The seasonal ozone hole over Antarctica will remain active well into November

The seasonal ozone hole over Antarctica will persist well into November, according to satellite and weather balloon observations from NASA and the National Oceanic and Atmospheric Administration (NOAA).

Ozone is a gas that in its natural zone in the stratosphere, acts like a "sunscreen" to life on Earth. In that region, ozone protects our planet from cancer-inducing ultraviolet radiation that also can damage plants and plankton. (Ozone also forms much closer to the ground as smog, when the sun's rays generate photochemical reactions with pollution from vehicle and industrial emissions.)

The natural stratospheric ozone depletes when chlorine and bromine from human activities latch on to the ozone atoms. Every winter in the Southern Hemisphere, the returning sun's rays cause the interactions that erode the ozone. The erosion will continue in the cold temperatures until the approach of spring, according to NASA.

Video: Antarctic ozone hole was the 12th largest on record in 2020
Related: Ozone pollution levels have increased over the past 20 years

"Persistent cold temperatures and strong circumpolar winds, also known as the polar vortex, supported the formation of a large and deep Antarctic ozone hole that should persist into November," NASA said in a statement Oct. 30.

"The annual Antarctic ozone hole reached its peak size at about 9.6 million square miles (24.8 million square kilometers), or roughly three times the area of the continental United States, on Sept. 20. Observations revealed the nearly complete elimination of ozone in a 4-mile-high [6.5 km] column of the stratosphere over the south pole," the agency added.

The 2020 ozone hole is the 12th largest by area in 40 years of satellite records, and has the 14th lowest amount of ozone as measured by balloon instruments, NASA said. The production of ozone, however, is much better than it was in the year 2000, when the size of the hole peaked. The hole has been diminishing ever since due to declines in ozone-depleting chemicals regulated by the 1987 Montreal Protocol, NASA added.

"From the year 2000 peak, Antarctic stratosphere chlorine and bromine levels have fallen about 16 percent towards the natural level," Paul A. Newman, chief scientist for Earth sciences at NASA's Goddard Space Flight Center in Maryland, said in the same statement. 

"We have a long way to go, but that improvement made a big difference this year. The hole would have been about a million square miles [2.6 million square km] larger if there was still as much chlorine in the stratosphere as there was in 2000."

Satellite instruments that measure the ozone include the Dutch-Finnish Ozone Monitoring Instrument on NASA's Aura satellite, the Microwave Limb Sounder on Aura, the Ozone Mapping Profiler Suite on the NASA-NOAA Suomi National Polar-orbiting Partnership (NPP) satellite, and another Ozone Mapping Profiler Suite on the NOAA-20 polar satellite, NASA said.

Follow Elizabeth Howell on Twitter @howellspace. Follow us on Twitter @Spacedotcom and on Facebook.