@Article{Massoud_GMD_20260427,
 author		= {Elias C. Massoud and Nathan Collier and Yaoping Wang and Jiafu Mao and Adrian Harpold and Steven A. Kannenberg and Gerbrand Koren and Mukesh Kumar and Pushpendra Raghav and Pallav Ray and Mingjie Shi and Jing Tao and Sreedevi P. Vasu and Huiqi Wang and Qing Zhu and Forrest M. Hoffman},
 title		= {Benchmarking Soil Moisture and Its Relationship to Ecohydrologic Variables in {E}arth {S}ystem {M}odels},
 journal	= GMD,
 volume		= 19,
 number		= 8,
 pages		= {3427--3453},
 doi		= {10.5194/gmd-19-3427-2026},
 day		= 27,
 month		= apr,
 year		= 2026,
 abstract	= {Soil moisture (SM) is a key regulator of ecosystem biogeophysics, influencing plant water relations and landatmosphere energy exchanges. We evaluate the representation of SM in 16 Earth System Models from the Coupled Model Intercomparison Project Phase 6 (CMIP6) using the International Land Model Benchmarking (ILAMB) framework, focusing on surface (0--5, 0--10~cm) and rootzone (0--100~cm) depths, as well as key ecohydrological variables like gross primary productivity (GPP), leaf area index (LAI), and evapotranspiration (ET), and their coupling. Models are benchmarked against multiple observational and assimilated datasets to assess both state variables and crossvariable relationships. Surface SM is generally well represented ($r > 0.87$), while rootzone SM variability is systematically overestimated (normalized standard deviation $> 1$).  ET shows strong agreement with observations ($r > 0.9$), whereas GPP and LAI exhibit larger inter-model spread.  Skill in individual variables does not guarantee realistic SM– ecohydrology coupling, which varies strongly across models and depends on the reference dataset. K\"{o}ppen-based regional analyses reveal strong regime dependence, with several models performing well in Tropical and Temperate regions but degrading in Continental (high-latitude) zones. Across both global and regional benchmarks, models cluster by land surface framework, indicating that structural choices in soil hydrology and soil–plant coupling exert a first-order control on performance. These results provide process-relevant benchmarks and suggest that improving the representation of vertical soil structure, rooting depth distributions, and soil–plant hydraulic coupling will be central to advancing soil moisture realism in next-generation Earth system models.}
}