Effects of time of bare cultivated soils observation and their roughness on the average diurnal soil albedo approximation by satellite data

This study explores the diurnal variation, from midday to sunset, in blue-sky albedo (α) of soil under clear-sky conditions, with respect to their surface roughness. Five roughness levels of soil surfaces shaped by a plow, spike tooth harrow and roller, then also modified by rain, developed from the same soil material, were examined. The relation between α and the solar zenith angle enabled us to predict in which solar local time for chosen days of year the a of such surfaces, located between the latitude angles of 70° in the Northern and Southern Hemispheres reaches its average diurnal value (α). The usefulness of remote sensing satellites on the sun-synchronous orbits close to that being optimal to the α approximation like NOAA-15, as well as the satellite on the orbits that most often have been used to the a estimation such as MODIS, is evaluated here.