Exceptionally hot summers in Central and Eastern Europe (1951–2010)

Abstract

The paper focuses on exceptionally hot summers (EHS) as a manifestation of contemporary climate warming. The study identifies EHS occurrences in Central and Eastern Europe and describes the characteristic features of the region's thermal conditions. Average air temperatures in June, July and August were considered, as well as the number of days with maximum temperatures exceeding 25, 30 and 35°C, and with a minimum temperature greater than >20°C, as recorded at 59 weather stations in 1951-2010. Extremely hot summers are defined as having an average temperature equal to or greater than the long-term average plus 2 SD. A calendar of EHSs was compiled and their spatial extent identified. The region experienced 12 EHSs, which occurred in a given year at 5 % or more stations (1972, 1981, 1988, 1992, 1997, 1998, 1999, 2002, 2003, 2006, 2007 and 2010). The EHS frequency of occurrence was found to be clearly on an increase. Indeed, only one EHS occurred during the first 30 years, but these occurred five times during the last 10 years of the study period. Their geographical extent varied both in terms of location and size. EHSs were observed at 57 out of the total of 59 weather stations in the study (the exceptions were Pecora and Cluj). The average air temperature of EHSs tended to exceed the relevant long-term average by 2-4°C. The summer of 2010 was among the hottest (temperature anomaly 5.5-6°C) and spatially largest.

Warm spells in Northern Europe in relation to atmospheric circulation

“…The increase in frequency of extreme weather phenomena, including heat waves, was found in the Czech Republic (Kyselý 2010), Poland (Kossowska-Cezak 2010; Tomczyk 2014b), Serbia (Unkašević and Tošić 2009), Ukraine (Shevchenko et al 2014) and Spitsbergen (Tomczyk and Bednorz 2014b). As Twardosz and Kossowska-Cezak (2013) showed, currently, in Central and Eastern Europe, there is an increase in a number of extremely hot months, which were most frequently recorded in the first decade of the twenty-first century. According to the predictions, heat waves in the twenty-first century are going to be more frequent and more intense (Meehl and Tebaldi 2004;Koffi and Koffi 2008;Kürbis et al 2009;Pongracz et al 2013;Amengual et al 2014;Zacharias et al 2015).…”

Exceptionally Hot and Cold Summers in Europe (1951-2010)

“…The same approach was followed when identifying exceptional months. This definition is analogous to the one used when identifying exceptionally hot months and seasons in Central and Eastern Europe (Kossowska-Cezak and Twardosz 2012a, b, 2013, Twardosz and Kossowska-Cezak 2013a. By referencing average thermal conditions in defining thermally anomalous periods, the study managed to take into account both the concept of a thermal anomaly in the form established in climatology and the actual thermal conditions to which the populations of the various European climatic regions were acclimatised.…”

Variability of air mass occurrence in southern Poland (1951–2010)

“…This influence goes beyond specific values of weather elements and also covers their timing (Niedźwiedź 1981;Twardosz 2005;Twardosz et al 2011a, b), especially in the case of dangerous atmospheric phenomena (Twardosz 2010). The study of air mass variability has the potential, therefore, to contribute to both applied meteorology and to a better understanding of the causes behind contemporary climate variation, especially the observed growth in air temperature (Kalkstein et al 1998;Twardosz and Kossowska-Cezak 2012). Nevertheless, climatologists rarely take up this topic because, as was aptly pointed out by Ustrnul (2007), there is a severe shortage of calendars of air mass types.…”