Geographical knowledge of the Arctic?

The North Pole refers to the vast area north of 66 degrees 34 minutes north latitude (Arctic Circle), also known as the Arctic region. The arctic region includes the polar arctic ocean, marginal land coastal zones and islands, arctic tundra and the outermost coniferous forest belt. If the Arctic Circle is the boundary of the Arctic, the total area of the Arctic region is 2 1 10,000 square kilometers, of which the land part accounts for 8 million square kilometers. Some scientists, from the phenological point of view, take the average isotherm in July 10℃ (the ocean is at 5℃) as the southern boundary of the Arctic region. In this way, the total area of the Arctic region has expanded to 27 million square kilometers, of which the land area is about120,000 square kilometers. If the Arctic is defined by the distribution of plant species and all the Taiga forest belts are included in the Arctic, the area of the Arctic region will exceed 40 million square kilometers. What is the boundary of the Arctic region? The standards of countries around the Arctic are not uniform, but most people are used to taking the Arctic Circle as the boundary of the Arctic region from a geographical perspective.

Arctic current

The Arctic is a world of ice and snow, but due to the movement of ocean currents, the sea ice on the surface of the Arctic Ocean is always drifting, cracking and melting, so it is impossible to accumulate thousands of meters of ice and snow like the Antarctic continent over millions of years. Therefore, the total amount of ice and snow in the Arctic is only close to110 in the Antarctic, and most of it is concentrated in the continental ice sheet of Greenland, while the permanent ice and snow in the Arctic Ocean, other islands and surrounding land only accounts for a small part.

Most of the surface of the Arctic Ocean is covered with sea ice all year round, and it is the only white ocean on the earth. The average thickness of the Arctic Ocean sea ice is 3m, covering 73% of the total ocean area in winter, about 1 1,000 ~10/0,000,000 square kilometers, and 53% in summer, about 7.5 ~ 8 million square kilometers. The sea ice in the central Arctic Ocean has existed for 3 million years and belongs to permanent sea ice.

Arctic hydrology

The southern boundary of sea ice is not fixed, and it can often change by hundreds of kilometers with the change of hydrometeorological conditions. Under the action of wind and current, ice floes can pile up and form huge floating icebergs. Most of the icebergs we usually see refer to those huge ice bodies with a diameter of more than 5 meters that have collapsed from the continental shelf or continental ice sheet. The thickness of large-scale platform icebergs can generally reach 200 ~ 300 meters, and the average life span is as long as 4 years. If we are lucky, we can also see a huge iceberg, which is tens of kilometers long, like a piece of white land across the dark gray sea.

Floating icebergs formed by sea ice in the Arctic Ocean, together with icebergs formed by glaciers and ice shelves from Greenland and other islands, enter the Atlantic Ocean or Alaska with the current, and some icebergs can drift south to 40 north latitude. 19 12 Titanic, the world's most luxurious passenger ship, hit an iceberg floating in the Arctic Ocean on its maiden voyage and sank, resulting in the famous "shipwreck in the ice sea" tragedy in the history of world navigation.

[Edit this paragraph] Arctic Ocean surface circulation

Although most of the ocean surface of the Arctic Ocean is covered with ice and snow, the seawater under the ice, like the seawater of other oceans in the world, keeps flowing according to certain rules. If the tide is the pulse of the ocean, then the circulation of the ocean is the life of the ocean. Two currents play a major role in the surface circulation of the Arctic Ocean: one is the Isspitsbergen current, a tributary of the Atlantic Ocean, which enters the Arctic Ocean from the east of Greenland and moves counterclockwise along the edge of the shelf; The other is the trans-polar ocean current (cold water flow at the bottom of East Greenland), which flows in from Chukchi Sea, flows through the Arctic and then flows out from Greenland Sea to the Atlantic Ocean. They control the basic marine hydrological characteristics of the Arctic Ocean, such as water mass distribution and water exchange between the Arctic Ocean and the high seas.

In addition, the role of Norwegian warm current and North Point warm current can not be ignored. According to the latest statistical observation data, the Atlantic Ocean current injects 72,000 cubic kilometers of seawater into the Arctic Ocean, 30,000 cubic kilometers into the North Pacific Ocean and 4,400 cubic kilometers of fresh water into the rivers around the land. In this way, the cold ocean bottom current of the Arctic Ocean must flow into the North Atlantic at an annual scale of 65,438+005,000 cubic kilometers through the Fromm Strait with a depth of 2,700 meters and a width of 450 kilometers. These arctic ocean currents have a great influence on the climate characteristics and ecological environment of the arctic and its surrounding areas.

Islands in the Arctic Ocean

The land area around the Arctic Ocean can be divided into two parts: one is Eurasia, the other is North America and Greenland, and the Bering Strait and Greenland Sea are separated between the two parts. From the geologist's point of view, there are many similarities between these two parts of land, both of which are composed of very old large hidden crust. The age of the Arctic Ocean (oceanic crust) is much younger, and it began to appear at the end of Cretaceous 80 million years ago due to plate expansion.

Alaska's low-lying coast

The coastline of the Arctic Ocean is tortuous and varied, including steep rocky coast and fjord coast, abrasive coast, low-level coast, delta and lagoon coast and composite coast. There are many shallow marginal seas and bays in the vast continental shelf area. There are many islands in the Arctic Ocean, with a total area of about 3.8 million square kilometers, which basically belong to mainland islands in the shelf area. The largest island is Greenland, with an area of 2 1.8 thousand square kilometers, which is larger than the total area of western and central Europe, so some people call it Greenland subcontinent. There are about 60,000 residents in Greenland, 90% of whom are Greenlanders and the rest are mainly Danes. The largest archipelago is Canada's Arctic archipelago, which consists of hundreds of islands with a total area of about 6,543,800 square kilometers. Ellesmere island, the largest island, lies in the northeast. The town of Arel in the north of the island has exceeded 82 N, so it is the starting point of many Arctic explorations.

Like the Antarctic, the vast ice fields on the land and islands in the Arctic region look distant and quiet, and seem to represent some kind of eternal stillness. But in fact, due to the weight of ice and snow, the land ice sheet keeps moving to the coast, and it is deep, slow and unstoppable. The average annual moving speed of the inland ice sheet in Greenland is several meters, while the coastal area can reach 100 ~ 200 meters. As for those huge glaciers, they move much faster. The so-called glacier is actually a river of ice and snow. Billions to tens of billions of tons of ice and snow are quietly pushed, rubbed and moved in valleys or lowlands where glaciers flow. They slowly but indomitable to the sea, and finally earth-shattering collapse into the sea. The ice sheet moved and finally collapsed, forming huge icebergs in the sea. Only in this way, Greenland's land ice sheet loses 150 cubic kilometers of ice every year. On the other hand, the total annual snowfall and ice accumulation in Greenland is about 170 cubic kilometers. But as in Antarctica, so far, scientists are not sure whether the continental ice sheet in Greenland is slowly growing or dying.

The climate of the Arctic

Winter in the Arctic Ocean lasts for six months from June 1 1 to April of the following year. May, June, September and 65438+ October belong to spring and autumn. In summer, it only lasts for seven or eight months. The average temperature in June+10/October in 5438 was between-20 and-40℃. The average temperature in the warmest August is only MINUS 8 degrees. The lowest temperature measured at the drifting station near the pole of the Arctic Ocean is -59℃. Due to the influence of ocean currents and Arctic anticyclones, the coldest place in the Arctic is not in the middle of the Arctic Ocean. The lowest temperature was recorded at -70℃ in Jansk, Vilho, Siberia, and at -62℃ in Alaska.

The closer to the pole, the more obvious the meteorological and climatic characteristics of the polar region. There is only one day and one night a year. Even in midsummer, the sun just hangs on the distant southern horizon, with a bleak white light. The sun never rises above 23.5 degrees. It moves slowly around this endless white world. A few months later, the sun's trajectory gradually approached the horizon, so the evening season in the Arctic began.

The Arctic has endless ice and snow and a long winter. Both the North Pole and the South Pole have extreme days and nights. The closer you get to the North Pole, the more obvious this is. Winter in the Arctic is long, cold and dark. From165438+1October 23rd every year, there will be days when the sun can't be seen at all for nearly half a year. The temperature will drop to MINUS 50 degrees Celsius. At this time, all the waves and tides disappeared, because the coast was frozen and only the wind wrapped in snow swept around.

In April, the weather gradually warmed up and the ice and snow gradually melted. Large pieces of ice began to melt, break and collide with each other, making a loud noise. There is gurgling water in the stream; The sky becomes bright and the sun shines on the earth. In May and June, plants put on the coat of life, and green animals began to be active and busy breeding. In this season, animals can get enough food and accumulate enough nutrition and fat to spend the long winter.

Autumn in the Arctic is very short, and the first snowstorm will come in early September. The arctic soon returned to the cold and dark winter. In the Arctic, the sun will never rise in the sky, even in midsummer, its rising angle will not exceed 23.5 degrees. The annual precipitation in the Arctic is generally 100-250 mm, and it can reach 500 mm in Greenland. The main form of precipitation is summer rain.

A brief history of the Arctic