between 26 - 13 kaBP), because there is no sediment of atmospheric dirt of that age on the seabed (4). The sea-ice cover must have been thicker during the last Ice Age (esp. There is some evidence that the Arctic sea-ice cover has decreased about 6% during the last two decades, and that the mean ice thickness has decreased as well. Yet even in winter the area between Norway and Svalbard is ice-free, notwithstanding its high latitude (about 77 °N), on account of the Gulf Stream. Much of the Arctic seasonal variation in ice cover can be found in the Bering Sea (mainly adjacent to the continents, and south to the Aleutian Islands), and in the Sea of Okhotsk, as far south as 42ºN, near Hokkaido, Japan. As a comparison, the contiguous USA is about 9 x 10 6 km 2 in size. In the Arctic, the sea-ice area ranges between 9 and 12 x 10 6 km 2 (as opposed to 4 and 19 x 10 6 km 2 around Antarctica). Therefore the seasonal variation of the area of sea ice is smaller in the Arctic than around Antarctica. Over these shelf areas, ice is absent at least part of the year, but ice is found year-round over the deep ocean. About one third of the Arctic Ocean is shallow, i.e. Most of the Arctic Ocean is over 1000 m deep and is continuously covered with ice whose thickness varies between 1-10 m. While almost all icebergs in the Southern Ocean are tabular (flat top), most are not in the Arctic, as in Fig 2. The ratio of the submerged mass to the total mass equals the ratio of the density of ice to that of water, i.e. Icebergs of course extend much deeper in the water than they are high. It is estimated that of the 15,000 to 30,000 icebergs produced annually by the glaciers of Greenland only one percent (150 to 300) ever make it to the Atlantic Ocean. It is notable that huge icebergs last to such a low latitude (the same as that of Rome), after drifting from Baffin Bay within the Arctic Circle ( Fig 2). The collision happened at a latitude of merely 42 ° N. The Titanic sank with the loss of 1513 lives in the icy waters. On 14 April, just before midnight, she collided at 22 knots with an iceberg estimated to be 70-150 m long and 20-40 m high above the water surface. The RMS Titanic, a great ocean liner believed to be unsinkable, made its maiden voyage from England to New York in 1912. Growlers are small chunks of ice (less than 5 m high and less than 15 m long) (Source: the International Ice Patrol) Observations of extreme icebergs or growlers are indicated. (right or below) The grey shaded area is the normal range of icebergs in the North Atlantic in spring. (left) an example of an iceberg of Newfoundland.Some underwater roots of the berg can be seen. The other lines are less important (source: GRID-Arendal, Norway)įig 2. The dark gray tone is the area of discontinuous permafrost and the light gray tone is continuous permafrost. The red broken line is the 10☌ July isotherm, the solid red line is the Arctic Circle (66☃3'N). There are a few other large islands in the eastern (Eurasian) hemisphere, in particular Svalbard and Novaya Zemlya.įig 1(right). The vegetation in summer is tundra, wherever there is neither bare ground, snowfields or glaciers. There are rugged mountains exceeding 2000 m towards Greenland, mainly Baffin Island, but the average elevation of the islands in the west is below 300 m. The Arctic Islands are numerous, the region is about two million km 2, 65% of which is land. It is almost entirely within the Arctic Circle (at 67 ° N). West of Greenland is the Canadian Arctic Archipelago (1, 3), extending from Resolution Island at 61 ° N to Ellesmere Island at 83 ° N, about 2,400 km away. Its northern tip is less than 800 km from the North Pole. Greenland is covered by an icecap up to 2,700 m thick. Therefore the two polar areas are very different. The Arctic ( Fig 1) is mostly ocean, surrounded by mostly land. The Arctic: the ocean, sea ice, icebergs, and climate The Arctic: the ocean, sea ice, icebergs, and climateĪntarctica (Section 16.3) is a continent in a hemisphere that is mostly water.
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