English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The phase space of driftons (drift-wave quanta) is studied within thegeneralized Hasegawa--Mima collisionless-plasma model in the presence of zonalflows. This phase space is made intricate by the corrections to the drifton rayequations that were recently proposed by Parker [J. Plasma Phys. $\textbf{82}$,95820602 (2016)] and Ruiz $\textit{et al.}$ [Phys. Plasmas $\textbf{23}$,122304 (2016)]. Contrary to the traditional geometrical-optics (GO) model ofthe drifton dynamics, it is found that driftons can be not only trapped orpassing, but they can also accumulate spatially while experiencing indefinitegrowth of their momenta. In particular, it is found that the Rayleigh--Kuothreshold known from geophysics corresponds to the regime when such "runaway"trajectories are the only ones possible. On one hand, this analysis helpsvisualize the development of the zonostrophic instability, particularly itsnonlinear stage, which is studied here both analytically and throughwave-kinetic simulations. On the other hand, the GO theory predicts that zonalflows above the Rayleigh--Kuo threshold can only grow; hence, the deteriorationof intense zonal flows cannot be captured within a GO model. In particular,this means that the so-called tertiary instability of intense zonal flowscannot be adequately described within the quasilinear wave kinetic equation,contrary to some previous studies.

On the structure of the drifton phase space and its relation to the Rayleigh--Kuo criterion of the zonal-flow stability