{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,28]],"date-time":"2026-02-28T04:30:20Z","timestamp":1772253020437,"version":"3.50.1"},"reference-count":48,"publisher":"MDPI AG","issue":"18","license":[{"start":{"date-parts":[[2020,9,7]],"date-time":"2020-09-07T00:00:00Z","timestamp":1599436800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100010661","name":"Horizon 2020 Framework Programme","doi-asserted-by":"publisher","award":["810139"],"award-info":[{"award-number":["810139"]}],"id":[{"id":"10.13039\/100010661","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100002341","name":"Academy of Finland","doi-asserted-by":"publisher","award":["318252"],"award-info":[{"award-number":["318252"]}],"id":[{"id":"10.13039\/501100002341","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100002341","name":"Academy of Finland","doi-asserted-by":"publisher","award":["319905"],"award-info":[{"award-number":["319905"]}],"id":[{"id":"10.13039\/501100002341","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia","doi-asserted-by":"publisher","award":["PD\/BD\/113932\/2015"],"award-info":[{"award-number":["PD\/BD\/113932\/2015"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia","doi-asserted-by":"publisher","award":["SFRH\/BSAB\/142981\/201"],"award-info":[{"award-number":["SFRH\/BSAB\/142981\/201"]}],"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>Monitoring lakes in high-latitude areas can provide a better understanding of freshwater systems sensitivity and accrete knowledge on climate change impacts. Phytoplankton are sensitive to various conditions: warmer temperatures, earlier ice-melt and changing nutrient sources. While satellite imagery can monitor phytoplankton biomass using chlorophyll a (Chl) as a proxy over large areas, detection of Chl in small lakes is hindered by the low spatial resolution of conventional ocean color satellites. The short time-series of the newest generation of space-borne sensors (e.g., Sentinel-2) is a bottleneck for assessing long-term trends. Although previous studies have evaluated the use of high-resolution sensors for assessing lakes\u2019 Chl, it is still unclear how the spatial and temporal variability of Chl concentration affect the performance of satellite estimates. We discuss the suitability of Landsat (LT) 30 m resolution imagery to assess lakes\u2019 Chl concentrations under varying trophic conditions, across extensive high-latitude areas in Finland. We use in situ data obtained from field campaigns in 19 lakes and generate remote sensing estimates of Chl, taking advantage of the long-time span of the LT-5 and LT-7 archives, from 1984 to 2017. Our results show that linear models based on LT data can explain approximately 50% of the Chl interannual variability. However, we demonstrate that the accuracy of the estimates is dependent on the lake\u2019s trophic state, with models performing in average twice as better in lakes with higher Chl concentration (&gt;20 \u00b5g\/L) in comparison with less eutrophic lakes. Finally, we demonstrate that linear models based on LT data can achieve high accuracy (R2 = 0.9; p-value &lt; 0.05) in determining lakes\u2019 mean Chl concentration, allowing the mapping of the trophic state of lakes across large regions. Given the long time-series and high spatial resolution, LT-based estimates of Chl provide a tool for assessing the impacts of environmental change.<\/jats:p>","DOI":"10.3390\/rs12182898","type":"journal-article","created":{"date-parts":[[2020,9,7]],"date-time":"2020-09-07T09:18:16Z","timestamp":1599470296000},"page":"2898","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":5,"title":["Spatial Variability and Detection Levels for Chlorophyll-a Estimates in High Latitude Lakes Using Landsat Imagery"],"prefix":"10.3390","volume":"12","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-9143-0692","authenticated-orcid":false,"given":"Filipe","family":"Lisboa","sequence":"first","affiliation":[{"name":"MARE\u2014Marine and Environmental Sciences Centre, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8612-4167","authenticated-orcid":false,"given":"Vanda","family":"Brotas","sequence":"additional","affiliation":[{"name":"MARE\u2014Marine and Environmental Sciences Centre, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal"},{"name":"PML\u2014Plymouth Marine Laboratory, Prospect Place, Plymouth PL1 3DH, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7316-1479","authenticated-orcid":false,"given":"Filipe Duarte","family":"Santos","sequence":"additional","affiliation":[{"name":"CCIAM-CE3C, Faculty of Sciences, University of Lisbon, Tapada da Ajuda, 1349-017 Lisboa, Portugal"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8802-8013","authenticated-orcid":false,"given":"Sakari","family":"Kuikka","sequence":"additional","affiliation":[{"name":"Faculty of Biological and Environmental Sciences, Ecosystems and Environment Research Programme, University of Helsinki, 00014 Helsinki, Finland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Laura","family":"Kaikkonen","sequence":"additional","affiliation":[{"name":"Faculty of Biological and Environmental Sciences, Ecosystems and Environment Research Programme, University of Helsinki, 00014 Helsinki, Finland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7932-1824","authenticated-orcid":false,"given":"Eduardo Eiji","family":"Maeda","sequence":"additional","affiliation":[{"name":"Department of Geosciences and Geography, University of Helsinki, P.O. Box 64, 00014 Helsinki, Finland"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2020,9,7]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1881","DOI":"10.1111\/gcb.13459","article-title":"Global patterns in lake ecosystem responses to warming based on the temperature dependence of metabolism","volume":"23","author":"Kraemer","year":"2017","journal-title":"Glob. Chang. Biol."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"2283","DOI":"10.4319\/lo.2009.54.6_part_2.2283","article-title":"Lakes as sentinels of climate change","volume":"54","author":"Adrian","year":"2009","journal-title":"Limnol. 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