Orateur
Description
Abstract: Ekman-inertial instability (EII) occurs in Ro=O(1) jets when the magnitude of the anticyclonic vertical vorticity exceeds that of the Coriolis parameter, and when surface stress differs from interior viscous stress of the thermal wind shear immediately under the surface. EII is to Ekman spirals what symmetric instability is to internal waves. It can grow explosively fast at first due to its non-normal nature and eventually stabilizes to a growth rate equal to that of classical inertial instability. Because of this fast onset, it can outcompete normal-mode instabilities immediately below the surface. We outline the 1D theory and then show, using constant-density, low-noise, 2D initial value problems, that EII outcompetes inertial instability. In baroclinic, low-noise, 2D initial value problems, EII outcompetes symmetric instability, resulting in distinct patterns in energy extraction from the balanced jet.