A theoretical study of the kinetic energy equation and the associated vertical circulation patterns in a limited atmospheric region

A kinetic energy budget study in different regions of an extended zonal channel is presented. A 10-level primitive equation model is developed and used to simulate the upstream and downstream development of baroclinic waves. The initial basic flow is a westerly zonal jet at 45 deg N on an f-plane upon which a local perturbation velocity of a zonal extent of 4000 km is superimposed. In the region where the downstream wave is developing, a dominating generation of zonal kinetic energy takes place and the gain of zonal kinetic energy is balanced by the conversion of zonal kinetic energy into zonal available potential energy. But in the region from which the kinetic energy is transferred downstream, the energy loss is compensated for by the conversion of zonal available potential energy into zonal kinetic energy. Hence, inside these two adjacent regions, two vertical circulations of opposite sense, i.e., a direct circulation and an indirect circulation, are set up.