Weddell Sea
The Weddell Sea is the largest of the approximately 14 marginal seas of the Southern Ocean on the Antarctic continent . Its boundaries are defined by the coasts of Coatsland to the east and Grahamland to the west. The easternmost coastal point is Cape Norvegia on the Crown Princess Martha Coast of Queen Maud Land , which forms the north point of the Riiser-Larsen Ice Shelf at 12°18′ West. To the east is König-Haakon-VII.-See . The Atlantic-Indian Ridge is the northern limit of the Weddell Sea, an undersea mountain range. The southern part is covered by a large ice shelf as a floating part of the Antarctic Ice Sheet ( Filchner-Ronne Ice Shelf ), smaller ice shelves border the coast to the east (Riiser-Larsen Ice Shelf) and west ( Larsen Ice Shelf ).
The western part of the Weddell Sea is permanently covered by pack ice up to the height of Elephant Island , in the rest of the Weddell Sea the ice cover recedes for about three months in summer.
In total, the Weddell Sea covers an area of 2.8 million km² ; the maximum latitude is 2150 km from Cape Norvegia to Elephant Island. It is between 500 and 5000 meters deep.
Great Britain , Chile and Argentina claim ownership of parts of this area ( see also: Political status of Antarctica ).
story
The sea's name comes from the British sailor James Weddell , who entered the nearly unnavigable bay in 1823 to the 74th parallel south . Apparently the weather conditions were particularly favorable that year, the route that Weddell had taken has only been passable by icebreakers since records began.
- From 1902 to 1904 the Weddell Sea was extensively explored and surveyed by the Scotsman William Speirs Bruce .
- At the same time, the expedition of the Swedish explorer Otto Nordenskjöld suffered a severe setback. The Antarctic , surrounded by pack ice, sank on February 12, 1903, the entire crew reached Paulet Island after a 16-day march and wintered in self-erected stone huts, where they were rescued 10 months later. The ruins are still preserved today.
- A similar fate befell in 1916 when explorer Ernest Henry Shackleton 's ship , the Endurance , was trapped by pack ice and wrecked. They too could be rescued months later after similar circumstances on Elephant Island .
- Wilhelm Filchner sailed into the Weddell Sea in 1911 with the expedition ship Deutschland as part of the German South Polar Expedition 1910-12. He intended to advance as far south as possible by ship and then undertake a sled expedition to the South Pole. In March 1912, the ship froze in the pack ice and drifted clockwise through the Weddell Sea for nine months, discovering the current conditions there.
- The construction of a first station took place on the SE coast during the International Geophysical Year 1957-58.
- Since 1983, the German research vessel Polarstern has been investigating the oceanography , biology , geology and bathymetry of the Weddell Sea on annual expeditions as a focus of polar climate and marine research .
research
Until the Mesozoic , Antarctica formed the central part of the supercontinent Gondwana , which began to split into several parts about 180 million years ago. Geologists now believe that Gondwana's breakup originated in the region around the Weddell Sea.
On the western side, the Weddell Sea is bounded by the Antarctic Peninsula , an essentially Mesozoic , magmatic arc formed by subduction of the Pacific and Proto-Pacific Oceans. To the south, the Weddell Sea continues to the continental shelf . This area is called the Filchner-Ronne Ice Shelf .
The current knowledge of the geological and tectonic structures of the Weddell Sea is essentially based on the interpretation of sea seismic data, which were obtained, for example, during measuring trips with the icebreaker and research ship Polarstern .
The Weddell Sea is inhabited by a large number of different creatures such as crabs and sea cucumbers , some of whose lifestyles and habits are not yet known and which therefore attract great research interest. The Weddell seal , named after the sea, is probably the best known .
In the west of the sea, the freezing of drift ice produces cold, salt-enriched bottom water that influences the temperature and salinity in large areas of the deep sea. Therefore, the Weddell Sea is, among other things, a focus of polar marine research.
In 2012, researchers at the Alfred Wegener Institute for Polar and Marine Research (AWI) determined that the ice shelf of the Weddell Sea, which was previously considered stable, was melting faster than previously assumed as a result of climate change .
The AWI has maintained the research station PALAOA ( PerenniAL Acoustic Observatory in the Antarctic Ocean ) on the Ekström Ice Shelf in the Wedell Sea around 25 kilometers north of the German Neumayer Station since 2006 Signals are recorded that are picked up by underwater microphones or hydrophones and sensors under the approximately 100 meter thick floating ice sheet ("oceanic acoustics").
On January 14, 2022, the AWI published that it had discovered an estimated 60 million active nests of the icefish Neopagetopsis ionah on the floor of the Weddell Sea using a towed underwater camera . According to this, the 240 km 2 area is the largest fish breeding area in the world.
Special flow situation
Between the southern tip of South America ( Tierra del Fuego ) and the long, north-reaching Antarctic Peninsula (Grahamland, see map), the west-east currents around Antarctica are squeezed in. Vortex shedding therefore occurs at the northern tip of Graham Land; these lead to a clockwise rotating current in the Weddell Sea behind it. This means that the pack ice in the shadow of Graham Land is moving much further north than in the northeastern part of the Weddell Sea. This current trapped the Shackleton expedition first in the pack ice and pushed them farther south. The pack ice continued to condense and gradually drifted west and then north until the hull could no longer withstand the ice pressure and ruptured about 7 degrees latitude (about 800 km) further north. The drift directly north finally led to the pack ice border. In the boats, the expedition sometimes had to fight against the current to Elephant Island .
Icebergs are being pushed much farther north from the pack ice boundary in the west of the Weddell Sea. The older ice patches in the satellite image on the right appear green, young smooth ice black. Dark blue is the warmer water to the north (top).
icebergs
Well-known, particularly large icebergs in the Wedell Sea include: A-38 (1998, 6,900 km²), A-68 (2017, 5,800 km²), A-74 (2021, 1,270 km²), A-76 (2021, 4,320 km²) .
web links
- AWI Bathymetric Chart of the Weddell Sea
- Fahrbach, Eberhard (1993) Circulation and water mass formation in the Weddell Sea. The Earth Sciences; 11, 7; 246-253; doi : 10.2312/geowissenschaften.1993.11.246
itemizations
- ↑ Britannica: Weddell Sea
- ↑ EC King, RA Livermore, BCStorey: Weddell Sea tectonics and Gondwana break-up – an introduction. Geological Society special publication. Vol. 108. Geological Society, London 1996, pp. 1-10. ISBN 1-897799-59-4
- ↑ Life under the Enamel. In: Zeit online.
- ↑ Polar explorers warn of mega meltdown. tagesschau.de, May 9, 2012, archived from the original on August 15, 2012 ; retrieved December 3, 2015 .
- ↑ awi.de , January 13, 2011: The world's only underwater listening station PALAOA celebrates its fifth birthday - live sounds from seals and whales from Antarctica (March 4, 2017)
- ↑ deutschlandfunk.de : radio play (March 4, 2017)
- ↑ World's largest fish breeding area discovered in Antarctica orf.at, January 14, 2022, retrieved January 14, 2022.
Coordinates: 75° 0′ 0″ S , 45° 0′ 0″ W