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Lambert Glacier and Amery Ic
…
The Lambert Glacier, seen in
…
2/20/01
| Date |
2/20/01 |
| Description |
The Lambert Glacier, seen in the center of this image, is one of the largest and longest of Antarctica's glaciers. It drains about 900,000 square kilometers (560,000 square miles) of East Antarctica. On the southern half of the image, several smaller ice streams, channeled by numerous exposed mountains including the Mawson Escarpment to the east, merge into the Lambert, which broadens as it eventually flows into the ocean and forms the Amery Ice Shelf. The Lambert has clearly visible surface flowlines, which extend hundreds of kilometers into the interior. In the center section, isolated features on the ice shelf that appear bright in the radar image are likely due to past occurrences of surface meltwater accumulating into small lakes and troughs. This mosaic was derived from RADARSAT imagery obtained during the 1997 Antarctic Mapping Mission and shows an area approximately 900 kilometers by 675 kilometers (560 by 415 miles). The Lambert Glacier is centered at approximately 72 degrees south latitude and 67.5 degrees east longitude. The Antarctic Mapping Mission is a joint project between NASA and the Canadian Space Agency. The project is led by Ohio State University in Columbus in partnership with the Alaska Synthetic Aperture Radar (SAR) Facility at the University of Alaska Fairbanks, NASA's Jet Propulsion Laboratory, Pasadena, Calif., and the Vexcel Corporation, Boulder, Colo. The Canadian Space Agency's RADARSAT-1 satellite carries a synthetic aperture radar, an imaging radar sensor that operates at C-band (5.3 GHz frequency) with horizontal transmit-horizontal receive polarization from an orbital altitude of about 800 kilometers (500 miles). The 1997 Antarctic Mapping Mission took place between Sept. 19 and Oct. 14 and mapped the entire Antarctic continent. The 2000 Antarctic Mapping Mission lasted from Sept. 3 to Nov. 4 and obtained complete coverage of Antarctica north of 82 degrees south latitude. Photo Credit: Canadian Space Agency/NASA/Ohio State University, Jet Propulsion Laboratory, Alaska SAR facility # # # # # |
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Weddell Sea/ScanSAR
Two radar images are shown i
…
10/26/95
| Date |
10/26/95 |
| Description |
Two radar images are shown in this composite to compare the size of a standard spaceborne radar image (small inset) to the image that is created when the radar instrument is used in the ScanSAR mode (large image). The predominant image shows two large ocean circulation features, called eddies, at the northernmost edge of the sea ice pack in the Weddell Sea, off Antarctica. The eddy processes in this region play an important role in the circulation of the global ocean and the transportation of heat toward the pole. The large image is the first wide-swath, multi- frequency, multi-polarization radar image ever processed. To date, no other spaceborne radar sensors have obtained swaths exceeding 100 kilometers (62 miles) in width. This developmental image was produced at NASA's Jet Propulsion Laboratory by the Alaska SAR Facility's ScanSAR processor system, using radar data obtained on October 5, 1994, during the second flight of the Spaceborne Imaging Radar C/X-Band Synthetic Aperture Radar (SIR- C/X-SAR) onboard the space shuttle Endeavour. The image is oriented approximately east-west, with a center location of around 56.6 degrees south latitude and 6.5 degrees west longitude. Image dimensions are 240 km by 350 km (149 miles by 218 miles). The smaller image inset (upper right edge) was obtained by SIR-C/X-SAR on October 6, 1994, and covers a portion of the same ice features that are shown in the large image. The inset image dimensions are 18 km by 50 km (11 miles by 31 miles). The ocean eddies have a clockwise (or cyclonic) rotation and are roughly 40 km to 60 km (25 miles to 37 miles) in diameter. The dark areas are new ice and the lighter green areas are small sea- ice floes that are swept along by surface currents, both of these areas are shown within the eddies and to the south of the eddies. First year seasonal ice, typically 0.5 meter to 0.8 meter (1.5 feet to 2.5 feet) thick, is shown in the darker green area in the lower right corner. The open ocean to the north is uniformly bright and appears blue, due to high winds making the surface rough. The colors in both images were obtained using the following radar channels: red is C-band vertically transmitted and vertically received, green is L-band horizontally transmitted and vertically received, and blue is L-band vertically transmitted and vertically received. The ScanSAR processor is being designed for implementation in 1996 at NASA's Alaska SAR Facility, located at the University of Alaska, Fairbanks, and will produce digital images from the forthcoming Canadian RADARSAT satellite, since its C-band horizontally transmitted, horizontally received polarization radar routinely obtains data over a considerable range of swath-widths and resolutions, including the important wide-swath (300 km to 500 km/186 miles to 310 miles) mode. ##### |
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Antarctic Peninsula
The Antarctica Peninsula is
…
2/20/01
| Date |
2/20/01 |
| Description |
The Antarctica Peninsula is the furthest north extension of the Antarctic continent and is exposed to slightly warmer climate conditions than the greater continent. This mosaic from the 2000 Antarctic Mapping Mission shows most of the peninsula. The blue line is the coastline seen in the 1997 Antarctic Mapping Mission. The broad Larsen Ice Shelf lies to the east, extending into the Weddell Sea, and smaller ice shelves including the Wordie and George VI are in the southwest corner. The northern Larsen Shelf has been retreating since the 1960s, with major collapses in the 1990s. Warming in both the air and ocean underlying the ice shelves leads to increased fracturing and eventually calving of the ice shelf fronts into icebergs. The 1995 Larsen calving events were due to anomalously warm summer temperatures in the early 1990s. The warming noted in the Antarctica Peninsula, as measured from several research stations located there, is not sufficient to affect the thicker and more extensive West Antarctic ice shelves to the south on the main continent. The two RADARSAT mosaics from 1997 and 2000 Antarctic imaging campaigns provide highly accurate snapshots of this rapidly changing region of the greater Antarctic continent. The Antarctic Mapping Mission is a joint project between NASA and the Canadian Space Agency. The project is led by Ohio State University in Columbus in partnership with the Alaska Synthetic Aperture Radar (SAR) Facility at the University of Alaska Fairbanks, NASA's Jet Propulsion Laboratory, Pasadena, Calif., and the Vexcel Corporation, Boulder, Colo. The Canadian Space Agency's RADARSAT-1 satellite carries a synthetic aperture radar, an imaging radar sensor that operates at C-band (5.3 GHz frequency) with horizontal transmit-horizontal receive polarization from an orbital altitude of about 800 kilometers (500 miles. The 1997 Antarctic Mapping Mission took place between Sept. 19 and Oct. 14 and mapped the entire Antarctic continent. The 2000 Antarctic Mapping Mission lasted from Sept. 3 to Nov. 4 and obtained complete coverage of Antarctica north of 82 degrees south latitude. Photo Credit: Canadian Space Agency/NASA/Ohio State University, Jet Propulsion Laboratory, Alaska SAR Facility # # # # # |
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Larsen Ice Shelf
This sub-image of the Antarc
…
2/20/01
| Date |
2/20/01 |
| Description |
This sub-image of the Antarctic Peninsula from the 2000 Antarctic Mapping Mission focuses on the northern end of the Larsen Ice Shelf. The blue line shows the coastline in 1997, the red line in 1992, based on synthetic aperture radar imagery from the European Space Agency, and the yellow line in the mid-1970s. The northern Larsen has been retreating since the 1960s, with major collapses in the 1990s. The southern Larsen was advancing until a major collapse in 1995. Small areas, however, also show advancement since 1997, including a section near the Sobral Peninsula in the center of the image. These advancements may indicate early rebuilding of the overall extent of the Larsen Shelf. The two RADARSAT mosaics from 1997 and 2000 Antarctic imaging campaigns provide highly accurate snapshots of this rapidly changing region of the greater Antarctic continent. The Antarctic Mapping Mission is a joint project between NASA and the Canadian Space Agency. The project is led by Ohio State University in Columbus in partnership with the Alaska Synthetic Aperture Radar (SAR) Facility at the University of Alaska Fairbanks, NASA's Jet Propulsion Laboratory, Pasadena, Calif., and the Vexcel Corporation, Boulder, Colo. The Canadian Space Agency's RADARSAT-1 satellite carries a synthetic aperture radar, an imaging radar sensor that operates at C-band (5.3 GHz frequency) with horizontal transmit-horizontal receive polarization from an orbital altitude of about 800 kilometers (500 miles). The 1997 Antarctic Mapping Mission took place between Sept. 19 and Oct. 14 and mapped the entire Antarctic continent. The 2000 Antarctic Mapping Mission lasted from Sept. 3 to Nov. 4 and obtained complete coverage of Antarctica north of 82 degrees south latitude. Photo Credit: Canadian Space Agency/NASA/Ohio State University, Jet Propulsion Laboratory, Alaska SAR Facility # # # # # |
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L-Band West Texas
This radar image of the Midl
…
6/22/95
| Date |
6/22/95 |
| Description |
This radar image of the Midland/Odessa region of West Texas, demonstrates an experimental technique, called ScanSAR, that allows scientists to rapidly image large areas of the Earth's surface. The large image covers an area 245 kilometers by 225 kilometers (152 miles by 139 miles). It was obtained by the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR- C/X-SAR) flying aboard the space shuttle Endeavour on October 5, 1994. The smaller inset image is a standard SIR-C image showing a portion of the same area, 100 kilometers by 57 kilometers (62 miles by 35 miles) and was taken during the first flight of SIR-C on April 14, 1994. The bright spots on the right side of the image are the cities of Odessa (left) and Midland (right), Texas. The Pecos River runs from the top center to the bottom center of the image. Along the left side of the image are, from top to bottom, parts of the Guadalupe, Davis and Santiago Mountains. North is toward the upper right. Unlike conventional radar imaging, in which a radar continuously illuminates a single ground swath as the space shuttle passes over the terrain, a Scansar radar illuminates several adjacent ground swaths almost simultaneously, by "scanning" the radar beam across a large area in a rapid sequence. The adjacent swaths, typically about 50 km (31 miles) wide, are then merged during ground processing to produce a single large scene. Illumination for this L-band scene is from the top of the image. The beams were scanned from the top of the scene to the bottom, as the shuttle flew from left to right. This scene was acquired in about 30 seconds. A normal SIR- C image is acquired in about 13 seconds. The ScanSAR mode will likely be used on future radar sensors to construct regional and possibly global radar images and topographic maps. The ScanSAR processor is being designed for 1996 implementation at NASA's Alaska SAR Facility, located at the University of Alaska Fairbanks, and will produce digital images from the forthcoming Canadian RADARSAT satellite. Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet Earth. The radars illuminate Earth with microwaves, allowing detailed observations at any time, regardless of weather or sunlight conditions. SIR-C/X-SAR uses three microwave wavelengths: L-band (24 cm), C-band (6 cm) and X- band (3 cm). The multi-frequency data will be used by the international scientific community to better understand the global environment and how it is changing. The SIR-C/X-SAR data, complemented by aircraft and ground studies, will give scientists clearer insights into those environmental changes which are caused by nature and those changes which are induced by human activity. SIR-C was developed by NASA's Jet Propulsion Laboratory. X-SAR was developed by the Dornier and Alenia Spazio companies for the German space agency, Deutsche Agentur fuer Raumfahrtangelegenheiten (DARA), and the Italian space agency, Agenzia Spaziale Italiana (ASI), with the Deutsche Forschungsanstalt fuer Luft und Raumfahrt e.v.(DLR), the major partner in science, operations, and data processing of X-SAR. ##### |
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Lambert Glacier Velocity Map
This image shows the movemen
…
2/20/01
| Date |
2/20/01 |
| Description |
This image shows the movement of the Lambert Glacier. The ice velocity vectors were obtained by using RADARSAT SAR imagery from the 2000 Antarctic Mapping Mission. Yellow represents the areas of no motion, which are either exposed land or stationary ice. The smaller confluent glaciers have generally low velocities, shown in green, of 100-300 meters (330-980 feet) per year, which gradually increase as they flow down the rapidly changing continental slope into the upper reaches of the faster flowing Lambert Glacier. Most of the Lambert Glacier itself has velocities between 400-800 meters (1,310-2,620 feet) per year, with a slight slowing in the middle section. As the glacier extends across Amery Ice Shelf, velocities increase to 1000-1200 meters (3,280-3,937 feet) per year as the ice sheet spreads out and thins. Only a handful of in-situ velocity measurements have been previously reported of this huge glacier system. While the in-situ and radar-derived measurements appear to be qualitatively similar, the extent and accuracy of the new measurements are unprecedented and provide quantitative baselines for future comparisons. The ice velocities are obtained from pairs of images obtained 24 days apart, using a technique called radar interferometry. This technique enables a highly precise alignment of image pairs that provides accurate measurements of topography as well as surfaces that have changed or moved over the short time interval, including glaciers. The Antarctic Mapping Mission is a joint project between NASA and the Canadian Space Agency. The project is led by Ohio State University in Columbus in partnership with the Alaska Synthetic Aperture Radar (SAR) Facility at the University of Alaska Fairbanks, NASA's Jet Propulsion Laboratory, Pasadena, Calif., and the Vexcel Corporation, Boulder, Colo. The Canadian Space Agency's RADARSAT-1 satellite carries a synthetic aperture radar, an imaging radar sensor that operates at C-band (5.3 GHz frequency) with horizontal transmit-horizontal receive polarization from an orbital altitude of about 800 kilometers (500 miles). The 1997 Antarctic Mapping Mission took place between Sept. 19 and Oct. 14 and mapped the entire Antarctic continent. The 2000 Antarctic Mapping Mission lasted from Sept. 3 to Nov. 4 and obtained complete coverage of Antarctica north of 82 degrees south latitude. Photo Credit: Canadian Space Agency/NASA/Ohio State University, Jet Propulsion Laboratory, Alaska SAR facility # # # # # |
|
Pine Island Iceberg Formatio
…
| Title |
Pine Island Iceberg Formation |
| Abstract |
This animation is a sequence showing the formation of the Pine Island iceberg and the glacial seaward flow upstream from the crack. It is a series of MISR images from the Terra satellite on top of the continental Radarsat view of Antarctica. The Pine Island Glacier is the largest discharger of ice in Antarctica and the continent's fastest moving glacier. Even so, when a large crack formed across the glacier in mid 2000, it was surprising how fast the crack expanded, 15 meters per day, and how soon the resulting iceberg broke off, mid-November, 2001. This iceberg, called B-21, is 42 kilometers by 17 kilometers and contains seven years of glacier outflow released to the sea in a single event. |
| Completed |
2002-01-15 |
|
Pine Island Iceberg Formatio
…
| Title |
Pine Island Iceberg Formation |
| Abstract |
This animation is a sequence showing the formation of the Pine Island iceberg and the glacial seaward flow upstream from the crack. It is a series of MISR images from the Terra satellite on top of the continental Radarsat view of Antarctica. The Pine Island Glacier is the largest discharger of ice in Antarctica and the continent's fastest moving glacier. Even so, when a large crack formed across the glacier in mid 2000, it was surprising how fast the crack expanded, 15 meters per day, and how soon the resulting iceberg broke off, mid-November, 2001. This iceberg, called B-21, is 42 kilometers by 17 kilometers and contains seven years of glacier outflow released to the sea in a single event. |
| Completed |
2002-01-15 |
|
Pine Island Iceberg Formatio
…
| Title |
Pine Island Iceberg Formation |
| Abstract |
This animation is a sequence showing the formation of the Pine Island iceberg and the glacial seaward flow upstream from the crack. It is a series of MISR images from the Terra satellite on top of the continental Radarsat view of Antarctica. The Pine Island Glacier is the largest discharger of ice in Antarctica and the continent's fastest moving glacier. Even so, when a large crack formed across the glacier in mid 2000, it was surprising how fast the crack expanded, 15 meters per day, and how soon the resulting iceberg broke off, mid-November, 2001. This iceberg, called B-21, is 42 kilometers by 17 kilometers and contains seven years of glacier outflow released to the sea in a single event. |
| Completed |
2002-01-15 |
|
Pine Island Iceberg Formatio
…
| Title |
Pine Island Iceberg Formation |
| Abstract |
This animation is a sequence showing the formation of the Pine Island iceberg and the glacial seaward flow upstream from the crack. It is a series of MISR images from the Terra satellite on top of the continental Radarsat view of Antarctica. The Pine Island Glacier is the largest discharger of ice in Antarctica and the continent's fastest moving glacier. Even so, when a large crack formed across the glacier in mid 2000, it was surprising how fast the crack expanded, 15 meters per day, and how soon the resulting iceberg broke off, mid-November, 2001. This iceberg, called B-21, is 42 kilometers by 17 kilometers and contains seven years of glacier outflow released to the sea in a single event. |
| Completed |
2002-01-15 |
|
Pine Island Iceberg Formatio
…
| Title |
Pine Island Iceberg Formation |
| Abstract |
This animation is a sequence showing the formation of the Pine Island iceberg and the glacial seaward flow upstream from the crack. It is a series of MISR images from the Terra satellite on top of the continental Radarsat view of Antarctica. The Pine Island Glacier is the largest discharger of ice in Antarctica and the continent's fastest moving glacier. Even so, when a large crack formed across the glacier in mid 2000, it was surprising how fast the crack expanded, 15 meters per day, and how soon the resulting iceberg broke off, mid-November, 2001. This iceberg, called B-21, is 42 kilometers by 17 kilometers and contains seven years of glacier outflow released to the sea in a single event. |
| Completed |
2002-01-15 |
|
Pine Island Iceberg Formatio
…
| Title |
Pine Island Iceberg Formation |
| Abstract |
This animation is a sequence showing the formation of the Pine Island iceberg and the glacial seaward flow upstream from the crack. It is a series of MISR images from the Terra satellite on top of the continental Radarsat view of Antarctica. The Pine Island Glacier is the largest discharger of ice in Antarctica and the continent's fastest moving glacier. Even so, when a large crack formed across the glacier in mid 2000, it was surprising how fast the crack expanded, 15 meters per day, and how soon the resulting iceberg broke off, mid-November, 2001. This iceberg, called B-21, is 42 kilometers by 17 kilometers and contains seven years of glacier outflow released to the sea in a single event. |
| Completed |
2002-01-15 |
|
Pine Island Iceberg Formatio
…
| Title |
Pine Island Iceberg Formation |
| Abstract |
This animation is a sequence showing the formation of the Pine Island iceberg and the glacial seaward flow upstream from the crack. It is a series of MISR images from the Terra satellite on top of the continental Radarsat view of Antarctica. The Pine Island Glacier is the largest discharger of ice in Antarctica and the continent's fastest moving glacier. Even so, when a large crack formed across the glacier in mid 2000, it was surprising how fast the crack expanded, 15 meters per day, and how soon the resulting iceberg broke off, mid-November, 2001. This iceberg, called B-21, is 42 kilometers by 17 kilometers and contains seven years of glacier outflow released to the sea in a single event. |
| Completed |
2002-01-15 |
|
Pine Island Iceberg Formatio
…
| Title |
Pine Island Iceberg Formation |
| Abstract |
This animation is a sequence showing the formation of the Pine Island iceberg and the glacial seaward flow upstream from the crack. It is a series of MISR images from the Terra satellite on top of the continental Radarsat view of Antarctica. The Pine Island Glacier is the largest discharger of ice in Antarctica and the continent's fastest moving glacier. Even so, when a large crack formed across the glacier in mid 2000, it was surprising how fast the crack expanded, 15 meters per day, and how soon the resulting iceberg broke off, mid-November, 2001. This iceberg, called B-21, is 42 kilometers by 17 kilometers and contains seven years of glacier outflow released to the sea in a single event. |
| Completed |
2002-01-15 |
|
Pine Island Iceberg Formatio
…
| Title |
Pine Island Iceberg Formation |
| Abstract |
This animation is a sequence showing the formation of the Pine Island iceberg and the glacial seaward flow upstream from the crack. It is a series of MISR images from the Terra satellite on top of the continental Radarsat view of Antarctica. The Pine Island Glacier is the largest discharger of ice in Antarctica and the continent's fastest moving glacier. Even so, when a large crack formed across the glacier in mid 2000, it was surprising how fast the crack expanded, 15 meters per day, and how soon the resulting iceberg broke off, mid-November, 2001. This iceberg, called B-21, is 42 kilometers by 17 kilometers and contains seven years of glacier outflow released to the sea in a single event. |
| Completed |
2002-01-15 |
|
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. |
|
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. |
|
Glacier Speeds Up After Ice
…
nasa, nasaimageofthedaygalle
…
* eoimages.gsfc.nasa.gov/ima
…
landsat_hektoria_20feb03
| mediatype |
IMAGE |
| mediatype |
image |
| date |
2003-02-20 |
| creator |
NASA -- Landsat imagery provided by Jennifer Bohlander, NSIDC. |
| identifier |
landsat_hektoria_20feb03 |
|
Global View of the Arctic Oc
…
PIA02970
Sol (our sun)
Imaging Radar
| Title |
Global View of the Arctic Ocean |
| Original Caption Released with Image |
NASA researchers have new insights into the mysteries of Arctic sea ice, thanks to the unique abilities of Canada's Radarsat satellite. The Arctic is the smallest of the world's four oceans, but it may play a large role in helping scientists monitor Earth's climate shifts. Using Radarsat's special sensors to take images at night and to peer through clouds, NASA researchers can now see the complete ice cover of the Arctic. This allows tracking of any shifts and changes, in unprecedented detail, over the course of an entire winter. The radar-generated, high-resolution images are up to 100 times better than those taken by previous satellites. Using this new information, scientists at NASA's Jet Propulsion Laboratory (JPL), Pasadena, Calif., can generate comprehensive maps of Arctic sea ice thickness for the first time. "Before we knew only the extent of the ice cover," said Dr. Ronald Kwok, JPL principal investigator of a project called Sea Ice Thickness Derived From High Resolution Radar Imagery. "We also knew that the sea ice extent had decreased over the last 20 years, but we knew very little about ice thickness.""Since sea ice is very thin, about 3 meters (10 feet) or less,"Kwok explained, "it is very sensitive to climate change." Until now, observations of polar sea ice thickness have been available for specific areas, but not for the entire polar region. The new radar mapping technique has also given scientists a close look at how the sea ice cover grows and contorts over time. "Using this new data set, we have the first estimates of how much ice has been produced and where it formed during the winter. We have never been able to do this before, " said Kwok. "Through our radar maps of the Arctic Ocean, we can actually see ice breaking apart and thin ice growth in the new openings. " RADARSAT gives researchers a piece of the overall puzzle every three days by creating a complete image of the Arctic. NASA scientists then put those puzzle pieces together to create a time-lapsed view of this remote and inhospitable region. So far, they have processed one season's worth of images."We can see large cracks in the ice cover, where most ice grows, " said Kwok. "These cracks are much longer than previously thought, some as long as 2,000 kilometers (1,200 miles)," Kwok continued. "If the ice is thinning due to warming, we'll expect to see more of these long cracks over the Arctic Ocean. " Scientists believe this is one of the most significant breakthroughs in the last two decades of ice research. "We are now in a position to better understand the sea ice cover and the role of the Arctic Ocean in global climate change, " said Kwok. Radar can see through clouds and any kind of weather system, day or night, and as the Arctic regions are usually cloud-covered and subject to long, dark winters, radar is proving to be extremely useful. However, compiling these data into extremely detailed pictures of the Arctic is a challenging task."This is truly, a major innovation in terms of the quantities of data being processed and the novelty of the methods being used, " said Verne Kaupp, director of the Alaska SAR Facility at the University of Alaska, Fairbanks. The mission is a joint project between JPL, the Alaska SAR Facility, and the Canadian Space Agency. Launched by NASA in 1995, the Radarsat satellite is operated by the Canadian Space Agency. JPL manages the Sea Ice Thickness Derived From High Resolution Radar Imagery project for NASA's Earth Science Enterprise, Washington, DC. The Earth Science Enterprise is dedicated to studying how natural and human-induced changes affect our global environment. |
|
Comparative Views of Arctic
…
PIA02971
Sol (our sun)
Imaging Radar
| Title |
Comparative Views of Arctic Sea Ice Growth |
| Original Caption Released with Image |
NASA researchers have new insights into the mysteries of Arctic sea ice, thanks to the unique abilities of Canada's Radarsat satellite. The Arctic is the smallest of the world's four oceans, but it may play a large role in helping scientists monitor Earth's climate shifts. Using Radarsat's special sensors to take images at night and to peer through clouds, NASA researchers can now see the complete ice cover of the Arctic. This allows tracking of any shifts and changes, in unprecedented detail, over the course of an entire winter. The radar-generated, high-resolution images are up to 100 times better than those taken by previous satellites. The two images above are separated by nine days (earlier image on the left). Both images represent an area (approximately 96 by 128 kilometers, 60 by 80 miles)located in the Baufort Sea, north of the Alaskan coast. The brighter features are older thicker ice and the darker areas show young, recently formed ice. Within the nine-day span, large and extensive cracks in the ice cover have formed due to ice movement. These cracks expose the open ocean to the cold, frigid atmosphere where sea ice grows rapidly and thickens. Using this new information, scientists at NASA's Jet Propulsion Laboratory (JPL), Pasadena, Calif., can generate comprehensive maps of Arctic sea ice thickness for the first time. "Before we knew only the extent of the ice cover," said Dr. Ronald Kwok, JPL principal investigator of a project called Sea Ice Thickness Derived From High Resolution Radar Imagery. "We also knew that the sea ice extent had decreased over the last 20 years, but we knew very little about ice thickness.""Since sea ice is very thin, about 3 meters (10 feet) or less,"Kwok explained, "it is very sensitive to climate change." Until now, observations of polar sea ice thickness have been available for specific areas, but not for the entire polar region. The new radar mapping technique has also given scientists a close look at how the sea ice cover grows and contorts over time. "Using this new data set, we have the first estimates of how much ice has been produced and where it formed during the winter. We have never been able to do this before," said Kwok. "Through our radar maps of the Arctic Ocean, we can actually see ice breaking apart and thin ice growth in the new openings." RADARSAT gives researchers a piece of the overall puzzle every three days by creating a complete image of the Arctic. NASA scientists then put those puzzle pieces together to create a time-lapsed view of this remote and inhospitable region. So far, they have processed one season's worth of images."We can see large cracks in the ice cover, where most ice grows," said Kwok. "These cracks are much longer than previously thought, some as long as 2,000 kilometers (1,200 miles)," Kwok continued. "If the ice is thinning due to warming, we'll expect to see more of these long cracks over the Arctic Ocean." Scientists believe this is one of the most, significant breakthroughs in the last two decades of ice research. "We are now in a position to better understand the sea ice cover and the role of the Arctic Ocean in global climate change," said Kwok. Radar can see through clouds and any kind of weather system, day or night, and as the Arctic regions are usually cloud-covered and subject to long, dark winters, radar is proving to be extremely useful. However, compiling these data into extremely detailed pictures of the Arctic is a challenging task."This is truly a major innovation in terms of the quantities of data being processed and the novelty of the methods being used," said Verne Kaupp, director of the Alaska SAR Facility at the University of Alaska, Fairbanks. The mission is a joint project between JPL, the Alaska SAR Facility, and the Canadian Space Agency. Launched by NASA in 1995, the Radarsat satellite is operated by the Canadian Space Agency. JPL manages the Sea Ice Thickness Derived From High Resolution Radar Imagery project for NASA's Earth Science Enterprise, Washington, DC. The Earth Science Enterprise is dedicated to studying how natural and human-induced changes affect our global environment. |
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Ice Types in the Beaufort Se
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PIA04300
Sol (our sun)
Multi-angle Imaging SpectroR
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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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