The evolution of ozone over the Arctic as shown through measurements of average ozone for March for the years 1979 through 1999, excluding 1995 and 1996. These measurements were made by the TOMS instruments on Nimbus-7, Meteor-3 and Earth Probe. Dark blue represent regions of low ozone and red represents regions of high ozone.
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 126.96.36.199.0