干旱区生态环境知识资源中心(Arid): Phenology of short vegetation cycles in a Kenyan rangeland from PlanetScope and Sentinel-2

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DOI	10.1016/j.rse.2020.112004
	Phenology of short vegetation cycles in a Kenyan rangeland from PlanetScope and Sentinel-2
	Cheng, Yan; Vrieling, Anton; Fava, Francesco; Meroni, Michele; Marshall, Michael; Gachoki, Stella
通讯作者	Vrieling, A
来源期刊	REMOTE SENSING OF ENVIRONMENT
ISSN	0034-4257
EISSN	1879-0704
出版年	2020
卷号	248
英文摘要	The short revisit times afforded by recently-deployed optical satellite sensors that acquire 3-30 m resolution imagery provide new opportunities to study seasonal vegetation dynamics. Previous studies demonstrated a successful retrieval of phenology with Sentinel-2 for relatively stable annual growing seasons. In semi-arid East Africa however, vegetation responds rapidly to a concentration of rainfall over short periods and consequently is subject to strong interannual variability. Obtaining a sufficient density of cloud-free acquisitions to accurately describe these short vegetation cycles is therefore challenging. The objective of this study is to evaluate if data from two satellite constellations, i.e., PlanetScope (3 m resolution) and Sentinel-2 (10 m resolution), each independently allow for accurate mapping of vegetation phenology under these challenging conditions. The study area is a rangeland with bimodal seasonality located at the 128-km(2) Kapiti Farm in Machakos County, Kenya. Using all the available PlanetScope and Sentinel-2 imagery between March 2017 and February 2019, we derived temporal NDVI profiles and fitted double hyperbolic tangent models (equivalent to commonly-used logistic functions), separately for the two rainy seasons locally referred to as the short and long rains. We estimated start and end-of-season for the series using a 50% threshold between minimum and maximum levels of the modelled time series (SOS50/EOS50). We compared our estimates against those obtained from vegetation index series from two alternative sources, i.e. a) greenness chromatic coordinate (GCC) series obtained from digital repeat photography, and b) MODIS NDVI. We found that both PlanetScope and Sentinel-2 series resulted in acceptable retrievals of phenology (RMSD of similar to 8 days for SOS50 and similar to 15 days for EOS50 when compared against GCC series) suggesting that the sensors individually provide sufficient temporal detail. However, when applying the model to the entire study area, fewer spatial artefacts occurred in the PlanetScope results. This could be explained by the higher observation frequency of PlanetScope, which becomes critical during periods of persistent cloud cover. We further illustrated that PlanetScope series could differentiate the phenology of individual trees from grassland surroundings, whereby tree green-up was found to be both earlier and later than for grass, depending on location. The spatially-detailed phenology retrievals, as achieved in this study, are expected to help in better understanding climate and degradation impacts on rangeland vegetation, particularly for heterogeneous rangeland systems with large interannual variability in phenology and productivity.
英文关键词	Phenology Multi-temporal analysis NDVI time series Sentinel-2 PlanetScope Spatial resolution Landscape variability Semi-arid rangelands Digital repeat photography
类型	Article
语种	英语
开放获取类型	Green Published, hybrid
收录类别	SCI-E
WOS记录号	WOS:000569153500005
WOS关键词	LAND-SURFACE PHENOLOGY ; DIGITAL REPEAT PHOTOGRAPHY ; TREE-GRASS INTERACTIONS ; RADIATIVE-TRANSFER CODE ; MODIS SATELLITE DATA ; TIME-SERIES ; SPRING PHENOLOGY ; CLIMATE-CHANGE ; GREEN-UP ; ATMOSPHERIC CORRECTION
WOS类目	Environmental Sciences ; Remote Sensing ; Imaging Science & Photographic Technology
WOS研究方向	Environmental Sciences & Ecology ; Remote Sensing ; Imaging Science & Photographic Technology
资源类型	期刊论文
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/326279
作者单位	[Cheng, Yan; Vrieling, Anton; Marshall, Michael; Gachoki, Stella] Univ Twente, Fac Geoinformat Sci & Earth Observat, POB 217, NL-7500 AE Enschede, Netherlands; [Fava, Francesco] Int Livestock Res Inst ILRI, POB 30709, Nairobi 00100, Kenya; [Meroni, Michele] European Commiss, Joint Res Ctr JRC, Via E Fermi 2749, I-21027 Ispra, VA, Italy; [Gachoki, Stella] Int Ctr Insect Physiol & Ecol ICIPE, POB 30772, Nairobi 00100, Kenya
推荐引用方式 GB/T 7714	Cheng, Yan,Vrieling, Anton,Fava, Francesco,et al. Phenology of short vegetation cycles in a Kenyan rangeland from PlanetScope and Sentinel-2[J],2020,248.
APA	Cheng, Yan,Vrieling, Anton,Fava, Francesco,Meroni, Michele,Marshall, Michael,&Gachoki, Stella.(2020).Phenology of short vegetation cycles in a Kenyan rangeland from PlanetScope and Sentinel-2.REMOTE SENSING OF ENVIRONMENT,248.
MLA	Cheng, Yan,et al."Phenology of short vegetation cycles in a Kenyan rangeland from PlanetScope and Sentinel-2".REMOTE SENSING OF ENVIRONMENT 248(2020).