Surface albedo measurement comparisons over sloping terrain with two different radiometer placements.

Abstract

Surface albedo plays an important role in the local- and regional-scale solar radiation budget. However, the in situ measurement of surface albedo over rugged terrain is usually confused by the radiometer placement. In this study, two commonly measured albedos with different sensor configurations were characterized and illustrated based on the radiometer orientation in the illumination and viewing geometry. They are: horizontal-horizontal sensor measured sloping surface albedo (HHSA), and inclined-inclined sensor measured sloping surface albedo (IISA). The 3-D Discrete Anisotropic Radiative Transfer (DART) model simulations were used to exemplified their difference. Results reveal that these two albedos show distinct patterns with slope and aspect. Therefore, the radiometer placement should be considered in the surface albedo measurement over rugged terrain.