IRIS: ICESat-2 River Surface Slope

ICESat-2 River Surface Slope (IRIS)

When using this data please cite Scherer D., Schwatke C., Dettmering D., Seitz F. : ICESat-2 Based River Surface Slope and Its Impact on Water Level Time Series From Satellite Altimetry. Water Resources Research, 10.1029/2022WR032842, 2022.

1. Summary
The unique multibeam lidar altimeter of ICESat-2 is used to measure reach-scale water surface slope (WSS) every time the spacecraft’s orbit crosses a reach. The method of deriving WSS from simultaneous ICESat-2 ATL13 (Jasinski et al., 2021) observations is described in detail and validated in Scherer et al. (2022). In this ICESat-2 River Surface Slope (IRIS) dataset, we provide the minimum, average, and maximum slope derived with three different approaches (across, along, and combined) per reach. Additionally, we give the standard deviation and epochs of the derived WSS data. The reaches are defined by the SWOT River Database (SWORD, Altenau et al., 2021).
Note that Version v0 only includes the reaches studied in Scherer et al. (2022) and uses SWORD Version v1. Following Versions of IRIS have global coverage (limited by ICESat-2 data availability and cloud cover) and use SWORD Version v2.

2. Data Format and Variable Description
The IRIS data is stored in a single NetCDF4 file which is structured in a single group containing the following variables:
reach_id:
The SWORD reach identifier [-]
lon:
Approx. centroid longitude of the SWORD reach [degrees east]
lat:
Approx. centroid latitude of the SWORD reach [degrees north]
across_flag, along_flag, combined_flag:
Flags indicating whether ICESat-2 [across/along/combined] slope is available (1) for the reach or not (0) [-]
avg_across_slope, avg_along_slope, avg_combined_slope:
Average ICESat-2 [across/along/combined] slope for the reach [mm/km]
min_across_slope, min_along_slope, min_combined_slope:
Minimum ICESat-2 [across/along/combined] slope for the reach [mm/km]
max_across_slope, max_along_slope, max_combined_slope:
Maximum ICESat-2 [across/along/combined] slope for the reach [mm/km]
std_across_slope, std_along_slope, std_combined_slope:
ICESat-2 [across/along/combined] slope standard deviation for the reach [mm/km]
n_across_slope, n_along_slope, n_combined_slope:
Number of days with ICESat-2 [across/along/combined] slope observations for the reach [-]
min_date_across_slope, min_date_along_slope:, min_date_combined_slope:
First date of ICESat-2 [across/along/combined] slope observations for the reach [days since 2000-01-01]
max_date_across_slope, max_date_along_slope:, max_date_combined_slope:
Latest date of ICESat-2 [across/along/combined] slope observations for the reach [days since 2000-01-01]

3. References
Scherer D., Schwatke C., Dettmering D., Seitz F. (2022): ICESat-2 Based River Surface Slope and Its Impact on Water Level Time Series From Satellite Altimetry, Water Resources Research, https://doi.org/10.1029/2022WR032842
Jasinski M., Stoll J., Hancock D., Robbins J., Nattala J., Morison J., Jones B., Ondrusek M., Pavelsky T.M., Parrish C. and the ICESat-2-Science-Team (2021). ATLAS/ICESat-2 L3A Inland Water Surface Height, Version 5. [Dataset]
Altenau E.H., Pavelsky T.M., Durand, M.T., Yang X., Frasson, R.P.d.M., Bendezu, L. (2021): SWOT River Database (SWORD) [Data set]. Zenodo. https://doi.org/10.5281/zenodo.3898569