How Unusual Were June 2019 Temperatures in the Context of European Climatology?

Abstract

The aims of the study were to assess the severity of temperature conditions in Europe, in June 2019, using a newly developed extremes index, as well as to evaluate circulation conditions that favored the occurrence of extremely hot days in June 2019, as seen over the long term. The main focus of this work was on two European regions particularly affected by high temperatures in June 2019, namely Central Europe and Iberia. To comprehensively characterize heat events in terms of their spatial extent and intensity, we proposed the extremity index (EI) and used it to compare hot days occurring in areas of different sizes and with different climatic conditions. The role of atmospheric circulation in the occurrence of hot days was evaluated using the Grosswetterlagen (GWL) circulation types catalog, as well as composite maps created with the bootstrap resampling technique. Our results reveal that June 2019 was unusually hot, and in terms of the magnitude of the anomaly, it has no analogue in the 70-year-long temperature record for Europe. However, the properties of heat events in the two considered regions were substantially different. The occurrence of hot days in June 2019, in Europe, was mainly associated with the GWL types forcing advection from the southern sector and co-occurrence of high-pressure systems which was significantly proven by the results of bootstrap resampling. In terms of the applicability of the new approach, the EI proved to be a useful tool for the analysis and evaluation of the severity of hot days based on their intensity and spatial range.

Seasonal Variability of Trends in Regional Hot and Warm Temperature Extremes in Europe

“…In order to characterize individual ETEs in terms of their spatial range and intensity, a slightly modified version of the Sulikowska and Wypych [39] Extremity Index (EI) was used in this study:…”

“…Its value usually equals several degrees Celsius. In this study the definition of TI was modified with respect to the original definition [39] for the purpose of analysis of long time series and the evaluation of long-term ETE trends. EI produces a neat way to combine spatial range and intensity information.…”

“…Human health is also affected. One of the effects of a warmer spring and summer is the earlier arrival of severe heatwaves such as those in 2017 and 2019 in Europe [38,39]. Founda et al [40] notes that the hot extremes season in the Eastern Mediterranean region is becoming longer by 3 to 10 days per decade since the mid-1970 s and is usually characterized by an earlier onset.…”

Bioclimatic Conditions of June 2019 in Poland on a Multi-Year Background (1966–2019)

“…The second hottest year in terms of mean air temperature, both at the global scale and in Europe, was 2019 [3]. That year was particularly characterised by high air temperature values in June [7][8][9]. As evidenced by Sulikowska and Wypych [8], citing local meteorological services, record-breaking values of the maximum air temperature in June were recorded in many places, e.g., in Spain (43.4 • C in Lleida), Germany (39.6 • C in Bernburg/Saale), Poland (38.2 • C in Radzyn), and the Czech Republic (38.9 • C in Doksany).…”

“…That year was particularly characterised by high air temperature values in June [7][8][9]. As evidenced by Sulikowska and Wypych [8], citing local meteorological services, record-breaking values of the maximum air temperature in June were recorded in many places, e.g., in Spain (43.4 • C in Lleida), Germany (39.6 • C in Bernburg/Saale), Poland (38.2 • C in Radzyn), and the Czech Republic (38.9 • C in Doksany). All-time temperature record (45.9 • C) for any single station was broken in France on 28 June in Gallargues-le-Montueux near the city of Nîmes [7].…”