Soil moisture-atmosphere feedbacks amplify atmospheric dryness and its spatial propagation

Global warming exacerbates atmospheric dryness, yet the role of soil moisture (SM)-atmosphere feedbacks in regulating its spatiotemporal dynamics remains poorly understood. This study employs Earth system model experiments to quantify how SM dynamics influence local atmospheric dryness and its spatial propagation. Reduced SM drives the self-intensification of extreme atmospheric dryness in three key hotspots: Europe, North America, and South America. SM-atmosphere feedbacks amplify the spread of atmospheric dryness from these hotspots to surrounding areas, yielding extreme dryness events that are more persistent, intense, and spatially extensive. Mechanistically, SM deficit alters surface energy fluxes, deepens the planetary boundary layer, and strengthens mid-tropospheric high-pressure ridges. These processes promote downward advection of dry air and accelerate spatial expansion of atmospheric dryness. These findings confirm that SM-atmosphere feedbacks enhance both the local intensification and spatial propagation of atmospheric dryness, underscoring critical implications for developing ecosystem and societal adaptation strategies to mitigate large-scale extreme dryness under future climate change.