A modified Bowen ratio method to determine sensible and latent heat fluxes
Liu, Heping; Foken, Thomas
The sensible heat flux (H) and the latent heat flux (Î»E) were measured above a grassland during June, 1997 (LINEX-97/1 Experiment), using the eddy covariance method (EC) and the Bowen ratio/Energy balance method (BREB). The results indicate that HBREB is about (30 Â± 20) Wm-2 higher than HEC, and Î»EBREB is about (180 Â± 40) Wm-2 higher than Î»EEC during the daytime, and this is mainly caused by an imbalance in the closure of the surface energy balance in the BREB. In order to avoid the inaccuracies associated with the surface energy balance method, we propose a modified Bowen ratio method (MBR) to determine sensible and latent heat fluxes without using the surface energy balance equation. The results and error analysis show that MBR can give more accurate results than BREB. For the MBR, a measurement system using a sonic anemometer together with temperature and humidity measurements at two levels is being recommended to obtain sensible and latent heat fluxes.