Soil moisture (SM) accounts for a small fraction of the total global freshwater yet exerts a large influence on the global water cycle (McColl, Alemohammad, et al., 2017). At fine spatial scale, soil governs plant growth, geochemical processes, and groundwater recharge. However at large spatial scales (several hundred meters to several kilometers), SM plays a crucial role in precipitation recycling (Baudena et al., 2008), cloud formation (Fast et al., 2019), land-atmospheric coupling (Schwingshackl et al., 2018), and numerous other critical processes for global energy, water, and carbon cycle. Global SM status and the characteristic soil water retention functions are needed as inputs to the large-scale Earth system models (Bonan & Doney, 2018; Dunne et al., 2012; Flato, 2011; Hurrell et al., 2013). However, the mechanistic understanding (and modeling) of SM dynamics for large-spatial scales is mainly driven by a Darcy-scale perspective, largely due to the unavailability of long-term observed data at large spatial scales. Hence, there is a need to critically reevaluate the process understanding and interpretations about the governing mechanisms of SM, dynamics specific to large spatial scales. The general trajectory of SM drydowns (period of sustained loss of SM) finds its origin in fine-scale studies (Guswa et al., 2002; Rodriguez-Iturbe, 2000; Rodriguez-Iturbe et al., 1999). Laio et al. (2001) proposed that mapping the trajectory of the rate of loss of the observed SM with decreasing SM can provide information about the dominant soil hydrologic regimes and the soil water retention properties like field capacity and wilting point. The pathway of SM drydown was assumed to be a piecewise-linear function where each limb represented a unique soil hydrologic regime. Moreover, the rate of drainage loss and the strength of the land-atmospheric interaction may also be inferred from the observed SM drydown curves. Operating in the L-band microwave frequency, the Soil Moisture Active Passive (SMAP) radiometer provides SM estimates for the top 5 cm of soil with a high retrieval accuracy at a spatial support scale of 36 km. The spatial support (36 km) and global extent make SMAP observations ideal for a global evaluation of SM drydowns at large spatial scales.