December 1, 2020 - A-68A and South Georgia Island

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   A-68A and South Georgia Island
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   Complex currents and strong wind continued to push Iceberg A-68A closer
   to South Georgia Island through November 2020. On November 25, the
   Moderate Resolution Imaging Spectroradiometer (MODIS) on board NASA’s
   Terra satellite acquired a true-color image of A-68A sitting
   approximately 176 miles (275 km) southeast of the island.

   Iceberg A-68 made headlines in July 2017 when the Delaware-sized block
   of ice broke from the Larsen C Ice Shelf on the Antarctic Peninsula.
   After a smaller piece of the berg broke away, the large “mother” berg
   was given the name A-68A, indicating it was the largest piece of the
   original iceberg. A-68A now measures about 94 miles (151 km) long and
   30 miles (48 km) wide—comparable to South Georgia’s length of 104 miles
   (167 km) and width of 23 miles (37 km).

   In just over three years at sea, Iceberg A-68A has drifted generally
   northward, passing the tip of the Antarctic Peninsula and floating into
   “Iceberg Alley”— a path taken by more than 90 percent of all Antarctic
   icebergs from the Weddell Sea. Most bergs follow the currents that flow
   southward past South Georgia, drifting well east of the island before
   catching a counter-current that carries them northwestward into warmer
   waters, where they ultimately melt. A few bergs drift into a different
   current and pass the island off the western shore. Even fewer are
   trapped by complex currents in this part of the South Atlantic and end
   up “grounding” (getting stuck) on the shallow shelves near the island
   or grind to a halt on the island itself— scenarios that could mean
   trouble for the island’s abundant wildlife if the berg blocks the
   foraging routes of penguins and seals, or if it damages the population
   of krill.

   Even as A-68A draws close to South Georgia, scientists still have
   difficulty predicting the path the iceberg will ultimately take. On
   November 5, A-68A was about 300 miles (500 km) to the southwest of the
   islands, drifting on a course that prompted concerns about grounding,
   despite the statistical probability of the berg taking the more common
   southern route safely around South Georgia. By November 30, the gap had
   closed to about 141 miles (227 km) as A-68A drifted on a wobbling path,
   tracking just slightly westward as the berg’s eastern tip dipped first
   southward and then northward by eddies and currents. NASA’s satellites
   will continue to monitor A-68A as it continues its perilous journey
   towards South Georgia Island.

   Image Facts
   Satellite:  Terra
   Date Acquired: 11/25/2020
   Resolutions:  1km (148.2 KB),  500m (516 KB),  250m (1.6 MB)
   Bands Used: 1,4,3
   Image Credit: MODIS Land Rapid Response Team, NASA GSFC



https://modis.gsfc.nasa.gov/gallery/individual.php?db_date=2020-12-01
 
