| 13 Mar 2026
Assessing VIIRS constellation seasonal snow cover over the French mountains with Sentinel-2
Abstract. Remote sensing observations of snow-covered area from moderate-resolution (100–1000 m) optical sensors are critical for water resource monitoring and climate-related applications. Many studies have relied on MODIS snow products, but NASA plans to stop science data collection from MODIS instruments in the next two years. The Visible Infrared Imaging Radiometer Suite (VIIRS), designed as follow-on instrument to MODIS, has similar characteristics and is currently onboard three satellite platforms with daily revisit. Several agencies now distribute operational snow cover products based on VIIRS data, yet independent evaluations of these products remain scarce, limiting their adoption by the snow science community. Here, we assess NASA VIIRS snow cover products over several mountain ranges in France using Sentinel-2 snow cover products as a high-resolution reference. We also evaluate a near-real-time VIIRS snow cover product developed by Météo-France over metropolitan France. The analysis covers an entire winter season and examines performance across contrasting topographic settings. Across the different products, we find an average bias close to zero and a root mean square error ranging from 10 to 15 % for snow cover fraction, while the corresponding binary snow classification achieves a F1-score of 92–93 %. However, uncertainties can reach 30 % for challenging observation conditions, including mixed pixels, forested areas, and north-facing slopes. Finally, we demonstrate that combining observations from multiple VIIRS platforms effectively reduces cloud cover without degrading snow cover retrieval quality.
Competing interests: At least one of the (co-)authors is a member of the editorial board of The Cryosphere.
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