On Nonlinear Cascades of Enstrophy over the Tropics at 200 mb during Two Northern Hemisphere Summers

Diagnostic computations of nonlinear cascades of enstrophy have been performed in the wavenumber domain for two northern summers. Attention is focused on the interactions among the waves, the interaction between the zonal flow and a given wave and the exchanges due to the beta effect. It is found that two wave ranges (low and intermediate wavenumbers) cascade enstrophy to two ranges of wavenumbers. Calculations are also performed to evaluate the contributions from the standing (92-day mean) and transient modes to the nonlinear enstrophy cascade.