Atmosphere Ocean Science Colloquium
Creation of coherent zonal structures from selective decay and secondary instability
Speaker: Di Qi, Courant
Location: Warren Weaver Hall 1302
Date: Wednesday, April 10, 2019, 3:30 p.m.
Persistent zonal flows have been widely observed in the mesoscale motions of the atmosphere and ocean and in the magnetically confined plasmas. The emergence of persistent zonal structures is studied following the strategies of the selective decay principle and the secondary instability analysis. The core physics in the edge regime of the magnetic-fusion tokamaks can be described qualitatively by the one-state modified Hasegawa-Mima (MHM) model, which creates enhanced zonal flows and more physically relevant features in comparison with the familiar Charney-Hasegawa-Mima (CHM) model for both plasma and geophysical flows. The secondary instability offers a characterization of the convergence process to the purely zonal structure together with the selective decay effect from the dissipation. Direct numerical simulations with forcing from the drift wave instability are carried out to confirm the theory.