Breakup of the World’s Largest Iceberg
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Iceberg B-15A was the largest iceberg in the world (measuring about 11,000 square kilometers) when it broke away from Western Antarctica’s Ross Ice Shelf in March 2000. It held that distinction for over three years until splitting into two pieces in early October, 2003. The Multi-angle Imaging SpectroRadiometer (MISR) acquired these views of the new iceberg B-15J (resting against Ross Island) and B-15A (now free to drift into the Southern Ocean) on October 26. Several massive icebergs (including B-15A) had migrated during 2000 and 2001 and ground against Ross Island, forming a barrier that influenced wind and current patterns and altered the regional ecology.

The two images provide information on both the spectral and angular reflectance properties of ice types in the region. The left-hand panel is a false-color view from MISR’s vertical-viewing (nadir) camera in which near-infrared, red and blue spectral data are displayed as red, green, and blue, respectively. Because of the tendency of water to absorb near-infrared wavelengths, some ice types exhibit an especially bright blue hue in this display. The right-hand panel is a multi-angular composite from three MISR cameras, in which color acts as a proxy for angular reflectance variations related to texture. Here, data from the red-band of MISR’s 60 degree forward-viewing, nadir, and 60 degree backward-viewing cameras are displayed as red, green, and blue, respectively. In the southern latitudes, MISR’s backward-pointing cameras receive a stronger signal from surfaces that predominantly forward scatter sunlight (these tend to be smooth surfaces), and MISR’s forward-pointing cameras receive a stronger signal from surfaces that predominantly backscatter sunlight (these tend to be rougher surfaces). Thus, the colors in this representation highlight textural properties of elements within the scene, with blue tones indicating smoother surfaces and red/orange hues indicating rougher surfaces.

The Multi-angle Imaging SpectroRadiometer observes the daylit Earth continuously and every 9 days views the entire Earth between 82 degrees north and 82 degrees south latitude. The MISR Browse Image Viewer provides access to low-resolution true-color versions of these images. These data products were generated from a portion of the imagery acquired during Terra orbit 20511. The panels cover an area of 129 kilometers x 221 kilometers, and utilize data from blocks 153 to 155 within World Reference System-2 path 56.

Image courtesy NASA/GSFC/LaRC/JPL, MISR Team. Text by Clare Averill (Raytheon/JPL).

Breakup of the World’s Largest Iceberg

November 13, 2003
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