Linear and nonlinear diagnostic models of stationary eddies in the upper troposphere during northern summer.

The model experiments and the budget calculations both show a simple Sverdrup balance to be a useful 1st approximation for the largest scales during this season. In this Sverdrup balance, the advection of planetary voriticity by the divergent component of the flow is found to be significant, particularly in the Southern Hemisphere tropics. Nonlinear barotropic models improve the simulation of regional structures. The correct position of the Tibetan high is explained by Sverdrup balance, but its amplitude and structure are reasonably well simulated only with the nonlinear models. With climatological forcing, the time-averaged solutions of the nonlinear model are insensitive to the strength of the damping included in the mode.-from Authors