loading page

Preferential Hydrologic States and Tipping Characteristics of Global Surface Soil Moisture
  • Vinit Sehgal,
  • Binayak P Mohanty
Vinit Sehgal
Biological and Agricultural Engineering, Texas A&M University, Water Management and Hydrological Science, Texas A& M University
Author Profile
Binayak P Mohanty
Biological and Agricultural Engineering, Texas A&M University

Corresponding Author:


A dynamic transition in soil hydrologic states through climate perturbations and terrestrial feedbacks governs soil-vegetation-climate (SVC) interactions, constrained by critical soil moisture (SM) thresholds. Observational and scaling constraints limit critical SM threshold estimation at the remote-sensing (RS) footprint scale. Using global surface SM (θRS) from NASA’s Soil Moisture Active Passive (SMAP) satellite, we characterize seasonal preferential hydrologic states of θRS and derive three tipping characteristics to estimate the intensity (Mean Tipping Depth, \(\overline{{\varepsilon}}\) ), frequency (Tipping Count, \(\eta\) ), and duration (Mean Tipped Time, \(\overline{{\tau}}\) ) of the excursion of θRS from wet- to dry-average conditions. The preferential state provides the seasonally dominant hydrological states of θRS, while tipping characteristics capture the ecosystem linkages of the dynamic transition in θRS hydrologic states. Globally, θRS predominantly exhibit a (unimodal) dry-preferential state, especially over arid/semi-arid drylands and a unimodal wet-preferential θRS state in high-latitude boreal forests and tundra biomes. Prevalence of (bimodal) bistable θRS state overlaps with regions of strong positive SM-precipitation coupling and monsoonal climate in semi-arid/ subhumid climates. Seasonal preferential hydrologic states co-vary with the regional variability in plant water stress threshold and land-atmospheric coupling strength. Tipping characteristics of θRS show sensitivity to intra-biome variability in SVC coexistence patterns and display high skill in partitioning global ecoregions. While \(\overline{{\varepsilon}}\)  and \(\eta\)  are climate-controlled, \(\overline{{\tau}}\)  is moderated by soil and vegetation through their influence over θRS drydown during Stage II evapotranspiration. Preferential states and tipping characteristics find applications in quantifying SVC coexistence patterns, climate model diagnosis, and assessing ecosystem sensitivity to climate change.
09 Mar 2023Submitted to ESS Open Archive
09 Mar 2023Published in ESS Open Archive