Heat Waves in Regional Climate Models: Three‐Dimensional Insight and Links to Atmospheric Circulation Over Middle Europe

Abstract To improve understanding of heat waves' biases in regional climate models (RCMs), we employ a novel approach to study them as three‐dimensional phenomena. Heat waves over Middle Europe are classified into four types based on their vertical cross‐sections of temperature anomalies. We show that most reanalysis‐driven CORDEX RCMs tend to overclassify heat waves as lower‐tropospheric at the expense of the other types. This bias is linked to overly frequent southerly advection that is too warm compared to the ERA5 reanalysis especially at the 850 hPa level, pointing to a weaker temperature gradient between the 2 m and 850 hPa levels. We also find substantial differences among the RCMs in frequencies of near‐ground and vertically extensive heat wave types, which are partially attributed to simulated characteristics of easterly advection. This suggests strong relationships between land–atmosphere coupling and those heat wave types in which near‐ground temperature anomalies are important.