The Antarctic ozone hole continues its downward trend

Oct. 26 () –

The annual Antarctic ozone hole reached an average area of ​​23.2 million square kilometers between September 7 and October 13, 2022.

This depleted area of ​​the ozone layer over the South Pole was slightly smaller than last year and overall The general downward trend of recent years continued.

“Over time, steady progress is being made and the hole is getting smaller,” he said. it’s a statement Paul Newman, chief scientist for Earth sciences at NASA’s Goddard Space Flight Center. “We do see some hesitation as weather changes and other factors cause the numbers to move slightly from day to day and week to week. But overall, we see it declining over the last two decades. The elimination of substances that deplete the ozone layer through the Montreal Protocol is reducing the hole.”

The ozone layer, the portion of the stratosphere that protects our planet from the Sun’s ultraviolet rays, thins to form an “ozone hole” over the South Pole each September. Chemically active forms of chlorine and bromine in the atmosphere, derived from human-produced compounds, stick to high-altitude polar clouds each southern winter. Reactive chlorine and bromine then initiate ozone-destroying reactions as the Sun rises at the end of the Antarctic winter.

NASA and NOAA researchers detect and measure the growth and rupture of the ozone hole with instruments aboard the Aura, Suomi NPP, and NOAA-20 satellites. On October 5, 2022, those satellites observed a single-day maximum ozone hole of 10.2 million square miles (26.4 million square kilometers), slightly larger than last year.

When the polar sun rises, NOAA scientists also make measurements with a Dobson spectrophotometer, an optical instrument that records the total amount of ozone between the surface and the edge of space, known as the total column ozone value. Worldwide, the average total column size is about 300 Dobson units.

On October 3, 2022, scientists recorded a lowest total column ozone value of 101 Dobson units over the South Pole. At that time, ozone was almost completely absent at altitudes between 14 and 21 kilometers, a pattern very similar to last year.

Some scientists were concerned about possible stratospheric impacts from the Hunga Tonga-Hunga Ha’apai volcano eruption in January 2022. The 1991 Mount Pinatubo eruption released substantial amounts of sulfur dioxide that amplified ozone depletion. However, no direct hits from Hunga Tonga have been detected in the Antarctic stratospheric data.