Properties of Steady Geostrophic Turbulence with Isopycnal Outcropping
| Autor: | M. J. Molemaker, Xavier Capet, Guillaume Roullet, James C. McWilliams |
|---|---|
| Přispěvatelé: | Laboratoire de physique des océans (LPO), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Institute of Geophysics and Planetary Physics [Los Angeles] (IGPP), University of California [Los Angeles] (UCLA), University of California-University of California |
| Rok vydání: | 2012 |
| Předmět: |
010504 meteorology & atmospheric sciences
Baroclinity Oceanography Atmospheric sciences 01 natural sciences Potential vorticity Physics::Fluid Dynamics Wavenumber Mesoscale processes [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography Physics::Atmospheric and Oceanic Physics Baroclinic flows 0105 earth and related environmental sciences Physics Isopycnal 010505 oceanography Turbulence Plane (geometry) Instability Geophysics Quasigeostrophic models Eddy 13. Climate action Geostrophic wind |
| Zdroj: | Journal of Physical Oceanography Journal of Physical Oceanography, American Meteorological Society, 2012, 42 (1), pp.18-38. ⟨10.1175/JPO-D-11-09.1⟩ |
| ISSN: | 1520-0485 0022-3670 |
| DOI: | 10.1175/jpo-d-11-09.1 |
| Popis: | High-resolution simulations of β-channel, zonal-jet, baroclinic turbulence with a three-dimensional quasigeostrophic (QG) model including surface potential vorticity (PV) are analyzed with emphasis on the competing role of interior and surface PV (associated with isopycnal outcropping). Two distinct regimes are considered: a Phillips case, where the PV gradient changes sign twice in the interior, and a Charney case, where the PV gradient changes sign in the interior and at the surface. The Phillips case is typical of the simplified turbulence test beds that have been widely used to investigate the effect of ocean eddies on ocean tracer distribution and fluxes. The Charney case shares many similarities with recent high-resolution primitive equation simulations. The main difference between the two regimes is indeed an energization of submesoscale turbulence near the surface. The energy cycle is analyzed in the (k, z) plane, where k is the horizontal wavenumber. In the two regimes, the large-scale buoyancy forcing is the primary source of mechanical energy. It sustains an energy cycle in which baroclinic instability converts more available potential energy (APE) to kinetic energy (KE) than the APE directly injected by the forcing. This is due to a conversion of KE to APE at the scale of arrest. All the KE is dissipated at the bottom at large scales, in the limit of infinite resolution and despite the submesoscales energizing in the Charney case. The eddy PV flux is largest at the scale of arrest in both cases. The eddy diffusivity is very smooth but highly nonuniform. The eddy-induced circulation acts to flatten the mean isopycnals in both cases. |
| Databáze: | OpenAIRE |
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