Geographia Polonica (2009) vol. 82, iss. 1

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Coldwaves in Poland – Frequency, Trends and Relationships with Atmospheric Circulation

Joanna Wibig, Agnieszka Podstawczyńska, Marcin Rzepa, Piotr Piotrowski

Geographia Polonica (2009) vol. 82, iss. 1, pp. 47-60

Abstract

The daily minimum and maximum temperatures at nine stations in Poland were used in ananalysis of the occurrence of coldwaves, where these are defi ned as days with temperatures exceedingselected thresholds (tmin ≤ -20°C, tmin ≤ -15°C and tmax ≤ -10°C) in the period 1951-2006. Cold nightsoccurred more often than very cold days and nights but the mean lengths of waves of cold nights weresimilar – lasting a little more than 2 days on average. The frequencies of extremely cold days revealeda slight, but statistically non-signifi cant downward trend. The occurrence of coldwaves was associatedwith high-pressure systems over Central Europe and with blocking episodes, but it was always linkedwith a thick layer of cold air.

Keywords: extremely low temperature, trend, Sen’s slope, least squares method, Poland

Joanna Wibig, Department of Meteorology and Climatology, Faculty of Biology and Earth Science, University of Lodz Lipowa 81, 90-568 Łódź, Poland
Agnieszka Podstawczyńska, Department of Meteorology and Climatology, University of Łódź Narutowicza 88, 90-139 Łódź, Poland
Marcin Rzepa, Department of Meteorology and Climatology, University of Łódź Narutowicza 88, 90-139 Łódź, Poland
Piotr Piotrowski, Department of Meteorology and Climatology, University of Łódź Narutowicza 88, 90-139 Łódź, Poland