Balance of kinetic energy in the tropical circulation over the Western Pacific

Abstract

AbstractThe balance of kinetic energy in the large‐scale disturbances and general flow of the tropical circulation was investigated with special Marshall Islands upper‐air network data during 1958.The cross‐isobaric generation of eddy kinetic energy has two maxima: in the lower boundary and in the upper troposphere. However, the intensity of generation is about one to two orders of magnitude smaller than that in synoptic disturbances in the middle latitudes. A major portion of the generated eddy kinetic energy is exported outside the area. The space eddies are shown to derive a significant amount of kinetic energy from the kinetic energy reservoir of the basic flow in the area. The eddy kinetic energy is mainly dissipated in the lower boundary. There is a small amount of eddy dissipation in the upper troposphere. However, as a whole the free atmosphere provides very little damping to the disturbances through eddy dissipation.The kinetic energy balance in the general flow is determined mainly by the cross‐isobaric generation of kinetic energy and the dissipation term. The vertical distribution of the cross‐isobaric generation shows there is a large internal source of kinetic energy in the tropospheric easterlies and the kinetic energy is destroyed adiabatically in the upper‐level westerlies and easterlies. The vertical profile of the dissipation closely follows that of the generation. Examination of the dissipation term obtained as the residual term of the kinetic energy equation suggests that processes of different scales of motion are significantly involved in the kinetic energy balance of the observed scale.