The role of gravity waves in coupling between the troposphere and the middle atmosphere

The Whole Atmosphere Community Climate Model, version 3 (WACCM3) is a comprehensive general circulation model extending from the surface to ~150 km. One of the reasons for the development of this model was the detailed examination of coupling processes between the troposphere and the middle atmosphere, including stratospheric sudden warmings, the quasi two-day wave, and tides. One of the largest uncertainties in WACCM3 (and alike models) is the drag from parameterized gravity waves, which is typically a highly tunable model parameter. Here we examine the sensitivity of sudden warmings and the two-day wave to changed gravity wave drag and discuss implications of the results for accurate studies of tropospheric-middle atmospheric coupling.