Comparison between different methods of measurement of momentum and sensible heat fluxes over canopies

Abstract

Différent methods of measurement of momentum and sensible heat flux densifies are presented and compared above a gras covered fallow. The aerodynamic (AD) and eddy covariance (EC) methods are presented and compared for both momentum and sensible heat measurements. In addition, the temperature fluctuation (TF) method is compared to the HEC method for the sensible heat flux measurement. The AD and EC methods are in good agreement for the momentum flux measurements. For the sensible heat flux, the AD method is very sensible to temperature errors. So it is unusable during night and gives biased estimations during the day. The TF method gives only estimations of the sensible heat flux. It is in good agreement with the EC method during the day but diverges completely during night, being unable to disceming positive from négative fluxes. From the three methods, the EC method is the sole that allows to measure continuously both momentum and sensible heat flux but it requires a loud data treatment. We présent in this paper the algorithm used for this treatment.

Keywords

• Eddy covariance
• temperature fluctuation
• aerodynamic method
• flux measurement