{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,24]],"date-time":"2026-06-24T18:43:10Z","timestamp":1782326590617,"version":"3.54.5"},"reference-count":38,"publisher":"MDPI AG","issue":"18","license":[{"start":{"date-parts":[[2020,9,8]],"date-time":"2020-09-08T00:00:00Z","timestamp":1599523200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100002830","name":"Centre National d\u2019Etudes Spatiales","doi-asserted-by":"publisher","award":["NA"],"award-info":[{"award-number":["NA"]}],"id":[{"id":"10.13039\/501100002830","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100000806","name":"European Environment Agency","doi-asserted-by":"publisher","award":["NA"],"award-info":[{"award-number":["NA"]}],"id":[{"id":"10.13039\/501100000806","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>Sentinel-2 provides the opportunity to map the snow cover at unprecedented spatial and temporal resolutions on a global scale. Here we calibrate and evaluate a simple empirical function to estimate the fractional snow cover (FSC) in open terrains using the normalized difference snow index (NDSI) from 20 m resolution Sentinel-2 images. The NDSI is computed from flat surface reflectance after masking cloud and snow-free areas. The NDSI\u2013FSC function is calibrated using Pl\u00e9iades very high-resolution images and evaluated using independent datasets including SPOT 6\/7 satellite images, time lapse camera photographs, terrestrial lidar scans and crowd-sourced in situ measurements. The calibration results show that the FSC can be represented with a sigmoid-shaped function 0.5 \u00d7 tanh(a \u00d7 NDSI + b) + 0.5, where a = 2.65 and b = \u22121.42, yielding a root mean square error (RMSE) of 25%. Similar RMSE are obtained with different evaluation datasets with a high topographic variability. With this function, we estimate that the confidence interval on the FSC retrievals is 38% at the 95% confidence level.<\/jats:p>","DOI":"10.3390\/rs12182904","type":"journal-article","created":{"date-parts":[[2020,9,8]],"date-time":"2020-09-08T09:03:48Z","timestamp":1599555828000},"page":"2904","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":50,"title":["Estimating Fractional Snow Cover in Open Terrain from Sentinel-2 Using the Normalized Difference Snow Index"],"prefix":"10.3390","volume":"12","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-4996-6768","authenticated-orcid":false,"given":"Simon","family":"Gascoin","sequence":"first","affiliation":[{"name":"CESBIO, Universit\u00e9 de Toulouse, CNES\/CNRS\/INRA\/IRD\/UPS, 31400 Toulouse, France"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zacharie","family":"Barrou Dumont","sequence":"additional","affiliation":[{"name":"CESBIO, Universit\u00e9 de Toulouse, CNES\/CNRS\/INRA\/IRD\/UPS, 31400 Toulouse, France"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"C\u00e9sar","family":"Deschamps-Berger","sequence":"additional","affiliation":[{"name":"CESBIO, Universit\u00e9 de Toulouse, CNES\/CNRS\/INRA\/IRD\/UPS, 31400 Toulouse, France"},{"name":"Centre d\u2019Etudes de la Neige, Universit\u00e9 Grenoble Alpes, Universit\u00e9 de Toulouse, M\u00e9t\u00e9o-France, CNRS, CNRM, 38400 Saint Martin d\u2019H\u00e8res, France"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1656-6124","authenticated-orcid":false,"given":"Florence","family":"Marti","sequence":"additional","affiliation":[{"name":"Magellium, 31400 Toulouse, France"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Germain","family":"Salgues","sequence":"additional","affiliation":[{"name":"Magellium, 31400 Toulouse, France"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7270-9313","authenticated-orcid":false,"given":"Juan Ignacio","family":"L\u00f3pez-Moreno","sequence":"additional","affiliation":[{"name":"Pyrenean Institute of Ecology, CSIC, 50820 Zaragoza, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5483-0147","authenticated-orcid":false,"given":"Jes\u00fas","family":"Revuelto","sequence":"additional","affiliation":[{"name":"Pyrenean Institute of Ecology, CSIC, 50820 Zaragoza, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Timoth\u00e9e","family":"Michon","sequence":"additional","affiliation":[{"name":"Tenevia, 38240 Meylan, France"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9759-6351","authenticated-orcid":false,"given":"Paul","family":"Schattan","sequence":"additional","affiliation":[{"name":"alpS Research, Institute of Geography, University of Innsbruck, A-6020 Innsbruck, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2358-0493","authenticated-orcid":false,"given":"Olivier","family":"Hagolle","sequence":"additional","affiliation":[{"name":"CESBIO, Universit\u00e9 de Toulouse, CNES\/CNRS\/INRA\/IRD\/UPS, 31400 Toulouse, France"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2020,9,8]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1431","DOI":"10.1175\/BAMS-D-13-00047.1","article-title":"The Concept of Essential Climate Variables in Support of Climate Research, Applications, and Policy","volume":"95","author":"Bojinski","year":"2014","journal-title":"Bull. 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