THE DETERMINATION OF BROAD-BAND SURFACE ALBEDO FROM AVHRR VISIBLE AND NEAR-INFRARED RADIANCES

A method for retrieving broad band surface albedo from top of atmosphere reflected solar radiances measured by the visible and near-infrared channels of the Advanced Very High Resolution Radiometer (AVHRR) is described. The algorithm developed was applied to eight passes over the British Isles and near continent for relatively cloud-free conditions between the months of April and October. The retrieved surface albedos are presented both as high resolution images to show up the detail in the spatial variability and as tables where each value is an average over a 15 km grid square. The surface albedos of the agricultural areas of the British Isles showed a marked increase from 17 to 22 per cent between April and July. In contrast urban areas and rougher hilly terrain (e.g. the Scottish Highlands) gave lower surface albedos of 13 per cent which remained more constant throughout the period between April and October. The results presented here are compared with those derived by other workers and found to be consistent with them, bearing in mind the uncertainty of the method presented here which is about 4 per cent in reflectance. © Taylor & Francis Ltd.