Present and future atmospheric blocking and its impact on European mean and extreme climate

Atmospheric blocking plays an important role in the mid-latitude climate variability and can be responsible for anomalous mean and/or extreme climate. In this study, a potential vorticity based blocking indicator is used to investigate the representation of Euro-Atlantic atmospheric blocking events in the ECHAM5/MPI-OM climate model. The impact of blocking events on present and future mean and extreme climate is studied by means of composite maps and correlation analyses. In comparison to ERA-40 re-analysis, the model represents the blocking frequency and seasonal distribution well. We show that European blocking events have a sustained influence particularly on anomalous cold winter temperatures in Europe. In a future climate, the blocking frequency is slightly diminished but the influence on the European winter climate remains robust. Due to a northeastward shift of the blocking pattern and an increase in maximum blocking duration, cold winter temperature extremes can still be expected in a future climate. Citation: Sillmann, J., and M. Croci-Maspoli (2009), Present and future atmospheric blocking and its impact on European mean and extreme climate, Geophys. Res. Lett., 36, L10702, doi: 10.1029/2009GL038259.