{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"institution":[{"name":"Research Square"}],"indexed":{"date-parts":[[2025,5,14]],"date-time":"2025-05-14T06:29:02Z","timestamp":1747204142298,"version":"3.40.5"},"posted":{"date-parts":[[2022,5,6]]},"group-title":"In Review","reference-count":0,"publisher":"Springer Science and Business Media LLC","license":[{"start":{"date-parts":[[2022,5,6]],"date-time":"2022-05-06T00:00:00Z","timestamp":1651795200000},"content-version":"unspecified","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"accepted":{"date-parts":[[2022,4,28]]},"abstract":"<title>Abstract<\/title>\n        <p>Thermokarst lakes and ponds are a common landscape feature resulting from permafrost thaw, but their intense greenhouse gas emissions are still poorly constrained as a feedback mechanism for global warming because of their diversity, abundance and remoteness. Thermokarst waterbodies may be small and optically diverse, posing specific challenges for optical remote sensing regarding detection, classification and monitoring. This is especially relevant when accounting for external factors that affect water reflectance, such as scattering and vegetation shadow casts. In this study in the forest-tundra zone of northern Canada, we evaluated the effects of shadowing across optically diverse waterbodies. We used ultra-high spatial resolution multispectral data and digital surface models obtained from Unmanned Aerial Systems for modelling and analyzing shadow effects on water reflectance at Earth Observation satellite overpass time. Our results show that shadowing causes variations in reflectance, reducing the usable area of remotely sensed pixels for waterbody analysis in small lakes and ponds. The effects were greater on brighter and turbid inorganic thermokarst lakes embedded in postglacial silt-clay marine deposits and littoral sands, where the mean reflectance decrease was from \u2212\u200951 to -70%, depending on the wavelength. These effects were also dependent on lake shape and vegetation height and were amplified in the cold season due to low solar elevations. Remote sensing will increasingly play a key role in assessing thermokarst lake responses and feedbacks to global change, and this study shows the magnitude and sources of optical variations caused by shading that need to be considered in future analyses.<\/p>","DOI":"10.21203\/rs.3.rs-1604397\/v1","type":"posted-content","created":{"date-parts":[[2022,5,6]],"date-time":"2022-05-06T15:19:58Z","timestamp":1651850398000},"source":"Crossref","is-referenced-by-count":0,"title":["Vegetation shadow casts impact remotely sensed reflectance from permafrost thaw ponds in the Subarctic forest-tundra zone."],"prefix":"10.21203","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-0752-0490","authenticated-orcid":false,"given":"Pedro","family":"Freitas","sequence":"first","affiliation":[{"name":"Universidade de Lisboa Instituto de Geografia e Ordenamento do Territorio"}]},{"given":"Gon\u00e7alo","family":"Vieira","sequence":"additional","affiliation":[{"name":"Universidade de Lisboa Instituto de Geografia e Ordenamento do Territorio"}]},{"given":"Carla","family":"Mora","sequence":"additional","affiliation":[{"name":"Universidade de Lisboa Instituto de Geografia e Ordenamento do Territorio"}]},{"given":"Jo\u00e3o","family":"Can\u00e1rio","sequence":"additional","affiliation":[{"name":"Universidade de Lisboa Instituto Superior Tecnico"}]},{"given":"Warwick F.","family":"Vincent","sequence":"additional","affiliation":[{"name":"Universit\u00e9 Laval: Universite Laval"}]}],"member":"297","container-title":[],"original-title":[],"link":[{"URL":"https:\/\/www.researchsquare.com\/article\/rs-1604397\/v1","content-type":"text\/html","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/www.researchsquare.com\/article\/rs-1604397\/v1.html","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2022,5,6]],"date-time":"2022-05-06T15:20:00Z","timestamp":1651850400000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.researchsquare.com\/article\/rs-1604397\/v1"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2022,5,6]]},"references-count":0,"URL":"https:\/\/doi.org\/10.21203\/rs.3.rs-1604397\/v1","relation":{},"subject":[],"published":{"date-parts":[[2022,5,6]]},"subtype":"preprint"}}