Antarctic icebergs are called from the Antarctic quadrant in which they were initially sighted, then a consecutive number, and then if the iceberg breaks, a sequential letter is added.
The map reveals the different positions of the berg over the course of its three-year journey. The map also includes historical iceberg tracks, based upon information from a number of satellites including ESAs ERS-1 and ERS-2 as part of the Antarctic Iceberg Tracking Database Credit: Contains customized Copernicus Sentinel information (2021 ), processed by ESA; Antarctic Iceberg Tracking Database.
For the first two years of its life, A-68A stayed in the cold waters of the Weddell Sea near its moms and dad ice rack. Here, it experienced little in the way of melting. Once the berg began its northward journey throughout the Drake Passage, it took a trip through progressively warm waters and started to melt.
Entirely, the A-68A iceberg thinned by 67 meters from its preliminary density of 235 meters, with the rate of melting rising sharply as the berg drifted in the Scotia Sea around South Georgia.
A paper released in Remote Sensing of Environment describes how scientists from the Centre for Polar Observation and Modelling in the UK and the British Antarctic Survey integrated measurements from various satellites to chart how A-68A changed in location and density throughout its life process.
A-68As position on December 17, 2020. Credit: British Antarctic Survey/ESAIn July 2017, a huge iceberg, named A-68, snapped off Antarcticas Larsen-C ice shelf and started an impressive journey throughout the Southern Ocean. Three and a half years later on, the primary part of iceberg, A-68A, drifted worryingly close to South Georgia. Issues were that the berg would run aground in the shallow waters offshore. This would not just trigger damage to the seafloor community but also make it hard for island wildlife, such as penguins, to make their way to the sea to feed. Utilizing measurements from satellites, researchers have actually charted how A-68A shrunk towards completion of its voyage, which fortunately prevented it from getting stuck. However, the downside is that it released an enormous 152 billion tonnes of freshwater near to the island, potentially having an extensive result on the islands marine life.
When A-68 was generated, it had a surface location of more than two times the size of Luxemburg– one of the biggest icebergs on record.
It lost a piece of ice nearly right away after being calved, resulting in the larger berg being renamed A-68A, and its offspring became A-68B. In April 2020, A-68A lost another piece subsequently called A-68C.
Credit: British Antarctic Survey/ESAIn July 2017, a giant iceberg, called A-68, snapped off Antarcticas Larsen-C ice shelf and began an impressive journey throughout the Southern Ocean. Three and a half years later on, the main part of iceberg, A-68A, wandered worryingly close to South Georgia. Using measurements from satellites, researchers have charted how A-68A shrunk towards the end of its trip, which fortunately prevented it from getting stuck. Credit: Contains customized Copernicus Sentinel information (2021 ), processed by ESA; Antarctic Iceberg Tracking Database.
For the very first 2 years of its life, A-68A remained in the cold waters of the Weddell Sea close to its moms and dad ice shelf.
The journey of A-68A was charted using observations from five different satellite missions.
To track how the location of A-68A altered, they used optical images from the Copernicus Sentinel-3 mission and from the MODIS instrument on the US Terra objective, together with radar information from the Copernicus Sentinel-1 mission. While the Sentinel-1 radar imagery uses all-weather ability and higher spatial resolution, MODIS and Sentinel-3 optical images have higher temporal resolution however can not be utilized during the polar night and on cloudy days.
To determine modifications in the icebergs freeboard, or the height of the ice above the sea surface, they used data from ESAs CryoSat mission and from the United States ICESat-2 objective. Knowing the freeboard of the ice implies that the density of the whole iceberg can be calculated.
All these measurements together allowed the scientists to determined how the icebergs volume altered and for that reason how much freshwater it launched.
Tommaso Parrinello, ESAs CryoSat Mission Manager, said, “Our ability to study every move of the iceberg in such detail is thanks to advances in satellite strategies and making use of a variety of measurements. Imaging satellites tape-record the shape of the iceberg and information from altimetry missions like CryoSat add another crucial dimension as they determine the height of surfaces– which is important for determining changes in volume.”
Visualizing the amount of freshwater released from A-68A. Credit: CPOM/ESA/Google basemap
The new research study exposes that A-68A collided only briefly with the sea flooring and broke apart soon later, making it less of a risk in regards to blockage. By the time it reached the shallow waters around South Georgia, the icebergs keel had actually decreased to 141 meters below the ocean surface area, shallow enough to just prevent the seabed which is around 150 meters deep.
, if an icebergs keel is too deep it can get stuck on the sea floor.. This can be disruptive in numerous methods; the scour marks can ruin animals, and the berg itself can obstruct ocean currents and predator foraging routes.
A side effect of the melting was the release of an enormous 152 billion tonnes of freshwater close to the island– a disruption that could have a profound impact on the islands marine habitat.
When icebergs detach from ice shelves, they wander with the ocean currents and wind, launching cold fresh meltwater and nutrients as they melt. This process affects the local ocean flow and promotes biological production around the iceberg.
Anne Braakmann-Folgmann, PhD candidate at the Centre for Polar Observation and Modelling and lead author of the study stated, “This is a huge quantity of meltwater, and the next thing we desire to learn is whether it had a negative or favorable influence on the ecosystem around South Georgia.
” Because A-68A took a common path throughout the Drake Passage, we intend to discover more about icebergs taking a comparable trajectory, and how they affect the polar oceans.”
For more on this research study, see Massive Iceberg Released Over 150 Billion Tons of Fresh Water Into Ocean As It Scraped Past South Georgia.
Reference: “Observing the disintegration of the A68A iceberg from space” by A. Braakmann-Folgmann, A. Shepherd, L. Gerrish, J. Izzard and A. Ridout, 10 January 2022, Remote Sensing of Environment.DOI: 10.1016/ j.rse.2021.112855.
