Ozone hole is big, but smaller than expected: NASA report
NASA, Nov 14: NASA and NOAA scientists found that the hole in the ozone layer that forms over Antarctica each September and October was slightly above average size in 2018, but smaller than expected for the weather conditions. Owing to colder-than-average temperatures in the Antarctic stratosphere created ideal conditions for destroying ozone, but declining levels of ozone-depleting chemicals prevented the hole from growing as large as it might have been 20 years ago.
Chlorine levels in Antarctic
Paul A. Newman, chief scientist for Earth Sciences at NASA's Goddard Space Flight Center, said, "Chlorine levels in the Antarctic stratosphere have fallen about 11 percent from the peak year." "This year's colder temperatures would have given us a much larger ozone hole if chlorine was still at levels we saw back in the year 2000, " said Newman.
ozone hole size
The ozone hole reached an average area of 8.8 million square miles in 2018, almost three times the size of the contiguous United States. It ranks 13th largest out of 40 years of NASA satellite observations.
State of Ozone hole
The maps on this page show the state of the ozone hole on the day of its maximum depth; that is, the day that the lowest ozone concentrations were measured in those years. The maps at the top of this page show 2000 and 2018, when ozone concentrations were 89 Dobson units and 102 Dobson units, respectively. The series below shows the day of minimum concentration in every year since 1979 (except 1995, when no data was available).
State of Ozone hole
According to NASA Earth Observatory, the ozone hole in 2018 was strongly influenced by a stable and cold Antarctic vortex, the stratospheric low-pressure system that flows clockwise in the atmosphere over the continent. These colder conditions-among the coldest since 1979-helped support the formation of more polar stratospheric clouds. Particles in such clouds activate ozone-destroying forms of chlorine and bromine compounds in the stratosphere.