Data from the GEDI instrument on the International Space Station can help answer questions about Earth’s biomes and ecosystem impacts on the carbon cycle and climate. Credit: NASA
New data distributed through NASA’s Oak Ridge National Laboratory Distributed Active Archive Center, or ORNL DAAC, provide an unprecedented picture of plants’ carbon storage capacity around the globe.
Generated by the Global Ecosystem Dynamics Investigation, or GEDI, instrument installed on the International Space Station, these data can help answer questions about Earth’s biomes and ecosystem impacts on the carbon cycle and climate.
From towering sequoia trees to the grasslands of the African savannah, plants pull carbon dioxide from the air and store that carbon in their tissues. Predicting how much carbon plants might store in the future starts with a better understanding of current environments.
“This is the first chance of getting a reasonably global view of biomass made by a consistent measurement technique,” said Bruce Wilson, head of the Remote Sensing and Environmental Informatics Group and lead for the ORNL DAAC. “These data provide a vertical profile of all vegetation above ground, including an exceptional amount of information about forest structure.”
GEDI data are filling a gap in that knowledge by supplying not only information about the location and spread of vegetation, but also details about the height of trees and the density of their canopies — creating a detailed record of three-dimensional forest structure and above-ground biomass.
To collect these data, GEDI relies on a light detection and ranging, or lidar, system that sends out laser beam pulses and records the reflected energy from plant stems, branches and leaves as well as the terrain. Launched on Dec. 5, 2018, GEDI has the highest resolution and densest sampling of any lidar ever put in orbit, using three lasers that each pulse 242 times per second to capture approximately 10 billion observations.
Because of the space station’s orbit, GEDI follows a somewhat unusual course in making these measurements. Its lasers scan in 25-meter footprints, recording the planet’s biomes between 52 degrees north and south latitudes in a pattern reminiscent of a gradually filling ball of yarn.
Curating data for the scientific community
Sharing these data in formats that scientists can use requires some translation on the part of NASA and its archive centers. The lower-level data from the individual laser shots were previously released through the Land Processes DAAC. The higher-level GEDI data, distributed through the ORNL DAAC, provide an aggregate of key metrics such as canopy height and vertical canopy profile for each square kilometer, creating a data grid that covers the observed area.
These new gridded data can be used to validate outputs from climate models and can fuel a variety of science, from examinations of habitat and biodiversity to carbon flux and the effects of physical disturbances on ecosystems.
The ORNL DAAC, which specializes in data related to terrestrial ecology and biogeochemical dynamics, provides data selection tools that allow users to choose GEDI data for precise geographic areas. Users will also have access to subsets of data for about 3,000 locations that are the subject of active multi-investigator ecology projects.
“Our team regularly supplies higher-level satellite data products to the terrestrial ecology communities,” Wilson said. “We process the data for ease of use by people who are not remote sensing experts while also providing the metadata and quality notations for power users.”
Later this year, the ORNL DAAC will host additional GEDI data, including gridded estimates of above-ground carbon. Those data are being derived from the lower-level data that are currently available. When they post, the picture of above-ground carbon distribution in terrestrial ecosystems will be even clearer.
The GEDI mission is led by a science team at the University of Maryland in collaboration with NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
ORNL is managed by UT-Battelle for the Department of Energy's Office of Science, the single largest supporter of basic research in the physical sciences in the United States. DOE’s Office of Science is working to address some of the most pressing challenges of our time. For more information, please visit https://www.energy.gov/science/.
