The role of anomalous SST and surface fluxes over the southeastern North Atlantic in the explosive development of windstorm Xynthia

摘要: In late February 2010 the extraordinary windstorm Xynthia crossed over southwestern and central Europe caused severe damage, affecting particularly Spanish French Atlantic coasts. The storm was embedded in uncommon large-scale atmospheric boundary conditions prior to during its development, namely enhanced sea-surface temperatures (SST) within low-level entrainment zone of air masses, an unusual southerly position polar jet stream, a remarkable split structure upper troposphere. To analyse processes that led rapid intensification this exceptional originating close subtropics (30°N), sensitivity cyclone latent heat release is determined using regional climate model COSMO-CLM forced with European Centre for Medium-range Weather Forecasts Reanalysis (ERA)-Interim data. A control simulation observed SST shows moist warm masses from subtropical North were involved cyclogenesis process formation vertical tower high values potential vorticity (PV). Sensitivity studies reduced or increased laminar roughness surface fluxes. This induced both weaker partly retarded development weakening PV tower, together diabatic heating rates, at lower mid-levels. We infer played crucial role phase deepening thus intensity southeastern Atlantic. suggest windstorms such as may occur more frequently under future due warming SSTs potentially latent-heat release, increasing risk Europe.