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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. #####
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 # # # # #
Weddell Sea, Antarctica L, C …
This Spaceborne Imaging Rada …
10/5/94
Date 10/5/94
Description This Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar color composite shows a portion of the Weddell Sea, which is adjacent to the continent of Antarctica. The image shows extensive coverage of first-year sea ice mixtures and patches of open water inside the ice margin. The image covers a 100 kilometer by 30 kilometer (62 mile by 18.5 mile) region of the southern ocean, centered at approximately 57 degrees south latitude and 3 degrees east longitude, which was acquired on October 3, 1994. Data used to create this image were obtained using the L-band (horizontally transmitted and vertically received) in red, the L-band (horizontally transmitted and received) in green, and the C-band (horizontally transmitted and received) in blue. The sea ice, which appears rust-brown in the image, is composed of loosely packed floes from approximately 1 meter to 2 meters (3 feet to 6.5 feet) thick and ranging from 1 meter to 20 meters (3 feet to 65.5 feet) in diameter. Large patches of open water, shown as turquoise blue, are scattered throughout the area, which is typical for ice margins experiencing off-ice winds. The thin, well-organized lines clearly visible in the ice pack are caused by radar energy reflected by floes riding the crest of ocean swells. The wispy, black features seen throughout the image represent areas where new ice is forming. Sea ice, because it acts as an insulator, reduces the loss of heat between the relatively warm ocean and cold atmosphere. This interaction is an important component of the global climate system. Because of the unique combination of winds, currents and temperatures found in this region, ice can extend many hundreds of kilometers north of Antarctica each winter, which classifies the Weddell Sea as one of nature's greatest ice-making engines. During the formation of sea ice, great quantities of salt are expelled from the frozen water. The salt increases the density of the upper layer of sea water, which then sinks to great depths. Oceanographers believe this process forms most of the oceans' deep water. Sea ice covering all of the southern oceans, including the Weddell Sea, typically reaches its most northerly extent in about September. As periods of daylight become gradually longer in the Southern Hemisphere, ice formation stops and the ice edge retreats southward. By February, most of the sea ice surrounding Antarctica disappears. Imaging radar is extremely useful for studying the polar regions because of the long periods of darkness and extensive cloud cover. The multiple frequencies of the SIR-C/X-SAR instruments allow further study into ways of improving the separation of the various thickness ranges of sea ice, which are vital to understanding the heat balance in the ice, ocean and atmospheric system. ----- 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.
Weddell Sea L & C bands
This is the first calibrated …
6/22/95
Date 6/22/95
Description This is the first calibrated, multi-frequency, multi-polarization spaceborne radar image of the seasonal sea-ice cover in the Weddell Sea, Antarctica. The multi-channel data provide scientists with details about the ice pack they cannot see any other way and indicates that the large expanse of sea-ice is, in fact, comprised of many smaller rounded ice floes, shown in blue-gray. These data are particularly useful in helping scientists estimate the thickness of the ice cover which is often extremely difficult to measure with other remote sensing systems. The extent, and especially thickness, of the polar ocean's sea-ice cover together have important implications for global climate by regulating the loss of heat from the ocean to the cold polar atmosphere. The image was acquired on October 3, 1994, by the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) onboard the space shuttle Endeavour. This image is produced by overlaying three channels of radar data in the following colors: red (C- band, HH-polarization), green (L-band HV-polarization), and blue (L-band, HH-polarization). The image is oriented almost east-west with a center location of 58.2 degrees South and 21.6 degrees East. Image dimensions are 45 kilometers by 18 kilometers (28 miles by 11 miles). Most of the ice cover is composed of rounded, undeformed blue-gray floes, about 0.7 meters (2 feet) thick, which are surrounded by a jumble of red-tinged deformed ice pieces which are up to 2 meters (7 feet) thick. The winter cycle of ice growth and deformation often causes this ice cover to split apart, exposing open water or 'leads'. Ice growth within these openings is rapid due to the cold, brisk Antarctic atmosphere. Different stages of new-ice growth can be seen within the linear leads, resulting from continuous opening and closing. The blue lines within the leads are open water areas in new fractures which are roughened by wind. The bright red lines are an intermediate stage of new-ice growth perhaps 5 to 10 centimeters (2 to 4 inches) thick. The more extensive dark zones are covered by a slightly thicker layer of smooth, level ice up to 70 centimeters (28 inches) thick. 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), andthe 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. #####
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
Space Radar Image of Weddell …
PIA01802
Sol (our sun)
Title Space Radar Image of Weddell Sea
Space Radar Image of Weddell …
PIA01786
Sol (our sun)
Title Space Radar Image of Weddell Sea Ice
Space Radar Image of Weddell …
PIA01737
Sol (our sun)
Title Space Radar Image of Weddell Sea, Antarctica
QuikScat Captures an Early M …
PIA03894
Sol (our sun)
SeaWinds Scatterometer
Title QuikScat Captures an Early Melt
Original Caption Released with Image The SeaWinds instrument on NASA's Quick Scatterometer (QuikScat) spacecraft captured these near-real-time backscatter images of melting on the Larsen C ice shelf in Antarctica's Weddell Sea between October 27 (left) and October 29 (right), 2002--the earliest documented melting event on the ice shelf since radar data began to be collected in the late 1970s. The melting extended as far south as 68 degrees South and resulted from a cyclone that delivered warm air to the region. The image on the right also shows a noticeable recession in the sea-ice margin to the west of the Antarctic peninsula. The darker grey values of the melt region indicate radar backscatter coefficients that are reduced by approximately 10 decibels from their typical end of winter values.
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