensitive not only to the overall level but to the detailed distribution of mixing. This spatial pattern is largely driven by the geography of generation, propagation and destruction of internal waves, which are thought to supply much of the power for turbulence in the ocean interior.The generation and propagation of internal waves (particularly internal tides) is a somewhat well understood problem, but the processes that control wave breaking, and the associated geography of mixing, remain an active area of research. In the upper ocean the phenomenology becomes even more complex, with not only internal waves but three-dimensional ageostrophic sub-mesoscale processes playing a key role in both upper ocean mixing and re-stratification. To complement the deep mixing discussion, I'll also present a few observations of such processes from recent fieldwork in the Bay of Bengal.