Gravity wave coupling from below: A review

Abstract

Gravity waves efficiently couple energy and momentum from source regions in the lower atmosphere to the middle and upper atmosphere. Wave dissipation results in a drag that drives meridional circulations that can profoundly affect the state of the middle atmosphere. New developments in various observing techniques, as well as a better appreciation of the limits imposed by observational selection, allow for a better understanding of the role of gravity waves in the atmosphere. Here we summarise recent advances in the measurement of wave parameters, especially those obtained by satellite and in situ techniques. Of particular importance is the development of techniques to measure momentum fluxes on a hemispheric or even global scale. Improved understanding of gravity wave coupling processes into the thermosphere-ionosphere has resulted from better formulations of dissipation effects. Allied with new rapid incoherent scatter measurements it may soon be possible to identify sources of small and medium scale ionospheric travelling disturbances that are not linked to auroral phenomena.