2003 EARTH SCIENCE VIDEOTAPES |
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Tape Title | Record ID | Date Produced | TRT: |
Synopsis |
| A SEASON OF THE OZONE HOLE: 25 YEARS OF TOMS-2003 (AGU 2003) | G03-066 | 12/08/03 | 00:13:43 | For the last 25 years, NASA's Total Ozone Mapping Spectrometer (TOMS) instruments have been looking at ozone and making daily maps of the ozone content of the atmosphere across the globe, showing scientists the evolution of the ozone hole from 1979 to today. This data was an essential factor in establishing international agreements that banned ozone destroying chlorofluorocarbons and halons. Years of TOMS measurements and TOMS studies have led to new capabilities and applications for this instrument: detection of desert dust and biomass burning aerosols, detection of sulfur dioxide and ash from volcanic eruptions, measurements of low level ozone or smog, and measurements of UV radiation at Earth's surface.
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TAPE CONTENTS: |
ITEM (1): Flying High On TOMS - NASA's Total Ozone Mapping Spectrometer (TOMS) instruments have flown on three different satellites over the past 25 years, starting with NIMBUS 7 1978-1993, followed by Meteor 3 from 1991-1994, and Earth Probe Satellite, shown in this animation, from 1996 to present. TOMS has monitored changes of the Antarctic ozone hole, sulfur dioxide and ash from volcanic eruptions, smoke from forest fires and the flux of ultraviolet radiation reaching the Earth's surface.
(a): The Antarctic Ozone Hole 2003 - TOMS provides dramatic visual evidence of the annual growth and decay of the Antarctic ozone hole. The ozone losses over Antarctica result from reactions with the products of man-made chlorine and bromine compounds. Because of the tilt of the EarthÕs axis, continuous darkness (dark purple) falls at the South Pole from March 21 to September 21. Beginning in August, returning sunlight reaches the edges of Antarctica providing chlorine and bromine compounds with energy to rapidly destroy ozone. By mid September, the ozone loss peaks, creating an ozone hole over Antarctic.
(b): Ground Level UV Exposure - Large Ozone hole means more ultraviolet exposure. TOMS tracks solar ultraviolet (UV-B radiation) measured at 290-320 nanometer wavelengths. Loss of stratospheric ozone has been linked to skin cancer in humans. Increased UV-B exposures for Southern continents can seriously impact phytoplankton and other species. Red represent high UV exposure, blue is low UV exposure.
(c): Nearing The Road To Recovery? - Continuous long-term monitoring of ozone levels is crucial in determining how much ozone loss is attributable to human activities and how much is the result of natural atmospheric processes. 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 2003 (excluding 1995). While the manufacture and use of chlorofluorocarbons (CFCs) and halons 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.
(d): 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.
(e): Polar Stratospheric Clouds - 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- water particles 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 loss.
(f): Whirlwind - 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. During SOLVE II, a research campaign to study the process that controlling ozone levels at low and midlevel altitudes, scientists examined whether polar stratospheric conditions are changing.
(g): Causes of 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.
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| ITEM (2): Tracking Aerosol-An Unexpected Gift - TOMS was not originally designed to study dust storms, smoke or pollution. While studying ozone, scientists noticed that something was interfering with data. That something turned out to be aerosols (very small particles). NASA Scientists have turned this interference into a very useful product for studying how aerosols from fires, pollution and dust impact climate. TOMS is the first instrument to allow observation of aerosols as the particles cross the land/sea boundary. This data made it is possible to track a wide range of phenomena such as desert dust storms, forest fires and biomass burning.
(a): Dust From China to the United States (NEW) - During spring 2001, TOMS watched a huge dust storm travel halfway around the world from China to the United States. Scientists use this data to study how regional ecosystems impact air quality and climate.
(b): California Smoke Trail - In fall 2003, TOMS tracked smoke from the California wildfires. TOMS observed smoke travel over the Pacific and across the United States. TOMS can distinguish among aerosols from fires, dust and pollution. This distinction allows scientists assess the human and natural impact on climate change. This sequence starts with Terra and Aqua satellite image of fire. Then TOMS shows smoke particles travel across the United States.
(c): Volcanic Ash - When Mt. Pinatubo erupted on June 15, 1991, it was the largest volcanic event in nearly a century with global consequences. Global average temperatures were one degree (F) cooler for over a year due to the massive injection of dust and gases into the upper atmosphere that reflected sunlight, and stratospheric aerosols increased by over 20 times. In addition, the protective ozone layer in the upper atmosphere weakened for more than a year from the gases injected into the stratosphere. Fortunately, the eruption also marked one of the largest climatic events to be observed by a fleet of spacecraft, creating one of science's greatest lab experiments. TOMS in particular observed the affected ozone and the aerosols, shown here. The many thousands of tons of sulfur dioxide gas being sent into the stratosphere were converted to sulfuric acid particles that helped to reflect sunlight and cool the Earth for a year.
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| ITEM (3): Continuing The TOMS Legacy - TOMS legacy lies in a new satellite called Aura, to be launched in the spring of 2004. Aura 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, giving scientists a more complete three-dimensional picture of atmospheric ozone distribution. This information will help scientists understand the long-term health of the upper atmosphere. Additionally, Aura carries instruments with much higher spatial resolution than TOMS. As a result, Aura can study air quality at a city level.
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