The Response of an Idealized Atmosphere to Localized Tropical Heating: Superrotation and the Breakdown of Linear Theory

摘要

An equatorial heat source mimicking the strong diabatic heating above the west Pacific is added to an idealized, dry general circulationmodel. For small (0.5Kday(-1)) heating rates the responses closelymatch the expectations fromlinear Matsuno-Gill theory, though the amplitudes of the responses increase sublinearly. This "linear'' regime breaks down for larger heating rates and it is found that this is because the stability of the tropical atmosphere increases. At the same time, the equatorial winds increasingly superrotate. This superrotation is driven by stationary eddy momentum fluxes by the waves excited by the heating and is damped by the vertical advection of lowmomentum air by the mean flow and, at large heating rates, by the divergence of momentum by transient eddies.