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New Data Set Reveals Changing Face of Earth Over the Course of One Year in Unprecedented Detail
By: Earth Big Data LLC (EBD)
and international levels, and to disaster planning and preparedness.
The data and images from the European Space Agency's Sentinel 1A and 1B satellites and its analysis was published in the journal Scientific Data ( https://www.nature.com/
"This is Earth as we've never seen it before," said Josef Kellndorfer, founder of Earth Big Data, LLC, and lead author of the study. "This level of detail will enable a far more nuanced understanding of how our planet is changing throughout the year and beyond."
The Sentinel-1 satellites orbit Earth once every 90 minutes and use synthetic aperture radar
(SAR) technology to create detailed images of the geo- and biophysical state of the land, ice, and water below. Unlike optical imagery of Earth's surface, which relies on light from the sun and can be blocked by clouds, dust, or smoke, SAR uses microwave energy to peer through any haze, and can even image the ground at night. In addition, consecutive images of the same location allow for detecting interference patterns, which reveal millimeter- to centimeter-scale deformations of the Earth surface. This technique, known as SAR interferometry, is a powerful way to evaluate deformations associated with tectonic activity, groundwater extraction, mining, landslides, or the inflation of volcanoes poised to erupt.
For their study, funded by JPL, the team looked at a full year of Sentinel-1 data—from December 1, 2019, to November 30, 2020—and separated the data into seasonal groups:
December-February, March-May, June-August, and September-November. Over the course of the year, both satellites passed over every point on land from 82 North to 79 South between 30 and 60 times. The resulting Petabyte (1,000 Terabytes) of data was processed with massive cloud-computing capacity, available through Amazon Web Services, in less than five days to produce this novel data set. At a resolution of 90 meters (300 feet), this data set unlocks for the first time the power of spaceborne radar interferometry at global scale. In addition to informing NASA and other space agencies' efforts designing future SAR missions, as well as geophysicists interested in surface deformation, the results of this work benefit a range of scientists and decision-makers who study topics like seasonal dynamics of vegetation, global areas of agricultural activity, land use change, soil moisture and irrigation patterns, or sea and inland ice extent and motion.
"This is really just a first step," said Kellndorfer, who is also a member of NASA's Science Team for the NISAR radar satellite mission which is slated to launch in partnership with the Indian Space Agency by early 2024, and will collect interferometry-
Oliver Cartus of Gamma Remote Sensing, Switzerland, and co-author of the study, added, "It is exciting to demonstrate that the wealth of information contained in interferometric radar data acquired by current SAR missions such as Sentinel-1 or upcoming missions such as NISAR becomes accessible at global scale with the computational power offered by modern cloud systems."
The published paper, all of the imagery and data from the study is open-access and freely
available at the NASA Alaska Satellite Facility Distributed Active Archive Centers (https://asf.alaska.edu/
About Earth Big Data LLC
Earth Big Data LLC (EBD), Woods Hole, MA, was founded in 2015 to address the big
environmental challenges of our time by providing access to modern computational tools and
that mine large Earth observation data sets. EBD is a fully cloud-based company and committed to open-source solutions that are scalable, flexible, and optimized to a wide range of budgets, deadlines, and objectives.
About Gamma Remote Sensing
Gamma Remote Sensing is a Swiss company involved in the development of satellite SAR
interferometry techniques and applications since the early days. It is appreciated for its software suite, terrestrial radar instruments, services, and consulting.
Josef Kellndorger, PhD
Earth Big Data, LLC