Atmosphere Ocean Science Colloquium

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Jet drift over topography and jet-topography interactions

Speaker: Hemant Khatri, Princeton

Location: Warren Weaver Hall 1302

Date: Wednesday, March 4, 2020, 3:30 p.m.

Synopsis:

Alternating jets play an important role in the heat and tracer transport in the oceans. Oceanic jets are seen to possess Spatio-temporal variability in the presence of topography. For example, over a zonally sloped topography, the jets tend to tilt from the zonal direction and drift in the meridional direction. 

We study why the jets tilt and drift over topography, and what implications these jets can have on the large-scale circulation. In a baroclinic quasi-geostrophic model, the jets drift to compensate for the potential vorticity (PV) advection across PV isolines by the mean flow. In addition, the drifting jets are directly forced by the imposed vertical shear via coupling through topography. On the other hand, eddies oppose the jets, which is opposite to the case of eddy-driven zonal jets. Also, eddy fluxes are significantly enhanced over topography.  It is shown that jet drift is controlled by linear dynamics and drift speeds agree well with phase speeds of Rossby waves.