GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 3.2 ___ GNGTS 2023 accumulation/ablation zones could be therefore responsible for the peculiar behavior of the EM waves. In fact, according to Campbell et al., 2012 and Gusmeroli et al., 2013 the percolation water of the firnification process and the release of latent heat originating in the ELA zone could affect the glacial body in terms of different amounts of water and heat and this could be visualized in the amplitude GPR sections as a free of scattering (i.e. EM transparent) zone, like in the data of Delf et al., 2022 here re-interpreted. Conclusion In this work we demonstrated the possibility to identify different EM facies that could occur in a polythermal glacier and how the use of the integrated GPR attributes can improve the glaciological interpretation of the data, giving additional information which cannot be extracted just considering the usual reflection amplitude data. We highlighted a coherent and not ubiquitous anomalous zone characterized by peculiar spectral content remarkable different from all the other GPR facies. Such a zone could be related to local temperature variations in turn caused by heat transfer, peculiar stress conditions or glacial metamorphism. Further researches are necessary to quantitative evaluate how such parameters affect the GPR data in terms of a variations of EM parameters and how these could be related to spectral anomalies of the GPR signals. References Bælum, K., and Benn, D.I., 2011. Thermal structure and drainage system of a small valley glacier (Tellbreen, Svalbard), investigated by ground penetrating radar . Cryosphere 5, 139-149. https://doi.org/10.5194/tc-5-139-2011. Campbell, S., Kreutz, K., Osterberg, E., Arcone, S., Wake, C., Introne, D., Volkening K., Winski, D., 2012, Melt regimes, stratigraphy, flow dynamics and glaciochemistry of three glaciers in the Alaska Range . Journal of Glaciology, 58(207), 99-109. doi:10.3189/2012JoG10J238. Delf, R., Bingham, R.G., Curtis, A., Singh, S., Giannopoulos, A., Schwarz, B., Borstad, C.P., 2022. Reanalysis of polythermal glacier thermal structure using radar diffraction focusing . Journal of Geophysical Research: Earth Surface, 127, e2021JF006382. https://doi. org/10.1029/2021JF006382. Forte, E., Santin, I., Ponti, S., Colucci, R.R., Gutgesell, P., Guglielmin, M., 2021. New insights in glaciers characterization by differential diagnosis integrating GPR and remote sensing techniques: A case study for the Eastern Gran Zebrù glacier (Central Alps) . Remote Sensing of Environment, Volume 267, 2021, 112715, ISSN 0034-4257, https://doi.org/10.1016/j.rse.2021.112715.