Drought Cascade in the Terrestrial Water Cycle: Evidence From Remote Sensing

Droughts are complex phenomena that typically evolve slowly over time. They originate through interactions between the atmosphere and the land surface, but show delayed evolution as they cascade through soil moisture, surface, and groundwater supplies, sometimes resulting in prolonged and insidious impacts on regional hydrological systems. While previous studies have observed this cascade phenomenon at select in situ locations, the temporal characteristics of drought cascades have never been quantitatively estimated at large scales using primarily remote sensing techniques. Here, we use satellite observations of vapor pressure deficit, Precipitation, and terrestrial water storage, and reanalysis-based estimates of column soil moisture to characterize cascade phenomena for four major US drought case studies. By mapping the time evolution through this suite of variables, we observe large-scale behavior generally consistent with theory and are able to quantify emergent patterns in the evolution of drought signals that may support improved future predictability.