Mesoscale to Submesoscale Transition in the California Current System. Part III: Energy Balance and Fluxстатья
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 29 сентября 2021 г.
Аннотация:This is the last of a suite of three papers about the transition that occurs in numerical simulations for an
idealized equilibrium, subtropical, eastern-boundary upwelling current system similar to the California
Current. The transition is mainly explained by the emergence of ubiquitous submesoscale density fronts and
ageostrophic circulations about them in the weakly stratified surface boundary layer. Here the highresolution
simulations are further analyzed from the perspective of the kinetic energy (KE) spectrum shape
and spectral energy fluxes in the mesoscale-to-submesoscale range in the upper ocean. For wavenumbers
greater than the mesoscale energy peak, there is a submesoscale power-law regime in the spectrum with an
exponent close to 2. In the KE balance an important conversion from potential to kinetic energy takes
place at all wavenumbers in both mesoscale and submesoscale ranges; this conversion is the energetic
counterpart of the vertical restratification flux and frontogenesis discussed in the earlier papers. A significant
forward cascade of KE occurs in the submesoscale range en route to dissipation at even smaller scales.
This is contrary to the inverse energy cascade of geostrophic turbulence and it is, in fact, fundamentally
associated with the horizontally divergent (i.e., ageostrophic) velocity component. The submesoscale dynamical
processes of frontogenesis, frontal instability, and breakdown of diagnostic force balance are all
essential elements of the energy cycle of potential energy conversion and forward KE cascade.