Earth Data School
About
Full catalog/GWELDYR
GWELDYR·v031·dataset

Yearly cloud-free global land mosaics (Landsat, 30m)

NASA Global Web-Enabled Landsat Data Annual Global 30 m V031
land NASA LPCLOUD Level 2 HDF-EOS2
In plain English

What it measures. Yearly, cloud-free mosaics of the world's land surface at 30-meter detail, including surface reflectance in several color bands, a top-of-atmosphere temperature for heat bands, a vegetation-greenness index, and quality information. Coverage is for the 1985, 1990, and 2000 time periods.

How it's made. Stitched together from all available Landsat 4, 5, and 7 imagery, processed to remove viewing-angle effects and clouds and aligned to NASA's MODIS tile grid for consistency.

How & where you'd use it. Provides clean, consistent snapshots of land cover and surface conditions for regional studies of how landscapes change over time.

What's measured

LAND SURFACE › LAND USE/LAND COVERBIOSPHERE › VEGETATION › VEGETATION INDEX › NORMALIZED DIFFERENCE VEGETATION INDEX (NDVI)LAND SURFACE › SURFACE RADIATIVE PROPERTIES › REFLECTANCE

Coverage & cadence

  • Time span1984-01-01 → 2001-12-31
  • Measured byLANDSAT-7 (ETM+) · LANDSAT-5 (TM) · LANDSAT-4 (TM)
  • Processing levelLevel 2
  • Spatial extent-180, -90, 180, 90
  • FormatsHDF-EOS2
  • StatusCOMPLETE

What you can do with it

  • Track deforestation, fire scars and land-cover change
  • Monitor crop and vegetation health (NDVI/EVI)
  • Map how built-up vs. green an area is over time
Official description

The NASA Making Earth System Data Records for Use in Research Environments ([MEaSUREs](https://earthdata.nasa.gov/about/competitive-programs/measures)) Global Web-Enabled Landsat Data Annual (GWELDYR) Version 3.1 data product provides Landsat data at 30 meter (m) resolution for terrestrial non-Antarctica locations over annual reporting periods for the 1985, 1990, and 2000 epochs. GWELD data products are generated from all available Landsat 4 and 5 Thematic Mapper (TM) and Landsat 7 Enhanced Thematic Mapper Plus (ETM+) data in the U.S. Geological Survey (USGS) Landsat archive. The GWELD suite of products provide consistent data to derive land cover as well as geophysical and biophysical information for regional assessment of land surface dynamics. The GWELD products include Nadir Bidirectional Reflectance Distribution Function (BRDF)-Adjusted Reflectance (NBAR) for the reflective wavelength bands and top of atmosphere (TOA) brightness temperature for the thermal bands. The products are defined in the Sinusoidal coordinate system to promote continuity of NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) land tile grid. Provided in the GWELDYR product are layers for surface reflectance bands 1 through 5 and 7, TOA brightness temperature for thermal bands, Normalized Difference Vegetation Index (NDVI), day of year, ancillary angle, and data quality information. A low-resolution red, green, blue (RGB) browse image of bands 5, 4, 3 is also available for each granule. Known Issues * GWELDYR known issues can be found in Section 4 of the Algorithm Theoretical Basis Document (ATBD).

Get the data

gweldyr_access.py
import earthaccess
earthaccess.login(strategy="netrc")          # free Earthdata Login

results = earthaccess.search_data(
    short_name="GWELDYR",
    version="031",
    bounding_box=(-122.5, 37.2, -121.8, 37.9),  # your area (W,S,E,N)
    temporal=("2024-01-01", "2024-12-31"),       # your dates
)
files = earthaccess.open(results)   # stream straight from LPCLOUD
Browsing CMR needs no login. Downloading or streaming bytes needs a free Earthdata Login + the earthaccess package.