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Ice in the Beaufort Sea
| Title |
Ice in the Beaufort Sea |
| Description |
From the time Europeans discovered the North American continent to the mid-twentieth century, sailors searched for a northwest passage that would connect the Atlantic Ocean (and Europe) to the Pacific Ocean (and Asia). No such passage exists through the continent, but during the summer, a northwest route through the Arctic opens up. By sailing around Greenland, threading the islands of the Canadian Arctic, and skimming along the Canadian and Alaska northern shores, a ship traveling from Europe to East Asia can save as much as 4,000 kilometers. However, the Northwest Passage is not a viable shipping route most of the year. During the winter, thick sea ice builds up, blocking the passage of all ships. Even during the summer, when the sea ice has melted or thinned, icebreakers must often accompany ships through the passage. The challenges of navigating the Northwest Passage are evident in these photo-like images of the Beaufort Sea north of Alaska and Canada's Yukon and Northwest Territories. Though the passage is often clear by the end of July, as it was in 2005 (lower image), the sea was still frozen almost to the shore by July 25, 2006 (top). Very little of the inky, blue-black sea is visible under the white expanse of ice. The ice is not smooth, rather, slightly darker areas show where new ice has formed around chunks of older ice from previous years. The section of the Beaufort Sea that is visible in the top image is clouded with brown sediment flowing into the water from the Mackenzie River. There are several reasons for the lingering ice, says Walt Meier of the National Snow and Ice Data Center. First, temperatures in the region dropped below average in the fall of 2005 and remained cool, so sea ice was able to form quickly. Record melting during 2005 allowed old, thick ice from the north to drift into the Beaufort Sea. Some of this old ice may still be in the sea, frozen among the new ice that formed over the winter. Finally, wind is probably pushing yet more ice toward the shore. Though there was more ice in the Beaufort Sea at the end of July 2006 than there had been in previous years, the Arctic as a whole continued to melt at an ever-quickening pace. By June 2006, sea ice in the Arctic covered 1.2 million fewer square kilometers than the long-term average measured between 1979 and 2000, said Meier. This put sea ice concentrations (the percentage of ice that covers a predefined area) at a record low for June, breaking the record set in June 2005, during which sea ice extent was down 0.8 million square kilometers from the average. The Moderate Resolution Imaging Spectroradiometer (MODIS [ http://modis.gsfc.nasa.gov ]) on NASA's Terra [ http://terra.nasa.gov/ ] satellite captured these images on July 25, 2006, and July 25, 2005. The large images provide above are at MODIS' maximum resolution of 250 meters per pixel. Both the 2005 and 2006, images are available in additional resolutions from the MODIS Rapid Response Team. NASA images courtesy Jeff Schmaltz, MODIS Rapid Response Team [ http://rapidfire.sci.gsfc.nasa.gov ] at NASA GSFC |
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Ice Types in the Beaufort Se
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| Title |
Ice Types in the Beaufort Sea, Alaska |
| Description |
browse image, of orbit 6663 (420 KB JPEG) Determining the amount and type of sea ice in the polar oceans is crucial to improving our knowledge and understanding of polar weather and long term climate fluctuations. These views from two satellite remote sensing instruments, the synthetic aperture radar (SAR) on board the RADARSAT satellite and the Multi-angle Imaging SpectroRadiometer (MISR), illustrate different methods that may be used to assess sea ice type. Sea ice in the Beaufort Sea off the north coast of Alaska was classified and mapped in these concurrent images acquired March 19, 2001 and mapped to the same geographic area. To identify sea ice types, the National Oceanic and Atmospheric Administration (NOAA) National Ice Center constructs ice charts using several data sources including RADARSAT SAR images such as the one shown at left. SAR classifies sea ice types primarily by how the surface and subsurface roughness influence radar backscatter. In the SAR image, white lines delineate different sea ice zones as identified by the National Ice Center. Regions of mostly multiyear ice (A) are separated from regions with large amounts of first year and younger ice (B-D), and the dashed white line at bottom marks the coastline. In general, sea ice types that exhibit increased radar backscatter appear bright in SAR and are identified as rougher, older ice types. Younger, smoother ice types appear dark to SAR. Near the top of the SAR image, however, red arrows point to bright areas in which large, crystalline "frost flowers" have formed on young, thin ice, causing this young ice type to exhibit an increased radar backscatter. Frost flowers are strongly backscattering at radar wavelengths (cm) due to both surface roughness and the high salinity of frost flowers, which causes them to be highly reflective to radar energy. Surface roughness is also registered by MISR, although the roughness observed is at a different spatial scale. Older, rougher ice areas are predominantly backward scattering to the MISR cameras, whereas younger, smoother ice types are predominantly forward scattering. The MISR map at right was generated using a statistical classification routine (called ISODATA) and analyzed using ice charts from the National Ice Center. Five classes of sea ice were found based upon the classification of MISR angular data. These are described, based on interpretation of the SAR image, by the image key. Very smooth ice areas that are predominantly forward scattering are colored red. Frost flowers are largely smooth to the MISR visible band sensor and are mapped as forward scattering. Areas mapped as blue are predominantly backward scattering, and the other three classes have statistically distinct angular signatures and fall within the middle of the forward/backward scattering continuum. Some areas that may be first year or younger ice between the multi year ice floes are not discernible to SAR, illustrating how MISR potentially can make a unique contribution, to sea ice mapping. The Multi-angle Imaging SpectroRadiometer observes the daylit Earth continuously and every 9 days views the entire globe between 82 degrees north and 82 degrees south latitude. The MISR Browse Image Viewer [ http://earthobservatory.nasa.gov/cgi-bin/redirect?http://eosweb.larc.nasa.gov/MISRBR/ ] provides access to low-resolution true-color versions of these images. This data product was generated from a portion of the imagery acquired during Terra orbit 6663. The MISR image has been cropped to include an area that is 200 kilometers wide, and utilizes data from blocks 30 to 33 within World Reference System-2 path 71. Image courtesy NASA/GSFC/LaRC/JPL, MISR Team. [ http://earthobservatory.nasa.gov/cgi-bin/redirect?http://www-misr.jpl.nasa.gov/ ] RADARSAT image courtesy NOAA Satellite Active Archive. Figure reprinted courtesy of IEEE. |
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Ice Types in the Beaufort Se
…
| Title |
Ice Types in the Beaufort Sea, Alaska |
| Description |
browse image, of orbit 6663 (420 KB JPEG) Determining the amount and type of sea ice in the polar oceans is crucial to improving our knowledge and understanding of polar weather and long term climate fluctuations. These views from two satellite remote sensing instruments, the synthetic aperture radar (SAR) on board the RADARSAT satellite and the Multi-angle Imaging SpectroRadiometer (MISR), illustrate different methods that may be used to assess sea ice type. Sea ice in the Beaufort Sea off the north coast of Alaska was classified and mapped in these concurrent images acquired March 19, 2001 and mapped to the same geographic area. To identify sea ice types, the National Oceanic and Atmospheric Administration (NOAA) National Ice Center constructs ice charts using several data sources including RADARSAT SAR images such as the one shown at left. SAR classifies sea ice types primarily by how the surface and subsurface roughness influence radar backscatter. In the SAR image, white lines delineate different sea ice zones as identified by the National Ice Center. Regions of mostly multiyear ice (A) are separated from regions with large amounts of first year and younger ice (B-D), and the dashed white line at bottom marks the coastline. In general, sea ice types that exhibit increased radar backscatter appear bright in SAR and are identified as rougher, older ice types. Younger, smoother ice types appear dark to SAR. Near the top of the SAR image, however, red arrows point to bright areas in which large, crystalline "frost flowers" have formed on young, thin ice, causing this young ice type to exhibit an increased radar backscatter. Frost flowers are strongly backscattering at radar wavelengths (cm) due to both surface roughness and the high salinity of frost flowers, which causes them to be highly reflective to radar energy. Surface roughness is also registered by MISR, although the roughness observed is at a different spatial scale. Older, rougher ice areas are predominantly backward scattering to the MISR cameras, whereas younger, smoother ice types are predominantly forward scattering. The MISR map at right was generated using a statistical classification routine (called ISODATA) and analyzed using ice charts from the National Ice Center. Five classes of sea ice were found based upon the classification of MISR angular data. These are described, based on interpretation of the SAR image, by the image key. Very smooth ice areas that are predominantly forward scattering are colored red. Frost flowers are largely smooth to the MISR visible band sensor and are mapped as forward scattering. Areas mapped as blue are predominantly backward scattering, and the other three classes have statistically distinct angular signatures and fall within the middle of the forward/backward scattering continuum. Some areas that may be first year or younger ice between the multi year ice floes are not discernible to SAR, illustrating how MISR potentially can make a unique contribution, to sea ice mapping. The Multi-angle Imaging SpectroRadiometer observes the daylit Earth continuously and every 9 days views the entire globe between 82 degrees north and 82 degrees south latitude. The MISR Browse Image Viewer [ http://earthobservatory.nasa.gov/cgi-bin/redirect?http://eosweb.larc.nasa.gov/MISRBR/ ] provides access to low-resolution true-color versions of these images. This data product was generated from a portion of the imagery acquired during Terra orbit 6663. The MISR image has been cropped to include an area that is 200 kilometers wide, and utilizes data from blocks 30 to 33 within World Reference System-2 path 71. Image courtesy NASA/GSFC/LaRC/JPL, MISR Team. [ http://earthobservatory.nasa.gov/cgi-bin/redirect?http://www-misr.jpl.nasa.gov/ ] RADARSAT image courtesy NOAA Satellite Active Archive. Figure reprinted courtesy of IEEE. |
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Polynya North of Alaska: Ima
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nasa, nasaimageofthedaygalle
…
In August 2006, a -- an irre
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beaufortsea_amo_2006254
| mediatype |
IMAGE |
| mediatype |
image |
| date |
2006-09-11 |
| creator |
NASA -- NASA image by Jeff Schmaltz, rapidfire.sci.gsfc.nasa.gov MODIS Rapid Response Team, Goddard Space Flight Center. |
| identifier |
beaufortsea_amo_2006254 |
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Fires in Northeast Alaska an
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nasa, nasanaturalhazards
In northeast Alaska near the
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Alaska.AMOA2003182
| mediatype |
IMAGE |
| mediatype |
image |
| date |
July 1, 2003 |
| creator |
NASA -- NASA Image Of The Day |
| identifier |
Alaska.AMOA2003182 |
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Sea Ice in the Beaufort Sea:
…
nasa, nasaimageofthedaygalle
…
From the time Europeans disc
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BeaufortSea_TMO_2006206
| mediatype |
IMAGE |
| mediatype |
image |
| date |
2006-07-25 |
| creator |
NASA -- NASA images courtesy Jeff Schmaltz, rapidfire.sci.gsfc.nasa.gov MODIS Rapid Response Team at NASA GSFC |
| identifier |
BeaufortSea_TMO_2006206 |
|
Sea Ice in the Beaufort Sea:
…
nasa, nasaimageofthedaygalle
…
From the time Europeans disc
…
BeaufortSea_TMO_2006206
| mediatype |
IMAGE |
| mediatype |
image |
| date |
2006-07-25 |
| creator |
NASA -- NASA images courtesy Jeff Schmaltz, rapidfire.sci.gsfc.nasa.gov MODIS Rapid Response Team at NASA GSFC |
| identifier |
BeaufortSea_TMO_2006206 |
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Ice Types in the Beaufort Se
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PIA04300
Sol (our sun)
Multi-angle Imaging SpectroR
…
| Title |
Ice Types in the Beaufort Sea, Alaska |
| Original Caption Released with Image |
Determining the amount and type of sea ice in the polar oceans is crucial to improving our knowledge and understanding of polar weather and long term climate fluctuations. These views from two satellite remote sensing instruments, the synthetic aperture radar (SAR) on board the RADARSAT satellite and the Multi-angle Imaging SpectroRadiometer (MISR), illustrate different methods that may be used to assess sea ice type. Sea ice in the Beaufort Sea off the north coast of Alaska was classified and mapped in these concurrent images acquired March 19, 2001 and mapped to the same geographic area. To identify sea ice types, the National Oceanic and Atmospheric Administration (NOAA) National Ice Center constructs ice charts using several data sources including RADARSAT SAR images such as the one shown at left. SAR classifies sea ice types primarily by how the surface and subsurface roughness influence radar backscatter. In the SAR image, white lines delineate different sea ice zones as identified by the National Ice Center. Regions of mostly multi-year ice (A) are separated from regions with large amounts of first year and younger ice (B-D), and the dashed white line at bottom marks the coastline. In general, sea ice types that exhibit increased radar backscatter appear bright in SAR and are identified as rougher, older ice types. Younger, smoother ice types appear dark to SAR. Near the top of the SAR image, however, red arrows point to bright areas in which large, crystalline "frost flowers" have formed on young, thin ice, causing this young ice type to exhibit an increased radar backscatter. Frost flowers are strongly backscattering at radar wavelengths (cm) due to both surface roughness and the high salinity of frost flowers, which causes them to be highly reflective to radar energy. Surface roughness is also registered by MISR, although the roughness observed is at a different spatial scale. Older, rougher ice areas are predominantly backward scattering to the MISR cameras, whereas younger, smoother ice types are predominantly forward scattering. The MISR map at right was generated using a statistical classification routine (called ISODATA) and analyzed using ice charts from the National Ice Center. Five classes of sea ice were found based upon the classification of MISR angular data. These are described, based on interpretation of the SAR image, by the image key. Very smooth ice areas that are predominantly forward scattering are colored red. Frost flowers are largely smooth to the MISR visible band sensor and are mapped as forward scattering. Areas mapped as blue are predominantly backward scattering, and the other three classes have statistically distinct angular signatures and fall within the middle of the forward/backward scattering continuum. Some areas that may be first year or younger ice between the multi year ice floes are not discernible to SAR, illustrating how MISR potentially can make a unique contribution to sea ice mapping. The, Multi-angle Imaging SpectroRadiometer observes the daylit Earth continuously and every 9 days views the entire globe between 82 degrees north and 82 degrees south latitude. This data product was generated from a portion of the imagery acquired during Terra orbit 6663. The MISR image has been cropped to include an area that is 200 kilometers wide, and utilizes data from blocks 30 to 33 within World Reference System-2 path 71. MISR was built and is managed by NASA's Jet Propulsion Laboratory,Pasadena, CA, for NASA's Office of Earth Science, Washington, DC. The Terra satellite is managed by NASA's Goddard Space Flight Center,Greenbelt, MD. JPL is a division of the California Institute ofTechnology. |
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Summer in the Arctic Nationa
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PIA03419
Sol (our sun)
Multi-angle Imaging SpectroR
…
| Title |
Summer in the Arctic National Wildlife Refuge |
| Original Caption Released with Image |
This colorful image of the Arctic National Wildlife Refuge and the Beaufort Sea was acquired by the Multi-angle Imaging SpectroRadiometer's nadir (vertical-viewing) camera on August 16, 2000, during Terra orbit 3532. The swirling patterns apparent on the Beaufort Sea are small ice floes driven by turbulent water patterns, or eddies, caused by the interactions of water masses of differing salinity and temperature. By this time of year, all of the seasonal ice which surrounds the north coast of Alaska in winter has broken up, although the perennial pack ice remains further north. The morphology of the perennial ice pack's edge varies in response to the prevailing wind. If the wind is blowing strongly toward the perennial pack (that is, to the north), the ice edge will be more compact. In this image the ice edge is diffuse, and the patterns reflected by the ice floes indicate fairly calm weather. The Arctic National Wildlife Refuge (often abbreviated to ANWR) was established by President Eisenhower in 1960, and is the largest wildlife refuge in the United States. Animals of the Refuge include the 130,000-member Porcupine caribou herd, 180 species of birds from four continents, wolves, wolverine, polar and grizzly bears, muskoxen, foxes, and over 40 species of coastal and freshwater fish. Although most of ANWR was designated as wilderness in 1980, the area along the coastal plain was set aside so that the oil and gas reserves beneath the tundra could be studied. Drilling remains a topic of contention, and an energy bill allowing North Slope oil development to extend onto the coastal plain of the Refuge was approved by the US House of Representatives on August 2, 2001. The Refuge encompasses an impressive variety of arctic and subarctic ecosystems, including coastal lagoons, barrier islands, arctic tundra, and mountainous terrain. Of all these, the arctic tundra is the landscape judged most important for wildlife. From the coast inland to an average of 30-60 kilometers, arctic tundra dominates the coastal plain, until reaching the foothills of the Brooks Mountain Range. Beneath the tundra, a layer of permafrost reaches an average depth of 600 meters, restricting water drainage through the soil, and increasing the sensitivity of tundra vegetation to disturbance. Precipitation is scarce (less than 16 centimeters per year) and the small amount of melt water or rain that soaks into the tundra remains near the surface. This is why the coastal plain can be classified as a wetland. The western boundary of the Refuge is marked by the Canning River, about halfway between the center and left-hand side of the image, and the eastern boundary is near the right-hand edge at the US/Canadian border. The two permanent human settlements within the image area are Kaktovic near the tip of the large rounded peninsula, and Arctic Village south of the Brooks Range near the southern Refuge boundary. The area represented by the image is approximately 380 kilometers x 540, kilometers. MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Office of Earth Science, Washington, DC. The Terra satellite is managed by NASA's Goddard Space Flight Center, Greenbelt, MD. JPL is a division of the California Institute of Technology. |
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