The mesosphere and lower thermosphere (MLT) form the link between the troposphere, the region of "weather", and the highest, near-space layers where e.g. the low-Earth-orbiting satellites are flying. The relevance of the middle atmosphere for our understanding of planet Earth and the reasons for its exploration are described in the scientific framework programme.
Exploration of the middle atmosphere
Precise soundings of the MLT are still challenging, because these altitude regions can (beside in situ measurements by rockets) only be explored by remote sensing. In the Department "Optical Soundings" mainly laser-based measurements by so-called "lidars" (Light Detection and Ranging) are performed. Main focus is given to:
The different layers of the atmosphere are not independent, but coupled by waves propagating horizontally and vertically through the atmosphere. Therefore, changes in the lower atmosphere (troposphere and stratosphere) influence the higher layers (mesosphere and thermosphere) and vice versa. Exploration of the middle and upper atmosphere thus helps understanding the troposphere and long-term changes of weather and climate. Main topics are
Long-term changes in the middle atmosphere
Climate change not only happens in the lower atmospheric layers, but also in the middle atmosphere. But, in the latter region the increase of carbon dioxide has a cooling effect. We aim for understanding the climate change in the mesosphere, being much larger than the effects in the troposphere, the regional differences and the influence on dynamics and trace gas distribution.