The 90-day ozone-hole period begins in late August with an increase in measurements at the Amundsen-Scott South Pole Station (ASSPS). Balloon-borne ozonesondes are launched two to three times a week in this period to monitor the ozone hole over Antarctica. Before rapid destruction of stratospheric ozone ensues, the peak in ozone concentration occurs at about 11 miles in altitude and at a total column amount of about 250 Dobson Units (DU). Total ozone diminishes at a rate of 3 to 5 DU per day throughout the month of September. Finally, nearly all the ozone is destroyed within a layer from 8.4 to 13.2 miles.
Recently, NOAA scientists reported that the seasonal peak had passed in September. NASA satellites measured on September 12 the maximum size of the 2008-ozone-hole to have an area of 10.5 million square miles and a depth of 4 miles. As my list below shows, this is larger than 2007's size, which was lower than 2006's by 14.9%.
List of some ozone thicknesses at ASSPS and some ozone-hole sizes:
28 September 2008: 107 DU
12 September 2008: 10.5 million square miles and 4 miles deep (5th largest)
08 October 2007: 9.7 million square miles (about the size of N America)
09 October 2006: 11.4 million square miles (the largest)
12 October 1993: 89 DU (the lowest)
Last year's hole was about as large as North America. This year's hole is larger than North America by 8.2%. These year-to-year fluctuations are mostly governed by the weather at the stratosphere and the various harmful human activities occurring globally. By late December, the southern-hemisphere's summer starts to build up again the ozone level for the annual cycle.
The increase in the ozone-hole size in 2008 appears to be due to the climate change, i.e. the Antarctic-ice melting. Man-made influences have produced both the climate change and the ozone destruction at the Antarctic zone.
Monitoring formation and severity of the Antarctic ozone hole is done currently by a combination of satellite, ground-based, and balloon observations. The latest weather satellite, in the Advanced Television Infrared Observational Satellites-N series, the NOAA-N Prime is already at its launch site for 4 February 2009 launch date. This polar-orbiting satellite will provide imaging and measurements of the Earth's atmosphere. Environmental monitoring will include atmospheric ozone, aerosol distribution, sea surface temperature, and vertical temperature and water profiles in both troposphere and stratosphere.
Total ozone values shown for high southern latitudes as measured by a NASA satellite instrument.
NOAA will have an additional eye on climate change and the ozone hole in 2009. My prediction is, unfortunately, a bigger hole in keeping up with trend set by many deleterious human activities. Do you agree with me?