This visualization shows the total ozone concentrations for the Earth from January 1, 2000 through December 31, 2003. Low ozone (less than 200 Dobson units) is depicted as regions of dark blue, with high ozone (greater than 330 Dobson units) depicted as yellow and red. The most visible and dynamic feature of the ozone distribution is the ozone hole that forms over Antarctica during September of each year. The amount of ozone in the stratosphere over Antarctica is reduced during this period due to unique atmospheric conditions which chemically reduce the amount of ozone in the region and prevent that ozone from mixing with the higher ozone concentrations just outside the hole. Ozone blocks harmful ultraviolet 'B' rays, and loss of statospheric ozone has been linked to skin cancer in humans and other adverse biological effects in plants and animals. The 2000 Antarctic ozone hole reached 11.5 million square miles on September 10, 2000, the largest hole ever recorded, slightly larger than the North American continent. The 2002 ozone hole was much smaller than normal, dividing into two parts on September 24 before dissipating completely, while the 2003 hole was the second largest observed, reaching 10.9 million square miles on September 11. This data was measured by the TOMS instrument on the Earth Probe satellite. TOMS experienced some days during this period for which data was not measured due to instrument problems.
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 184.108.40.206.0