A coupled canopy-soil model for the simulation of the modification of atmospheric turbulence by tall vegetation

The NOAH land-surface model already contains a fairly complete representation of the soil-water-vegetation system and how it responds to the atmosphere. However, the canopy is implemented as a single ``big-leaf" which does not allow for canopy induced stability effects to modify the vertical mixing of scalars emitted with the sub-canopy. Motivated by the work of van de Wiel et al. (2002) who demonstrated the importance of the canopy for simulating intermittent turbulence in the stable boundary layer, we have developed a coupled canopy-soil model by extending the NOAH land-surface system to include a vertical distribution of the sensible-, radiative-, and latent-heat fluxes, a height-dependent leaf-area density, stomatal resistance and leaf boundary layer resistances. This new land-surface model is suitable for coupling with either one-dimensional models of canopy turbulence and scalar transport that could be implemented in mesoscale models, or with turbulence resolving simulations like those generated by large-eddy simulation. The intent is to allow for the dynamic calculation of scalar sources/sinks by the vegetation based on atmospheric demand, and to provide an avenue for the fluid mechanics to respond to rapid and local fluctuations in leaf temperature. We will describe the model, and show results testing the model against observational data, and time permitting will present results from a coupled-canopy large-eddy simulation.