European heat waves can develop downward from higher atmospheric layers
Hourly atmospheric data reveal different vertical paths for European heat waves in a peer-reviewed study. Near-surface events accumulated warmth upward, while events affecting more of the atmospheric column developed faster downward propagation. Comparing four types in France and two other areas, Middle Europe and the British Isles also revealed distinct nighttime layers, revealing why similar ground temperatures can accompany different structures above.
Science··Evening
Heat takes different vertical paths
European heat waves followed contrasting paths through the atmosphere in a peer-reviewed analysis of hourly temperatures. Near-surface events built positive temperature anomalies gradually upward from the ground. Events extending through more of the atmospheric column instead showed faster downward propagation from higher tropospheric layers. Two other types, concentrated in the lower or higher troposphere, also showed downward movement, though less strongly.[1]
Hourly data distinguish nighttime layers
The analysis used 19 pressure levels in ERA5, an atmospheric reanalysis combining observations and modelling. It compared Middle Europe, France and the British Isles using an earlier classification covering 1979–2022. Warm nighttime layers detached from the surface were characteristic of near-surface heat waves and merged into the daytime boundary layer. Other types could have high surface temperatures without sharing that same vertical structure.[1]
Warmth can remain after surface cooling
During some events' termination, warmth persisted aloft after the ground-level atmosphere cooled. This adds a vertical dimension to describing when a heat wave ends. The results concern the selected European regions, and fixed geographical domains can miss portions of an event beyond their boundaries. Daytime boundary-layer depth, fine turbulence and uneven terrain are also subject to limitations in the reanalysis representation.[1]
