Impact of a coupled canopy-soil model on canopy-resolving turbulence simulation

The NOAH land-surface model is already a fairly complete representation of the soil-water-vegetation system and how it responds to the atmosphere, but until recently the canopy has been 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 dynamic calculation of vegetation-imposed scalar sources/sinks determined by atmospheric demand, and to provide an avenue for the fluid mechanics to respond to rapid and local fluctuations in leaf temperature. We will briefly describe the model and show results testing the model against data from the CHATS campaign. Emphasis will be placed on presenting turbulence statistics and structure from large eddy simulation output comparing uncoupled- versus coupled-canopy simulations.