Heat waves in Poland in the period 1951-2015: trends, patterns and driving factors

Abstract

Heat waves were analysed on the basis of maximum daily temperature from 24 meteorological stations in Poland. Heat waves are defined as the longest continuous period during which Tmax (daily maximum air temperature) is equal to or higher than 30°C in at least three days, the mean Tmax during the whole heat wave is equal or higher than 30°C and Tmax does not drop below 25°C during the whole period of heat wave duration. Heat waves occur in Poland from April to September with their maximums in July and August. Four-day-long heat waves are most frequent but the longest one lasted 31 days. The most persistent heat waves were in 1994 and 2015. An increasing trend in heat wave frequency and intensity is observed in Poland, however the increase is statistically significant at only about 60% of analysed stations. Four synoptic patterns favouring heat waves have been distinguished. A strong high over the Azores accompanies all of them, as well as slightly higher than normal pressure over Central Europethis causes calm and sunny weather over Poland. Strong blocking appears over the North Atlantic during heat wave events, proofing that the development of strong heat waves in Poland is related to large scale circulation and that they are not of local origin. The analysis of the impact of soil moisture in months leading up to the development of heat waves should be the next step in analysis.

The extreme year—analysis of thermal conditions in Poland in 2018

“…Particularly year 2015 showed the record air temperature values in many regions (Hoy et al 2017). It was also the year when numerous heat waves stroked Central Europe (Wibig 2018;Tomczyk and Bednorz 2019). During that summer, four heat waves occurred in Poland (Sulikowska et al 2016).…”

Occurrence of strong and very strong heat stress in Poland and its circulation conditions

“…In summer, these types of systems favour the occurrence of extreme thermal conditions in the form of heat waves, and in winter, cold waves (Ustrnul et al 2010;Porębska and Zdunek 2013;Unkašević and Tošić 2015). Therefore, the effect of atmospheric circulation on thermal conditions, and particularly on the occurrence of thermal extremes in Poland, has been a subject of great interest for many years (Wibig et al 2009;Tomczyk and Bednorz 2016;Wibig 2018;Tomczyk et al 2019).…”

Evaluation of the potential for the use of lakes in restoring water resources and flood protection, with the example of the Noteć Zachodnia River catchment (Gniezno Lakeland, Poland)

“…This is expressed primarily by the distinct decreasing trends in water flows observed in the main rivers, the source zones of which are situated in this part of Poland (Tomaszewski 2007;Wrzesiński 2009;Nowak 2018a), and by the lowering of the water levels in the lakes (Ilnicki 1996;Ilnicki, Orłowski 2006a;Orłowski, Ilnicki 2007;Choiński, Ptak 2008;Kędziora 2008;Kowalik et al 2008;Marszelewski, Radomski 2008;Kunz et al 2010;Marszelewski et al 2011;Ptak, Ławniczak 2011;Ilnicki et al 2012a, b;Nowak, Gezella-Nowak 2012;Piasecki, Marszelewski 2013;Piasecki, Skowron 2014;Stachowski et al 2016;Nowak 2018a) and ground water levels (Przybyłek, Nowak 2011a, b;Nowak 2018a). The lowering of the level of surface and ground waters in the study region is also related to climate factors (Kędziora 2008;Przybyłek, Nowak 2011a;Ilnicki et al 2012a, b;Stachowski et al 2016;Nowak 2018a), such as the increase in air temperature observed for many years (Kundzewicz, Matczak 2012;Twardosz, Kossowska-Cezak 2013;Graczyk, Kundzewicz 2014;Graczyk et al 2016;Wibig 2018). Equally important is human activity, such as the meliorations realized in this part of Poland on a large scale since the middle of the 19 th century (Choiński, Ptak 2008;Marszelewski et al 2011;Ptak, Ławniczak 2011;Ilnicki et al 2012a, b) or the excessive uptake of waters for municipal and agricultural purposes …”