Snow Grain Size Mapping Using Prisma Hyperspectral Data over the South Lhonak Glacier

Snow grain size is a fundamental property of snow and is directly proportional to its surface area. The stability of the snowpack has often been investigated in snow avalanches using data from the size and shape of the snow grains. The spatial and temporal change in the snow grain size can help characterize the thermal state of the snowpack, and to estimate the temporal and spatial distribution of snowmelt. The grain size of snow becomes coarser with melting and shows lower spectral albedo. This study shows the snow grain size mapping of the South Lhonak glacier region after the flash flood event of a Lake occurred on 4
^th
October 2023. The snow grain size mapping is performed using recent PRISMA hyperspectral data acquired on 8
^th
October 2023 by the Italian Space Agency. The JHU spectral library of snow grain size is given as an endmember, input to spectral information divergence method for hyperspectral grain size mapping. In the absence of the in-situ measurement absorption band area method, which signifies the amount of energy absorbed by the snow/ice particles has been employed to validate the mapped snow grain size. The trend of energy absorbed by mapped snow grain size and the corresponding JHU spectral library corroborate well. The wavelength region centered at 1.03μm is found to be suitable for understanding the grain size of the snowpack. Coarser snow was found to be prominent in the study area which aggress with the Himalayan field circumstances in the month of ablation.