Recent European heat waves under three dimensional insight

In recent summers, Europe was struck by numerous heat extremes that have almost completely redrawn the map of the most severe heat waves recorded across the continent (Lhotka and Kyselý 2022). For example, daily maximum temperature over 40°C was measured for the first time ever in the United Kingdom in 2022, surpassing the previous all-time high (recorded only three years earlier) by 1.5°C. During the past decade, heat waves were extensively studied due to their growing negative consequences on environment and society. Those studies mostly focused on hazardous near surface temperatures and their impacts, however, heat waves depend on processes taking place through the entire troposphere. In this study, we assess heat waves not only in terms of near surface temperatures but also temperatures at the 850 and 500 hPa levels from the ERA5 reanalysis. Heat waves are defined based on spatially conditioned exceedance of the 90% quantile of summer daily temperature distribution with a three-day minimum persistence criterion (at any pressure level). Their characteristics (magnitude, length, intensity, and spatial extent) are analysed for several European regions from 1989 to 2022 (with backward extensions planned). Preliminary results suggest that a large number of heat waves is detectable in atmospheric column spanning from the Earths’ surface approximately to the 300 hPa level. Other events, by contrast, are limited to lower or upper troposphere only, suggesting different driving mechanisms. Interannual variability and trends of heat wave characteristics in three dimensional space are also investigated.

References:

Lhotka, O., & Kyselý, J. (2022). The 2021 European heat wave in the context of past major heat waves. Earth and Space Science, 9. https://doi.org/10.1029/2022EA002567