Spatiotemporal variations of albedo using MODIS and PCA analysis in Iran

The aim of this study is to investigate the spatiotemporal variations of albedo in Iran. To this aim, the daily albedo datasets of Moderate Resolution Imaging Spectroradiometer (MODIS) from onboard Aqua and Terra (MCD43A3v006) were applied for the period of 2000 to 2019 with a spatial resolution of 500 × 500 m2. First, the long-term average of Iran’s albedo was calculated; the obtained results show that the average albedo of spring, summer, autumn, and winter in Iran is 13.7%, 14.7%, 15.2%, and 19.2%, respectively. Second, the temporal-spatial variations of albedo values in Iran were analyzed using principal component analysis, and the results showed that the three main components are able to explain 97% of the data variation. The first component explains more than 74% of the total changes, the second component more than 20%, and finally, the third component explains more than 3% of the changes. Finally, the linkage between the three main components with aspect, slope, and elevation was examined in Iran. The results showed that the role of solar zenith angle, elevation, and aspect in the first and third components and also the role of slope and elevation in the second component were the most significant. In general, it can be said that snow cover in the first component, salt cover in the second component, and also snow reservoirs in the third component had albedo above average; this issue depends on the roughness and the surface of the ground. The results showed that this technique is very suitable for the analysis of the spatiotemporal variations of Albedo.