Trace gas observations for the investigation of mean age and stratospheric transport under the influence of solar variability and long term change.
Dr. Andreas Engel
J.W. Goethe Universität
Institut für Meteorologie und Geophysik
The aim of this proposal is to characterise stratospheric transport time scales and the influence of solar variability and long term change on these time scales, using observations of the age tracers CO2 and SF6 in the stratosphere. Differences between mean age derived from both tracers will be used to study the coupling between the mesosphere and the stratosphere. For this purpose we propose to use existing data sets, in combination with reanalyses of archived stratospheric whole air samples and observations performed with a new light weight balloon borne cryogenic whole air sampler. Together these data sets will cover a period starting in 1973 up to the present. By reanalyzing archived samples, it will be possible to derive high quality data of mean age for the entire period. It is planned to use this data set to characterise stratospheric transport time scales and their variability over the last 30 years under the influence of solar variability and long term change. We will also investigate the potential use of MIPAS satellite SF6 data for the retrieval of mean age. In co-operation with several modelling groups we plan to use the data for model validation and to use the models to study the effect of solar variability on stratospheric dynamics and transport time scales. In particular we want to address the following questions:
- under which conditions can SF6 be used to characterise stratospheric transport time scales?
- does the solar cycle influence the mesospheric chemistry of SF6 and does this lead to an artefact in SF6 based mean age determination?
- Does solar variability influence stratospheric transport to the extend that this leads to changes in the meanage?
- How often is mesospheric air transported in to the polar vortices in significant amounts? Which dynamic process drive this effect and what is the impact of solar variability on the polar winter stratosphere?