Rossby Waves Entering the Equatorial Middle Atmosphere

点击翻译按钮获取中文摘要

Extratropical planetary Rossby waves are known to propagate energy upward and equatorward from their tropospheric source region. Much of this wave activity reaches the equatorial middle atmosphere, where relatively little is known about its fate. Satellite data reveal that, around the solstices, when the equatorial middle atmosphere is inertially unstable, vertically layered disturbances (so-called "pancake structures") appear over the equator, but only when a burst of Rossby wave activity is impinging on the region. In this fundamental hydrodynamic study, the PI will use a high vertical resolution middle atmosphere version of the National Center for Atmospheric Research (NCAR) Community Climate Model (CCM) to test the hypothesis that the pancake structures are caused by Rossby waves entering an inertially unstable region. A hierarchy of experiments will be performed in which high latitude wave forcing is controlled and the mean flow is specified successively to be inertially stable, inertially unstable, and finally allowed to evolve with the wave field. In addition to gaining insight into the fate of Rossby waves at low latitudes, this study will improve understanding of interhemispheric tracer transport. Cross-equatorial transport diagnosed in the CCM will be parameterized in a two-dimensional middle atmosphere assessment model currently used to model ozone distribution.