Piotr Piotrowski

Articles

Moisture and circulation conditions during heavy precipitation events in Łódź

Piotr Piotrowski

Geographia Polonica (2017) vol. 90, iss. 1, pp. 81-92
doi: http://dx.doi.org/10.7163/GPol.0080

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Abstract:

A detailed analysis was performed of precipitation data from the years 2011-2013 collected from 17 stations in the city of Łódź over six days with the highest six-hour precipitation periods. Each day was analyzed in respect of the synoptic conditions affecting the weather, with particular emphasis placed on moisture conditions. The highest precipitation was recorded during the May to August period. The convergence of thermally contrasting air masses and significant amounts of water vapor transported to the area of Central Europewere the main cause of extreme precipitation in the area of Łódź. During the advection of warm air masses, the significant amount of water vapor in the air originated not only from the warm sea basins, but also from evapotranspiration during the air masses travelling over hot land areas. A high content of precipitable water during heavy precipitation events was reported in the area of Poland and its neighborhood.

Keywords: extreme precipitation, water vapor flux, precipitable water, atmospheric circulation

Piotr Piotrowski, Department of Meteorology and Climatology, University of Łódź Narutowicza 88, 90-139 Łódź, Poland

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 | Full text

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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

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 | Full text

Further information

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