NASA's Earth Polychromatic Imaging Camera (EPIC) sits onboard NOAA's Deep Space Climate Observatory (DSCOVR) satellite at the Lagrange point 1, a million miles away from Earth.
EPIC has been imaging the sunlit side of Earth between 13 and 22 times a day since 2015. Now, scientists have developed ways to use these images to study specific elements of our home planet's atmosphere and plant life, like ozone in the stratosphere, the makeup of clouds and the health of vegetation on land.
GCMD keywords can be found on the Internet with the following citation:
Olsen, L.M., G. Major, K. Shein, J. Scialdone, S. Ritz, T. Stevens, M. Morahan, A. Aleman, R. Vogel, S. Leicester, H. Weir, M. Meaux, S. Grebas, C.Solomon, M. Holland, T. Northcutt, R. A. Restrepo, R. Bilodeau, 2013. NASA/Global Change Master Directory (GCMD) Earth Science Keywords. Version 22.214.171.124.0