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

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Heatwaves 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. 33-46

Abstract

The daily minimum and maximum temperatures at seven Polish stations were used in ananalysis of the occurrence of heatwaves in the years 1951-2006. Heatwaves were defi ned as days withtemperatures exceeding selected thresholds (tmax ≥25°C, tmax ≥30°C, tmin ≥18°C). The mean length ofa wave of very warm days lasts from 2-4 days, the longest no fewer than 23 days. Waves comprising hotdays and nights are shorter. The frequencies of very warm and hot days and hot nights increased in theanalyzed period, especially its second half (1979-2006). The occurrence of heatwaves characteristicallylinks up with high-pressure systems over Central Europe, along with associated blocking episodes.

Keywords: extreme temperatures, Sen’s slope, Lund classifi cation, composite 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