The total column ozone (the amount of ozone in a vertical column of air) over Syowa Station, the main Japanese research station in Antarctica, hit a record low of 117 milli-atmosphere centimeters (m atm-cm) on October 3, 2006, the Japan Meteorological Agency announced on October 5 based on measurements by the 47th Antarctic research expedition team. The column ozone at the site was at its lowest level since late August 2006.

According to satellite measurements by the National Aeronautics and Space Administration (NASA), the size of this year's ozone hole and the ozone deficit reached the highest levels on September 24. The size of the hole (defined as the area having column ozone below 220 m atm-cm) was 29.3 million square kilometers, the second largest since 2000. The deficit (the mass of ozone that would need to be added to the stratosphere to recover to the global average of 300 m atm-cm) was 105 million tons, the second largest since 2003.

To explain this serious depletion of the ozone layer, the agency cited two factors. One is concentrations of ozone-depleting substances in the atmosphere, which are still high after peaking in the late 1990s. The other factor is very cold stratospheric air (below minus 78 degrees Celsius) over Antarctica, which accelerates ozone destruction. During the period from late June to September 2006, the low-temperature area in the Antarctic stratosphere was at its maximum, the largest size in about a decade, since 1995.

http://www.jma.go.jp/jma/indexe.html

Posted: 2007/01/12 11:29:04 AM
Japanese version

TAG Ecosystem , Government