G.~Holloway has proposed a simple method to estimate the effective horizontal eddy diffusivity for oceanic tracers using satellite measurements of sea-surface height variability. In this method, the diffusivity is assumed to scale as the r.m.s.~eddy geostrophic streamfunction. This method should apply analogously in an atmospheric context, in which the energetic eddies are well resolved in data sets and models, and in which both the effective diffusivity and tracer fluxes can be directly calculated. We evaluate Holloway's method using lower-tropospheric daily atmospheric reanalysis data, and find that at a given height the method succesfully yields estimates of the divergent part of the atmospheric sensible-heat flux, to within a fairly uniform scaling factor. We argue, therefore, that since oceanic and atmospheric baroclinic turbulence are fundamentally similar, altimeter-generated maps of sea-level variability may very well provide reliable estimates of near-surface eddy diffusivity over the world ocean.
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12th Conference on Atmospheric and Oceanic Fluid Dynamics