Gravity wave coupling processes and their decadal variation.
Dr. Manfred Ern
Solar energy is deposited at various heights of the Earth’s atmosphere via different processes. To identify whether solar influence is caused in-situ or imposed from another altitude region physical and quantitative understanding of the coupling processes between different atmospheric layers is essential. One major coupling process is dynamical coupling by gravity waves (GWs). Some fundamental questions still to be answered are the relative contribution of different wave source mechanisms and their spatial and temporal variations as well as the absolute strength of GW momentum flux. GWs in global climate models (GCMs) are implemented by parameterizations using simplifications as e.g. immediate and merely vertical propagation of GWs. We will generate two long-term data sets of GW variance from satellite measurements (several GPS occultation missions starting from 2001 and GPS-MET (1995-1997), and SABER data, starting 2002) to study seasonal and multiennial variations. These data will also be compared to global GW modeling employing the Warner and McIntyre (W&M) spectral model as well as explicit modeling of mountain waves (NRL/MWFM) and convectively generated GWs. The W&M model will be compared to ray-trace simulations (GROGRAT) to study the effects of slant GW propagation. In a multi-decadal W&M model run variations in the coupling and their relations to the solar cycle will be investigated. Finally, we will use measurement-optimized GW parameterizations in an atmospheric model (COMMA-LIM) to study the interactions of GWs, mean circulation, and planetary waves.