Identification, interpretation and quantitative analysis of changes of atmospheric chemical species (gases), in particular water vapour and ozone, but also of UV radiation and of climate are central tasks of atmospheric research. The concentration of stratospheric ozone has decreased significantly during the last two decades, especially over the Antarctic in spring time (ozone hole). The further development of the ozone layer will depend on the evolution of distinct meteorological and chemical values (parameters). Water vapour in the stratosphere and in the troposphere is one of the most important greenhouse gases. It is not only important for the climate (e.g., clouds in the troposphere) but also for the formation of polar stratospheric clouds (PSCs) and for atmospheric chemistry, especially ozone.
Employing the fully coupled chemistry-climate model ECHAM/CHEM of DLR it has been shown for the first time that the recent development of the stratospheric ozone layer can be reproduced adequately. Based on scenario calculations, an assessment of the future development of the ozone layer until the year 2015 has been made (see figure). The recovery of the ozone layer is influenced strongly by the changes of stratospheric temperatures. In the case of a cooling, which has been calculated for antarctic spring, the recovery of the ozone layer is very slow and the ozone hole will continue in its current form for several years. If the stratosphere will become warmer, the increase of ozone values towards "normal" conditions needs only a few years.
The valuation of nitric acid measurements of the environmental satellite ENVISAT will be prepared. An instrument has been developed and will be employed in the stratospheric research aircraft GEOPHYSICA. Nitric acid plays a major role for the formation of PSCs and therefore for the destruction of stratospheric ozone in polar regions. A UV climatology for the Norwegian sea has been established. For individual days UV radiation has been calculated.