{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,13]],"date-time":"2025-10-13T15:31:42Z","timestamp":1760369502597,"version":"build-2065373602"},"reference-count":38,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2019,3,18]],"date-time":"2019-03-18T00:00:00Z","timestamp":1552867200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia","doi-asserted-by":"publisher","award":["UID\/GEO\/00295\/2013"],"award-info":[{"award-number":["UID\/GEO\/00295\/2013"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>Thermokarst waterbodies caused by permafrost thawing and degradation are ubiquitous in many subarctic and Arctic regions. They are globally important components of the biogeochemical carbon cycle and have potential feedback effects on climate. These northern waters are mostly small lakes and ponds, and although they may be mapped using very high-resolution satellites or aerial photography, these approaches are generally not suitable for monitoring purposes, due to the cost and limited availability of such images. In this study we evaluated the potential use of widely available high-resolution imagery from Sentinel-2 (S2) for the characterization of the spectral reflectance of thermokarst lakes and ponds. Specifically, we aimed to define the minimum lake area that could be reliably imaged, and to identify challenges and solutions for remote sensing of such waters in the future. The study was conducted in subarctic Canada, in the vicinity of Whapmagoostui-Kuujjuarapik (Nunavik, Qu\u00e9bec), an area in the sporadic permafrost zone with numerous thermokarst waterbodies that vary greatly in size. Ground truthing lake reflectance data were collected using an Unmanned Aerial System (UAS) fitted with a multispectral camera that collected images at 13 cm resolution. The results were compared with reflectance from Sentinel-2 images, and the effect of lake area on the reflectance response was assessed. Our results show that Sentinel-2 imagery was suitable for waterbodies larger than 350 m2 once their boundaries were defined, which in the two test sites would allow monitoring from 11% to 30% of the waterbodies and 73% to 85% of the total lake area. Challenges for remote sensing of small lakes include the confounding effects of water reflection (both direct radiation and diffuse), wind and shadow. Given the small threshold area and frequent revisit time, Sentinel-2 provides a valuable approach towards the continuous monitoring of waterbodies, including ponds and small lakes such as those found in thermokarst landscapes. UASs provide a complementary approach for ground truthing and boundary definition.<\/jats:p>","DOI":"10.3390\/rs11060657","type":"journal-article","created":{"date-parts":[[2019,3,18]],"date-time":"2019-03-18T12:18:53Z","timestamp":1552911533000},"page":"657","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":20,"title":["Identification of a Threshold Minimum Area for Reflectance Retrieval from Thermokarst Lakes and Ponds Using Full-Pixel Data from Sentinel-2"],"prefix":"10.3390","volume":"11","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-0752-0490","authenticated-orcid":false,"given":"Pedro","family":"Freitas","sequence":"first","affiliation":[{"name":"Centro de Estudos Geogr\u00e1ficos, Instituto de Geografia e Ordenamento do Territ\u00f3rio (CEG\/IGOT), Universidade de Lisboa, 1600-276 Lisboa, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7611-3464","authenticated-orcid":false,"given":"Gon\u00e7alo","family":"Vieira","sequence":"additional","affiliation":[{"name":"Centro de Estudos Geogr\u00e1ficos, Instituto de Geografia e Ordenamento do Territ\u00f3rio (CEG\/IGOT), Universidade de Lisboa, 1600-276 Lisboa, Portugal"},{"name":"Centre d\u2019\u00c9tudes Nordiques (CEN), D\u00e9partement de Biologie, Takuvik Joint International Laboratory, Universit\u00e9 Laval, Qu\u00e9bec, QC G1V 0A6, Canada"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5190-446X","authenticated-orcid":false,"given":"Jo\u00e3o","family":"Can\u00e1rio","sequence":"additional","affiliation":[{"name":"Centre d\u2019\u00c9tudes Nordiques (CEN), D\u00e9partement de Biologie, Takuvik Joint International Laboratory, Universit\u00e9 Laval, Qu\u00e9bec, QC G1V 0A6, Canada"},{"name":"Centro de Qu\u00edmica Estrutural, Instituto Superior T\u00e9cnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal"}]},{"given":"Diogo","family":"Folhas","sequence":"additional","affiliation":[{"name":"Centro de Qu\u00edmica Estrutural, Instituto Superior T\u00e9cnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal"}]},{"given":"Warwick F.","family":"Vincent","sequence":"additional","affiliation":[{"name":"Centre d\u2019\u00c9tudes Nordiques (CEN), D\u00e9partement de Biologie, Takuvik Joint International Laboratory, Universit\u00e9 Laval, Qu\u00e9bec, QC G1V 0A6, Canada"}]}],"member":"1968","published-online":{"date-parts":[[2019,3,18]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"171","DOI":"10.1038\/nature14338","article-title":"Climate change and the permafrost carbon feedback","volume":"520","author":"Schuur","year":"2015","journal-title":"Nature"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"39","DOI":"10.1139\/as-2016-0027","article-title":"Arctic permafrost landscapes in transition: Towards an integrated Earth system approach","volume":"3","author":"Vincent","year":"2017","journal-title":"Arct. Sci."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"186","DOI":"10.1002\/lol2.10063","article-title":"Increasing dominance of terrigenous organic matter in circumpolar freshwaters due to permafrost thaw","volume":"3","author":"Wauthy","year":"2018","journal-title":"Limnol. Oceanogr."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"115","DOI":"10.4319\/lo.2010.55.1.0115","article-title":"Variability in greenhouse gas emissions from permafrost thaw ponds","volume":"55","author":"Laurion","year":"2010","journal-title":"Limnol. Oceanogr."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"S150","DOI":"10.1002\/lno.10311","article-title":"High methane emissions from thermokarst lakes in subarctic peatlands","volume":"61","author":"Matveev","year":"2016","journal-title":"Limnol. Oceanogr."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"251","DOI":"10.1657\/1938-4246-46.1.251","article-title":"Subarctic thermokarst ponds: Investigating recent landscape evolution and sediment dynamics in thawed permafrost of northern Qu\u00e9bec (Canada)","volume":"46","author":"Bouchard","year":"2014","journal-title":"Arct. Antarct. Alp. Res."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"999","DOI":"10.1134\/S0001433815090145","article-title":"Remote analysis of changes in the number of small thermokarst lakes and their distribution with respect to their sizes in the cryolithozone of western Siberia","volume":"51","author":"Polishchuk","year":"2015","journal-title":"Izv. Atmos. Ocean. Phys."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"3262","DOI":"10.1038\/s41467-018-05738-9","article-title":"21st-century modeled permafrost carbon emissions accelerated by abrupt thaw beneath lakes","volume":"9","author":"Anthony","year":"2018","journal-title":"Nat. Commun."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"108","DOI":"10.1002\/ppp.1779","article-title":"Advances in thermokarst research","volume":"24","author":"Kokelj","year":"2013","journal-title":"Permafr. Periglac. Process."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"1635","DOI":"10.1139\/F09-108","article-title":"Limnological properties of permafrost thaw ponds in northeastern Canada","volume":"66","author":"Breton","year":"2009","journal-title":"Can. J. Fish. Aquat. Sci."},{"key":"ref_11","first-page":"1","article-title":"Optical diversity of thaw ponds in discontinuous permafrost: A model system for water color analysis","volume":"116","author":"Watanabe","year":"2011","journal-title":"J. Geophys. Res."},{"key":"ref_12","first-page":"1","article-title":"Sedimentology and geochemistry of thermokarst ponds in discontinuous permafrost, subarctic Quebec, Canada","volume":"116","author":"Bouchard","year":"2011","journal-title":"J. Geophys. Res."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1029\/2004GL020358","article-title":"Accelerated thawing of subarctic peatland permafrost over the last 50 years","volume":"31","author":"Payette","year":"2004","journal-title":"Geophys. Res. Lett."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"015501","DOI":"10.1088\/1748-9326\/7\/1\/015501","article-title":"Shrub expansion at the forest\u2013tundra ecotone: Spatial heterogeneity linked to local topography","volume":"7","author":"Ropars","year":"2012","journal-title":"Environ. Res. Lett."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"9535","DOI":"10.1038\/s41598-018-27770-x","article-title":"Emissions from thaw ponds largely offset the carbon sink of northern permafrost wetlands","volume":"8","author":"Kuhn","year":"2018","journal-title":"Sci. Rep."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"1498","DOI":"10.3390\/rs5041498","article-title":"Water body distributions across scales: A remote sensing based comparison of three Arctic tundra wetlands","volume":"5","author":"Muster","year":"2013","journal-title":"Remote Sens."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"1687","DOI":"10.1109\/JSTARS.2017.2666787","article-title":"Mapping thermokarst lakes on the Qinghai\u2013Tibet plateau using nonlocal active contours in Chinese GaoFen-2 multispectral imagery","volume":"10","author":"Tian","year":"2017","journal-title":"IEEE J. Sel. Top. Appl. Earth Obs. Remote Sens."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"6396","DOI":"10.1002\/2014GL060641","article-title":"A global inventory of lakes based on high-resolution satellite imagery","volume":"41","author":"Verpoorter","year":"2014","journal-title":"Geophys. Res. Lett."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"418","DOI":"10.1038\/nature20584","article-title":"High-resolution mapping of global surface water and its long-term changes","volume":"540","author":"Pekel","year":"2016","journal-title":"Nature"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"317","DOI":"10.5194\/essd-9-317-2017","article-title":"PeRL: A circum-Arctic permafrost region pond and lake database","volume":"9","author":"Muster","year":"2017","journal-title":"Earth Syst. Sci. Data"},{"key":"ref_21","first-page":"1682","article-title":"Object based thermokarst lake change mapping as part of the ESA data user element (DUE) permafrost","volume":"XXXVIII-4\/C7","author":"Hese","year":"2010","journal-title":"ISPRS"},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Du, Y., Zhang, Y., Ling, F., Wang, Q., Li, W., and Li, X. (2016). Water bodies\u2019 mapping from Sentinel-2 imagery with modified normalized difference water index at 10-m spatial resolution produced by sharpening the SWIR band. Remote Sens., 8.","DOI":"10.3390\/rs8040354"},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Toming, K., Kutser, T., Laas, A., Sepp, M., Paavel, B., and N\u00f5ges, T. (2016). First experiences in mapping lake water quality parameters with Sentinel-2 MSI imagery. Remote Sens., 8.","DOI":"10.3390\/rs8080640"},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"Manfreda, S., McCabe, M.F., Miller, P.E., Lucas, R., Madrigal, V.P., Mallinis, G., Dor, E.B., Helman, D., Estes, L., and Ciraolo, G. (2018). On the use of unmanned aerial systems for environmental monitoring. Remote Sen., 10.","DOI":"10.20944\/preprints201803.0097.v1"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"182","DOI":"10.2980\/18-3-3469","article-title":"Environmental change in the Great Whale River region, Hudson Bay: Five decades of multidisciplinary research by Centre d\u2019\u00e9tudes nordiques (CEN)","volume":"18","author":"Bhiry","year":"2011","journal-title":"\u00c9coscience"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"2313","DOI":"10.1111\/j.1365-2486.2012.02708.x","article-title":"Satellite-based evidence for shrub and graminoid tundra expansion in northern Quebec from 1986 to 2010","volume":"18","author":"McManus","year":"2012","journal-title":"Glob. Chang. Boil."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"1638","DOI":"10.3732\/ajb.1200279","article-title":"The importance of ecological constrains on the control of multi-species treeline dynamics in Eastern Nunavik, Qu\u00e9bec","volume":"99","author":"Vriendt","year":"2012","journal-title":"Am. J. Bot."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"035501","DOI":"10.1088\/1748-9326\/7\/3\/035501","article-title":"Recent expansion of erect shrubs in the Low Arctic: Evidence from Eastern Nunavik","volume":"7","author":"Tremblay","year":"2012","journal-title":"Environ. Res. Lett."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"354","DOI":"10.1139\/as-2016-0017","article-title":"Permafrost thaw lakes and ponds as habitats for abundant rotifer populations","volume":"3","author":"Vincent","year":"2017","journal-title":"Arct. Sci."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"54","DOI":"10.1139\/juvs-2018-0018","article-title":"Vegetation monitoring using multispectral sensors\u2014Best practices and 3 lessons learned from high latitudes","volume":"7","author":"Assmann","year":"2019","journal-title":"NRC J. Unmanned Veh. Syst."},{"key":"ref_31","unstructured":"MicaSense (2018). Sequoia User Guide, Drones Parrot SAS."},{"key":"ref_32","unstructured":"ESA (2012). Sentinel-2: ESA\u2019s Optical High-Resolution Mission for GMES Operational Services, European Space Agency."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"4610","DOI":"10.1109\/TGRS.2017.2694881","article-title":"Super-resolving multiresolution images with band-independent geometry of multispectral pixels","volume":"55","author":"Brodu","year":"2017","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_34","unstructured":"Pix4D (2017). Pix4Dmapper 4.0 User Manual, Pix4D SA."},{"key":"ref_35","unstructured":"(2008, January 08). Canadian Digital Elevation Model, Available online: https:\/\/open.canada.ca\/data\/en\/dataset\/7f245e4d-76c2-4caa-951a-45d1d2051333."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"2321","DOI":"10.3390\/rs3112321","article-title":"Terrestrial remotely sensed imagery in support of public health: New avenues of research using object-based image analysis","volume":"3","author":"Kelly","year":"2011","journal-title":"Remote Sen."},{"key":"ref_37","unstructured":"Dey, V. (2011). A Supervised Approach for the Estimation of Parameters of Multiresolution Segmentation and Its Application in Building Feature Extraction from VHR Imagery. [Master\u2019s Thesis, Department of Geodesy and Geomatics Engineering, University of New Brunswick]."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"196","DOI":"10.4236\/ars.2015.43016","article-title":"A review on extraction of lakes from remotely sensed optical satellite data with a special focus on cryospheric lakes","volume":"4","author":"Jawak","year":"2015","journal-title":"Adv. Remote Sens."}],"container-title":["Remote Sensing"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-4292\/11\/6\/657\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T12:38:41Z","timestamp":1760186321000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-4292\/11\/6\/657"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2019,3,18]]},"references-count":38,"journal-issue":{"issue":"6","published-online":{"date-parts":[[2019,3]]}},"alternative-id":["rs11060657"],"URL":"https:\/\/doi.org\/10.3390\/rs11060657","relation":{},"ISSN":["2072-4292"],"issn-type":[{"type":"electronic","value":"2072-4292"}],"subject":[],"published":{"date-parts":[[2019,3,18]]}}}