2003 EARTH SCIENCE VIDEOTAPES |
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Tape Title | Record ID | Date Produced | TRT: |
Synopsis |
| WHAT A DIFFERENCE A YEAR MAKES:
COLD WINTER BRINGS WIDER 2003 OZONE HOLE | G03-054 | 09/25/03 | 00:11:35 | After a relatively warm Antarctic winter in 2002, the thinning of the protective ozone layer over Antarctica, known as the ozone 'hole,' seems to be as severe as ever in 2003. Due to colder than average temperatures, the 'hole' stretches over an area as large as the North American continent, possibly reaching populated areas of South America and exposing them to ultraviolet rays normally absorbed by ozone. However, scientists have new tools to study this annual phenomenon, and the human-produced compounds that contribute to ozone breakdown are decreasing.
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TAPE CONTENTS: |
| ITEM (1): 2003 Antarctic Ozone 'Hole'
- By mid-September 2003, the ozone thinning already extended over 28.2 million square kilometers (10.9 million square miles). The maximum area in 2000 reached 29.2 million square kilometers, the largest on record. Since winter temperatures dipped lower than usual, driving the chemical reactions that deplete ozone, this year's 'hole' (dark blue) was very large. The thinnest point so far this year is 106 Dobson Units (a layer about 1.06 millimeters at sea-level pressure), 40% as thick as normal levels. This series shows the daily extent of the ozone 'hole,' regions. Data come from NASA's Total Ozone Mapping Spectrometer (TOMS) on the Earth Probe satellite, from Aug. 1-Sept. 23, 2003.
Courtesy: NASA
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| ITEM (2): Calm, Cool Skies Spell Losses - This year, colder temperatures and calmer winds allowed chemical reactions that break down ozone to occur at about the same rates as the past few years. However, last year's unusually moderate Antarctic temperatures and highly variable upper atmospheric winds kept the ozone 'hole' relatively small, about 40% smaller in area than the record sizes seen in 2000, 2001, and this year. In 2002, the 'hole' also split into two parts for the first time since 1979, also due to unusual weather patterns. These comparisons pit the near-record size of this year's 'hole' against a) the small area of last year's hole, b) the split shape from last year, and c) the record-size hole from 2000. Data from TOMS-EP.
Courtesy: NASA
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| ITEM (3): Nearing The Road to Recovery?
- Last year's unusual reduction in ozone losses proved just that - unusual. The ozone hole grew larger throughout the late 1980's and early 1990's, as shown in this time series of maximum areas from 1979 to 2002 (excluding 1995). This year the hole reached nearly the same size as 2000 and 2001, larger than the North American continent. While the manufacture and use of chlorofluorocarbons and halons (CFCs) that contribute to yearly ozone destruction have decreased, the chemicals will linger in the upper atmosphere for decades before the ozone layer will consistently recover.
Courtesy: NASA
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| ITEM (4): Arctic Losses Closer to Home
- While the Antarctic regularly experiences ozone losses, warmer temperatures in the Arctic prevent such massive losses from occurring as often near the North Pole. However, when large Arctic ozone losses occur, the depletion can threaten populated areas with harmful doses of ultraviolet rays. Here we show the winters of 2003, 2000, and 1997, particularly severe losses stretching over populated areas such as Northern Europe. Data from TOMS-EP.
Courtesy: NASA
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| ITEM (5): New Satellite Senses Ozone
- NASA's soon-to-be-launched Aura satellite will see ozone in both the upper and lower atmosphere for the first time. Current missions examine ozone in an isolated part of the atmosphere, but Aura will track ozone and other gas transport between the lower and upper atmosphere. This information is extremely important to understanding the long-term health of the upper atmosphere. Aura's new sensors will give scientists a more complete three-dimensional picture of atmospheric ozone distribution.
Courtesy: NASA
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| ITEM (6): Mostly Cloudy (From SOLVE II)
- In the stratosphere, 15-50 kilometers (9-31 miles) above Earth, extreme low temperatures lead to the formation of polar stratospheric clouds. These clouds of nitric acid lead to the break down of ozone and allow harmful ultraviolet rays to reach Earth's surface. Extremely low Arctic temperatures enabled polar stratospheric clouds (PSCs) to last longer during the 1999-2000 winter, causing additional ozone losses. This sequence shows a calculation, based on temperature measurements, of ozone-destroying cloud presence in the Arctic from Nov. 1999 - March 2000. SOLVE II scientists studied these clouds during their Arctic ozone study in 2003 at Kiruna, Sweden, the red dot on the map.
Courtesy: NASA
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| ITEM (7): Whirlwind (from SOLVE II)
- Swirling stratospheric winds around the North and South Pole in winter, called the polar vortex, confine cold air and provide conditions conducive to polar stratospheric cloud (PSC) formation. Warmer temperatures in the Arctic as compared to the Antarctic have historically prevented regular PSC and ozone 'hole' formation. SOLVE II scientists examined whether conditions are changing.
Courtesy: NASA
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| ITEM (8): What Causes Ozone Loss? - Intense ultraviolet (UV) radiation in the upper atmosphere produces ozone (O3). The radiation breaks typical oxygen molecules (O2) into free oxygen atoms (O). The free oxygen atoms (O) then join with molecular oxygen (O2) to form a molecule of ozone (O3). The ozone molecule generally absorbs UV, shielding the Earth from the harmful rays. Chemical reactions involving gases such as chlorine, bromine, nitrogen, and hydrogen destroy ozone. The ozone depletion over Antarctica results from the combined actions of very cold conditions, the return of sunlight in the Antarctic spring, and these chemicals, which often come from human-produced compounds.
Courtesy: NASA
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| ITEM (9): Tools For Monitoring - Scientists monitor not only the Antarctic ozone hole, but also a smaller one in the Arctic, which could potentially affect more populated areas. Using tools such as aircraft-, balloon- and ground-based sensors as well as satellite data, the scientists study not only ozone levels, but also the chemicals in the atmosphere and weather patterns that enhance or defuse the chemical reactions that break down ozone. 2003's SOLVE II (SAGE III Ozone Loss and Validation Experiment), marked the second time an international team of scientists met in Sweden to assess Arctic ozone (SAGE III is the third Stratospheric Aerosol and Gas Experiment).
Courtesy: NASA
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| ITEM (10): B-Roll of Dr. Paul Newman in Lab
Courtesy: NASA
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| ITEM (11): Earth Probe Satellite - To measure the thickness of the stratospheric ozone layer over the Earth, NASA uses the Total Ozone Mapping Spectrometer (TOMS) instrument aboard the satellite shown here, Earth Probe (EP). NASA launched TOMS-EP in 1996.
Courtesy: NASA
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Earth Science Gallery