Role of adjacency effect in the remote sensing of aerosol

Adjacency effect is known to reduce apparent surface contrast by decreasing the top of the atmosphere radiance over bright pixels and increasing the brightness of the dark pixels. This effect is systematic and thus becomes important for the land remote sensing applications developed for use with either dark or bright targets. In this paper we trace the error caused by adjacency effect in the data processing chain from aerosol retrieval over dark targets to the atmospheric correction of the top of the atmosphere radiance. A systematic overestimation of the retrieved aerosol optical thickness and underestimation of surface albedo is demonstrated in accurate numeric simulations for a variety of atmospheric conditions and surface models. Results obtained suggest that 3-D radiation effects should be taken into account not only in the atmospheric correction algorithms but also in the aerosol retrieval over land at a high-to-medium (up to 1 km) resolution of sensor.