Global River Radar Altimetry Time Series (GRRATS): new river elevation earth science data records for the hydrologic community

• Published in: Earth system science data Vol. 12; no. 1; pp. 137 - 150
• Main Authors: Coss, Stephen, Durand, Michael, Yi, Yuchan, Jia, Yuanyuan, Guo, Qi, Tuozzolo, Stephen, Shum, C. K, Allen, George H, Calmant, Stéphane, Pavelsky, Tamlin
• Format: Journal Article
• Language: English
• Published: Katlenburg-Lindau Copernicus GmbH 22-01-2020; Copernicus Publications
• Subjects: Altimeters; Altimetry; Correlation coefficient; Correlation coefficients; Data; Datasets; Drainage; Drainage area; Earth; Elevation; Evaluation; Hydrologic data; Hydrology; Inland waters; Ocean surface; Ocean surface topography; Oceans; Parameterization; Quality control; Radar; Radar altimeters; Radar altimetry; Radar data; Radar systems; Radio altimeters; Remote sensing; Rivers; Sciences of the Universe; Scientific visualization; Time series; Arctic region
• ISSN: 1866-3516; 1866-3508; 1866-3516
• DOI: 10.5194/essd-12-137-2020

The capabilities of radar altimetry to measure inland
water bodies are well established, and several river altimetry datasets are
available. Here we produced a globally distributed dataset, the Global River
Radar Altimeter Time Series (GRRATS), using Envisat and Ocean Surface
Topography Mission (OSTM)/Jason-2 radar altimeter data spanning the time
period 2002–2016. We developed a method that runs unsupervised, without
requiring parameterization at the measurement location, dubbed virtual
station (VS) level, and applied it to all altimeter crossings of ocean-draining rivers with widths >900 m (>34 % of
the global drainage area). We evaluated every VS, either quantitatively for VS
locations where in situ gages are available or qualitatively using a grade
system. We processed nearly 1.5 million altimeter measurements from 1478
VSs. After quality control, the final product contained 810 403 measurements
distributed over 932 VSs located on 39 rivers. Available in situ data allowed
quantitative evaluation of 389 VSs on 12 rivers. The median standard deviation of
river elevation error is 0.93 m, Nash–Sutcliffe efficiency is 0.75, and
correlation coefficient is 0.9. GRRATS is a consistent, well-documented
dataset with a user-friendly data visualization portal, freely available for
use by the global scientific community. Data are available at https://doi.org/10.5067/PSGRA-SA2V1 (Coss et al., 2016).