Dynamic Surface Water Extent rasters - Land Cover Mapping, North Slope of the Arctic National Wildlife Refuge, Alaska, 2019

We prepared a water phenology product from the Landsat Level-3 Dynamic Surface Water Extent (DSWE) science product, which provides a water classification for each Landsat scene at 30 m resolution (Jones 2015, Jones 2019). After masking clouds, cloud shadows, and snow, the DSWE product identities 4 categories of water confidence:
1. Not Water;
2. Open Water, High Confidence;
3. Open Water, Moderate Confidence;
4. Partial Surface Water, Conservative; and
5. Partial Surface Water, Aggressive.
We reviewed and summarized the DSWE products for 1999–2018 and prepared two metrics of surface water occurrence (defined as the percentage of the observations when surface water was present):
1. June/July/August, 1999–2018, Conservative Surface Water Occurrence (treating the Partial Surface Water, Aggressive class as Not Water); and
2. June/July/August, 1999–2018, Aggressive Surface Water Occurrence (treating all 4 categories of water confidence as Water).