A global ocean circulation model is formulated in terms of the “residual mean” and used to study eddy–mean flow interaction. Adjoint techniques are used to compute the three-dimensional eddy stress field that minimizes the departure of the coarse-resolution model from climatological observations of temperature. The resulting 3D maps of eddy stress and residual-mean circulation yield a wealth of...

The effects of a prescribed surface intensification of the thickness (and isopycnal) diffusivity on the solutions of an ocean general circulation model are documented. The model is the coarse resolution version of the ocean component of the National Center for Atmospheric Research (NCAR) Community Climate System Model version 3 (CCSM3). Guided by the results of Ferreira et al. (2005) [Ferreira,...

Aims. We investigate the confinement and long-term dynamics of the magnetised solar tachocline. Methods. Starting from first principles, we derive the values of turbulent transport coefficients in the magnetised solar tachocline and then explore the implications for the confinement and long-term dynamics of the tachocline. Results. For reasonable parameter values, the turbulent eddy viscosity i...

Eddy length scales, eddy velocity scales, and the amplitude of eddy fluxes in the mid-latitude troposphere are discussed, primarily from the qualitative perspective provided by studies of quasi-geostrophic turbulence. The utility of a diffusive picture for the near surface poleward flux of heat is emphasized, as is the extent to which a full closure theory for the troposphere, including the int...

The generation of large-scale magnetic field in the kinematic regime in the absence of an α-effect is investigated by following two different approaches, namely the testfield method and multiscale stability theory relying on the homogenisation technique. We show analytically that the former, applied for the evaluation of magnetic eddy diffusivities, yields results that fully agree with the latt...

Oil droplet transport under a non-breaking deep water wave field is investigated herein using Computational Fluid dynamics (CFD). The Reynolds-averaged Navier–Stokes (RANS) equations were solved to simulate regular waves in the absence of wind stress, and the resulting water velocities agreed with Stokes theory for waves. The RANS velocity field was then used to predict the transport of buoyant...

Our understanding of biosphere–atmosphere exchange has been considerably enhanced by eddy covariance measurements. However, there remain many trace gases, such as molecular hydrogen (H2), that lack suitable analytical methods to measure their fluxes by eddy covariance. In such cases, flux-gradient methods can be used to calculate ecosystem-scale fluxes from vertical concentration gradients. The...

The robustness of Nakamura’s effective diffusivity diagnostic for quantifying eddy diffusivities of tracers in a streamwise-average framework is carefully examined in an oceanographic context and the limits of its applicability are detailed. The nearsurface Southern Ocean geostrophic flow, obtained from altimetric observations, is chosen for particular examination. The temporal variability of t...