SAR 3 Band Model Shorelines Dataset

This dataset contains satellite-derived shoreline positions and cross-shore change time series for 16 regions of interest spanning eight coastal communities in western and northern Alaska (Unalakleet, Shaktoolik, Golovin, Nome, Shishmaref, Kotzebue, Kivalina, and Utqiagvik), covering the 2016 to 2024 open-water seasons. Shorelines were mapped from 4,606 Sentinel-1 C-band SAR acquisitions using a U-Net water-segmentation model with a ResNet-50 encoder initialized from Sentinel-1 self-supervised (SSL4EO-S12 MoCo) weights and trained on a three-band VV, VH, VV−VH composite; the deployed model reaches an overall accuracy of 0.972 and a water IoU of 0.957 on held-out sites. The model is available at : https://huggingface.co/2320sharon/SAR_3_band_model . Because SAR is unaffected by cloud cover, which routinely obscures 70 to 80 percent of this coast in summer, the archive provides a large increase in observation density over optical shoreline mapping. For each region of interest, the dataset provides raw shoreline vectors as a GeoPackage, cross-shore distance time series on 2,370 transects (raw, tidally corrected, suitability-scored, and filtered, totaling 240,224 retained observations), and a full accuracy assessment against a tidally corrected optical shoreline record from Landsat 7/8/9, Sentinel-2, and PlanetScope. Across 97,797 matched SAR–optical pairs, the SAR shoreline sits a mean 5.9 m landward of the optical reference, with a cross-shore MAE of 16.6 m and an RMSE of 21.2 m over the inner 95 percent of residuals. All vectors are in EPSG:4326, and all timestamps are UTC. See the included README for file-level documentation, per-site statistics, and known limitations.