Magazine article Science News

Northern Ozone Suffered Heavy Winter Loss

Magazine article Science News

Northern Ozone Suffered Heavy Winter Loss

Article excerpt

Earth's ozone layer weathered a tough winter this year. Concentrations of the protective gas were well below normal over the United States and much of the Northern Hemisphere, apparently brought down by natural weather patterns and chemical pollution. Ozone amounts set record lows above some Arctic regions, but the northern depletions were not severe enough to qualify as an ozone hole.

In years past, atmospheric scientists had discerned the seeds of Arctic ozone loss in the form of destructive chlorine molecules amassing within northern skies. Such pollutants would take a substantial bite out of the polar ozone, researchers claimed, if the stratosphere stayed cold in late winter. Those predictions came true as temperatures set record lows this March, enabling pollutants to devour ozone in the far north.

The National Oceanic and Atmospheric Administration last week released satellite measurements of wintertime ozone collected by its orbiting SBUV/2 instrument. The greatest depletions occurred over Siberia, where ozone concentrations dropped 35 percent below the values observed in 1979, before substantial ozone destruction had begun.

Sensors on NASA's Upper Atmosphere Research Satellite also confirmed that chlorine chemicals munched away ozone in the Arctic. The satellite instruments detected high concentrations of the destructive molecule chlorine monoxide in the Arctic vortex -- a region of cold air enclosed by swirling winds that circle the pole. "There's no question there has been significant loss in the Arctic this winter and ozone values are low," says Joe W. Waters of NASA's Jet Propulsion Laboratory in Pasadena, Calif.

Ozone in Earth's stratosphere (12 to 50 kilometers above the surface) protects life by blocking out harmful ultraviolet radiation from the sun. Chlorine and bromine pollution began eating away the beneficial layer in the late 1970s. …

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