A January Angular Momentum Balance in the OSU Two-Level Atmospheric General Circulation Model

Abstract The atmospheric angular momentum balance is studied by analyzing the data during a simulated January of the Oregon State University two-level atmospheric general circulation model. Monthly zonal means of the Coriolis torques, the vertical transfer of relative angular momentum by penetrating convection, midlevel convection, background viscosity, pressure force and vertical motion, the meridional transfer of relative angular momentum by the standing zonal mean motion, standing eddies and transient motion, and the surface exchange of relative angular momentum by oceanic and continental friction and mountain torque are computed. It is found that midlevel convection is a negligible component in the momentum balance, and the midlevel pressure torque is a significant downward transfer only in the Northern Hemisphere middle latitudes where the major mountains of the model exist. The momentum transfers by penetrating convection and background viscosity are comparable and generally downward, except for the...