| 21 Sep 2026
Noah-MP-ML² v1.0: Development of a multilayer canopy land surface model with improved representation of vadose zone soil water dynamics
Abstract. Land surface models (LSMs) simulate surface processes and land–atmosphere exchanges of energy, water, and carbon. However, many LSMs still rely on simplified parameterizations of surface-layer radiative transfer, canopy turbulence, and vadose-zone hydrology. This paper describes Noah-MP-ML², a multilayer canopy extension of the community Noah-MP LSM developed to address these limitations. Noah-MP-ML² implements a roughness-sublayer scheme and the Medlyn stomatal-conductance parameterization to represent canopy turbulence and photosynthetic processes. The implementation of the Speedy Algorithm for Radiative Transfer through Cloud Sides (SPARTACUS)-Surface scheme enables consistent N-stream shortwave and longwave radiative transfer across multiple spectral bands while accounting for lateral radiative exchange within heterogeneous vegetation canopies. A multilayer implicit solution is used to calculate canopy scalar concentrations and the temperatures of sunlit and shaded foliage. Soil-water movement is represented using a mass-conserving, mixed-form, one-dimensional Richards-equation solver with van Genuchten water-retention relationships. Noah-MP-ML² was evaluated against observations from five forest flux-tower sites spanning different vegetation types and climatic regimes. The results demonstrate improved representation of surface energy partitioning, turbulence through friction velocity, and soil-water dynamics relative to the community Noah-MP LSM.
Competing interests: At least one of the (co-)authors is a member of the editorial board of Geoscientific Model Development.
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