气候变化领域集成服务门户(CCPortal): Investigating ESA Sentinel-2 products' systematic cloud cover overestimation in very high altitude areas

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DOI	10.1016/j.rse.2020.112163
	Investigating ESA Sentinel-2 products' systematic cloud cover overestimation in very high altitude areas
	Tiede D.; Sudmanns M.; Augustin H.; Baraldi A.
发表日期	2021
ISSN	00344257
卷号	252
英文摘要	Cloud detection in optical remote sensing imagery is crucial because undetected clouds can produce misleading results in analyses. Almost all optical remote sensing data access portals rely to some degree on a cloud cover filter. Here we show that cirrus as well as opaque cloud cover in Sentinel-2 Level-1C (L1C) and Level-2A (L2A) imagery is systematically and significantly overestimated in very high altitude areas (e.g. Himalayas, Andes). We argue that this systematic bias is created by applying simple thresholds to single bands instead of using a multi-band spectral signature in the cloud detection process. This results in a lot of “hidden” data for very high altitude areas when each image's estimated cloud cover is used as an automated selection criterion for analysis (e.g. global analyses, cloud-free mosaic production). We show geographic locations exemplifying this overestimation, and compare the L1C and L2A cloud masks produced by ESA to cloud masks generated by an expert system that uses comprehensive spectral signatures, showing that reliable cloud estimations are possible in very high altitudes. Based on this comparison, we argue for changes to L1C and L2A cloud detection algorithms in order to improve initial querying and selection of big EO data, where reliable yet automated quality indicators are necessary to handle an overwhelming data volume and velocity. Our contribution raises awareness of potential bias when pre-selecting images based on reported cloud cover in very high altitude areas for researchers and users of Sentinel-2 imagery in the environmental domain. © 2020 The Author(s)
英文关键词	Big EO data image selection; Cloud cover overestimation; Geographical bias; Sentinel-2 cloud mask
语种	英语
scopus关键词	Expert systems; Remote sensing; Automated selection; Cloud detection algorithms; Geographic location; Global analysis; Optical remote-sensing imagery; Quality indicators; Spectral signature; Systematic bias; Image analysis; algorithm; altitude; cloud cover; estimation method; remote sensing; satellite altimetry; satellite data; satellite imagery; Sentinel; Andes; Himalayas
来源期刊	Remote Sensing of Environment
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/179060
作者单位	Department of Geoinformatics – Z_GIS, University of Salzburg, Schillerstr. 30, Salzburg, 5020, Austria; Italian Space Agency (ASI), Via del Politecnico, Roma RM, 00133, Italy
推荐引用方式 GB/T 7714	Tiede D.,Sudmanns M.,Augustin H.,et al. Investigating ESA Sentinel-2 products' systematic cloud cover overestimation in very high altitude areas[J],2021,252.
APA	Tiede D.,Sudmanns M.,Augustin H.,&Baraldi A..(2021).Investigating ESA Sentinel-2 products' systematic cloud cover overestimation in very high altitude areas.Remote Sensing of Environment,252.
MLA	Tiede D.,et al."Investigating ESA Sentinel-2 products' systematic cloud cover overestimation in very high altitude areas".Remote Sensing of Environment 252(2021).