Meteorological-to-agricultural drought propagation in Southwest China: Spatiotemporal characteristics and driving mechanisms from a three-dimensional perspective

Study region Southwest China is a climatically and topographically complex region frequently affected by drought, posing substantial risks to agriculture, water security, and ecosystems. Study focus This study develops a three-dimensional event-based framework to investigate meteorological-to-agricultural drought (MD-to-AD) propagation in Southwest China during 1961–2021. MD and AD were characterized at the monthly scale using standardized drought indices with a 3-month accumulation period. Drought events were identified through connected-component labeling and linked using spatiotemporal matching. Trajectory clustering and atmospheric diagnostics were then used to distinguish dominant propagation patterns and associated atmospheric mechanisms. New hydrological insights for the region A total of 220 MD and 105 AD events were identified, with severe events becoming more persistent and intense after 2000. MD exhibited greater spatial mobility, whereas AD showed stronger persistence and memory. 30 propagation relationships were detected, comprising 24 one-to-one and six one-to-many types. One-to-one propagation had a shorter mean response time but a longer mean distance, whereas one-to-many propagation showed a longer lag, a shorter distance, and weaker individual AD responses. Two distinct patterns emerged: slower, longer-distance, predominantly southward propagation in western–central Southwest China and faster, shorter-distance, mainly eastward and southeastward propagation in central-eastern and southeastern regions. These patterns were associated with distinct atmospheric circulation configurations and may be jointly modulated by large-scale circulation anomalies, Tibetan Plateau effects, land–atmosphere feedbacks, and land-surface heterogeneity.