Two Similarities Between Atmospheric Eddies and Linear Baroclinic Waves

Very good agreement is shown to exist between the meridional distributions of the zonal wavenumber n of rapidly amplifying baroclinic waves on a sphere and of an average wavenumber n of “grid-scale” atmospheric eddies. As a consequence, the zonal wavelength of both baroclinic and atmospheric eddies remains virtually constant, i.e., within a factor of 2, over the extratropics. The values of n at different latitudes have been obtained by using linearized baroclinic theory on different meridional profiles of the unperturbed zonal wind (MPUZW). Since they agree with n, atmospheric eddies are, in relation to linear baroclinic waves, independent of MPUZW. In this senses n is controlled locally rather than globally. The mutual dependence of the upward and poleward transports of (sensible) heat in baroclinic wave theory is correctly formulated-as compared to a direct analysis of the first law of thermodynamics.