Structural determinism of equilibrated baroclinic waves in a two-layer model and equivalent barotropy

Abstract

The time-average structures, zonal flows, and energies of a 21 by 21 wave quasi-geostrophic two-level channel model in the absence of zonally inhomogeneous external forcing mechanisms such as topography are contrasted on the β- and f-planes for several different parameter sets. In all cases, the phase lag, as well as the amplitude, of the temperature component relative to the streamfunction field for the longer waves is considerably less on the β-plane than the f-plane. The zonal flow speeds are also considerably faster on the β-plane. The results are examined in the light of quasi-geostrophic turbulence and structural determinism, heat-transport efficiency/equilibration concepts of Reinhold. The analysis suggests that the equivalent barotropic arrangements of the large-scale atmospheric waves may be primarily a response to the quasi-linear influences of the spherical geometry on the structures of the disturbances, which then, in turn, influence the level of amplitude equilibration and zonal flow speeds.