Meteorological-to-agricultural drought propagation based on the "Press-Pulse" framework

Drought propagation is a key process linking meteorological anomalies to agricultural impacts within the hydrological cycle. Under climate warming, the superimposition of long-term increasing temperature trends ("Press") and short-term extreme drought events ("Pulse") fundamentally alters the propagation dynamics from meteorological drought to agricultural drought. Therefore, it is important to elucidate the driving mechanisms and impact patterns of this superposition effect on the drought propagation process. Using multi-source hydrometeorological datasets, we developed a Copula-based "Press–Pulse" framework to quantify meteorological-to-agricultural drought propagation (MTAD) in the Yellow River Basin during 1961–2021, with a focus on propagation probabilities, propagation thresholds, and temperature-regulation effects,with a focus on propagation probabilities, propagation thresholds, and the temperature-regulation effects on MTAD. The results show that: (1) Propagation exhibits strong spatiotemporal heterogeneity, peaking in early summer (June) with basin-averaged probabilities exceeding 0.6 and response areas covering ∼23% of the basin, before attenuating to ∼0.3–0.4 by August due to precipitation replenishment. (2) The superimposition of high-temperature 'Press' significantly amplifies this risk, increasing agricultural drought probabilities by 10–25% and systematically deepening the triggering SPEI thresholds (e.g., from −0.5 to −1.0), particularly in the water-limited middle reaches. (3) Identification of a critical Press Tipping Point reveals a distinct spatial divergence: while an intensified temperature press exacerbates drought susceptibility across the semi-arid Loess Plateau by accelerating soil moisture depletion, it conversely exerts a localized buffering effect in the upstream high-altitude regions, where the press-induced snowmelt recharge offsets pulse (precipitation) deficits. Overall, warming systematically lowers the barriers for drought propagation, underscoring the necessity of incorporating temperature-dependent dynamic thresholds into drought early warning and adaptation strategies.