NASA's Oak Ridge National Laboratory Distributed Active Archive Center (ORNL DAAC) released a new Global Ecosystem Dynamics Investigation (GEDI) Level 4D Imputed Waveforms data product.
This dataset provides spatially continuous estimates of GEDI waveforms at a 30-m resolution across the global land surface. A nearest neighbor algorithm was used with Landsat time series data to impute high-quality GEDI shots identified using a combination of metrics. For every 30-meter pixel, this product contains the imputed GEDI waveform in the form of multiple relative height (RH) metrics, as well as the corresponding canopy cover and aboveground biomass density (AGBD), derived from the GEDI Level 2B and Level 4A products, respectively. This product also provides estimates of the prediction quality for GEDI waveforms, canopy cover, and AGBD within each 10-km grid cell, using root mean square error (RMSE) and the Kolmogorow-Smirnov (KS) test.
The imputed GEDI waveforms were predicted using the k-nearest neighbors (k-NN) algorithm to choose the single most similar waveform (k = 1) for every pixel based on several variables derived from Landsat time series and Global Shuttle Radar Topography Mission Continuous Heat-Insolation Load Index (SRTM CHILI) data. These globally imputed GEDI waveforms offer richer structural information than standard canopy metrics such as height and cover, enabling comprehensive forest analysis across scales and can be integrated with local field measurements to support a wide range of applications in biodiversity assessment and habitat modeling.
GEDI is a full-waveform lidar instrument aboard the International Space Station (ISS) that collects high-resolution laser ranging measurements of Earth’s vertical structure. The instrument uses 3 lasers to produce eight beam ground transects, sampling ~25 m footprints spaced approximately every 60 m along-track. Beam transects are spaced approximately 600 m apart in the cross-track direction, resulting in an across-track width of ~4.2 km. GEDI’s precise measurements of canopy height, vertical structure, and surface elevation greatly advance our understanding of forest ecosystems, carbon and water cycling, biodiversity, and habitat structure.
The GEDI Level 4D Imputed Waveforms dataset is distributed in cloud-optimized GeoTIFF (COG) format, with an additional GeoPackage file summarizing imputation performance quality. The dataset is available through the dataset landing page, NASA Earthdata Search, and Earthdata Cloud.
If you have questions, please contact ORNL DAAC user services or visit NASA's Earthdata Forum.