2001 EARTH SCIENCE VIDEOTAPES |
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Tape Title | Record ID | Date Produced | TRT: |
Synopsis |
| NEW SATELLITE IMAGERY REVEAL HIDDEN ANTARCTIC TERRAIN AND A MAJOR ICE FRACTURE | G01-013 | 03/22/01 | 00:14:17 | Antarctica is a dynamic and changing continent. Recent mapping missions from multiple satellites, including Landsat 7 and RADARSAT-1 (from the Canadian Space Agency), have studied the continent extensively and discovered several new features which highlight the evolution of the continent as ice cracks, shifts, flows and melts. From the formation of a new iceberg, to the break-up of an ice shelf, Antarctica is more than just a land frozen in time.
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TAPE CONTENTS: |
| ITEM (1): An Iceberg Forms on Pine Island Glacier - The formation of an iceberg is captured by satellite for the very first time. Beginning with a wide shot of Antarctica using the RADARSAT satellite, the image then zooms in and dissolves to a Landsat 7 sequence of Pine Island Glacier. On March 6, 2000, no crack is present. By January 4, 2001 a crack had stretched over 25 km (15 miles), more than two-thirds of the width of Pine Island glacier. Courtesy: NASA/CSA/USGS
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| ITEM (2): A Crack Spans The Ice - The crack on Pine Island glacier is also seen by the ASTER instrument, onboard the TERRA satellite. This image, taken on December 12th, 2000, pans across the crack as it stretches across the glacier. At its widest point, the crack is 400-500 meters across. On the left hand side of the image, stress fractures in the ice are clearly seen. Courtesy: NASA
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| ITEM (3): Larsen Ice Shelf - In 1995 alone, a region of ice on the Larsen Ice Shelf more than two-thirds the size of Rhode Island disintegrated in a fierce storm. Additional ice broke away from the rest of the shelf in 1998. This dramatic change to so much ice is the product of several forces acting in concert. In this visualization we start from above and zoom in to the specific area of study. Courtesy: NASA/CSA/OSU/USGS
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| ITEM (4): Surface Water - This image shows a section of the remaining Larsen Ice Shelf. The dark patches scattered around the white background are regions of surface melt water, formed during the summer season. It's from these pools that water drained into cracks in the shelf to form the wedges that ultimately shattered the ice. NASA's Landsat 7 spacecraft took this picture on February 21, 2000. Courtesy: NASA/USGS
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| ITEM (5): A Process of Change: What Happened to Shatter The Ice - As melting water on the surface of an ice shelf fills in fissures and crevasses, pressure builds in the structure of the sheet. That process can either increase gradually, or it can be repeated seasonally. What happens is a gradual splintering of a wide section of shelf, which is then ultimately rent asunder by tides or storms. The process is believed to be more a function of mean summertime temperatures, as opposed to overall annual temperatures.This visualization shows the shattered remains of the Larsen Ice Shelf after its big breakup. This is a Landsat image from August, 2000. Courtesy: NASA/USGS
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| ITEM (6): Lambert Glacier Velocity Map - A velocity map showing the direction and speed of the ice of Lambert Glacier, an ice stream more than 500 km (311 miles) long. The stream of ice reaches speeds of more than one km (about two-thirds of a mile) a year once the ice spreads onto the Amery Ice Shelf. Courtesy: NASA/CSA
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| ITEM (7): Ronne Ice Shelf - The Ronne Ice Shelf grows primarily due to a constant flow from inland ice sheets. Where shearing stresses are greater than the strength of the ice itself, cracks form. These cracks ultimately widen and spread like varicose veins in the frozen skin of the coast, only to break loose and become icebergs. In the late 1990's several large slabs of ice broke free from this area. A recent iceberg more than 40 miles wide now floating in the South Atlantic originated from the Ronne Ice Shelf. Courtesy: NASA/CSA/OSU
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| ITEM (8): Fimbul Ice Shelf - Icebergs form when hunks of ice break away from glaciers pushing into the ocean. Ice shelves are the edges of those glaciers, extending out into the ocean faster than icebergs can break off from the edge. The Fimbul Ice Shelf has remained relatively consistent in its appearance for the last thirty years, but researchers are paying close attention to changes. Ice shelves are considered to be particularly sensitive to climatic changes and scientists have detected a marked retreat along the Antarctic Peninsula.
Courtesy: NASA/CSA/OSU
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| ITEM (9): Amery Ice Shelf - At the mouth of the Lambert Glacier spreads the Amery Ice Shelf. For the most part, ice shelves grow from glaciers pushing down into the sea. They also grow from precipitation. Ice Shelves respond to climate change faster than sheets of ice on the ground or continental glaciers. Of particular interest is whether observed changes in various ice shelves are the result of natural processes or are anthropogenic, that is, the result of actions taken by humans. Courtesy: NASA/CSA/OSU
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| ITEM (10): A Look at The Retreating Ice Sheet - We start this animation with a look at Antarctica's ice pack as it appears today. Then the scene changes to describe how the continent likely looked at the peak of the last ice age, nearly 20,000 years ago. As the years roll backwards, we see just how significantly the area can be altered as planetary conditions change. Consider that since the last ice age, the west Antarctic ice sheet has lost nearly two thirds of its mass during this period, a volume of ice sufficient to raise sea levels approximately 33 feet around the globe.
Courtesy: NASA
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| ITEM (11): Interview Excerpts - Dr. Robert Bindschadler, Glaciologist.
Courtesy: NASA
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| ITEM (12): LANDSAT 7 - Landsat 7 completed its second annual continent-wide mapping of Antarctica in February, 2001. Launched in April 1999, Landsat passes over the Antarctic continent 16 times a day in its nearly pole-to-pole orbit, taking an average of 300 images a week during the Antarctic summer. Landsat 7 has the capability to see features as small as 15 meters (50 feet) across, providing highly detailed observations. Courtesy: NASA
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| ITEM (13): The RADARSAT Satellite - NASA launched the RADARSAT satellite for the Canadian Space Agency in exchange for certain operational executions. Unlike mapping satellites that rely on reflected sunlight or infrared readings, RADARSAT's Synthetic Aperture Radar (SAR) is able to penetrate cloud cover or work in the dark of night.
Courtesy: NASA/CSA
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Earth Science Gallery