B-WP2 - STRATO-II: The role of the stratosphere for decadal predictions - Validation and assessment of the MiKlip model system (STRATO-II)

Stratospheric interannual variability influences weather and climate on the decadal time scale, hence ignoring stratospheric variability increases the uncertainty of decadal predictions. The provision of reliable and robust decadal climate predictions requires proper representation of decadal stratospheric variability, its interaction with tropospheric weather and the feedback with the oceans.

STRATO-II - Fig1. (Click to enlarge)
Fig. 1: Decadal PSA based on reanalysis dataset ERA-Interim. The calculation here, used zonal wind at a stratospheric level at 30 hPa. The variance (given in log m²/s²) is colour coded and is plotted against period (given in months) and latitude. Large values of variance can be found in the tropics at a period around 24 months. This prominent feature is attributable to a great extent the QBO.

Major factors with decadal impact have been identified in the MiKlip precursor project STRATOSTRATO. It was shown that the consideration of stratospheric processes leads to an improvement of the prediction of decadal climate variations (Dameris, 2015). Regarding stratospheric dynamics at a decadal time scale, the so called quasi-biennial-oscillation (QBO) in the tropics and the polar vortex in winter are dominating stratospheric variability. This was clearly visualised with the decadal power-spectra-analysis (figure 1). The analysis of the representation of the variability induced by the solar cycle in the preceding development stages of the MiKlip models showed a clear overestimation, e. g. the solar signal in the short-wave heating rates was too strong. Short wave heating waves are significantly characterised by the prescribed ozone field of the models (figure 2).

Fig. 2: Solar signal in short-wave radiative heating rates (a and b) and in ozone (c and d). Shown are regression coefficients on the F10.7cm solar radio flux as proxy for solar activity. a and c) results of a coupled AO-CCM simulation with EMAC-O, b and d) ensemble mean of five simulations with MPI-ESM-LR


The aim of STRATO-II is to validate and improve the performance of the MiKlip prediction system with respect to the representation of stratospheric decadal variability due to solar forcing, climate change and ozone recovery, and its implications on European climate.
STRATO-II will allow for a detailed evaluation of the MiKlip prediction system including a risk assessment and determination of uncertainties with respect to stratospheric effects. Results derived from the MiKlip prediction system will be evaluated with corresponding results from the Chemistry-Climate Model (CCM) EMAC. An innovative aspect is the consideration of chemistry-climate feedbacks. For example, the role of stratospheric water vapor fluctuations (on short- and long-term) and the variability of the stratospheric ozone layer including the expected recovery due to the regulation of Chlorofluorocarbons (CFC) (according to the Montreal protocol) are explicitly considered in EMAC, and can therefore be studied in detail. Climate-chemistry feedbacks and in particularly ozone feedbacks will be analysed in cooperation with the project FAST O3 II. In the future, opposite regional trend patterns are anticipated, e.g. a decrease of tropical ozone and an increase of ozone in the extra-tropics, which are affected by climate change (depending on the assumed future greenhouse gas scenarios; see Scientific Assessment of Ozone Depletion: 2014, WMO (2014)). Here we will investigate possible impacts for the European sector, i.e. assessing the climate change and (direct and indirect) effects for Europe, and its consequence on the decadal timescale.


Freie Universität Berlin, Institut für Meteorologie
Prof. Dr. Ulrike Langematz

Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR), Institut für Physik der Atmosphäre (IPA)
Prof. Dr. Martin Dameris

Classification of stratospheric extreme events according to their downward propagation to the troposphere

2016 - Geophys. Res. Lett., Vol. 43, pp. 6665–6672

Runde, T., | M. Dameris, H. Garny, and D. E. Kinnison