IDENTIFICATION OF CYCLONE-TRACK REGIMES IN THE NORTH-ATLANTIC

A Langrangian-type climatology of North Atlantic cyclones is establish ed based on the high-resolution European Centre for Medium-Range Weath er Forecasts data-set of the 1000 hPa height-field. First, an algorith m is introduced to identify mid-latitude cyclones and cyclone paths wi th as few constraints as possible. Cluster analysis of relative cyclon e displacements yields three types of cyclone tracks characterizing st ationary-, north-eastward- and zonally-travelling storms. The internal Lagrangian statistics of these cyclone-track types reveal representat ive life-cycles for central pressure and geopotential-height gradients and a power-law scaling behaviour of cyclone displacements. Finally, a basic climatology of North Atlantic cyclone-track regimes is deduced in terms of a time-series and circulation statistics.