1999 EARTH SCIENCE VIDEOTAPES |
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Tape Title | Record ID | Date Produced | TRT: |
Synopsis |
| 1999 ANTARCTIC "HOLE" SMALLER THAN LAST YEAR | G99-073B | 10/6/99 | 00:7:25 | The latest images from NASA show the depleted region of ozone commonly known as the ozone "hole" -- is a bit smaller in 1999 than it was last year. Scientists are closely monitoring ozone levels in Antarctica after observing record low levels of ozone in 1998. The Antarctic "ozone hole" develops each year between late August and early October.
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TAPE CONTENTS: |
| ITEM (1): 1999 ANTARCTIC OZONE "HOLE" - Time lapse images show evolution of the 1999 Antarctic ozone hole which covered 9.8 million square miles on Sept. 15. The record area of Antarctic ozone depletion of 10.5 million square miles was set on Sept. 19, 1998. The Antarctic "ozone hole" develops each year between late August and early October.
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| ITEM (2): A UNUSUAL SIDEKICK - This year's study found that an ozone "low" had formed between New Zealand and Antarctica on Sept. 17. This sort of ozone low, commonly referred to as a "mini-hole," is a result of the redistribution of ozone by a large weather system. The "mini-hole" moved eastward along the rim of the Antarctic ozone "hole" for a number of days after Sept. 17.
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| ITEM (3): 1998 OZONE "HOLE" LARGEST EVER - The 1998 Antarctic ozone hole was the largest ever observed. Data from the satellites show that ozone depletion reached a record size of 10.5 million square miles on Sept. 19, 1998. Scientists believed the unusually cold stratospheric temperatures contributed to the record size of the "hole".
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| ITEM (4): OZONE TRENDS - Yearly comparison of ozone levels in Antarctic. NASA and NOAA instruments have been measuring Antarctic ozone levels since the early 1970s. Large regions of depleted ozone began to develop over Antarctica in the early 1980s. Though ozone "holes" of substantial size and depth are likely to continue to form during the next few years, scientists expect to see a reduction in ozone losses as levels of ozone destroying CFCs are gradually reduced.
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| ITEM (5): HOW OZONE PROTECTS - Ozone protects the Earth by absorbing harmful ultraviolet radiation. The ozone molecule is split into one free oxygen atom and one molecule of ordinary oxygen. The free oxygen usually reacts with another oxygen molecule to reform the ozone molecule.
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| ITEM (6): OZONE DESTRUCTION - Scientists say this year's abnormally cold Antarctic winter contributed to the ozone hole by activating more destructive chlorine. Chlorofluorocarbons (CFCs) lead to destruction of the protective ozone molecules located in the stratosphere. Chlorine atoms liberated from CFCs steal oxygen atoms, thus destroying the protective ozone molecule. One chlorine atom can destroy many thousands of ozone molecules over its lifetime in the stratosphere. The ozone hole appears because of the normally very cold Antarctic winter conditions.
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| ITEM (7): STRATOSPHERE ANIMATION - Most atmospheric ozone is found in the stratosphere -- in a thin layer 6 to 18 miles above the Earth's surface. The term "ozone hole" is used to describe a large area of intense ozone depletion that occurs over Antarctica during late August through early October and typically breaks up in late November. Ozone is a molecule that shields life on Earth from the harmful effects of the Sun's ultraviolet radiation.
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| ITEM (8): TOMS SATELLITE - The measurements were obtained this year using the Total Ozone Mapping Spectrometer (TOMS) instrument aboard NASA's Earth Probe (TOMS-EP) satellite.
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| ITEM (9): OZONE SCIENTISTS - B-ROLL - Scientists and others have a keen interest in ozone depletion, given that the increased amounts of ultraviolet radiation that reach the Earth's surface because of ozone loss have the potential to increase the incidence of skin cancer and cataracts in humans, harm some crops, and interfere with marine life.
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Earth Science Gallery