Hyperspectral, microphysical and mineralogical interdisciplinary characterisation of the 224 m long ice core drilled on the Adamello glacier (Italian Alps)

Ice-covered surfaces capability to reflect the solar electromagnetic radiation can be affected by mineral dust (one of the main components of aerosols), that vary the ice reflectance so that a major portion of the radiation is absorbed as a function of dust concentration, mineralogical composition, particles optical footprint, etc. Ice cores from mid-latitude glaciers are essential to infer recent climate variability. The aim of this work is to extract a hyperspectral, microphysical and mineralogical characterisation of the 224 m long ADA270 ice core drilled in 2021 from the Adamello glacier (Pian di Neve, Italian Alps) applying an interdisciplinary approach. A non-destructive Hyperspectral imaging sensor is used to create highly resolved images described, pixel-by-pixel, by the reflectance, in the VNIR spectrum (380-1000 nm). Measurements are done at the EuroCold Lab. (University Milano-Bicocca). Three optical descriptors are extracted from reflectance: Albedo, Snow Darkening Index (SDI) and Impurity Index (II). When the reflectance increases, albedo accordingly increases, while SDI and II decreases. The SDI record is useful to select samples for microphysical and mineralogical analyses, using respectively a Beckman Coulter Counter Multisizer in the range 1-30 µm and an X-Ray Diffractometer (XRD) at the Dept. of Earth and Environmental Sciences (University Milano - Bicocca). Finally, a hyperspectral microscope will produce reflectance spectra in VNIR range of single dust grains (Central Washington University). The hyperspectral characterisation between 3.4-100 m depth of the ice core, highlights a succession of ice lenses, bubbles portions and dusty layers, which show high albedo, medium-high albedo and high SDI. These data are in accordance with low and high concentrations from microphysics. The XRD shows a great relative abundance of Quartz, Chlorite and Biotite, for local transport and Kaolinite (a secondary mineral), that can be attributed to a Saharan dust transport. Unifying hyperspectral, microphysical and XRD data, a complete characterisation of ice-cores impurities can be done. Single grain Raman spectroscopy coupled with micro-hyperspectral measurements, will provide a quantitative identification of different single minerals encountered in the ice core through time helping identifying their impact on atmospheric optics and glacier melting rate. Ice-covered surfaces capability to reflect the solar electromagnetic radiation can be affected by mineral dust (one of the main components of aerosols), which vary the ice reflectance so that a major portion of the radiation is absorbed as a function of dust concentration, mineralogical composition, grains optical footprint, etc. Ice cores from mid-latitude glaciers are essential to infer recent climate variability. The aim of this work is to extract a hyperspectral, microphysical and mineralogical characterisation of the 224 m long ADA270 ice core drilled in 2021 from the Adamello glacier (Pian di Neve, Italian Alps) applying an interdisciplinary approach. A non-destructive Hyperspectral imaging sensor is used to create highly resolved images described, pixel-by-pixel, by the reflectance, in the VNIR spectrum (380-1000 nm). Measurements are done at the EuroCold Lab. (University Milano-Bicocca). Three optical descriptors are extracted from reflectance: Albedo, Snow Darkening Index (SDI) and Impurity Index (II). When the reflectance increases, albedo accordingly increases, while SDI and II decreases. The SDI record is useful to select samples for microphysical and mineralogical analyses, using respectively a Beckman Coulter Counter Multisizer in the range 1-30 µm, an X-Ray Diffractometer (XRD) and a Raman spectrometer at the Dept. of Earth and Environmental Sciences (University Milano - Bicocca). Finally, a hyperspectral microscope will produce reflectance spectra in VNIR range of single dust grains (Central Washington University). The hyperspectral characterisation between 3.4-150 m depth of the ice core, highlights a succession of ice lenses, bubbles portions and dusty layers, which show high albedo, medium-high albedo and high SDI signals. These data are in accordance with low and high concentrations from microphysics. The XRD shows a great relative abundance of Quartz, Chlorite and Biotite, for local transport, and Kaolinite (a secondary mineral) that can be attributed to a Saharan dust transport. Unifying hyperspectral, microphysical and XRD data, a complete characterisation of ice-cores impurities can be done. Single grain Raman spectroscopy coupled with micro-hyperspectral measurements, will provide a quantitative identification of different single minerals encountered in the ice core through time helping identifying their impact on atmospheric optics and glacier melting rate.