Gravity Wave Interactions and Effects in the Middle and Upper Atmosphere: Recent Progress and Outstanding Issues

Gravity waves are now recognized to have significant influences on the large-scale structure and variability throughout the atmosphere. In the mesosphere and lower thermosphere (MLT), these effects can be dramatic and include 1) vigorous wave breaking, turbulence generation, and local boding forcing, 2) strong forcing of the mean circulation and thermal structure, and 3) significant filtering by and interactions with tidal and planetary waves. Gravity wave influences also extend to significantly higher altitudes, though these are less quantified at this time. Potential influences at these higher altitudes include seeding of plasma instabilities, local body forces and heating, and mapping of MLT influences to higher altitudes, all of which are also anticipated to exhibit significant solar cycle variations.