Image above: The build-up of ozone-depleting chlorine- and bromine-containing chemicals (known as halocarbons) in the Antarctic stratosphere peaked around the year 2000 and is now declining. Different projections of future emissions of these chemicals have been used to predict when ozone recovery will occur. Those predictions fall within a 15-year range around the year 2050. New evidence that reservoirs of these chemicals in developed countries may be larger than expected suggests a delay in ozone recovery. Click on image to enlarge. Credit: Dale Hurst, NOAA
Images/animations above: NASA's Aura satellite, launched in 2004, is keeping a close watch on global ozone levels and the different chemicals high in the atmosphere involved in ozone destruction. Here seasonal changes of ozone and other chemicals in the lower stratosphere are shown over the Arctic and Antarctic during the past year. These observations are from the Microwave Limb Sounder (MLS) instrument on Aura. The Aura MLS continues and improves on a long-term monitoring record of global chlorine changes that are key to recovery of the ozone layer. Click each image to view corresponding animations (no audio;animation 1 - 28 Mb, animation 2 - 30 Mb) Credit: Michelle Santee, NASA Jet Propulsion Laboratory
Image above: Recovery of the ozone layer over the Antarctic and Arctic are predicted to happen very differently. In the Antarctic (top panel) an "ozone hole" developed very rapidly, closely following the increase of ozone-destroying halogen compounds in the atmosphere (red line). Over the Arctic (bottom panel), ozone changes are more influenced by changes in atmospheric winds. Model predictions of future ozone recovery (green symbols) are more certain over the Antarctic than the Arctic because the meteorology there is notoriously difficult to simulate. Observations of ozone levels (black triangles) closely match model simulations (blue symbols). Click on image to enlarge. Credit: John Austin, NOAA
Slides from the Presentation: Click on each one to enlarge.