https://doi.org/10.5061/dryad.mkkwh7189

Description of the data and file structure

Data products contain SWE-changes from NASA UAVSAR flights during the SnowEx 2020 and 2021 Time Series Campaigns. Products are continuous from 12 February to 12 March 2020. The 2021 products are continuous from 15 January to 10 March. The 10–16 March unwrapped InSAR pair yielded no coincident data for phase calibration and thus was not included here. The final interval for 2021 is 16–22 March. The products have not been atmospherically corrected because it was determined in the manuscript (https://doi.org/10.5194/egusphere-2024-236) that an atmospheric correction was not warranted. These products are analysis ready.

Most SWE-change products have a temporal baseline of 5–8 days. However, two intervals were longer and may have higher uncertainty: 26 February to 12 March 2020 and 3–23 February 2021.

Some files may be missing data due to phase unwrapping errors. See NASA UAVSAR for phase unwrapping methodology.

File Naming Convention:

Date1_Date2_YYYY_Polarization_Heading.tif

• Date1: The first UAVSAR flight date for the InSAR interval.
• Date2: The second UAVSAR flight date for the InSAR interval.
• YYYY: The year the pair of UAVSAR flights took place.
• Polarization: Two digit letter code describing the transmitting and receiving polarization.
  • HH: Horizontally transmitted/Horizontally received
  • HV: Horizontally transmitted/Vertically received
  • VH: Vertically transmitted/Horizontally received
  • VV: Vertically transmitted/Vertically received
• Heading: Three digit number code for the UAVSAR flight heading. For this dataset, the primary flight heading is northeast (141) and the secondary flight heading is southwest (321).
• .tif: These files are provided as geotiffs.

Coordinate System:

• All geotiffs are provided in WGS84 (EPSG:4326). This was the original coordinate system provided by NASA UAVSAR.

Sharing/Access information

This dataset contains changes in snow water equivalent (SWE) derived from the NASA UAVSAR Rocky Mountains NP, CO flight line. Original unwrapped InSAR pairs are archived with NASA UAVSAR and the Alaska Satellite Facility Distributed Active Archive Center. The SLC files can be found at NASA UAVSAR:

• https://uavsar.jpl.nasa.gov/cgi-bin/product.pl?jobName=rockmt_14107_01#data
• https://uavsar.jpl.nasa.gov/cgi-bin/product.pl?jobName=rockmt_32109_02#data

UAVSAR unwrapped InSAR pairs were converted to SWE-change rasters following methods outlined by Guneriussen et al. (2001):

• https://doi.org/10.1109/36.957273

The Guneriussen et al. (2001) method requires phase change (the unwrapped InSAR pairs referenced previously), relative permittivity, local incidence angles, snow surface densities, and phase calibration:

• Relative permittivity was calculated from snow surface densities using the empirical equation from Kovacs et al. (1995): 
  • https://doi.org/10.1016/0165-232X(94)00016-Q
• Snow surface densities were measured in situ during the NASA SnowEx Time Series Campaigns:
  • 2020: https://doi.org/10.5067/POT9E0FFUUD1%0d
  • 2021: https://doi.org/10.5067/QIANJYJGRWOV
• Local incidence angles were calculated from the UAVSAR look vectors (see SLC stacks above) and the Copernicus 30 m DEM (downsampled to ~5m) within uavsar_pytools:
  • https://doi.org/10.5281/zenodo.6789624
• Phase calibration was computed as the median difference between a subset of ground-penetrating radar measurements of SWE-change and UAVSAR SWE-change. Ground-penetrating radar datasets are archived here:
  • 2020: https://doi.org/10.5067/U4Q3X27BMRR4
  • 2021: https://doi.org/10.5067/SRWGLYCB6ZC4