Deliverable D2.1 Snow cover data set

This report pertains to the Deliverable D2.1: Snow cover data set, as described in ANNEX 1, part A (p. 32) of the EC/REA Grant Agreement for project number 101184962, “LIQUIDICE”. Work Package 2 of the LIQUIDICE project is led by NORCE with the support of CNR, IISC, IITB, GEUS, UNIVBRIS, SIOS-KC and IG PAS. Other beneficiaries were also asked to contribute to the deliverable by reaching out to key people and organisations in each of their own countries. The enhancement of observations about the snow cover in remote areas requires novel strategies for limiting gaps associated with cloud cover, darkness, topography, and data availability. Two different approaches have been selected, and they both converge to the intermediate spatial resolution of Sentinel-2 imagery. The first solution is based on imagery obtained by time-lapse cameras located in the Ny-Ålesund area (Svalbard). The projection of such oblique cameras into a 10m-grid provides the estimation of the Fractional snow-covered area that can be easily integrated with Sentinel-2 data. The second approach is focused on two datasets produced for two study areas: Svalbard and Jotunheimen (Norway). While one dataset is at lower resolution with a long-term period based on Terra MODIS (2000-2025), the second one is shorter with higher resolution from Sentinel-2 data (2016-2025). The overarching idea is to find the connection between those satellite-derived datasets by training on a common time-period using state-of-the-art machine learning techniques.