Перегляд за Автор "Alieva, A. J."

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    Investigation of Possibility of Measuring the Albedo of Earth’s Surface in Visible and Near Infrared Bands in Conditions of Aerosol Pollution of Atmosphere Using Unmanned Aerial Vehicles
    (КПІ ім. Ігоря Сікорського, 2024) Asadov, H. H.; Alieva, A. J.; Ashrafov, M. G.
    It is well-known that such processes as agricultural activities, urbanization processes, climatic changes leading to abnormal precipitation, etc. affect the magnitude of the Earth’s albedo. At the same time, the results of remote albedo measurement in visible and near infrared bands also depend on the degree of aerosol pollution of the atmosphere. These factors leading to changes in the earth’s albedo lead to the need for periodic measurements of regional values of the albedo of the earth’s surface. There are a number of problems related to measuring the albedo of the earth, related to the spatial and temporal variability of this indicator. These include the dependence of albedo on the zenith angle of the Sun, the need to create albedo measurement networks in the form of numerous geographically distributed pyranometers, the dependence of satellite albedo measurements on the state of the atmosphere, leading to the need for inter-satellite calibration, or groundbased validation measurements. At the same time, the issue of fully accounting for the effect of atmospheric aerosol on the results of measuring the albedo of the Earth’s surface is still open. The article is devoted to the measurement of the Earth’s albedo visible and near infrared bands using UAVs in conditions of aerosol pollution of the atmosphere. The model of single scattering of the optical source signal of an atmospheric aerosol was adopted as the basis of the conducted research. The interrelation of such optical indicators as the optical thickness of the aerosol and the albedo of the Earth’s surface is analyzed. A criterion for the effectiveness of atmospheric measurements using UAVs is proposed, in which efficiency is defined as the ratio of the total radiation entering the on-board spectroradiometer to the amount of extra-atmospheric radiation from the Sun. By switching from a discrete model to a continuous model created to calculate the proposed efficiency criterion, it is shown that with a synchronous change in the optical thickness of the aerosol and albedo, according to the calculated law, the minimum efficiency of measurements of the albedo of the earth’s surface is achieved.
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    Ordered Test Site Method for Onboard Measurement Results Validation of Medium Resolution Spectroradiometers
    (КПІ ім. Ігоря Сікорського, 2022) Asadov, H. H.; Alieva, A. J.
    The reduction or elimination of uncertainties is one of the main tasks in the analysis of remote sensing data. For this purpose, the upscaling and downscaling of spectroradiometric data operations are widely used. The downscaling operation is particularly used to validate medium resolution spectroradiometer data. The onboard measurement validation data is a complex task and it includes the solution of such important subtasks as (a) selection of the test site type; (b) determining the site size; (c) determining the sampling order. At the same time, after carrying out selective measurements, the question of scaling up (upscaling or generalization) of the obtained ground data arises, its purpose is to carry out validation of satellite data with low spatial resolution. Solving the problem of remote sensing data validation, terrestrial test sites are often used, their heterogeneity must always be taken into account. This problem is usually solved by applying special weighting coefficients and performing temporary periodic measurements, then using the regularization procedure for the averaged results of iterative calculations. In the absence of temporary changes, the need for regularization is eliminated. In this case, as an alternative, the method of the ordered test section can be proposed, it allows to determine the weight coefficients of the ground validation measurement results, providing a minimum of the newly proposed quadrature cost function. To solve the problem of achieving the proposed cost function minimum, the ordered subsections method as part of a single heterogeneous test section is proposed, the measurements are carried out by a sensor mounted on a low-flying carrier. The optimization problem is formulated to calculate the correction coefficients for the measurement results, where the sum of the squares of difference between the corrected data and the known representative estimate is minimized. The optimization problem is solved using a certain restrictive condition imposed on the sum of the correction factors.