Arctic Ocean. The Arctic Ocean lies to the north of Europe, Asia, and North America, and surrounds the North Pole; it is usually defined as the water area within the Arctic Circle. The influence of the Gulf Stream, however, carries a relatively mild climate a long way within the Arctic Circle off the coasts of Norway; and, on the other hand, the Arctic currents along the east coast of Greenland, and through Davis Strait, bring down Arctic conditions a long distance into the Atlantic. Physiographically, the Norwegian Sea and Greenland Sea, situated between Norway and Greenland, belong to the same basin as the Arctic Ocean, it being cut off from the Atlantic by the ridges stretching between Greenland, Iceland, the Faroe Islands, and the north of Scotland, which have an average depth over them of 240 fathoms. If the Arctic Ocean be regarded as lying wholly within the Arctic Circle, then it is almost land-locked between that circle and the parallel of N. It communicates with the Pacific by Behring Strait, and with the Atlantic through Davis Strait and the wide sea between Norway and Greenland. The area of the ocean is about 5,500,000 sq. m., and into it there drain about 8,600,000 sq. m. of land. The rainfall on this land is estimated at 2100 cubic miles per annum. The coasts of Europe and Asia are low, and have several deep indentations, the principal being the White Sea and Gulf of Obi. The shores of North America are skirted by a most irregular assemblage of islands, forming numerous gulfs, bays, and channels. The principal islands of the Arctic Ocean are Greenland, Spitzbergen, Franz-Josef Land, Nova Zembla, New Siberia, Wrangel Island, Prince Patrick Island, Melville Island, Banks Land, Ellesmere Land, Grinnell Land, &c. The principal rivers from Asia are the Lena, Yenesei, and Obi; from Europe, the Onega, Dwina, and Petchora; from America, the Mackenzie. The Arctic highlands are covered with an enormous depth of snow and ice. In some places this results in the formation of great glaciers, one of the most remarkable of which is the Humboldt Glacier, in N. lat., on the west coast of Greenland. There are, however, no large, flat-topped tabular icebergs, like those of the southern hemisphere, within the Arctic Ocean; and this of itself is good evidence that there is no expanse of land towards the North Pole. The whole ocean is covered by immense ice-fields from 5 to 50 feet in thickness. During winter these are bound together by the severe frost, but these continuous masses break up during the summer months into floes and floe-bergs. Sometimes vast spaces of water and long lanes are formed between the floes and ice-fields, and these have, doubtless, given rise to the notions regarding an open Polar Sea which at one time prevailed. When these great floating ice-fields come together, the margins where they collide are piled up on each other, and thus is produced the well-known hummocky ice-floes. When this hummocky ice is jammed against a shallow shore, and becomes fixed for long periods of time, the appearances are produced to which Nares gave the name of 'Palæocrystic Sea.' In the more open parts of the ocean the ice is, however, always in motion. Immense quantities of field and hummocky ice pass down each year between Spitzbergen and Greenland, and Greenland and Iceland, these waters being almost always blocked. Frozen in this ice, whole pine-trees are not uncommonly found; these have most probably been carried right across the pole, after having been carried into the Arctic Ocean by the rivers of the Old and New World. Large fresh-water ponds and lakes are formed on the ice-fields during summer by the rain and melting snow. When these are frozen again, a 'black ice' is formed, which contrasts strongly with the 'white ice' formed from salt water. The whalers supply themselves with water by picking up the 'black ice.' Parry found, as he travelled over the ice north of Spitzbergen, that it was moving in a body to the south. He reached a latitude of , Markham reached , and Lockwood (of Greely's expedition, 1882) , the most northerly point yet attained. In 1850 M'Crew entered Behring Strait, and brought his crew home by Davis Strait, thus discovering the North-west Passage. In 1878 and 1879 Nordenskiöld sailed from the Atlantic to the Pacific along the northern shores of Europe and Asia, thus discovering the North-east Passage.
Nansen (q.v.) found that the depth suddenly increased north of the New Siberian islands from 100 fathoms to 1800 or 2000—depths noted throughout his adventurous voyage: below the cold layer of 200 fathoms the water was warmer by as much as 2.4° C. than at the surface (−1.6° C. and +0.8° C.). The pole is probably in deep water. Cold Arctic water penetrates the Faroe Channel, but is stopped by the Wyville-Thomson Ridge; on the north of this ridge there is, at a depth of 400 and 500 fathoms, a temperature of 30° F.; while on the south side, at the same depths, the temperature is 45° F. The width of this ridge is about 10 miles, and on it there is a depth of 250 fathoms. The warm Gulf Stream water flows over this ridge and on to the coasts of Norway, rendering its northern shores and those of Lapland relatively mild and habitable, the July temperature off the North Cape being 47° F. Musk-oxen, reindeer, foxes, hares, and wolves are met with on Arctic land. Polar bears roam widely over the ice-fields. Whales, walruses, narwhals, and seals abound. Guillemots, little auks, gulls, and other sea-birds are found in vast numbers near Spitzbergen and other islands. Eider-ducks nest on the low lands, and their down is collected as an article of commerce. There are valuable seal, whale, walrus, and shark fisheries; and cod, mackerel, herring, and lobsters are also captured. There is a great amount of invertebrate life at the surface of the sea, and diatoms are also abundant. The Norwegian expeditions show that life exists at great depths, but it is by no means so abundant as in the Antarctic. The ocean appears to be shallow to the north of Europe and Asia, the depth 500 miles to the north of the Lena being only 38 fathoms; and Markham found only 72 fathoms at his most northerly point off the American coast. Between Spitzbergen and Lapland the depths are from 100 to 200 fathoms; but between Spitzbergen and the north of Greenland there is a deep opening into the frozen sea, where the depth is 2500 fathoms. Between Norway and Iceland and Greenland the depths are sometimes over 2000 fathoms, and generally over 1000 fathoms in the central parts. The depths in Behring Strait are less than 100 fathoms. The deposits in the Arctic Ocean are blue muds, composed almost wholly of land débris. In the south-east portions of the Norwegian Sea, some of the deposits approach in character to a globigerina ooze. South-westerly winds prevail along the coasts of Norway, and as far as Franz-Josef Land; to the westward of this line, north-easterly winds prevail. In winter, winds blow from Northern Asia to the Arctic Ocean; in summer, from the ocean to the land. The direction of the winds over the Arctic Ocean at different seasons is controlled by the positions of the barometric maxima and minima in the north parts of Asia and the North Atlantic. Fogs and mists are of most frequent occurrence during the six months of day and summer. In winter the temperature of the air is sometimes as low as −47° F., and in summer is usually a little above the freezing-point. There is a large export trade in fossil ivory from the New Siberia (Liakhoff) Islands. This consists of the tusks of the mammoth, whose remains are abundant in Northern Russia. For an account of Arctic expeditions, see POLAR EXPLORATION.