Transfer characteristics for a heterogeneous surface of large aerodynamic roughness

Values of z o and Z T , roughness scaling lengths for momentum and heat, are found to be 0.4±0.2m and 0.035±0.02m, respectively, for a heterogeneous surface comprising 8m high trees with transpiring foliage, 1 m high dry grass, and sandy soil. Determination of Z T utilizes aircraft and ground‐based radiometric observations of surface temperature. The ratio Z o /Z T ≈ 12 was found essentially constant over the observed roughness Reynolds number range 5000–25000, consistent with values published for homogeneous natural vegetated surfaces.