The collaborative research project ROSA (Role of stratospheric Aerosol in Climate and Atmospheric Science)

Scientific aims of ROSA:
ROSA is a collaborative research project between the Institute of environmental Physics at the University of Bremen and the Institute of Physics at Ernst-Moritz-Arndt-University of Greifswald. The overarching goal of the project is to improve the scientific understanding of the importance of stratospheric aerosol for climate and the atmosphere. Stratospheric aerosol consists of sulphuric acid/water droplets and plays an essential role in many physical and chemical processes in the stratosphere, e.g., by scattering incident solar radiation and thus enhancing the planetary albedo. Additionally, stratospheric aerosol also affect the catalytic cycles that control stratospheric ozone levels. Despite its importance, the scientific understanding of many aspects of stratospheric aerosol has to be considered low. This is particularly true in terms of the sources of variability in the stratospheric aerosol layer and aerosol composition. This variability is one of the main research foci of this collaborative research project, and will be investigated by synergies between global satellite observations of stratospheric aerosol and model simulations with a chemical transport model (CTM), that considers all microphysical processes relevant for a thorough modeling of stratospheric aerosol. Stratospheric aerosol extinction profiles and particle sizes will be obtained from measurements with the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) on the European environmental research satellite Envisat. As part of this project a numerical algorithm for the retrieval of aerosol extinction profiles and particle size information from SCIAMACHY solar occultation measurements will be implemented, and the existing aerosol data product retrieved from SCIAMACHY limb-scatter observations will be improved. In terms of modeling capability, an aerosol microphysics module will be coupled to an existing CTM. The detailed research aims of the project include the investigation of variability of aerosol extinction and particle sizes, the long-term variation of the stratospheric aerosol load in the last decade and the impact of this change on stratospheric ozone chemistry, particularly in the polar winter stratosphere. In addition, the model simulations will be employed to study the effects of changes of the Brewer-Dobson-Circulation on the distribution of stratospheric aerosol and its composition, and to improve the understanding of potential effects of solar radiation management experiments on stratospheric aerosol and ozone chemistry.


Dr. Rene Hommel
Institut für Umweltphysik
Universität Bremen
Otto-Hahn-Allee 1
28359 Bremen
Prof. Dr. Christian v. Savigny
Institut für Physik
Ernst-Moritz-Arndt-Universität Greifswald
Felix-Hausdorff-Str. 6
17489 Greifswald