This year there was a hole in the ozone over the North Pole as well

NASA is concerned about the imminent end of life of the Aura and Calypso spacecraft that measure ozone levels in the stratosphere, without having a replacement

Research led by NASA documented an unprecedented loss of the ozone layer that protects the Earth's surface from ultraviolet radiation during the winter and spring in the Northern Hemisphere in 2011. This was apparently caused by a continuous cold wave at high altitude - in the stratosphere.

The study, published in the online issue of the journal Nature yesterday (Sunday), found that the amount of ozone destroyed in the Arctic region in 2011 was comparable to what has been seen for several years in the Antarctic region where a hole has been created in the ozone layer since the mid-XNUMXs.

The stratospheric ozone layer, which extends 15-35 kilometers above the ground, protects life on Earth from dangerous ultraviolet rays.

The ozone hole is formed when extreme cold conditions, common in the stratosphere during the Antarctic winter, drive reactions that convert chlorine atoms from man-made chemicals into ozone-destroying forms. The same ozone-destroying process occurs every winter over the Arctic region as well, but the warmer stratospheric conditions there limit the area where the chemicals are effective and the time window during which these chemical reactions appear. This is expressed in a smaller loss of ozone in most years in the north than in the south.

To investigate the loss of ozone in the North in 2011, scientists from 19 institutes in nine countries (USA, Germany, Netherlands, Canada, Russia, Finland, Denmark, Japan and Spain) joined to analyze the measurement data. These measurements included daily observations to monitor gases and clouds from NASA's Aura and Calypso spacecraft, as well as ozone measurements using balloons, meteorological data and atmospheric models. The scientists found that at some altitudes, the cold period in the Arctic region lasted 30 days longer in 2011 than in all winters since measurements began, leading to an unprecedented loss of ozone. Further research is needed to determine what causes the cold period to last so long.

"Day-to-day measurements of temperatures in the Arctic winter of 2010-2011 did not reach as low as in previous cold winters," said lead researcher Gloria Maney of NASA's JPL in Pasadena, California, and the Institute of Minerals and Technology in New Mexico. "The difference compared to previous winters was that the temperature was low enough to produce ozone-destroying forms of chlorine for a longer time. This is possible if winter temperatures in the stratosphere drop only slightly in the future, for example as a result of climate change, cases of ozone holes will occur even in the north more often." saying.

According to her, despite this, the northern hole was significantly smaller than the southern hole. This is because the Arctic vortex, which is a type of permanent cyclone in which the ozone hole phenomenon occurs, was 40% smaller than the Antarctic vortex. But although the hole was smaller and shorter-lived than the southern counterpart, the Arctic vortex is more mobile than the southern one, which moved the hole to densely populated areas in the northern continents. The decrease in ozone density has led to an increase in the amount of ultraviolet radiation known to have a destructive effect on humans and other living creatures.

Despite being smaller than the southern hole, the amount of ozone destroyed was twice as great because at the beginning of the Arctic winter there is a much larger amount of ozone in the stratosphere compared to the amount in the south at the beginning of winter there.

According to Maney, if it weren't for the 1989 Montreal Protocol, an international agreement that limited the production of ozone-depleting products, chlorine levels would be so high that black northern ozone would appear every spring. The lifetime of these chemical products that are already in the atmosphere will mean that the southern hole, and occasionally a large hole in the north, will accompany us for decades to come.

"Our ability to measure ozone levels in the atmosphere, thanks to the Aura and Calypso spacecrafts, is going to be compromised because these spacecrafts are reaching the end of their operational life," Mani said. "It is difficult to see how such an ability to measure ozone levels would be maintained in an environment of changing climate, without these spacecraft or their replacements."
For information on the NASA website

For information on the NASA website