Search Results
transferring energy to the deep ocean. Fig . 1. Wavenumber frequency diagram with the dispersion relations for equatorial Kelvin waves (green), Yanai waves (red), and baroclinic Rossby waves (blue). Only the first baroclinic mode is represented. The dispersion relation for barotropic Rossby waves with different meridional wavenumbers (0, 1 × 10 −6 , 2 × 10 −6 , and 4 × 10 −6 m −1 from top to bottom) are in black. The frequency and wavenumbers of the forcing used in the experiments conducted in this study
transferring energy to the deep ocean. Fig . 1. Wavenumber frequency diagram with the dispersion relations for equatorial Kelvin waves (green), Yanai waves (red), and baroclinic Rossby waves (blue). Only the first baroclinic mode is represented. The dispersion relation for barotropic Rossby waves with different meridional wavenumbers (0, 1 × 10 −6 , 2 × 10 −6 , and 4 × 10 −6 m −1 from top to bottom) are in black. The frequency and wavenumbers of the forcing used in the experiments conducted in this study
another aspect of the interannual-to-decadal variability of the AMOC computed along geopotential levels. Both studies revealed that when mesoscale eddies are (even partially) resolved, nonlinearities become significant and the phase of the AMOC time series is no longer locked to the phase of the atmospheric forcing: it becomes partly chaotic, up to decadal time scales. Using a laminar global OGCM with an increase in resolution in the Agulhas region driven by an atmospheric reanalysis, Biastoch et al
another aspect of the interannual-to-decadal variability of the AMOC computed along geopotential levels. Both studies revealed that when mesoscale eddies are (even partially) resolved, nonlinearities become significant and the phase of the AMOC time series is no longer locked to the phase of the atmospheric forcing: it becomes partly chaotic, up to decadal time scales. Using a laminar global OGCM with an increase in resolution in the Agulhas region driven by an atmospheric reanalysis, Biastoch et al
the EDJs as basin modes does not appear to be essential to the theory. EIC-like currents also appear but only within a few degrees from the western boundary, inconsistent with the Atlantic observations. To remedy this discrepancy, Ménesguen et al. (2009) explore the case where the forcing is still along the western boundary but is now confined to the upper 2500 m—instead of appearing as a single baroclinic mode. In this case, the forcing excites not only the short low baroclinic mode MRG waves
the EDJs as basin modes does not appear to be essential to the theory. EIC-like currents also appear but only within a few degrees from the western boundary, inconsistent with the Atlantic observations. To remedy this discrepancy, Ménesguen et al. (2009) explore the case where the forcing is still along the western boundary but is now confined to the upper 2500 m—instead of appearing as a single baroclinic mode. In this case, the forcing excites not only the short low baroclinic mode MRG waves
are distributed on the same ¼° grid. We also use a numerical simulation performed in the framework of the Drakkar project ( Barnier et al. 2014 ) with the ORCA12 model. It is based on the NEMO modeling framework ( Madec 2008 ) for the ocean and sea ice. The isotropic tripolar grid covers the global ocean with a resolution of 1/12° (9.3 km) at the equator, refined at higher latitudes (6.5 km at 45°, 1.8 km in the Ross and Weddell seas). The atmospheric forcing, the Drakkar forcing set (DFS4.4), is
are distributed on the same ¼° grid. We also use a numerical simulation performed in the framework of the Drakkar project ( Barnier et al. 2014 ) with the ORCA12 model. It is based on the NEMO modeling framework ( Madec 2008 ) for the ocean and sea ice. The isotropic tripolar grid covers the global ocean with a resolution of 1/12° (9.3 km) at the equator, refined at higher latitudes (6.5 km at 45°, 1.8 km in the Ross and Weddell seas). The atmospheric forcing, the Drakkar forcing set (DFS4.4), is
link between layering and mixing is within reach, making such links for the case of LCEs might be a more challenging prospect. Warm-core rings are, in general, near-surface ventilated eddies ( Dewar 1987 , 1988 ), and atmospheric forcing in the Gulf of Mexico is particularly intense, including hurricanes and cold fronts. These latter processes result in pronounced momentum and heat fluxes that mix and cool the ocean as well as generate inertia gravity waves (IGWs) that penetrate deep into the
link between layering and mixing is within reach, making such links for the case of LCEs might be a more challenging prospect. Warm-core rings are, in general, near-surface ventilated eddies ( Dewar 1987 , 1988 ), and atmospheric forcing in the Gulf of Mexico is particularly intense, including hurricanes and cold fronts. These latter processes result in pronounced momentum and heat fluxes that mix and cool the ocean as well as generate inertia gravity waves (IGWs) that penetrate deep into the
et al. (1993) , the barotropic streamfunction is obtained by integrating along potential vorticity contours the two forcings: the Ekman pumping and the baroclinic contribution to bottom pressure torque [the so-called JEBAR effect found by Sarkisyan and Ivanov (1971) ]. (v) Quite a number of other studies used full blown OGCMs to spin up the barotropic circulation keeping the model temperature and salinity close to the observed time-mean temperature and salinity ( Sarkisyan and Keonjiyan 1975
et al. (1993) , the barotropic streamfunction is obtained by integrating along potential vorticity contours the two forcings: the Ekman pumping and the baroclinic contribution to bottom pressure torque [the so-called JEBAR effect found by Sarkisyan and Ivanov (1971) ]. (v) Quite a number of other studies used full blown OGCMs to spin up the barotropic circulation keeping the model temperature and salinity close to the observed time-mean temperature and salinity ( Sarkisyan and Keonjiyan 1975
. This permanent source of available potential energy (APE) parameterizes forcing in the ocean acting on large scales and balances the conversion of available potential energy into kinetic energy by baroclinic production. The kinetic energy injected by baroclinic production has to be balanced by some kind of dissipation and we apply two different kinds of kinetic energy dissipation. Momentum dissipation by a linear drag of the zonal-mean velocity field acts predominantly on the largest scales. This
. This permanent source of available potential energy (APE) parameterizes forcing in the ocean acting on large scales and balances the conversion of available potential energy into kinetic energy by baroclinic production. The kinetic energy injected by baroclinic production has to be balanced by some kind of dissipation and we apply two different kinds of kinetic energy dissipation. Momentum dissipation by a linear drag of the zonal-mean velocity field acts predominantly on the largest scales. This
basin using a pseudospectral NHB model on a cubic domain [(4500 m) 3 , up to 2048 3 grid points]. Their grid aspect ratio dx / dz is set to 1 in order to properly represent nonhydrostatic dynamics. They highlight a forward energy cascade generated by a stochastic forcing at scales smaller than the forcing scale (around 450 m in their oceanic application). Pouquet and Marino (2013) show an increase of the forward cascade with higher Rossby and Reynolds numbers, while Marino et al. (2015) show
basin using a pseudospectral NHB model on a cubic domain [(4500 m) 3 , up to 2048 3 grid points]. Their grid aspect ratio dx / dz is set to 1 in order to properly represent nonhydrostatic dynamics. They highlight a forward energy cascade generated by a stochastic forcing at scales smaller than the forcing scale (around 450 m in their oceanic application). Pouquet and Marino (2013) show an increase of the forward cascade with higher Rossby and Reynolds numbers, while Marino et al. (2015) show
momentum and density are equal (Prandtl number is 1), suppressing McIntyre’s instability ( McIntyre 1970 ). The time integration follows a leapfrog scheme with the Matsuno scheme blended every five time steps. The baroclinic time step is 20 s. No explicit forcing is applied. The initial vortex profile is a solution of the QG dynamics and therefore will be weakly unstable in the PE framework. Small random perturbations are initially added to the energy of the system in order to accelerate the slow
momentum and density are equal (Prandtl number is 1), suppressing McIntyre’s instability ( McIntyre 1970 ). The time integration follows a leapfrog scheme with the Matsuno scheme blended every five time steps. The baroclinic time step is 20 s. No explicit forcing is applied. The initial vortex profile is a solution of the QG dynamics and therefore will be weakly unstable in the PE framework. Small random perturbations are initially added to the energy of the system in order to accelerate the slow
.25 × 10 −5 m 4 s −1 for a vertical grid step of 5 m. The use of the same diffusion coefficient for temperature and salinity inhibits the occurrence of any double-diffusive process. The time integration is done using a leapfrog scheme with the Matsuno scheme blended every 20 time steps. No explicit forcing is applied. c. The quasigeostrophic numerical model The model used is Hua and Haidvogel’s (1986) fully spectral QG model. It is run with horizontal and vertical grid steps of dx = 500 m and
.25 × 10 −5 m 4 s −1 for a vertical grid step of 5 m. The use of the same diffusion coefficient for temperature and salinity inhibits the occurrence of any double-diffusive process. The time integration is done using a leapfrog scheme with the Matsuno scheme blended every 20 time steps. No explicit forcing is applied. c. The quasigeostrophic numerical model The model used is Hua and Haidvogel’s (1986) fully spectral QG model. It is run with horizontal and vertical grid steps of dx = 500 m and
