Adlin Dancheva

The study presents a spectral assessment and analysis of various data and methods for snow cover analysis in different ranges of the electromagnetic spectrum through a differentiated approach applied to the territory of Bansko, Pirin Mountain. The aim of the presented research is to assess the effectiveness and accuracy of satellite observations together with field (in situ) measurements and to create a model of an integrated methodology. To achieve this goal, several indices, such as land surface temperature (LST), optical indices, Tasseled Cap Transformation (TCT) with wetness component (TCW), High-Resolution (HR) imagery, and Synthetic Aperture Radar (SAR) measurements, were analyzed. The results of the analysis proved that combining satellite and field data through a mobile thermal camera provides an accurate and comprehensive picture of snow conditions in high mountain regions for powder, hard-packed and wet snow. As the most important, there is the verification and validation of the results through the so-called regression analysis of the different data types, through which multiple correlations (over 10) were established, both in data from Sentinel 1SAR, Sentinel 2MSI, Sentinel 3 SLSTR, and PlanetScope. The results showed the effectiveness of optical indices for hard and fresh snow and radar and LST data for wet snow. The results can be used to improve snow surveys, event prediction (e.g., avalanches), and the interpretation of spectral analysis of snow. The study does not aim to perform a temporal analysis; all satellite data is from the temporal period 30 December 2024–5 January 2025.

The Magnesium-Air battery is a very attractive energy source due to its high specific energy, low cost and the possibility of rapid mechanical recharge. The use of citric acid as an additive to the electrolyte (sea water) prevents the precipitation of Mg(OH)2 and enhances the behaviour of the magnesium electrode. Due to the better access of electrolyte to the electrode surface, ohmic and polarization resistances are reduced, and the rate of electrochemical reaction is increased. The equilibrium potential is displaced towards lower values for both pure magnesium and magnesium alloy AZ63.Citric acid favours also the performance of the GDE by removing the Mg(OH)2 precipice. A functioning battery is tested under polar conditions at the Bulgarian Antarctic station at Livingstone island.