Mesoscale to Submesoscale Transition in the California Current System. Part I: Flow Structure, Eddy Flux, and Observational Testsстатья
Статья опубликована в высокорейтинговом журнале
Информация о цитировании статьи получена из
Web of Science,
Scopus
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 29 сентября 2021 г.
Аннотация:In computational simulations of an idealized subtropical eastern boundary upwelling current system,
similar to the California Current, a submesoscale transition occurs in the eddy variability as the horizontal
grid scale is reduced to O(1) km. This first paper (in a series of three) describes the transition in terms of
the emergent flow structure and the associated time-averaged eddy fluxes. In addition to the mesoscale
eddies that arise from a primary instability of the alongshore, wind-driven currents, significant energy is
transferred into submesoscale fronts and vortices in the upper ocean. The submesoscale arises through
surface frontogenesis growing off upwelled cold filaments that are pulled offshore and strained in between
the mesoscale eddy centers. In turn, some submesoscale fronts become unstable and develop submesoscale
meanders and fragment into roll-up vortices. Associated with this phenomenon are a large vertical vorticity
and Rossby number, a large vertical velocity, relatively flat horizontal spectra (contrary to the prevailing
view of mesoscale dynamics), a large vertical buoyancy flux acting to restratify the upper ocean, a submesoscale
energy conversion from potential to kinetic, a significant spatial and temporal intermittency in the
upper ocean, and material exchanges between the surface boundary layer and pycnocline. Comparison with
available observations indicates that submesoscale fronts and instabilities occur widely in the upper ocean,
with characteristics similar to the simulations.