{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,8]],"date-time":"2026-01-08T16:35:36Z","timestamp":1767890136799,"version":"3.49.0"},"reference-count":53,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2021,1,19]],"date-time":"2021-01-19T00:00:00Z","timestamp":1611014400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100013324","name":"MAVA Foundation","doi-asserted-by":"publisher","award":["project \u201cWaders of the Bijag\u00f3s: Securing the ecological integrity of the Bijag\u00f3s archipelago as a key site for waders along the East Atlantic Flyway\u201d"],"award-info":[{"award-number":["project \u201cWaders of the Bijag\u00f3s: Securing the ecological integrity of the Bijag\u00f3s archipelago as a key site for waders along the East Atlantic Flyway\u201d"]}],"id":[{"id":"10.13039\/100013324","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":["Project \u201cMigraWebs: Migrants as a seasonal ecological force shaping communities and ecosystem functions in temperate and tropical coastal wetlands\u201d (PTDC\/BIA-ECO\/28205\/2017)"],"award-info":[{"award-number":["Project \u201cMigraWebs: Migrants as a seasonal ecological force shaping communities and ecosystem functions in temperate and tropical coastal wetlands\u201d (PTDC\/BIA-ECO\/28205\/2017)"]}],"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":["Strategic project to CESAM (UIDP\/50017\/2020 and UIDB\/50017\/2020)"],"award-info":[{"award-number":["Strategic project to CESAM (UIDP\/50017\/2020 and UIDB\/50017\/2020)"]}],"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":["Grant SFRH\/BD\/131148\/2017 to MH"],"award-info":[{"award-number":["Grant SFRH\/BD\/131148\/2017 to MH"]}],"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":["Contract IF\/00694\/2015 to TC"],"award-info":[{"award-number":["Contract IF\/00694\/2015 to TC"]}],"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>Intertidal areas provide key ecosystem services but are declining worldwide. Digital elevation models (DEMs) are important tools to monitor the evolution of such areas. In this study, we aim at (i) estimating the intertidal topography based on an established pixel-wise algorithm, from Sentinel-2 MultiSpectral Instrument scenes, (ii) implementing a set of procedures to improve the quality of such estimation, and (iii) estimating the exposure period of the intertidal area of the Bijag\u00f3s Archipelago, Guinea-Bissau. We first propose a four-parameter logistic regression to estimate intertidal topography. Afterwards, we develop a novel method to estimate tide-stage lags in the area covered by a Sentinel-2 scene to correct for geographical bias in topographic estimation resulting from differences in water height within each image. Our method searches for the minimum differences in height estimates obtained from rising and ebbing tides separately, enabling the estimation of cotidal lines. Tidal-stage differences estimated closely matched those published by official authorities. We re-estimated pixel heights from which we produced a model of intertidal exposure period. We obtained a high correlation between predicted and in-situ measurements of exposure period. We highlight the importance of remote sensing to deliver large-scale intertidal DEM and tide-stage data, with relevance for coastal safety, ecology and biodiversity conservation.<\/jats:p>","DOI":"10.3390\/rs13020320","type":"journal-article","created":{"date-parts":[[2021,1,20]],"date-time":"2021-01-20T03:34:25Z","timestamp":1611113665000},"page":"320","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":13,"title":["Using Sentinel-2 Images to Estimate Topography, Tidal-Stage Lags and Exposure Periods over Large Intertidal Areas"],"prefix":"10.3390","volume":"13","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-7207-3474","authenticated-orcid":false,"given":"Jos\u00e9 P.","family":"Granadeiro","sequence":"first","affiliation":[{"name":"CESAM, Faculdade de Ci\u00eancias, Universidade de Lisboa, 1749-016 Lisboa, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1772-8367","authenticated-orcid":false,"given":"Jo\u00e3o","family":"Belo","sequence":"additional","affiliation":[{"name":"CESAM, Faculdade de Ci\u00eancias, Universidade de Lisboa, 1749-016 Lisboa, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3061-5423","authenticated-orcid":false,"given":"Mohamed","family":"Henriques","sequence":"additional","affiliation":[{"name":"CESAM, Faculdade de Ci\u00eancias, Universidade de Lisboa, 1749-016 Lisboa, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1028-4644","authenticated-orcid":false,"given":"Jo\u00e3o","family":"Catal\u00e3o","sequence":"additional","affiliation":[{"name":"IDL, Faculdade de Ci\u00eancias, Universidade de Lisboa, 1749-016 Lisboa, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4047-9995","authenticated-orcid":false,"given":"Teresa","family":"Catry","sequence":"additional","affiliation":[{"name":"CESAM, Faculdade de Ci\u00eancias, Universidade de Lisboa, 1749-016 Lisboa, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2021,1,19]]},"reference":[{"key":"ref_1","unstructured":"Rafaelli, D., and Hawkins, S.J. 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