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Keywords:

  • deep cyclones;
  • tracks of cyclones;
  • air pressure;
  • Krakow;
  • Central Europe

Abstract

This article discusses patterns in the long-term and seasonal occurrence of deep cyclones over Krakow. This study analysed the frequency of occurrence of air pressure values equal to or lower than the 1st percentile (equivalent to ≤995.3 hPa) of all air pressure values recorded at 12:00 UTC over a period of 110 years (1900/1901–2009/2010). Special attention was devoted to the tracks of deep cyclones. No distinct changes were found in the frequency of occurrence of deep cyclones during the study period. Overall the frequency peaked in December, but in recent years there has been an increase in frequency towards the end of winter and beginning of spring. A similar general lack of noticeable change in the number of days with deep cyclones can also be found in specific tracks. There were minor increases in the frequency of occurrence of cyclones from the Norwegian Sea (T1), the Atlantic (T3), Bay of Biscay (T6) and the Mediterranean (T7) after 1950. The study also found confirmation of the theory that cyclone tracks had shortened at their northeastern extremities. Copyright © 2012 Royal Meteorological Society