Changes in storm track and cyclone activity in three SRES ensemble experiments with the ECHAM5/MPI-OM1 GCM

摘要: Synoptic activity over the Northern Hemisphere is evaluated in ensembles of ECHAM5/MPI-OM1 simulations for recent climate conditions (20C) and three scenarios (following SRES A1B, A2, B1). A close agreement found between present day respective results from reanalysis. Significant changes winter mid-tropospheric storm tracks are detected all scenario simulations. Ensemble mean signals rather similar, with particularly large increases downstream Atlantic track Western Europe. The magnitude this signal largely dependent on imposed change forcing. However, differences individual ensemble members may be large. With respect to surface cyclones, runs produce a reduction cyclonic density mid-latitudes, even areas increasing activity. largest decrease densities occurs at subtropical latitudes, e.g., Mediterranean Basin. An increase cyclone intensities limited (e.g., near Great Britain Aleutian Isles) A1B A2 experiments. synoptic associated alterations circulation background (blocking frequencies, jet stream). North Oscillation index also shows increased values enhanced effects changing activity, regional accompanied by extreme winds, Britain, Baltic Seas, as well vanishing sea ice, decreases much subtropics.