Assessing Canopy and Roughness‑Sublayer Turbulence Representation in Noah‑MP over Forest and Grassland at Lindenberg (Germany)

Land–atmosphere exchange in tall canopies is strongly controlled by turbulence within and above the canopy and in the roughness sublayer (RSL), where classical Monin–Obukhov similarity theory (MOST) is known to be imperfect. Recent developments in the Noah‑MP land surface model (LSM) include a unified turbulence parameterization that aims to provide a consistent treatment of turbulence from within the canopy, through the RSL, to the surface layer (Abolafia‑Rosenzweig et al., 2021). While this scheme has been tested primarily under snow‑dominated conditions, its performance for non‑snow, multi‑canopy environments over long time periods remains largely unexplored.

Here, we evaluate the unified canopy–RSL turbulence parameterization in Noah‑MP (version 5.1.1) using multi‑year, multi‑level observations from the Lindenberg observatory of the German Meteorological Service (DWD). We focus on two contrasting sites: (i) Kehrigk, a tall evergreen needleleaf forest canopy where RSL effects are expected to be strong, and (ii) Falkenberg, a short grassland site that more closely conforms to MOST assumptions. Both sites provide continuous 30‑min data since 2005, including eddy‑covariance fluxes of sensible and latent heat, radiation components, soil heat flux at 5 cm depth, skin temperature, and multi‑level profiles of air temperature, humidity, and wind speed up to 30 m (forest) and 10 m (grassland). All forcing and flux data undergo standard DWD quality control procedures.

Noah‑MP is run offline at both sites with identical land and soil parameterizations, driven by observed meteorology. We compare a standard configuration (MOST‑based surface‑layer and canopy treatment) with the unified canopy–RSL turbulence configuration. Beyond standard flux evaluation, we will diagnose friction velocity, Monin–Obukhov length, bulk transfer coefficients for heat and moisture, and the vertical structure of wind and temperature in the surface and roughness sublayers. Model performance will be analysed as a function of season, canopy type, and atmospheric stability.

By linking detailed, long‑term observations to alternative turbulence representations in a widely used LSM, this study aims to clarify under which conditions enhanced canopy–RSL formulations improve land–atmosphere coupling in next‑generation Earth System Models.