气候变化领域集成服务门户(CCPortal): Impact of water characteristics on the discrimination of benthic cover in and around coral reefs from imaging spectrometer data

CCPortal

DOI	10.1016/j.rse.2019.111631
	Impact of water characteristics on the discrimination of benthic cover in and around coral reefs from imaging spectrometer data
	Bell T.W.; Okin G.S.; Cavanaugh K.C.; Hochberg E.J.
发表日期	2020
ISSN	00344257
卷号	239
英文摘要	Coral reefs are the foundation of productive ecosystems in the global, tropical oceans and are under threat from a variety of local to global scale stressors. Satellite imagery provides a tool to identify and understand the processes that control coral reef degradation, however due to the dynamic nature of seawater constituents, current spaceborne multispectral sensors cannot reliably discriminate between the many coral reef benthic classes necessary to detect change. Hyperspectral imagers may provide sufficient spectral resolution to estimate water column properties and differentiate benthic classes, however, the effects of depth, seawater constituents, and classification algorithm on the accuracy of benthic classifications have not been systematically assessed. Here, we simulate the ability of a spaceborne hyperspectral imager to accurately map fractional cover of coral reef benthic classes under a variety of conditions. Benthic reflectance is simulated by combining pure reflectance spectra of coral, algae, and sand and projecting these mixed spectra through a fully crossed set of water columns. We then use a semi-analytical optimization procedure to estimate the water column properties and multiple endmember spectral mixture analysis to estimate the fractional cover of the benthic classes using many independent endmember spectra. We compare our estimated benthic class fractions to the original, actual fractions used to produce the mixed coral reef spectra to quantify several measures of error. We found that multiple endmember spectral mixture analysis decreases fractional retrieval error, which is also reduced when the first derivative of the mixed and endmember spectra is used prior to unmixing. The estimation of fractional benthic class cover is most accurate for depths ≤3 m for most water conditions. Depths ≥5 m should be classified only if chlorophyll and sediment concentration are <0.1 mg m− 3 and <0.1 g m− 3, respectively. Our results indicate that the fractional cover of coral and algae should be at least 25% for accurate benthic class estimates (mean relative error < 50%), however there will be many ways to leverage the repeat measurements of a hyperspectral satellite sensor, such as a stable depth retrievals and benthic cover estimates, to produce more accurate and useful fractional cover data. We show how this simulation analysis can be used to generate maps of predicted benthic cover fractional retrieval uncertainty across a coral reef system using aerial hyperspectral imagery acquired over Hawaii, USA, although reef-specific, within pixel variations in depth and benthic class complexity should be considered. © 2020 Elsevier Inc.
语种	英语
scopus关键词	Aerial photography; Algae; Antennas; Errors; Mixtures; Reefs; Reflection; Satellite imagery; Search engines; Seawater effects; Spectroscopy; Classification algorithm; Coral reef degradation; Hyper-spectral imageries; Hyperspectral satellite; Multiple endmember spectral mixture analysis; Multispectral sensors; Sediment concentration; Water characteristics; Uncertainty analysis; benthic environment; coral reef; satellite data; spectrometer; algae; Anthozoa
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/179452
作者单位	Dept. of Geography, University of California, Los Angeles, Los Angeles, CA 90095, United States; Bermuda Institute of Ocean Sciences, St. George's, Bermuda, Bermuda
推荐引用方式 GB/T 7714	Bell T.W.,Okin G.S.,Cavanaugh K.C.,et al. Impact of water characteristics on the discrimination of benthic cover in and around coral reefs from imaging spectrometer data[J],2020,239.
APA	Bell T.W.,Okin G.S.,Cavanaugh K.C.,&Hochberg E.J..(2020).Impact of water characteristics on the discrimination of benthic cover in and around coral reefs from imaging spectrometer data.Remote Sensing of Environment,239.
MLA	Bell T.W.,et al."Impact of water characteristics on the discrimination of benthic cover in and around coral reefs from imaging spectrometer data".Remote Sensing of Environment 239(2020).