2001 EARTH SCIENCE VIDEOTAPES |
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Tape Title | Record ID | Date Produced | TRT: |
Synopsis |
| 2001 OZONE HOLE SIZE OF NORTH AMERICA
| G01-068A | 10/16/01 | 00:05:29 | New satellite images show the depleted region of ozone known as the ozone "hole" that develops each year over Antarctica has reached about the same magnitude as those of the past several years - slightly larger than the size of North America. With the peak on September 17, the hole reached about 26 million square kilometers (about 10 million square miles). Last year the geographic area covered by the ozone hole was one of the largest on record and ozone depletion started earlier than usual.
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TAPE CONTENTS: |
| ITEM (1): 2001 Antarctic Ozone Hole
-This sequence shows the evolution of the 2001 Antarctic ozone "hole". Purple colors indicate very low levels of ozone and red colors show higher levels of ozone. Ozone forms a layer that surrounds and protects the Earth from the harmful effects of the sun's ultraviolet (UV) radiation. Excessive amounts of UV radiation can damage important plant and animal life on Earth and in the oceans as well as contribute to increases in skin cancer and cataracts in humans. Data for these image sequences was collected by NASA's Total Ozone Mapping Spectrometer (TOMS), currently aboard the Earth Probe satellite.
Courtesy: NASA/NOAA
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| ITEM (2): A Trend Towards Larger Losses - The following animation shows how ozone loss at the south pole has grown since the mid-80s. Early readings over Antarctica indicate little or no ozone depletion beyond naturally predicted levels. But as the 80s and 90s progress, a clear change in atmospheric chemistry takes place at the bottom of the world. The hole starts small in the late 80s and spreads as subsequent winter cycles break apart ozone molecules.
Courtesy: NASA/NOAA
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| ITEM (3): What Causes Ozone Loss? - Ozone is produced by intense ultraviolet radiation in the upper stratosphere. This radiation breaks typical oxygen molecules (O2) into free oxygen atoms. Those free atoms of oxygen (O) then join with molecular oxygen (O2) and form molecules of ozone (O3). The ozone molecule generally absorbs ultra-violet radiation. But ozone is destroyed when it reacts with one of a variety of chemicals in the stratosphere such as chlorine, nitrogen, bromine or hydrogen. The hole showing up now over the south pole is the result of air patterns in the upper atmosphere working in concert with high concentrations of ozone destructive chemicals.
Courtesy: NASA
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| ITEM (4): Ozone Satellite Sentinels - NASA and NOAA use satellites to measure the extent and depth of the ozone hole. NASA's Total Ozone Mapping Spectrometer (TOMS), currently aboard the Earth Probe satellite, and NOAA's Solar Backscattering Ultra-Violet (SBUV/2) instrument aboard the Polar-orbiting Operational Environmental Satellites, have been measuring Antarctic ozone levels for more than 20 years.
Courtesy: NASA/NOAA
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