Annual US Landsat Composites for Land Cover and Vegetation Analysis

NASA's Web-Enabled Landsat Data (WELD) provides annual 30-meter resolution satellite mosaics for the conterminous United States and Alaska. The dataset spans from 2002 to 2012, with each annual composite covering a 12-month period from December of the preceding year through November. It was produced through a collaboration between NASA, the USGS Earth Resources Observation and Science Center, and South Dakota State University.

Use Cases

• Calculating the Normalized Difference Vegetation Index (NDVI) using Band 3 and Band 4 Top of Atmosphere Reflectance for vegetation health monitoring.
• Analyzing land cover change over time using annual Top of Atmosphere Reflectance composites.
• Deriving biophysical products like brightness temperature for regional climate and surface energy studies.
• Conducting multi-year regional assessments of surface dynamics and geophysical processes.

Strengths

• Provides consistent, 30-meter resolution data across the entire conterminous US and Alaska for an 11-year period (2002-2012).
• Includes scientifically validated products like Top of Atmosphere Reflectance, Brightness Temperature, and the derived NDVI index.
• Data is composited over annual periods to reduce cloud cover and provide a more consistent surface view.

Limitations

• The dataset (WELDUSYR.015) was officially decommissioned in December 2019, with users directed to newer GWELD versions.
• Specific row counts, file sizes, and a complete column list are not provided by the source platforms.
• The last updated date conflicts between sources (2012-11-30 vs. 2026-03-12), indicating potential metadata inconsistency.

Provenance

Source

National Aeronautics and Space Administration (NASA), USGS Earth Resources Observation and Science (EROS) Center, South Dakota State University (SDSU) Geospatial Sciences Center of Excellence.

Collection Method

Generated from composited Landsat Enhanced Thematic Mapper Plus (ETM+) mosaics.

Time Range

2002 to 2012 (each annual product covers December of the prior year through November).

Freshness

2026-03-12 23:28:12.743002

Geography

Conterminous United States and Alaska.