Search Results

You are looking at 1 - 10 of 16 items for :

  • The Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean (DIMES) x
  • All content x
Clear All
Byron F. Kilbourne and James B. Girton

) found that the ocean surface mixed layer responds like a damped harmonic oscillator to impulsive wind forcing if momentum is assumed to diffuse instantaneously throughout the surface mixed layer (i.e., the layer acts like a solid, rather than a liquid, at time scales long relative to turbulence but short relative to the general circulation and mesoscale eddies). D’Asaro (1985) used this “slab” model to estimate the average wind energy flux from several long-term wind recording moorings surrounding

Full access
Dhruv Balwada, Joseph H. LaCasce, Kevin G. Speer, and Raffaele Ferrari

discussed. Here, β is proportional to the third root of the energy flux across scales or the energy dissipation rate, I n () is the n -order modified Bessel function, M () is the Kummer’s function, T L is proportional to the inverse cubic root of the enstrophy dissipation rate or the inverse square root of the total enstrophy, C n are constants, and other expressions are the same as defined in the text. The text (asymptotic) implies that the expressions are for the asymptotic limit. Table 2

Open access
Ivana Cerovečki and Matthew R. Mazloff

three Southern Hemisphere subtropical oceans ( Schmitz 1996 ; Hanawa and Talley 2001 ; Herraiz-Borreguero and Rintoul 2011 ). The properties of these water masses show high spatial and temporal variability due to the complex mix of formation processes, including air–sea buoyancy fluxes, wind-driven Ekman flow, eddy-induced transport, diapycnal ocean mixing, and upwelling (e.g., Sallée et al. 2010 ; Sloyan et al. 2010 ; Holte et al. 2012 ). Understanding these processes is fundamental for

Full access
Jesse M. Cusack, Alberto C. Naveira Garabato, David A. Smeed, and James B. Girton

of lee-wave momentum fluxes and convergence in the Southern Ocean are required to test this hypothesis. The results would have implications for numerical models that do not resolve small-scale topography and internal waves, since their effect on the momentum balance would need to be parameterized. In this paper, we document the first observations of a lee wave in the Southern Ocean and determine its properties, fluxes of energy and horizontal momentum and turbulent kinetic energy dissipation

Full access
Matthew R. Mazloff, Raffaele Ferrari, and Tapio Schneider

are no lateral topographic boundaries to support a zonal pressure or buoyancy gradient, nonlinear eddy terms become important: one can show that below the surface Ekman and diabatic layers and above any bottom boundary layers, the planetary geostrophic equations, ignoring eddy fluxes of buoyancy and momentum, would imply constant vertical velocities, , and no stratification, ( Samelson 1999 ). Here f is the Coriolis parameter, w is the vertical velocity, τ x is the zonal wind stress, and

Full access
Michael Bates, Ross Tulloch, John Marshall, and Raffaele Ferrari

) . Here, we focus on an eddy diffusivity that can be used for tracers—including potential vorticity—that depends on the state of the large-scale flow and so can change as the climate changes. Recently, Abernathey and Marshall (2013) estimated the surface cross-stream eddy diffusivity for passive tracers by diagnosing the part of the downgradient eddy flux associated with irreversible mixing using the Osborn and Cox (1972) relation, as described in section 2 . They show overall agreement with the

Full access
J. Alexander Brearley, Katy L. Sheen, Alberto C. Naveira Garabato, David A. Smeed, and Stephanie Waterman

enhanced turbulent kinetic energy (TKE) dissipation. The theory of lee waves, initially developed by Bell (1975) , has recently been generalized from two- to one-dimensional topography and modified to account for saturation of the energy radiation flux at steep topography ( Nikurashin and Ferrari 2010a ). Coarse-scale regional and global estimates of lee-wave energy radiation ( Nikurashin and Ferrari 2010b ; Scott et al. 2011 ) are now available. Alongside the development of modified linear lee

Full access
Alberto C. Naveira Garabato, Kurt L. Polzin, Raffaele Ferrari, Jan D. Zika, and Alexander Forryan

“Reynolds decomposition” of variables into a slowly changing mean state (indicated by an overbar) and fluctuations (denoted by primes) has been adopted to allow investigation of the influence of the fluctuations on the mean. Here, u is the three-dimensional velocity vector, and κ is the molecular diffusivity of θ . The first term on the right-hand side represents the eddy flux. The second term is the dissipation of mean potential temperature gradients by molecular motions and may be generally

Full access
Ross Tulloch, Raffaele Ferrari, Oliver Jahn, Andreas Klocker, Joseph LaCasce, James R. Ledwell, John Marshall, Marie-Jose Messias, Kevin Speer, and Andrew Watson

on Earth’s climate. Above the sill depth of the Drake Passage, the circulation is dominated zonally by the ACC and meridionally by the sum of a wind-driven meridional overturning circulation (MOC) plus a MOC driven by the turbulent eddies generated through instabilities of the ACC ( Johnson and Bryden 1989 ; Speer et al. 2000 ; Marshall and Radko 2003 ). The air–sea fluxes and Earth’s climate are therefore very sensitive to oceanic turbulence in the Southern Ocean. The current debate as to

Full access
Ru Chen, Sarah T. Gille, Julie L. McClean, Glenn R. Flierl, and Alexa Griesel

average, and u i is the Eulerian velocity (e.g., Plumb and Mahlman 1987 ). Consider the scenario from section 2a : eddies are of small amplitude compared to the mean flow and the system is spatially homogenous, with the spatial scale of the mean (e.g., mean flow and mean eddy flux) much larger than the eddy scale. Appendix B shows that in this scenario is equivalent to the multiwavenumber diffusivity tensor derived from the Lagrangian perspective [Eqs. (16) and (17) ], when κ 0 is very

Full access