THE EFFECT OF HETEROGENEOUS TERRAIN ON MICROMETEOROLOGICAL FLUX MEASUREMENTS - A CASE-STUDY FROM HAPEX-SAHEL

The use of gradient or eddy correlation methods for surface flux measurements has become routine in homogeneous terrain. The measurements and the methods are now increasingly being sited in heterogeneous terrain. While the methods still may be appropriate for this terrain, the interpretation of the measurements presents difficulties. In this paper the underlying source distribution of fluxes contributing to the gradient or eddy correlation measurement is shown to be at variance with both the areal estimates of available energy and with adjacent similar measurements of surface fluxes. The recent HAPEX-Sahel experiment provides an extreme example of a natural heterogeneous surface for this modelling exercise.