气候变化领域集成服务门户(CCPortal): Coarse-Resolution Satellite Images Overestimate Urbanization Effects on Vegetation Spring Phenology

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DOI	10.3390/rs12010117
	Coarse-Resolution Satellite Images Overestimate Urbanization Effects on Vegetation Spring Phenology
	Tian, Jiaqi; Zhu, Xiaolin; Wu, Jin; Shen, Miaogen; Chen, Jin
通讯作者	Zhu, XL (通讯作者)
发表日期	2020
EISSN	2072-4292
卷号	12 期号:1
英文摘要	Numerous investigations of urbanization effects on vegetation spring phenology using satellite images have reached a consensus that vegetation spring phenology in urban areas occurs earlier than in surrounding rural areas. Nevertheless, the magnitude of this rural-urban difference is quite different among these studies, especially for studies over the same areas, which implies large uncertainties. One possible reason is that the satellite images used in these studies have different spatial resolutions from 30 m to 1 km. In this study, we investigated the impact of spatial resolution on the rural-urban difference of vegetation spring phenology using satellite images at different spatial resolutions. To be exact, we first generated a dense 10 m NDVI time series through harmonizing Sentinel-2 and Landsat-8 images by data fusion method, and then resampled the 10 m time series to coarser resolutions from 30 m to 8 km to simulate images at different resolutions. Afterwards, to quantify urbanization effects, vegetation spring phenology at each resolution was extracted by a widely used tool, TIMESAT. Last, we calculated the difference between rural and urban areas using an urban extent map derived from NPP VIIRS nighttime light data. Our results reveal: (1) vegetation spring phenology in urban areas happen earlier than rural areas no matter which spatial resolution from 10 m to 8 km is used, (2) the rural-urban difference in vegetation spring phenology is amplified with spatial resolution, i.e., coarse satellite images overestimate the urbanization effects on vegetation spring phenology, and (3) the underlying reason of this overestimation is that the majority of urban pixels in coarser images have higher diversity in terms of spring phenology dates, which leads to spring phenology detected from coarser NDVI time series earlier than the actual dates. This study indicates that spatial resolution is an important factor that affects the accuracy of the assessment of urbanization effects on vegetation spring phenology. For future studies, we suggest that satellite images with a fine spatial resolution are more appropriate to explore urbanization effects on vegetation spring phenology if vegetation species in urban areas is very diverse.
关键词	GREEN-UP DATE MODIS SURFACE REFLECTANCE CLIMATE-CHANGE TIME-SERIES CARBON UPTAKE FUSION MODEL RIVER DELTA TEMPERATURE IMPACTS ECOSYSTEMS
英文关键词	urbanization effects; vegetation spring phenology; spatial resolution; satellite image; time series
语种	英语
WOS研究方向	Environmental Sciences & Ecology ; Geology ; Remote Sensing ; Imaging Science & Photographic Technology
WOS类目	Environmental Sciences ; Geosciences, Multidisciplinary ; Remote Sensing ; Imaging Science & Photographic Technology
WOS记录号	WOS:000515391700117
来源期刊	REMOTE SENSING
来源机构	中国科学院青藏高原研究所
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/259915
推荐引用方式 GB/T 7714	Tian, Jiaqi,Zhu, Xiaolin,Wu, Jin,et al. Coarse-Resolution Satellite Images Overestimate Urbanization Effects on Vegetation Spring Phenology[J]. 中国科学院青藏高原研究所,2020,12(1).
APA	Tian, Jiaqi,Zhu, Xiaolin,Wu, Jin,Shen, Miaogen,&Chen, Jin.(2020).Coarse-Resolution Satellite Images Overestimate Urbanization Effects on Vegetation Spring Phenology.REMOTE SENSING,12(1).
MLA	Tian, Jiaqi,et al."Coarse-Resolution Satellite Images Overestimate Urbanization Effects on Vegetation Spring Phenology".REMOTE SENSING 12.1(2020).