Nonlinear equilibration of two-dimensional Eady waves: a new perspective

To avoid subgrid turbulence parameterizations and computational diffusion, the analogy is developed using Eady's generalized baroclinic instability problem. Eady's generalized model has two semi-infinite regions of large PV surrounding a layer of relatively small PV. Without boundaries, frontal collapse, or strong diffusion the model still produces equilibrated states, with structure similar to the vortex streets that emerge from unstable barotropic shear layers. The similarity is greatest when the baroclinic development is viewed in isentropic coordinates. The contrast between the present equilibrated solutions, which exhibit no vertical tilt, and Blumen's diffusive frontogenesis model, which allows the wave to retain its phase tilt, is briefly discussed. -Authors