lmd_LEGACY1985_abstracts.html

1985 .

R. Sadourny and C. Basdevant. Parameterization of Subgrid Scale Barotropic and Baroclinic Eddies in Quasi-geostrophic Models: Anticipated Potential Vorticity Method. Journal of Atmospheric Sciences, 42:1353-1363, July 1985. [ bib | DOI | ADS link ]

A lateral diffusion scheme designed to efficiently parameterize the subgrid scale lures associated with barotropic and baroclinic transients is presented and tested on a quasi-geostrophic, two layer model, with law-scale thermal forcing. The scheme is based on formal energy conservation and potential enstrophy dissipation. At very coarse resolutions, where the cutoff scale is of the order of the internal radius of deformation, the diffusion scheme is shown to produce a realistic amount of potential-to-kinetic energy conversions, and realistic amplitudes of the large-scale barotropic modes.

A. Babiano, C. Basdevant, and R. Sadourny. Structure functions and dispersion laws in two-dimensional turbulence. Journal of Atmospheric Sciences, 42:941-949, May 1985. [ bib | DOI | ADS link ]

The classical phenomenological relations between dispersion laws, second-order structure functions and energy spectra are reexamined from a more quantitative standpoint. It is shown that when a nonlocal energy spectrum (steeper than k to the -3rd power) is substituted into the relation giving structure functions or dispersion laws, an infrared divergence occurs so that the structure functions or dispersion laws at inertial-range separation are not dominated by contributions from the inertial range spectrum; they saturate and become independent of spectral steepness. It follows that the spectral steepness of real flows in the enstrophy inertial range must be extremely difficult to estimate from correlation or dispersion measurements alone. This might explain why the existence of steep spectra, speculated on the basis of numerical modeling, has not been confirmed by real flow measurements.