Remote measurement of soil albedo along aircraft flight paths

The redistribution of solar radiation in the geographical envelope plays an important climate-forming role. The radiation reflected by the Earth's surface (albedo) is a component of the Earth's radiation balance. The albedo of the Earth's surface depends primarily on the angle of incidence of sunlight, the color of the underlying surface, and its roughness relative to the incident rays. It also depends on the degree of specularity, so the water surface reflects the rays falling on it almost mirror-like, almost regardless of the presence of ripples or waves on it. The article examines the dependence of albedo, the surface of the soil not covered with vegetation, on these factors. Taking into account the known regression dependence of the albedo of the earth's soil surface on the roughness index or the standard deviation of the height of the measured points on the Earth's surface, the problem of achieving maximum information content of the measurements of the roughness of the Earth's surface is formulated and solved, and the optimal dependence of the zenith angle of the Sun on the time interval between two consecutive time points of roughness measurements is revealed. The influence of the zenith angle of the Sun on the conducted albedometric measurements is investigated. Based on the well-known fact that the albedo of the Earth's surface in the range of the zenith angle of the Sun θ = 10° - 60° increases almost linearly depending on it. The values of the zenith angle of the Sun obtained in this way are called the most informative zenith angles in the sense of ensuring maximum informative measurement of the earth's surface, and the albedo values corresponding to these zenith angles are the optimal albedo values at which optimal (maximally informative) roughness measurements can be carried out in the zenith angle range of 10° - 60°.