Comparison of evapotranspiration using the aerodynamic and Bowen ratio energy balance methods

The stability-corrected aerodynamic method was used to estimate fluxes of sensible and latent heat over an irrigated winter wheat field at Maricopa Agricultural Center in southern Arizona. These estimates were compared against the more precise Bowen ratio energy balance measurements made at the same location. The data were collected for 43 consecutive days over a range of canopy conditions. The aerodynamic method performed poorly against the validated Bowen ratio method at this site. Fluxes of latent heat were underestimated by the stability-corrected aerodynamic method. Sensible heat fluxes sometimes agreed well, but were often low. A new model was developed by combining AERO sensible heat (H(aero) with net radiation and soil heat flux to estimate latent energy as a residual (Le(resid)) in the surface energy balance equation. This aerodynamic energy balance (AEB) method, produced R² values of 0.97 and 0.78 for the wet and dry periods respectively.