European cyclone track analysis based on ECMWF ERA-40 data sets

Changes in large-scale circulation patterns over the North-Atlantic-European region are presented and analyzed for the 20th century. First, changes in decadal frequency of Hess-Brezowsky macrocirculation patterns (MCP) are evaluated for the period between 1881 and 2000. Frequency of several MCP types increased or decreased considerably during these 120 years, which may be explained by large-scale changes in circulation characteristics, e.g. by changes in cyclone activity in the different regions. Therefore, cyclone center identification and cyclone tracks and intensity analysis have been accomplished on the basis of the European Centre for Medium-range Weather Forecast (ECMWF) reanalysis data sets (ERA-40) on a 2.5 degrees horizontal resolution grid for the period between 1957 and 2002. Results suggest that both the number of midlatitude cyclones and the cyclone activity increased considerably in the. North-Atlantic-European region, especially in the northwestern part of the domain. Copyright (c) 2006 Royal Meteorological Society.