The project STRATO aims to study and evaluate the importance of the stratosphere for mid-term predictions of climate change. The focus is laid on the quantification of reactions of the coupled atmosphere-ocean system to decadal stratospheric variability. Recent analyses of observations and data from numerical model simulations show a clear impact of decadal stratospheric fluctuations on the troposphere. Therefore one can proceed from the assumption that a consideration of stratospheric processes will lead to improved decadal climate predictions. STRATO concentrates on investigations of the role of the decadal solar activity (i.e. the 11-year solar cycle, cf. Figure 1) and internal stratospheric variability on decadal time-scales and the subsequent tropospheric reactions (cf. Figures 2 and 3).
STRATO provides quantitative statements for improvements of a numerical prediction model for mid-term climate change due to the consideration of stratospheric processes (module B). The expertise of STRATO is used for the evaluation of the reliability of mid-term climate forecasts, in particular regarding the role of the stratosphere and its variability on decadal time scales (module D). STRATO provides necessary data for the initialisation of stratospheric conditions needed in the new MiKlip-model system (module A). Data derived from numerical studies performed in STRATO are analysed; these data are provided to other MiKlip-groups, e.g. they can be used to test methods and techniques which are needed for downscaling smaller spatial structures in the upper troposphere and lower stratosphere (module C). Furthermore, STRATO provides quantitative information regarding uncertainties of recently used model systems of the upper troposphere and stratosphere (module E).
It is expected that results of the STRATO project will establish enhanced knowledge of the in-teractions between the stratosphere and the troposphere-ocean system, improving mid-term climate prediction. In particular, STRATO will improve the basic understanding of the impacts of decadal solar variability and internal stratospheric fluctuations on the atmosphere-ocean system on decadal time-scales. Based on investigations carried out in STRATO, recommendations to further develop the MiKlip-forecast system will be transfered to the respective team; appropriate software will be provided to improve the quality of climate prediction on decadal time-scales. STRATO aims to contribute to a better understanding of the Earth’s climate system, leading to a generally improved climate modelling.