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/

Zendy Plus

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

Zendy Tools

Zendy Open

In the Nastrom-Gage spectrum of atmospheric turbulence we observe a $k^{-3}$energy spectrum that transitions into a $k^{-5/3}$ spectrum, with increasingwavenumber $k$. The transition occurs near a transition wavenumber $k_t$,located near the Rossby deformation wavenumber $k_R$. The Tung-Orlando theoryinterprets this spectrum as a double downscale cascade of potential enstrophyand energy, from large scales to small scales, in which the downscale potentialenstrophy cascade coexists with the downscale energy cascade over the samelength-scale range. We show that, in a temperature forced two-layerquasi-geostrophic model, the rates with which potential enstrophy and energyare injected place the transition wavenumber $k_t$ near $k_R$. We also showthat if the potential energy dominates the kinetic energy in the forcing range,then the Ekman term suppresses the upscale cascading potential enstrophy morethan it suppresses the upscale cascading energy, a behavior contrary to whatoccurs in two-dimensional turbulence. As a result, the ratio $\gn/\gee$ ofinjected potential enstrophy over injected energy, in the downscale direction,decreases, thereby tending to decrease the transition wavenumber $k_t$ further.Using a random Gaussian forcing model, we reach the same conclusion, under themodeling assumption that the asymmetric Ekman term predominantly suppresses thebottom layer forcing, thereby disregarding a possible entanglement between theEkman term and the nonlinear interlayer interaction. Based on these results, weargue that the Tung-Orlando theory can account for the approximate coincidencebetween $k_t$ and $k_R$. We also identify certain open questions that requirefurther investigation via numerical simulations.

The effect of asymmetric large-scale dissipation on energy and potential enstrophy injection in two-layer quasi-geostrophic turbulence