Continental ice sheet

directory

About two factors into the ice of Greenland ice sheet Antarctic ice formation ice mass balance of the natural characteristics of the fabric moving ice core temperature Expand edit this section Introduction continental ice sheets continental ice sheet continental ice sheets in cold climate, there is a certain amount of polar snow and high latitudes, except for a few peaks protruding ice surface, almost all of the ground for the few hundred meters to several kilometers thick continuous ice cover. Central part of the continental ice sheet accumulation area, the edge of the ablation zone. Ice ice almost independent of the underlying topography, the outflow from the center to the edges; edge portion extending from land to sea, some floating in the sea ice called ice shelves (ice shelf), ice shelf or ice barrier. Ice shelf break, collapse into the sea after the formation of icebergs. In the Arctic and polar regions near the islands, shape and characteristics of the continental ice sheet similar, but much smaller ice called ice caps or ice dome. Edit this paragraph outlined two major ice sheets on Earth extant continental ice sheets of Greenland and Antarctica ice sheets there. These two global glacier ice about 97% of the total area, 99% of the total ice volume. Antarctic ice sheet total area of ​​13.98 million square kilometers, accounting for 86% of the total area of ​​the glacier, with a total storage capacity of 21.6 million cubic kilometers, the total storage capacity of the world's glaciers for 90%. The average thickness of the Antarctic ice sheet is about 2000 to 2500 meters, the known maximum thickness of 4267 m. If the entire Antarctic ice sheet melted, sea levels would rise about 61 meters the world, even to restore the balance deduction Antarctica, sea levels have increased by about 40 meters. Trans-Antarctic Mountains to the Antarctic ice sheet is divided into two parts with different characteristics: in most parts of the West Antarctic ice sheet, the bottom lies below sea level, even if all the ice melted, the land balance rises, the ground is still below sea level, this part of the Sea ice called ice. Most of the West Antarctic ice through Ross and Ronne ice shelves into the sea. East Antarctic ice Antarctic ice sheet ice volume has more than 80%, is a maximum elevation of over 4000 meters of dome-shaped ice. In addition to individual small areas, the underlying bedrock were above sea level. Total area of ​​the Greenland ice sheet 1,802,400 km2, with a total storage capacity of 2.34 million cubic kilometers, if all melted, sea level would rise 7 meters world. The average thickness of the Greenland ice sheet 1515 m, near the center of the largest ice sheet thickness 3408 m. The highest point of the Greenland ice sheet elevation of 3157 m, with an average height of 2135 meters. Antarctic Antarctic ice sheet began in late Oligocene. Dating back at least five million years ago reached its present size. Most distributed in the Antarctic ice sheet circle diameter of about 4500 kilometers, an area of ​​about 13,980,000 square kilometers, accounting for about 98% of the area of ​​the Antarctic continent. The average thickness of 2000 to 2500 m, the maximum thickness of over 4000 m. The total ice volume of about 24.5 million cubic kilometers, accounting for the world's land ice volume 90%, 70% of total freshwater. Ice sheets are developed peripheral area of ​​about 1.5 million square kilometers of the ice shelf, mainly in the Ross Ice Shelf, Filchner Ice Shelf and the Amery Ice Shelf and so on. In the inland ice sheet supply and promotion of the ice shelf edge a large number of landslides constantly topped iceberg. Antarctic ice sheet from east and west part of the synthesis, in order to traverse the Antarctic mountain range is bounded. Antarctic ice sheets are cold glacier. Is characterized by low temperature, a small amount of accumulation and ablation, long slow ice formation, such as high altitude station (latitude 79 ° 15 ', longitude 40 ° 30') into the ice process takes 3500 years, so relatively stable. Antarctica is Earth's most dry and cold areas, the annual average temperature plateau as low as -55 ℃, annual precipitation is less than 50 mm, the ice all year round, ice formation process slow. Ice edge average annual temperature is -10 ~ -15 ℃, the highest minimum temperature of 10 ℃ and -40 ℃, annual precipitation is 200 to 500 mm in summer (November to next February) snow and ice ablation strongly ablation zone altitude of 1000 to 1400 meters below the snow line altitude sector in the 0 to 100 meters. Therefore, the Antarctic ice sheet is a typical inland polar continental glaciers, coastal zones and the Antarctic Peninsula are having a polar maritime glaciers properties. Antarctica is Earth's largest freezer and cold source, its formation and development of global climate change, sea level changes and human life have a significant impact. If all of the Antarctic ice sheet melted, the world ocean will rise by about 60 meters. Greenland formed in the Quaternary, about 18,000 years ago when the ice cover over this area seven times, and is connected with the then North American ice sheet. Greenland, mostly in the Arctic Circle, the island area of ​​2,180,000 square kilometers, is the world's largest island. Greenland ice sheet area of ​​about 1.8 million square kilometers, with an average thickness of about 1500 m, the maximum thickness of 3200 m, accounting for 7% of the world's ice ~ 9%. It consists of two north-south link from ice dome, to the sea ice edge has been covered with many glaciers tongue toward the sea, in some fjords in the formation of many icebergs. Some of West Greenland glaciers, such as Jakobshavn Glacier · Yi Sibo according to an annual flow rate of up to 7000 meters, is the world's fastest flowing glacier. Ice west of the ice surface of the central annual rate of 0.1 m in thickness, while the east side is slightly thinner. Ice ice surface ablation zone west coast thinning approximately 0.2 meters per year. Greenland ice sheet shows a stronger polar maritime glaciers in nature. Ice southwestern coast of the annual average temperature of up to 1 ℃, 1 January and July, the average temperature was -7.8 ℃ and 9.7 ℃, annual rainfall of 1000 mm, the amount of snow and ice accumulation and ablation are great. Ice sheet internal situation significantly different from the average annual temperature of about -30 ℃, 2 February and July, the average temperature was -47.2 ℃ and - 12.2 ℃, annual precipitation is only 200 mm, low temperatures, less precipitation, snow and ice accumulation volume and ablation was smaller, and the slow process of ice formation, such as the century camp (latitude 77 ° 11 ', longitude 61 ° 10') into the ice process takes 125 years. Edit this paragraph factors into ice ice formation ice formation continental ice sheet melt water in the absence of participation (only in the solid phase and the gas phase) carried out under cold type metamorphism called ice formation, or dry-type metamorphism ice formation. Ice formation process to subsidence and sublimation recrystallization based. Ice formed ice called primary recrystallization, this ice bubble much smaller particles (1 to 3 mm). Dry snow complementary ice time than temperate glaciers long. Temperature of Seward glacier about 13 m deep firn becomes ice time is only 3 to 5 years. Dorset Greenland glacier, at 66 meters deep into the ice time up to 100 years. East Antarctica standing 100 meters deep into the ice time as high as 4,000 years. Fabric Fabric ice ice finger morphology and distribution of bubbles, crystal size, shape and orientation. Structure of ice growth is mainly affected by stress type, total strain and temperature control on the assumption has been drilling ice cores in many fabric study, get a satisfactory explanation. Is generally believed that a multi-polar structure in a large group of well below the melting point of the ice can not form, but in the Antarctic station 2164 m deep borehole Byrd, about 650 to 974 m deep ice temperature of -28 ℃, ice fabric There are two or three very large portfolio. Throughout the continental ice sheets at 5 meters deep into ice and firn between the depths of the crystal at a constant rate of growth, after crystal growth rate decreased as the temperature decreases. Many studies have shown that holes: In modern ice and glacial ice latest at the boundary of the narrow crystal size obvious phenomenon. Unaffected strain in glacier ice cold generally spherical bubbles, the bubble shape deformation varies with ice. However, the edge of the ice caps Barnes latest glacial glacier ice characterized by containing a small spherical bubbles, even at the adjacent bed of ice, after such a strong shearing glacier sphere also found inside the bubbles. Mass balance of the climate is characterized by high-latitude low temperatures, the Antarctic Vostok near the average annual temperature is -56 ℃, the lowest temperature recorded was -88.3 ℃. Annual precipitation is less, about half of the Antarctic region net accumulation of less than 10 cm / year. Therefore, the accumulation of a small amount of continental ice sheets, ablation is weak, the low level of material balance. The ice is relatively stable. It is estimated that the annual Antarctic ice sheet mass balance ranged from +80 to -30 mm equivalent water depth, but most estimates is positive. Antarctic ice shelf edge material consumption is mainly the continued disintegration of a large amount of snow and strong winds blowing from the ice sheet. Because the temperature is low, ablation confined to favorable locations in the material expenditures subordinated. Greenland ice sheet mass balance estimates are also positive. The average total accumulation of 446 cubic kilometers / year,new mercurial 2013, with a total volume of 315 cubic kilometers ablation / yr water equivalent. According to information on 127 sites by latitude, longitude and altitude analysis showed that annual accumulation in northern Greenland, 15 to 50 g / cm, increasing from northeast to southwest. Southern Greenland highest value (more than 90 g / cm water equivalent) appear in the southeast coast, westward decrease. Edit this paragraph based on observations of natural characteristic temperature compared to the Greenland and Antarctic ice sheets many locations annual average temperature and 10 m deep firn temperature difference just within 2 ℃, the general trend is firn temperature just below the air temperature. This situation is only at the highest temperatures below 0 ℃ areas appear. According to the polar ice caps and glaciers in the temperature measurement, Byrd Antarctic station, Mir station, labor Dome White and Canadian Arctic glaciers are at the bottom of the melting point of ice temperature. Bottom temperature is equal to the freezing point of seawater ice shelf, bottom shelf heat flux depends on water temperature, salinity and sea water circulation under the ice shelf. Because the ice shelf replenishment, therefore, also affects the temperature distribution within the ice shelf temperature distribution. Sport ice and glaciers is no essential difference in mechanical properties, therefore, apart from the obvious differences (eg Gubi impact on glacier movement), the general theory of glacier movement still apply ice. Ice core precipitation hydrogen, oxygen, heavy, light atomic concentration ratio depends on the temperature. Therefore, the ice cores isotopic ratios with depth can be used to explain past temperature changes, such a climate record for inspection and glacial genesis theory of climate change is essential. Some ice core analysis has provided more than a dozen years to the most recent detailed climate information. More than 400 meters drilled ice core analysis obtained in the last 12 million years of climate records. Ice cores also contain small amounts of various substances from the atmosphere and scattered, like sea salt, pollen, wind and dust, volcanic ash, outer material (meteorites, etc.) and natural pollution and nuclear testing trace elements. Pre-industrial concentration of trace elements can be measured, comparing it with the current value, you can get the world-wide spread of pollutants information. Some fallout showed obvious seasonal changes,soccer cleats, such as particle concentration, trace elements (Na, Mg, Ca, K, AI) and polar snow oxygen and hydrogen isotope ratios. According to the information of these changes can be measured ice age and past precipitation rate. Fallout after the volcanic eruption and temperature changes can also be measured through the ice core analysis; ice within the ice bubbles of the past into the atmosphere when the sample. ■ Beijing at 14:45 on the 12th, 17 Chinese expedition Warriors after more than 21 days, 1286 km long and difficult journey, successfully climbed the highest point of the Antarctic inland ice sheet ■ This is the Chinese for the first time in human history, trek through the ground Arrival Dome A, once again successfully boarded the Antarctic "ice on top" "China firmament" sculpture stands Antarctic "ice on top" Height: 1.6 m Weight: 180 kg cast from brass. Sinan upper and lower stone Cong is engraved with the Seal text after up to 21 days, 1286 km long and difficult journey, Chinese Antarctic inland ice sheet of 17 expedition members at Beijing at 14:45 on the 12th, successfully boarded --- Antarctic inland ice sheet elevation of 4093 meters the highest point of the ice dome A. This is the January 18, 2005 China for the first time in human history, trek through the ground to reach Dome A, once again successfully boarded the Antarctic "ice on top." After the summit, the players held a solemn flag-raising ceremony, and to erect a "China firmament" Memorial Sculpture. Currently players in good physical condition, very excited. The day before the summit, the team members of altitude sickness worsened, so the summit was postponed for a day time. Players learned the news of the successful ascent, Chinese 24th Antarctic scientific expedition temporary party immediately from the Great Wall Station expedition to the inland ice sheet sent congratulatory messages, and that this good news to report to the State Oceanic Administration. Inland icecap expedition on December 22, 2007 from China Zhongshan Station, Antarctica ice sheet near the edge of departure. January 2 this year, Ping An expedition across from Zhongshan Station about 330-560 km of the ice crack intensive areas; January 4, reaches 806 km from Zhongshan Station eagle camp; January 6, successfully reached an altitude of 3000 meters above the plateau region; January 9, into the Antarctic Dome A core area. The inland ice sheet in Antarctica for China to establish a third scientific research station site to make early preparations while performing "International Polar Year" Chinese heart of the action plan --- Panda Plan: systematically carried glaciology, earth physics, astronomy and other several visits. Expedition plans to investigate Dome A region about 20 days. Implemented in the region, a series of scientific investigation, is expected to make China the Antarctic "ice on top" of the understanding reached a whole new level. More than 95% of the entire Antarctic continent of the area are covered by thick ice, like wearing a huge "white hat", known as "ice." Located at latitude 80 degrees 22 minutes east longitude 77 degrees 22 minutes of Dome A, is not only the highest point of the Antarctic inland ice sheet, but also by the international community recognized the commanding heights of the Antarctic research. In the past 12 years, China's scientific staff had five in-depth scientific investigation hinterland of the Antarctic ice sheet. How much focus buried under the Antarctic ice sheet scientific secrets? As the largest on earth, "cold", the Antarctic ice sheet scientists studying global climate change is a key area. □ Antarctica is Earth's southernmost "condenser" an area of ​​14 million square kilometers of Antarctica, more than 95% of the area covered by ice, as if was wearing a huge "hat", known as "ice cover. " Antarctica is Earth's largest ice sheet ice, the total world ice volume 90%. It is like an installation in the southern end of the earth "condenser", cooling the hot air from the equator to adjust the global heat balance, the impact of global climate change. Dome A is not only the highest area of ​​the Antarctic inland ice sheet has also been internationally recognized as the highest point of the Antarctic scientific research. Dome A region in the long term to carry out scientific observations, the study of global climate change is important. □ Antarctic ice cores is to record changes in Earth's gloomy "Repository" Antarctica ice sheet extrusion by the snow. Scientists drill through the ice core samples from the ice sheet. Bears precious ice core paleoclimate and environmental information, to find age-old ice core, as well as for the reconstruction of Earth's history evolution predict the evolution of the global climate and environmental significance. □ Antarctic ice plateau on Earth is the ideal place nearly ten years of astronomical research shows that the Earth's surface is excellent Antarctic millimeter, submillimeter, radio, infrared astronomy observatory site. The Antarctic Dome A because of its special geographical location, most likely the best Antarctic astronomical observatory sites. □ buried beneath the Antarctic ice sheet is unknown scientific secrets buried under the Antarctic ice sheet is unknown how many scientific secrets? Dome A region covered by ice, "Gan Bocai Fu" subglacial mountains, its rock structure how? How the ice sheet at the bottom of the environment? There is no subglacial lake? How subglacial drainage structure? Of the Antarctic scientific expedition in search of deep ice core at the same time, scientists will try to find subglacial lake, mountain contours exploratory ice, ice ridges migration dynamic evolution and tectonic theory Dome evidence to reveal the interior Dome A ice layer of ice flow recorded history and change mechanism, the rate of net accumulation of ice characteristics and temporal variation, Antarctic Dome A ice build depth and age of the relationship. Analysis of Chinese polar expedition from the big country into a powerhouse Beijing at 14:45 on January 12, Chinese Antarctic inland icecap expedition team boarded the Antarctic ice sheet elevation of 4093 meters the highest point --- ice dome A. This is the second time in human history, but also the history of China's second, this "summit" witnessed the Chinese polar expedition from the polar expedition power to power a solid step forward. Among the Earth's southernmost Antarctica, is competing countries demonstrate comprehensive national strength of the big stage, but also the national ethos of the expedition team members demonstrate scientific positions. Value from the point of view of scientific investigation, the Antarctic a total of four main points: extreme, freezing point, the magnetic point and high point. Currently the United States has been in the "South Pole", the French in the "South Pole magnetic point", the former Soviet Union in the "Antarctic freezing" the establishment of a research station; 2005, Chinese Antarctic expedition team finally highest point --- Dome A is also established its own research station. Antarctic expedition, is a long-term interests of the Chinese nation's strategic decisions. Despite the great Antarctic expedition in the international arena, China belatedly due to historical reasons, but the field of scientific research in the Antarctic China has made unremitting exploration, only in just 20 years time, China's Antarctic expedition has formed a "one ship "(" Snow Dragon "polar expedition ship)," two points "(Antarctic Great Wall Station and Zhongshan Station) and" a center "(China Polar Research Center) business support system and research platform. Information "China firmament" stands Antarctic "ice on top" stands in the Antarctic "ice on top" memorial sculpture "China sky", from Fuzhou University, Xiamen Academy of Art Sculpture Artist Wu Xi Huang's hands. Sculpture, 1.6 meters high and weighs 180 kg, cast from brass. "China firmament" sculpture upper Sinan, the lower is the stone Cong, engraved with the Seal text. Chinese Spring and Autumn Period invention Ian is a north-south direction, indicating the earliest guide device, is one of the four great inventions of ancient China --- the compass of the prototype. Shi Cong foreign inner circle, it appears four or five thousand years ago, China's ancient ritual of gift is one of the people on behalf of China's earliest understanding of heaven and earth, that is, "hemispherical dome." Sculpture engraved with 24 glittering big Zhuanti text, a positive word for "China firmament Antarctic Giant", both sides were "peaceful scientific use of the Antarctic" and "rejuvenating the benefit of mankind." Documented throughout the sculpture of the Chinese nation on the Antarctic, the magnetic field and the direction of the first to recognize, reflecting the nation's long history and splendid civilization. The back of the sculpture, a monument inscribed with text in English, recording Dome A location, altitude and the Chinese Antarctic expedition team and the difficult process of exploration and other scientific purposes. BACKGROUND [1] Chinese Antarctic inland ice sheet all previous first: in 1997, in China during the 13th Antarctic expedition, eight inspection team lasted 13 days, to the Antarctic inland ice sheet in the hinterland of the direction of advance of the Dome A 300 km. Second: In 1998, eight inspection team which lasted 17 days, the direction of advancing to the Dome A 464 km. During the inspection, the minimum temperature of minus 44.5 degrees Celsius, all the players face varying degrees of frostbite. Third: In 1999, 10 inspection team to enter the Dome A region. The icecap expedition lasted 50 days, and achieved fruitful results. Fourth: In 2002, eight inspection team at a distance of 170 km at Zhongshan Station erected an automatic weather station. Fifth: In 2005,adidas f50 2013, 13 inspection team for the first time in human history to reach the highest point of Dome A, and carried out scientific investigation work. Sixth: January 12, 2008, 17 Chinese Antarctic expedition team successfully boarded again Dome A, to carry out the Antarctic inland ice sheet.