气候变化领域集成服务门户(CCPortal): Multiband (X, C, L) radar amplitude analysis for a mixed sand- and gravel-bed river in the eastern Central Andes

CCPortal

DOI	10.1016/j.rse.2020.111799
	Multiband (X, C, L) radar amplitude analysis for a mixed sand- and gravel-bed river in the eastern Central Andes
	Purinton B.; Bookhagen B.
发表日期	2020
ISSN	00344257
卷号	246
英文摘要	Synthetic Aperture Radar (SAR) amplitude measurements from spaceborne sensors are sensitive to surface roughness conditions near their radar wavelength. These backscatter signals are often exploited to assess the roughness of plowed agricultural fields and water surfaces, and less so to complex, heterogeneous geological surfaces. The bedload of mixed sand- and gravel-bed rivers can be considered a mixture of smooth (compacted sand) and rough (gravel) surfaces. Here, we assess backscatter gradients over a large high-mountain alluvial river in the eastern Central Andes with aerially exposed sand and gravel bedload using X-band TerraSAR-X/TanDEM-X, C-band Sentinel-1, and L-band ALOS-2 PALSAR-2 radar scenes. In a first step, we present theory and hypotheses regarding radar response to an alluvial channel bed. We test our hypotheses by comparing backscatter responses over vegetation-free endmember surfaces from inside and outside of the active channel-bed area. We then develop methods to extract smoothed backscatter gradients downstream along the channel using kernel density estimates. In a final step, the local variability of sand-dominated patches is analyzed using Fourier frequency analysis, by fitting stretched-exponential and power-law regression models to the 2-D power spectrum of backscatter amplitude. We find a large range in backscatter depending on the heterogeneity of contiguous smooth- and rough-patches of bedload material. The SAR amplitude signal responds primarily to the fraction of smooth-sand bedload, but is further modified by gravel elements. The sensitivity to gravel is more apparent in longer wavelength L-band radar, whereas C- and X-band is sensitive only to sand variability. Because the spatial extent of smooth sand patches in our study area is typically <50 m, only higher resolution sensors (e.g., TerraSAR-X/TanDEM-X) are useful for power spectrum analysis. Our results show the potential for mapping sand-gravel transitions and local geomorphic complexity in alluvial rivers with aerially exposed bedload using SAR amplitude. © 2020 Elsevier Inc.
英文关键词	ALOS-2 PALSAR-2; Fluvial geomorphology; Radar backscatter; SAR amplitude; Sentinel-1; Surface roughness; TerraSAR-X/TanDEM-X
语种	英语
scopus关键词	Agricultural robots; Backscattering; Gravel; Mining laws and regulations; Power spectrum; Radar measurement; Regression analysis; Sand; Satellites; Spectrum analysis; Surface roughness; Synthetic aperture radar; Agricultural fields; Amplitude analysis; Amplitude measurements; Backscatter signals; Fourier frequency analysis; Kernel density estimate; Space-borne sensor; Stretched exponential; Rivers; amplitude; backscatter; bedload; digital mapping; geomorphology; heterogeneity; radar altimetry; sand and gravel; signal-to-noise ratio; synthetic aperture radar; Andes
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/179271
作者单位	Institute of Geosciences, University of Potsdam, Karl-Liebknecht-Str. 24-25, Potsdam-Golm, 14476, Germany
推荐引用方式 GB/T 7714	Purinton B.,Bookhagen B.. Multiband (X, C, L) radar amplitude analysis for a mixed sand- and gravel-bed river in the eastern Central Andes[J],2020,246.
APA	Purinton B.,&Bookhagen B..(2020).Multiband (X, C, L) radar amplitude analysis for a mixed sand- and gravel-bed river in the eastern Central Andes.Remote Sensing of Environment,246.
MLA	Purinton B.,et al."Multiband (X, C, L) radar amplitude analysis for a mixed sand- and gravel-bed river in the eastern Central Andes".Remote Sensing of Environment 246(2020).