Bottom topography and oceanic variability


Joseph LaCasce


University of Oslo


Wed, 14/11/2018 - 11:00am


RC-4082, The Red Centre, UNSW


Many fundamental theories of ocean circulation
neglect bottom topography. Indeed, ocean models with a flat
bottom are still often used to study different phenomena. Here
we examine evidence that the bottom affects eddies throughout
the water column. Current meter data point to the existence of a mode
of variability which is largest at the surface and decreases to
near zero at the bottom. We show that the gravest baroclinic mode
over a sloping bottom has the same shape, even with very weak
slopes. Then we examine how topography affects ocean jets, like the
Antarctic Circumpolar Current. Having relatively modest bottom bumps
can suppress baroclinic instability, favoring lateral (barotropic)
instability instead. Taken together, the results suggest topography
exerts an important influence on variability, and thus that flat bottom
models may be misleading.

Joe LaCasce did his PhD in the MIT/WHOI Joint program in physical
oceanography. He was a post-doc at IFREMER in Brest, France
before returning to Woods Hole as an assistant scientist. He moved
to Norway in 2002 and has been a professor at the University of
Oslo since 2007.

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