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 measu rements has become routine in homogeneous terrain. The measurements an d the methods are now increasingly being sited in heterogeneous terrai n. While the methods still may be appropriate for this terrain, the in terpretation of the measurements presents difficulties. In this paper the underlying source distribution of fluxes contributing to the gradi ent or eddy correlation measurement is shown to be at variance with bo th the areal estimates of available energy and with adjacent similar m easurements of surface fluxes. The recent HAPEX-Sahel experiment provi des an extreme example of a natural heterogeneous surface for this mod elling exercise.