Utqiagvik Rain-on-Snow SAR Dataset: Sentinel-1 RTC Change Detection for the Alaska North Slope Trail Network (2016-2024)

Sentinel-1 C-band SAR (VV polarisation, Radiometrically Terrain Corrected) change-detection dataset for rain-on-snow (RoS) event mapping across the Utqiagvik (Barrow), Alaska trail network. Coverage: 130 x 124 km, EPSG:32605 (UTM Zone 5N), 40 m/pixel, 2016–2024. Contents: baselines/ — 9 October dry-snow median composites (dB) scenes/ — 49 post-RoS event acquisitions (dB) delta_vv/ — 49 ΔVV change-detection layers (post minus baseline, dB); negative values indicate backscatter decrease from wet snow or ice crust wetsnow/ — 49 binary wet-snow/ice-crust masks (1 = wet-snow, ΔVV < −3 dB; 0 = dry; 255 = nodata) manifest.csv — event metadata: date, orbit, baseline year, mean ΔVV (dB), network wet-snow fraction (%) Physical basis: C-band backscatter drops −5 to −10 dB when liquid water infiltrates the snowpack. On refreeze, a smooth ice crust maintains a −2 to −4 dB deficit for weeks to months. Wet-snow threshold: ΔVV < −3.0 dB (Ulaby et al. 2014). Source data: Sentinel-1 RTC processed by ASF, accessed via Microsoft Planetary Computer (collection: sentinel-1-rtc). Same-orbit-direction baselines enforced to prevent spurious 2–3 dB artefacts from look-angle mixing. Ecological context: The dataset supports analysis of forage-lockout impacts on the Teshekpuk Lake caribou herd (TLH) and subsistence hunting access. RoS frequency has increased 4× since the 1980s (2 → 8 days/year). SAR confirms mid-winter events (Jan–Feb) lock 24.5% of the network under ice crust despite low frequency. Analysis code: https://github.com/amstringer0303/utqiagvik-ros-sar