Temporal Dynamics of Aerodynamic Canopy Height Derived From Eddy Covariance Momentum Flux Data Across North American Flux Networks

Aerodynamic canopy height (h_a) is the effective height of vegetation canopy for its influence on atmospheric fluxes and is a key parameter of surface-atmosphere coupling. However, methods to estimate h_a from data are limited. This synthesis evaluates the applicability and robustness of the calculation of h_a from eddy covariance momentum-flux data. At 69 forest sites, annual h_a robustly predicted site-to-site and year-to-year differences in canopy heights (R² = 0.88, 111 site-years). At 23 cropland/grassland sites, weekly h_a successfully captured the dynamics of vegetation canopies over growing seasons (R² > 0.70 in 74 site-years). Our results demonstrate the potential of flux-derived h_a determination for tracking the seasonal, interannual, and/or decadal dynamics of vegetation canopies including growth, harvest, land use change, and disturbance. The large-scale and time-varying h_a derived from flux networks worldwide provides a new benchmark for regional and global Earth system models and satellite remote sensing of canopy structure.