Spatiotemporal evolution and lifecycle dynamics of soil-atmosphere compound droughts in Central Asia: A three-dimensional perspective

Abstract

Study Region Central Asia, including the five Central Asian countries and northwestern China Study Focus Most assessments of soil–atmosphere compound droughts focus on simultaneous water limitation, overlooking antecedent and residual stages that shape event development and recovery. Here, we extended three-dimensional (3D) event tracking to reconstruct the complete lifecycle of soil–atmosphere compound droughts in Central Asia from 1981 to 2024. Soil-moisture drought (D SM ) and vapor-pressure-deficit drought (D VPD ) clusters were independently identified and then linked within a lifecycle-oriented framework that distinguishes initiation, compound, and decay phases, as well as simple and complex pathways. New Hydrological Insights for the Region: D SM behaved as a stationary–persistent stressor with longer durations and localized clustering, whereas D VPD acted as a mobile–expansive driver with larger spatial footprints and higher intensities. Both drought types increased markedly after 2000, accompanied by earlier D SM onset in spring and summer. Only 13.6% of compound events began with simultaneous D SM and D VPD onset; 51.1% were D SM -initiated with longer propagation lags, whereas 35.2% were D VPD -initiated and developed more rapidly under strong atmospheric moisture demand. Moreover, 63.6% of compound events ended only after delayed dissipation of soil-moisture deficits, highlighting soil-memory effects. Although simple one-to-one pathways accounted for 65.9% of events, complex pathways substantially enlarged and prolonged the compound phase. This lifecycle perspective provides a process-oriented basis for interpreting soil–atmosphere drought interactions and improving drought early warning in drylands.