气候变化领域集成服务门户(CCPortal): Evaluation of Sentinel-3 SRAL SAR altimetry over Chinese rivers

CCPortal

DOI	10.1016/j.rse.2019.111546
	Evaluation of Sentinel-3 SRAL SAR altimetry over Chinese rivers
	Jiang L.; Nielsen K.; Dinardo S.; Andersen O.B.; Bauer-Gottwein P.
发表日期	2020
ISSN	00344257
卷号	237
英文摘要	Satellite radar altimetry observations of water surface elevation (WSE) have become an important data source to supplement river gauge records. Sentinel-3 is the first radar altimetry mission operating with a synthetic aperture radar (SAR) altimeter at global scale and with a new on-board tracking system (i.e. open-loop), which has great potential in terms of delivering reliable observations of inland water bodies for the next two decades (several future missions include an open-loop tracking mode). In this context, it is very important to investigate the data quality at an early stage. In this study, a comprehensive evaluation of Sentinel-3A (S3A) is conducted at 50 virtual stations (VS) located on a wide range of rivers in China. The evaluation of Level 1 data shows that, over mountain rivers, a good prior surface elevation estimate on-board is vital to deliver useful datasets using the S3A open-loop tracking system. The Open-Loop Tracking Command version 5 (OLTC V5) has significantly improved the placement of the range window, which was misplaced and resulted in lack of data over many mountain rivers prior to OLTC V5 (March 2019). However, application of S3A over mountain rivers still requires careful evaluation, especially before March 2019. Four retrackers are evaluated including a physical SAR Altimetry Mode Studies and Applications retracker (SAMOSA+), a traditional Offset Center Of Gravity (OCOG), a Primary Peak Center Of Gravity (PPCOG), and a modified Multiple Waveform Persistent Peak (MWaPP+) retracker. For 26 VSs in plain areas, retracked WSE data achieved a root mean square error (RMSE) ranging from 0.12 m to 0.9 m. The comparison of retracking methods reveals that SAMOSA+, OCOG, and PPCOG are unable to handle multi-peak waveforms. But the MWaPP+ can significantly improve the accuracy of the estimated WSE over large rivers, especially when the waveforms are contaminated. Moreover, our result shows no considerable difference between medium (ca. 300 m wide) and large (wider than 500 m) rivers. Instead, surrounding topography and homogeneity of surroundings are very important factors influencing the shape of a waveform. For rivers surrounded by lakes, man-made channels etc., special care must be taken when processing altimetry data. Dedicated retracking methods, such as MWaPP+, and sophisticated methods for outlier detection are needed to improve precision over such rivers, as demonstrated here for the Yangtze River. © 2019 Elsevier Inc.
英文关键词	OLTC; Open-loop; Radar altimetry; Retracking; SAR; Sentinel-3; Water surface elevation
语种	英语
scopus关键词	Data handling; Landforms; Mean square error; Rivers; Topography; Tracking (position); OLTC; Open-loop; Radar altimetry; Re-tracking; Sentinel-3; Water surface elevations; Synthetic aperture radar; radar altimetry; river system; satellite data; satellite mission; Sentinel; synthetic aperture radar; tracking; China; Yangtze River
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/179536
作者单位	Department of Environmental Engineering, Technical University of Denmark, Kgs. Lyngby, 2800, Denmark; DTU Space, National Space Institute, Technical University of Denmark, Kgs. Lyngby, 2800, Denmark; He Space, Robert Bosch Strasse 7, Darmstadt, 64293, Germany
推荐引用方式 GB/T 7714	Jiang L.,Nielsen K.,Dinardo S.,et al. Evaluation of Sentinel-3 SRAL SAR altimetry over Chinese rivers[J],2020,237.
APA	Jiang L.,Nielsen K.,Dinardo S.,Andersen O.B.,&Bauer-Gottwein P..(2020).Evaluation of Sentinel-3 SRAL SAR altimetry over Chinese rivers.Remote Sensing of Environment,237.
MLA	Jiang L.,et al."Evaluation of Sentinel-3 SRAL SAR altimetry over Chinese rivers".Remote Sensing of Environment 237(2020).