Programme Topic 4: Composition and dynamics of the upper troposphere and stratosphere

The upper troposphere / stratosphere (UTS) region plays a key role in the climate system. Changes in the structure and chemical composition of the lower part of this region (UTLS) result in particularly large changes in the so-called radiative forcing of the atmosphere, which trigger climate change. In spite of its immense significance, the UTLS region is one of the least understood regions of the atmosphere. This is a result of its great dynamical, microphysical and chemical complexity.

The Institute of Meteorology and Climate Research contributes to Topic 4 with its divisions IMK-ASF and IMK-AAF.

Programme Topic 4 (PT4) will provide detailed knowledge about the role of the UTS in the Earth system, in particular in the context of climate change and climate variability. The participating centers are particularly strong in investigating the role of meso-scale processes (e.g., exchange processes, atmospheric waves, clouds) and their occurrence at the global scale. The envisaged scientific analyses are based on the synergetic use of airborne instruments (e.g., HALO), satellite observations (e.g., ENVISAT), and atmospheric models. Expected achievements include considerable improvements of our predictive capabilities with respect to societal challenges, such as climate change, climate engineering risks, the recovery of the ozone layer, and the climatic impact of future energy systems.

The analyses within PT4 are based on the synergetic use of field observations (research aircraft, balloon), satellite observations, ground-based measurements, chamber measurements, and atmospheric modelling. In particular, the new German long-range research aircraft HALO opens new perspectives for the UTLS research of PT4. Complementary commercial aircraft programs provide a wealth of long-term observations. Full exploitation of MIPAS-ENVISAT satellite observations remains an important task of PT 4. Additional information on global high-resolution UTLS temperature fields is obtained from GPS radio occultation measurements. In addition to these ongoing space activities, the participating centres play a leading role in studies of a new ESA atmosphere mission with unprecedented spatial resolution: PREMIER. This mission will focus on the link between atmospheric composition and climate. FZJ and FZK join their forces to realise this ambitious project by strengthening the scientific and technical case of the PREMIER mission and by developing a prototype instrument (infrared limb imager) for integration on the research aircraft HALO. Further development of the infrared limb-imaging technique (e. g. for implementation on long-duration ballons) requires major future investments by both centres.

Responsible and contact: Prof. Dr. Johannes Orphal (IMK-ASF), Prof. Dr. Thomas Leisner (IMK-AAF)