Parametric Study of Large-Scale Eddy Properties. Part II. The Zonal Scale

Abstract

Laboratory experiments reveal an approximate inverse dependence of the azimuthal wavenumber upon the radial temperature gradient, in the steady Rossby regime. To verify the occurrence of a similar relationship in the atmosphere, it being an unsteady system, we define an average zonal wavenumber n and correlate it with the meridional temperature gradient ?T. The values of the correlation coefficient r(n,?T) vary considerably from month to month and therefore are unreliable. The values of r(n,?T), where the bars denote averages over a month, are very small except in the vicinity of 35°N. Linear baroclinic theory shows that there is a functional dependence between the zonal wavelength of the most rapidly amplifying waves and static stability S. In the case of the atmosphere r(n,S) is as unreliable as r(n,?T), but r(n,S) is considerably superior to r(n,?T). Therefore, the meridional and vertical temperature gradients in the atmosphere must be decoupled, at least at 45 and 55°N where r2(n,S) is very large.