Inter-seasonal connection of typical European heatwave patterns to soil moisture

This study aims to increase the general understanding and predictability of heatwaves by identifying and analyzing stable classes, i.e., recur- ring patterns, of heatwaves present in Europe. In this study, we use data from a regional climate model large ensemble (Canadian Regional Climate Model version 5, CRCM5-LE) consisting of 50 possible real- izations of climate in the years 1981-2010 for a Central European domain with a spatial resolution of 0.11◦. We find nine stable heat- wave patterns in Europe, which correspond well with clusters derived from an observational dataset (E-OBS) and extreme historical heat- wave events. We show that historical extreme events can be explained by a dominant manifestation of the same recurring pattern. More- over, we analyze the occurrence of heatwaves in the identified clusters regarding a soil moisture deficit present before and after the event. We show that soil moisture anomalies in preceding winter/spring (JFMA) can serve as a predictor for heatwaves in South Europe. For North Europe we find a negative correlation between the number of heatwave days in summer and autumn (OND) soil moisture anomaly.