Long-Term Variation of Global GEOV2 and MODIS Leaf Area Index (LAI) and Their Uncertainties: An Insight into the Product Stabilities

Leaf area index (LAI) is an essential climate variable that is crucial to understand the global vegetation change. Long-term satellite LAI products have been applied in many global vegetation change studies. However, these LAI products contain various uncertainties that are not been fully considered...

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Autores principales:	Hongliang Fang, Yao Wang, Yinghui Zhang, Sijia Li
Formato:	article
Lenguaje:	EN
Publicado:	American Association for the Advancement of Science (AAAS) 2021
Materias:	Environmental sciences GE1-350 Physical geography GB3-5030
Acceso en línea:	https://doaj.org/article/76ead834c6ea4f30b8cb596b9b17701f
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spelling	oai:doaj.org-article:76ead834c6ea4f30b8cb596b9b17701f2021-11-22T08:31:11ZLong-Term Variation of Global GEOV2 and MODIS Leaf Area Index (LAI) and Their Uncertainties: An Insight into the Product Stabilities2694-158910.34133/2021/9842830https://doaj.org/article/76ead834c6ea4f30b8cb596b9b17701f2021-01-01T00:00:00Zhttp://dx.doi.org/10.34133/2021/9842830https://doaj.org/toc/2694-1589Leaf area index (LAI) is an essential climate variable that is crucial to understand the global vegetation change. Long-term satellite LAI products have been applied in many global vegetation change studies. However, these LAI products contain various uncertainties that are not been fully considered in current studies. The objective of this study is to explore the uncertainties in the global LAI products and the uncertainty variations. Two global LAI datasets—the European Geoland2 Version 2 (GEOV2) and Moderate Resolution Imaging Spectroradiometer (MODIS) (2003-2019)—were investigated. The qualitative quality flags (QQFs) and quantitative quality indicators (QQIs) embedded in the product quality layers were analyzed to identify the temporal anomalies in the quality profile. The results show that the global GEOV2 (0.042/10a) and MODIS (0.034/10a) LAI values have steadly increased from 2003 to 2019. The global LAI uncertainty (0.016/10a) and relative uncertainty (0.3%/10a) from GEOV2 have also increased gradually, especially during the growing season from April to October. The uncertainty increase is larger for woody biomes than for herbaceous types. Contrastingly, the MODIS LAI product uncertainty remained stable over the study period. The uncertainty increase indicated by GEOV2 is partly attributed to the sensor shift in the product series. Further algorithm enhancement is necessary to improve the cross-sensor performance. This study highlights the importance of studying the LAI uncertainty and the uncertainty variation. Temporal variations in the LAI products and the product quality revealed herein have significant implications on global vegetation change studies.Hongliang FangYao WangYinghui ZhangSijia LiAmerican Association for the Advancement of Science (AAAS)articleEnvironmental sciencesGE1-350Physical geographyGB3-5030ENJournal of Remote Sensing, Vol 2021 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Environmental sciences GE1-350 Physical geography GB3-5030
spellingShingle	Environmental sciences GE1-350 Physical geography GB3-5030 Hongliang Fang Yao Wang Yinghui Zhang Sijia Li Long-Term Variation of Global GEOV2 and MODIS Leaf Area Index (LAI) and Their Uncertainties: An Insight into the Product Stabilities
description	Leaf area index (LAI) is an essential climate variable that is crucial to understand the global vegetation change. Long-term satellite LAI products have been applied in many global vegetation change studies. However, these LAI products contain various uncertainties that are not been fully considered in current studies. The objective of this study is to explore the uncertainties in the global LAI products and the uncertainty variations. Two global LAI datasets—the European Geoland2 Version 2 (GEOV2) and Moderate Resolution Imaging Spectroradiometer (MODIS) (2003-2019)—were investigated. The qualitative quality flags (QQFs) and quantitative quality indicators (QQIs) embedded in the product quality layers were analyzed to identify the temporal anomalies in the quality profile. The results show that the global GEOV2 (0.042/10a) and MODIS (0.034/10a) LAI values have steadly increased from 2003 to 2019. The global LAI uncertainty (0.016/10a) and relative uncertainty (0.3%/10a) from GEOV2 have also increased gradually, especially during the growing season from April to October. The uncertainty increase is larger for woody biomes than for herbaceous types. Contrastingly, the MODIS LAI product uncertainty remained stable over the study period. The uncertainty increase indicated by GEOV2 is partly attributed to the sensor shift in the product series. Further algorithm enhancement is necessary to improve the cross-sensor performance. This study highlights the importance of studying the LAI uncertainty and the uncertainty variation. Temporal variations in the LAI products and the product quality revealed herein have significant implications on global vegetation change studies.
format	article
author	Hongliang Fang Yao Wang Yinghui Zhang Sijia Li
author_facet	Hongliang Fang Yao Wang Yinghui Zhang Sijia Li
author_sort	Hongliang Fang
title	Long-Term Variation of Global GEOV2 and MODIS Leaf Area Index (LAI) and Their Uncertainties: An Insight into the Product Stabilities
title_short	Long-Term Variation of Global GEOV2 and MODIS Leaf Area Index (LAI) and Their Uncertainties: An Insight into the Product Stabilities
title_full	Long-Term Variation of Global GEOV2 and MODIS Leaf Area Index (LAI) and Their Uncertainties: An Insight into the Product Stabilities
title_fullStr	Long-Term Variation of Global GEOV2 and MODIS Leaf Area Index (LAI) and Their Uncertainties: An Insight into the Product Stabilities
title_full_unstemmed	Long-Term Variation of Global GEOV2 and MODIS Leaf Area Index (LAI) and Their Uncertainties: An Insight into the Product Stabilities
title_sort	long-term variation of global geov2 and modis leaf area index (lai) and their uncertainties: an insight into the product stabilities
publisher	American Association for the Advancement of Science (AAAS)
publishDate	2021
url	https://doaj.org/article/76ead834c6ea4f30b8cb596b9b17701f
work_keys_str_mv	AT hongliangfang longtermvariationofglobalgeov2andmodisleafareaindexlaiandtheiruncertaintiesaninsightintotheproductstabilities AT yaowang longtermvariationofglobalgeov2andmodisleafareaindexlaiandtheiruncertaintiesaninsightintotheproductstabilities AT yinghuizhang longtermvariationofglobalgeov2andmodisleafareaindexlaiandtheiruncertaintiesaninsightintotheproductstabilities AT sijiali longtermvariationofglobalgeov2andmodisleafareaindexlaiandtheiruncertaintiesaninsightintotheproductstabilities
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Long-Term Variation of Global GEOV2 and MODIS Leaf Area Index (LAI) and Their Uncertainties: An Insight into the Product Stabilities

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