CRAAS-3: A 20-year cloud regime dataset over Europe linking cloud structure and circulation

Cloud regimes provide a useful observational framework to link cloud properties, organisation, and variability to large-scale circulation across spatial and temporal scales. We present CRAAS-3, a cloud regime dataset over Europe derived from 20 years of daytime MSG-SEVIRI observations from the CLAAS-3 cloud property dataset. Cloud regimes are defined from joint histograms of cloud optical thickness, cloud top pressure, and thermodynamic phase, clustered with a refined k-means method into eight prototypical regimes. The high temporal resolution of SEVIRI enables analyses of regime persistence, transitions, and regional variability, which can be related to large-scale circulation and synoptic conditions. We further combine CRAAS-3 with high-resolution cloud properties from polar-orbiting satellites to investigate how cloud structural characteristics vary across regimes, and with vertical profiles from ACTRIS stations to characterise typical regime-specific cloud profiles. This integrated approach exploits the high temporal resolution of geostationary observations together with detailed cloud structural information to enable process-oriented analyses of cloud evolution across regimes and circulation contexts.