Discovery reveals large year-round ozone hole over tropics

Discovery reveals large year-round ozone hole over tropics

Time series of decadal mean annual ozone changes, differences in annual ozone climatology, and decadal mean zonal mean latitude-altitude distributions of temperature reveal the size of the “new” ozone hole. Credit: Qing-Bin Lu

An ozone hole, seven times larger than the ozone hole in Antarctica, is currently over tropical regions and has been around since the 1980s, according to a Canadian researcher.

In AIP ProgressQing-Bin Lu, a scientist from the University of Waterloo in Ontario, Canada, unveils a large ozone hole– defined as an area of ​​ozone loss greater than 25% compared to the undisturbed atmosphere – in the lower stratosphere above the tropics that is comparable in depth to that of the well-known Antarctic spring hole, but the area is about seven times taller.

“The tropics are half the planet” surface and are home to about half the world’s population,” said Lu. “The existence of the tropical ozone hole could be a major global concern.

“The exhaustion of the ozone layer can lead to increased UV radiation at ground level, which can increase the risk of skin cancer and cataracts in humans, as well as weaken the human immune system, agricultural productivityand adversely affect sensitive aquatic organisms and ecosystems.”

Lu’s observation of the ozone hole comes as a surprise to his colleagues in the scientific community because it was not predicted by conventional photochemical models. His observed data agree well with the cosmic ray-driven electron reaction (CRE) model and strongly indicate that the identical physical mechanism works for both Antarctic and tropical ozone holes.

As with the polar ozone hole, about 80% of the normal ozone value appears to be depleted in the center of the tropical ozone hole. Show preliminary reports: depletion of the ozone layer levels above the equator are already endangering large populations and the associated UV radiation reaching these regions is much greater than expected.

In the mid-1970s, atmospheric research suggested the ozone layer, which absorbs most of the sun ultraviolet radiation, can be depleted by industrial chemicals, especially chlorofluorocarbons (CFCs). The discovery of the ozone hole in the Antarctic in 1985 confirmed the depletion of the ozone layer caused by CFCs. While a ban on such chemicals has helped slow ozone depletion, evidence suggests that ozone depletion continued.

Lu said the tropical and polar ozone holes play an important role in cooling and regulating stratospheric temperatures, reflecting the formation of three “temperature holes” in the global stratosphere. He said this finding could be crucial for a better understanding global climate change

Lu’s discovery builds on previous studies of the CRE-initiated ozone-depleting mechanism that he and his colleagues originally proposed about two decades ago.

“The current discovery requires further careful studies of ozone depletion, UV radiation change, increased cancer risks and other adverse effects on health and ecosystems in the tropical areas‘ said Lu.

The article “Observation of large ozone losses in all seasons over the tropics” is written by Qing-Bin Lu.

Image: 2015 Antarctic ozone hole region approaches annual maximum

More information:
Observation of large ozone losses in all seasons above the tropics, AIP Progress (2022).

Quote: Discovery Reveals Large Year-Round Ozone Hole Over Tropics (2022, July 5) Recovered July 5, 2022 from

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