Abstract
The transfers of kinetic energy between harmonic components of the 500 mb geostrophic flow over the Northern Hemisphere have been measured for an ensemble of daily maps covering a nine-year period, based on a truncation at zonal wave number, n = 15. The results show (1) that, in the mean, all waves (n = 1–15) transfer their energy to the zonally-averaged motion (n = 0) and, of more physical significance, the aggregate of all waves in the group n = 2–15 transfer energy to support the asymmetric polar vortex comprised of wave numbers zero and one, and (2) that, among the waves themselves, waves of n = 2 and 5–10 are sources of kinetic energy and all the rest are sinks. The energy source at n = 2 seems to be a significant new result indicating a strong forced conversion of energy on the scale of the major continents and oceans. Seasonal variations are discussed.