Long-term variability of droughts and their links to circulation in Europe

Ing. Zuzana Poppová

Doctoral thesis

Abstract:

Severe European droughts and more frequent heat waves, which seriously impact agriculture, industry, and human health, have become increasingly perceived by the wider public in recent years. Thanks to the availability of long-term time series data, it is possible to analyse drought trends and monitor changes in atmospheric circulation over Europe. To this end, we first studied spatiotemporal changes of drought in three commonly used data sets (E-OBS, CRU and ERA5) to identify differences between them as well as regions and periods with the most pronounced development of dry areas. Based on these results, we focused on the central latitude strip of Europe and the period after 1980, and analysed the drying trends and their connections with atmospheric circulation. Here, we pointed out a shift in the drying trends from Western to Eastern Europe during the vegetation season, and linked this shift to the increase in anticyclonic and southern circulation types. This led to the question of how the dry and hot seasons are lengthening and what future scenarios look like. To this end, we evaluated scenarios of dry-hot seasons in Europe as simulated by regional climate models for three time slices in the 21st century, and discussed the role of temperature and precipitation changes. In the final study that completes this dissertation thesis, we analysed the previously unexplored connections between atmospheric circulation and three-dimensional heat wave types. The new insight into heat waves’ typology showed that near-surface heat waves in Middle Europe are primarily influenced by land-atmospheric coupling, while higher-tropospheric heat waves are related to anticyclonic vorticity. Dry surface conditions and atmospheric circulation therefore play roles which markedly differ among the heat wave types, and this topic merits further investigation for other regions as well as climate models.

Keywords

Drought, Atmospheric circulation, Climate variability, Air temperature, Precipitation, Potential evapotranspiration, Heat waves, Regional climate models, Europe

Jazyk práce: English

Datum vytvoření / odevzdání či podání práce: 26. 1. 2025

Obhajoba závěrečné práce

• Vedúci: doc. RNDr. Jan Kyselý, Ph.D.
• Oponent: Vera Potopová, doc. Dr. Mgr., Adam Vizina, externi, Romana Beranová, externi

Czech University of Life Sciences Prague

Faculty of Environmental Sciences

Doctoral programme / specializace:
Environmental Earth Sciences / Environmental Modelling