Atmosphere Ocean Science Student Seminar

Lagrangian mean flow generated by vertically confined internal gravity wavepackets

Speaker: Wenjing Dong, PhD Student

Location: Warren Weaver Hall 1314

Date: Friday, February 22, 2019, 3:30 p.m.

Synopsis:

Internal gravity wavepackets exert stress on the fluids, and can induce nonzero Lagrangian mean motion of second order in the wave amplitude. Since passive tracers are advected by fluids, understanding the Lagrangian mean motion is important to studies in the transport of passive tracers in the ocean. I will present theoretical and numerical computations of the Lagrangian mean flow generated by a horizontally slowly varying, vertically confined wavepacket.  Previous results show that the Lagrangian mean flow response consists only of a weak baroclinic mode, which is steady in the frame moving with the wavepacket. I will show that resonance can occur in the baroclinic mode response for physical parameters that are relevant in the ocean, leading to a strong baroclinic response eventually. When resonance does not occur, the barotropic mode response, missing from previous studies, dominates over the baroclinic mode response.