WELDAKYR: Alaska Landsat 30m Annual Composites (2002-2012)

NASA's Web-Enabled Landsat Data (WELD) WELDAKYR.015 provides annual 30-meter resolution mosaics of Alaska from Landsat Enhanced Thematic Mapper Plus (ETM+) imagery. The dataset includes Top of Atmosphere Reflectance, Brightness Temperature, and a derived Normalized Difference Vegetation Index (NDVI) for the period 2002 to 2012. This product was decommissioned in 2019, with users directed to newer Global Web-Enabled Landsat Data (GWELD) versions.

Use Cases

• Monitoring land cover change in Alaska based on annual 30m reflectance composites.
• Analyzing vegetation health trends using the derived Normalized Difference Vegetation Index (NDVI).
• Conducting regional assessments of surface dynamics with Top of Atmosphere Reflectance and Brightness Temperature data.
• Studying geophysical and biophysical processes over a decadal time series (2002-2012).

Strengths

• Provides consistent, annual 30-meter resolution data for a full decade (2002-2012).
• Includes scientifically relevant layers like Top of Atmosphere Reflectance, Brightness Temperature, and a derived NDVI.
• Is a product of a collaboration between NASA, USGS EROS, and South Dakota State University.

Limitations

• Dataset is decommissioned (as of Dec 2, 2019) and superseded by newer GWELD versions.
• Metadata on row/column counts and specific data size is unavailable across all sources.
• Conflicting 'last updated' dates (2012 vs. 2026) suggest potential metadata freshness issues.

Provenance

Source

NASA, in collaboration with USGS Earth Resources Observation and Science (EROS) Center and South Dakota State University (SDSU) Geospatial Sciences Center of Excellence (GSCE).

Collection Method

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

Time Range

2002 to 2012 (annual composites covering December of the preceding year through November of the nominal year).

Freshness

The dataset was decommissioned on December 2, 2019. Platform metadata shows a last updated date of 2026-04-10, but this likely refers to catalog maintenance, not data updates.

Geography

Alaska, United States.