The role of cyclones and potential vorticity cutoffs for the occurrence of unusually long wet spells in Europe

Matthias Rothlisberger1, Barbara Scherrer2, Andries de Vries3 and Raphael Portmann2, (1)ETH Swiss Federal Institute of Technology Zurich, Institute for Atmospheric and Climate Science, Zurich, Switzerland, (2)Institute for Atmospheric and Climate Science, ETH Zürich, Zürich, Switzerland, (3)Institute of Earth Surface Dynamics, University of Lausanne, Lausanne, Switzerland