{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,12]],"date-time":"2026-03-12T19:35:10Z","timestamp":1773344110592,"version":"3.50.1"},"reference-count":37,"publisher":"MDPI AG","issue":"15","license":[{"start":{"date-parts":[[2021,8,2]],"date-time":"2021-08-02T00:00:00Z","timestamp":1627862400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100005416","name":"Norges Forskningsr\u00e5d","doi-asserted-by":"publisher","award":["269927"],"award-info":[{"award-number":["269927"]}],"id":[{"id":"10.13039\/501100005416","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>The Arctic is a region that is expected to experience a high increase in temperature. Changes in the timing of phenological phases, such as the onset of growth (as observed by remote sensing), is a sensitive bio-indicator of climate change. In this paper, the study area was the central part of Spitsbergen, Svalbard, located between 77.28\u00b0N and 78.44\u00b0N. The goals of this study were: (1) to prepare, analyze and present a cloud-free time-series of daily Sentinel-2 NDVI datasets for the 2016 to 2019 seasons, and (2) to demonstrate the use of the dataset in mapping the onset of growth. Due to a short and intense period with greening-up and frequent cloud cover, all the cloud-free Sentinel-2 data were used. The onset of growth was then mapped by a NDVI threshold method, which showed significant correlation (r2 = 0.47, n = 38, p &lt; 0.0001) with ground-based phenocam observation of the onset of growth in seven vegetation types. However, large bias was found between the Sentinel-2 NDVI-based mapped onset of growth and the phenocam-based onset of growth in a moss tundra, which indicates that the data in these vegetation types must be interpreted with care. In 2018, the onset of growth was about 10 days earlier compared to 2017.<\/jats:p>","DOI":"10.3390\/rs13153031","type":"journal-article","created":{"date-parts":[[2021,8,4]],"date-time":"2021-08-04T02:16:07Z","timestamp":1628043367000},"page":"3031","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":29,"title":["Time-Series of Cloud-Free Sentinel-2 NDVI Data Used in Mapping the Onset of Growth of Central Spitsbergen, Svalbard"],"prefix":"10.3390","volume":"13","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-9456-6990","authenticated-orcid":false,"given":"Stein Rune","family":"Karlsen","sequence":"first","affiliation":[{"name":"NORCE Norwegian Research Centre AS, P.O. Box 6434, 9294 Troms\u00f8, Norway"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9802-8962","authenticated-orcid":false,"given":"Laura","family":"Stendardi","sequence":"additional","affiliation":[{"name":"Department of Agriculture, Food, Environment and Forestry (DAGRI), University of Florence, Piazzale delle Cascine, 18-50144 Firenze, Italy"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7273-1695","authenticated-orcid":false,"given":"Hans","family":"T\u00f8mmervik","sequence":"additional","affiliation":[{"name":"Norwegian Institute for Nature Research (NINA), FRAM\u2014High North Research Centre for Climate and the Environment, P.O. Box 6606, Langnes, 9296 Troms\u00f8, Norway"}]},{"given":"Lennart","family":"Nilsen","sequence":"additional","affiliation":[{"name":"Department of Arctic and Marine Biology, UiT\u2014The Arctic University of Norway, 9037 Troms\u00f8, Norway"}]},{"given":"Ingar","family":"Arntzen","sequence":"additional","affiliation":[{"name":"NORCE Norwegian Research Centre AS, P.O. Box 6434, 9294 Troms\u00f8, Norway"}]},{"given":"Elisabeth J.","family":"Cooper","sequence":"additional","affiliation":[{"name":"Department of Arctic and Marine Biology, UiT\u2014The Arctic University of Norway, 9037 Troms\u00f8, Norway"}]}],"member":"1968","published-online":{"date-parts":[[2021,8,2]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Isaksen, K., Nordli, \u00d8., F\u00f8rland, E.J., Lupikasza, E., Eastwood, S., and Nied\u017awied\u017a, T. (2016). Recent warming on Spitsbergen\u2014Influence of atmospheric circulation and sea ice cover. J. Geophys. Res. 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