2002 EARTH SCIENCE VIDEOTAPES |
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Tape Title | Record ID | Date Produced | TRT: |
Synopsis |
| NORTHERN OZONE "HOLE" MAY FORM AFTER LARGE VOLCANIC ERUPTIONS
| G02-016 | 3/4/02 | 00:10:59 | An ozone 'hole' could form over the northern polar regions after periods of high volcanic activity, according to the March 5th cover story of the Proceedings of the National Academy of Sciences. A northern ozone hole could be significant because more people live in Arctic regions than near the South Pole.
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TAPE CONTENTS: |
| ITEM (1): The Arctic Ozone "Hole" - The purple colors in this sequence depict the depleted region of ozone over the North Pole that occurred in the winter of 2000. Though ozone 'holes' appear each year over the South Pole, they only occasionally form over the northern polar regions. Scientists say the northern ozone hole may reappear for several consecutive years after a period of high volcanic activity. A northern ozone hole could be significant because more people live in Arctic regions than near the South Pole. The data for these images were collected by the Total Ozone Mapping Spectrometer (TOMS) satellite.
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| ITEM (2): Volcanic Plume Spreads - This computer model shows the dispersion of the volcanic plume from the Mt. Pinatubo volcano. The 1991 Pinatubo eruption was sulfur-rich, producing volcanic clouds that lasted a number of years in the stratosphere. The Pinatubo eruption widely expanded the area of ozone loss over the Arctic and Antarctic. Red colors indicate higher elevations and blue colors indicate lower elevations for the plume.
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| ITEM (3): Stratospheric Ozone Destroying Clouds - Large volcanic eruptions pump sulfur compounds into the Earth's atmosphere. This artist's concept depicts the formation of sulfuric acid clouds after an eruption which can damage the Earth's ozone near the polar regions.
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| ITEM (4): The Antarctic Ozone Hole - This satellite sequence shows the evolution of the ozone "hole" that developed over the Antarctic in 2001. 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.
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| ITEM (5): A Trend Towards Larger Losses - The following sequence 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.
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| ITEM (6): Pinatubo's Impact on Ozone - During the year and a half after the 1991 eruption, global stratospheric ozone levels decreased as a result of chemical reactions with the ozone and the sulfur dioxide gases released by the volcano. However, the initial effect of the injection of sulfur dioxide into the atmosphere was so strong, that a small hole was created in the ozone layer as seen here, in blue, using TOMS data. This visualization shows global ozone levels before and after the eruption. After the hole dissipates, continued low levels of ozone, in very light blue, can be seen around the tropics.
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| ITEM (7): Sulfur Dioxide After the Eruption - The eruption of Mt. Pinatubo blasted a huge cloud of sulfur dioxide, shown in red, into the stratosphere. This data taken from NASA's Total Ozone Mapping Spectrometer (TOMS) instrument shows that initial burst of sulfur dioxide and its international path in the days following the eruption, from June 16th to June 30th. The sulfur gas cloud dissipates as the gas turns into droplets of sulfuric acid. Both the gas and subsequent acid were contributors to ozone depletion and a dust cloud that cooled the global climate.
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| ITEM (8): Landsat View of Mt. Pinatubo - This recent false color Landsat-7 image, from January 2001, shows Mt. Pinatubo as it stands today. The caldera is seen in the middle of the image, underneath clouds. Ten years after the blast, vegetation is re-growing on the slopes of the mountain (in green.) Streams of mud, called lahars, continue to flow down the sides of the mountains, as well as channels of water (darker streams). However, as vegetation grows back, the ash becomes more stabilized and less likely to form the destructive lahars.
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| ITEM (9): TOMS Satellite - The Total Ozone Mapping Spectrometer is continuing NASA's long term daily mapping of the global distribution of the Earth's atmospheric ozone. In addition to ozone, however, TOMS measures sulfur dioxide released in volcanic eruptions.
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