Zonal jets are striking and beautiful examples of the propensity for geophysical turbulent flows to spontaneously self-organize into robust, large scale coherent structures. There exist many dynamical mechanisms for the formation of zonal jets: statistical theories (kinetic approaches, second order or larger oder closures), deterministic approaches (modulational instability, $\beta$-plumes, radiating instability, zonostrophic turbulence, and so on). A striking remark is that all these different...

Topics: Atmospheric and Oceanic Physics, Fluid Dynamics, Statistical Mechanics, Physics, Condensed Matter

Source: http://arxiv.org/abs/1602.06714

The wave kinetic equation (WKE) describing drift-wave (DW) turbulence is widely used in studies of zonal flows (ZFs) emerging from DW turbulence. However, this formulation neglects the exchange of enstrophy between DWs and ZFs and also ignores effects beyond the geometrical-optics limit. We derive a modified theory that takes both of these effects into account, while still treating DW quanta ("driftons") as particles in phase space. The drifton dynamics is described by an equation of...

Topics: Atmospheric and Oceanic Physics, Physics, Plasma Physics

Source: http://arxiv.org/abs/1608.05373

The impact of uncertainties in surface layer physics on the atmospheric general circulation is comparatively unexplored. Here the sensitivity of the zonal-mean circulation to reduced air-sea momentum roughness ($Z_{0m}$) at low flow speed is investigated with the Community Atmosphere Model (CAM3). In an aquaplanet framework with prescribed sea surface temperatures, the response to reduced $Z_{0m}$ resembles the La Ni$\tilde{\text{n}}$a minus El Ni$\tilde{\text{n}}$o response to El...

Topics: Atmospheric and Oceanic Physics, Physics

Source: http://arxiv.org/abs/1606.00566