OPERA DIST-ALERT-HLS (Version 1)

OPERA DIST-ALERT-HLS (Version 1) is a near-real-time land surface disturbance alert product produced by NASA JPL and distributed by LP DAAC. It detects vegetation disturbance across all terrestrial biomes (forest, savanna, shrubland, and wetland) at 30 m ground sample distance using Harmonized Landsat Sentinel-2 (HLS) optical composite inputs.^[1][2]

Alerts are delivered as MGRS-tiled rasters with 19 output layers per tile. The detection approach compares recent HLS observations against a pre-disturbance reference to flag anomalous spectral change; confidence tier thresholds separate confirmed from provisional alerts. According to product support documentation as of 2026-05-24, the exact threshold values for each confidence tier are described in the OPERA DIST-ALERT Algorithm Theoretical Basis Document, though the ATBD PDF has not been made available in machine-readable form via LP DAAC as of 2026-05-24.^[1]

NASA CMR metadata states global land coverage up to approximately 90 degrees latitude.^[1] In practice, non-vegetated pixels carry a no-data mask, so effective coverage is limited to vegetated land surfaces.^[2]

Cloud and shadow masking artefacts are inherited from HLS input and affect detection latency in persistently clouded humid-tropical regions.^[2] At 30 m resolution, selective logging or small-patch disturbance below the pixel footprint may not be detected. The product is available at no cost under the NASA Earthdata use policy via LP DAAC and Earthdata Search.^[1][2]