The energy budget of the mesosphere - an investigation using satellite data and coupled global models

Dr. Miriam Sinnhuber, Dr. Thomas Reddmann, Dr. Thomas von Clarmann, and Dr. Stefan Bender
Karlsruhe Institute of Technology, Institute for Meteorology and Climate Research

Recent observations suggest that disturbances of the middle atmosphere dynamics can propagate from the mesosphere (~50-95 km) down to the surface. Therefore, a good understanding of the processes determining the energy budget of the mesosphere is crucial for an accurate representation of atmospheric dynamics in the middle and lower atmosphere in coupled chemistry-climate models. It is therefore a prerequisite to determine the impact of middle atmosphere processes on surface climate.

Important processes determining the energy budget of the mesosphere are solar heating and radiative cooling as well as dynamical and chemical heating, and in the auroral region also Joule dissipation. In the framework of this project, global observations of the satellite instruments SCIAMACHY and MIPAS on ENVISAT (2002 - 2012) will be used to determine the most important drivers of the mesospheric energy budget. These include temperature, radiative cooling in the infrared region from observed emissions, solar heating from excited states of O2, chemical heating from the emissions of excited states of OH and O2, dynamical heating from inert trace gases, and possibly Joule heating from NO emissions in the auroral regions. Some of the observational data will be processed within the project, others will be provided within cooperations with other Romic projects.

These data will then be used in two ways: on the one hand to derive an energy budget of the mesosphere and identify possible missing contributions to the energy budget. On the other hand, to evaluate the representation of the different contributions to the energy budget in coupled chemistry-climate models. Model deficiencies will be identified and modified to improve the representation of the temperatures and dynamics of the middle atmosphere in state-of-the art coupled chemistry-climate models.