Links between heat waves, drought, and atmospheric circulation in Central Europe

Heat waves and drought are phenomena associated with large negative impacts on society and environment. Their common features include increasing frequency and intensity in recent decades in many regions of Europe, as well as interconnectedness of the factors that contribute to their development. In this study, we evaluate links between heat waves and drought in Central Europe using E-OBS data and ERA-5 reanalysis in the 19792022 period. Heat waves are classified according to their 3-dimensional structure of positive temperature anomalies into near-surface, lower-tropospheric, higher-tropospheric, and omnipresent types. We show that the associations to soil moisture conditions and development of flash drought (based on the daily climatic water balance index) differ for the individual heat wave types; the links are most pronounced for near-surface heat waves, illustrating the compound nature of the heat-drought events. We also employ the JenkinsonCollison classification to identify circulation types with significantly increased frequency during periods of heat waves and droughts, and study changes in their occurrence. The analysis contributes to better understanding of the interrelationships between drought, heat waves, atmospheric circulation and other driving mechanisms.