A Synthetic Global Spatiotemporal Sampled River Discharge Database for Different Satellite Altimetry Mission Orbits

If you use this Synthetic Global Spatiotemporal Sampled River Discharge Database for Different Satellite Altimetry Mission Orbits in your work, please cite: Sikder et al., [2020], A Synthetic Dataset Inspired by Satellite Altimetry and Impacts of Sampling on Global Spaceborne Discharge Characterization, Water Resources Research [submitted].

This dataset was prepared using a simulated global discharge dataset [Lin et al., 2019] and several satellite altimetry mission orbits. The files in this database can be grouped as:

• GRADES-simulated global discharge data & river network
• Satellite altimetry mission orbits, coverage & sampling sequence
• Global sampled discharge dataset
• Statistical analysis and plots

1) GRADES-simulated global discharge data & river network:

The 10-year (2000-09) GRADES discharge data at 2.9 million river reaches were used as an analogue of true global river discharge. This discharge dataset, as well as the associated river network were developed by Lin et al., [2019]. A set of large river reaches were selected using the mean flow as a threshold (where, Qmean >= 125 m³/s), considering the observational capabilities of satellite altimeters. Daily discharge of these large river reaches were considered as the reference data here.

This section contains the following files;

Discharge data at 2.9 million river reaches: GRADES_Q_v01_pfaf_*_20000101_20091231.tar.gz (* = 01 to 08)

Long-term (2000-2009) mean discharge: GRADES_Qmean_20000101_20091231.tar.gz

Discharge at large river reaches (Qmean >= 125 m³/s): GRADES_Q_125cms_20000101_20091231.tar.gz

River network of large river reaches: riv_network_shp.tar.gz

River network map: fig_river_network.pdf

Note: River network shapefiles of 2.9 million reaches are available at http://hydrology.princeton.edu/data/mpan/MERIT_Basins/MERIT_Hydro_v00_Basins_v01/level_01

2) Satellite altimetry mission orbits, coverage & sampling sequence:

The satellite altimetry mission orbit files were acquired from AVISO⁺ and Sentinel websites. These files were processed, and the sampling sequence for large river reaches were derived. Another set of sampling sequence was also prepared, considering only regular temporal sampling (i.e., without using any orbit file).

The following files are included in this section;

Orbit shapefiles: orbit_shp_*.tar.gz (* = satellite altimetry missions)

Sampling sequence: sampling_csv_*.tar.gz (* = orbit or regular)

Orbit coverage: orbit_coverage_*.tar.gz (* = satellite altimetry missions)

Orbit coverage maps: fig_orbit_coverage.pdf

3) Global sampled discharge dataset:

Several sets of global sampled discharge dataset were derived from the reference dataset (i.e., 10-year GRADES daily discharge at large rivers), using the sampling sequence for different satellite altimetry mission orbits, as well as for regular temporal sampling.

The sampled discharge data files;

Regular temporal sampled files: regular_spl_*day.tar.gz (* = 3, 5, 10, 21, 27, 35)

Satellite orbit sampled files: orbit_spl_*.tar.tz (* = satellite altimetry missions)

Animation files: anim_*.mp4 (* = satellite altimetry missions)

4) Statistical analysis and plots:

Statistical analysis was carried out to identify the variation in flow magnitude (i.e., mean, maximum, minimum flow) for different sampling strategies with respect to the reference. Similar analysis was conducted to see the variation in average event duration too, where flow is exceeding the 75^th percentile.

The analysis and plot files;

Flow magnitude analysis: flow_magnitude_stat_*.tar.gz (* = for different sampling strategies)

Event duration analysis: event_duration_stat_*.tar.gz (* = for different sampling strategies)

Cumulative distribution plots: fig_cum_dist_*_spl.pdf (* = for different sampling strategies)

Spatial distribution of variation: fig_*_var.pdf (* = for different sampling strategies)

Other necessary links associated with this database:

GRADES discharge: http://hydrology.princeton.edu/data/mpan/GRADES

River network: http://hydrology.princeton.edu/data/mpan/MERIT_Basins/MERIT_Hydro_v00_Basins_v01/level_01

Satellite orbit files: https://www.aviso.altimetry.fr/en/data/tools/pass-locator.html, and

https://sentinels.copernicus.eu/web/sentinel/missions/sentinel-3/satellite-description/orbit

Processing and analysis scripts: https://github.com/c-h-david/rrr

References:

Sikder, M. S., M. Bonnema, C. M. Emery, C. H. David, P. Lin, M. Pan, et al. [2020], A Synthetic Dataset Inspired by Satellite Altimetry and Impacts of Sampling on Global Spaceborne Discharge Characterization, Water Resources Research [submitted]

Lin, P., M. Pan, H. E. Beck, Y. Yang, D. Yamazaki, R. Frasson, et al. [2019], Global reconstruction of naturalized river flows at 2.94 million reaches, Water Resources Research, 55, 6499–6516, doi:10.1029/2019WR025287.

Acknowledgments:

This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration including grants from the SWOT Science Team and the Terrestrial Hydrology Program.

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