Trajectory Slopes, Countergradient Heat Fluxes and Mixing by Lower Stratospheric Waves

Abstract

In large-scale wave disturbances in the lower stratosphere, the poleward and upward velocity components are positively correlated so that typical air trajectories, when projected onto the meridional plane, slope upward toward the pole. The slope of the air trajectories can be reconciled with the observed poleward, countergradient eddy heat flux at these levels if one takes into account the poleward acceleration of warm air in the wave troughs and the equatorward acceleration of cold air in the ridges. These temperature anomalies are produced by subsidence in the wave troughs and ascent in the ridges. The same processes are capable of producing poleward and downward eddy fluxes of potential vorticity, ozone, and other tracers whose values or concentrations increase rapidly with height.