THE EXTENDED NUMERICAL INTEGRATION OF A SIMPLE BAROTROPIC MODEL

Abstract

A simple barotropic model is integrated for 39 days by one-hour time steps over 94 per cent of the earth's surface. By suitably smoothing the stream function at each time step, time truncation errors are controlled and the total energy of the system varies within only two per cent of the initial value over the entire integration period. By initiating the integration with energy in the mean flow and in planetary waves one and three, a pronounced periodic exchange of energy is observed over the integration period. The predominant periodicity is a six-day exchange between planetary wave number three and the mean flow. The energy distribution in the higher wave numbers appears to be capable of a statistical interpretation.