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Ice-sheet Dynamics
Ice sheet dynamics describe the motion within large bodies of ice, such those currently on Greenland and Antarctica. Ice motion is dominated by the movement of glaciers, whose gravity-driven activity is controlled by two main variable factors: the temperature and the strength of their bases. A number of processes alter these two factors, resulting in cyclic surges of activity interspersed with longer periods of inactivity, on both hourly and centennial time scales. Ice-sheet dynamics are of interest in modelling future sea level rise. General Boundary conditions The interface between an ice stream and the ocean is a significant control of the rate of flow. Ice shelves are thick layers of ice floating on the sea – can stabilise the glaciers that feed them. These tend to have accumulation on their tops, may experience melting on their bases, and calve icebergs at their periphery. The catastrophic collapse of the Larsen B ice shelf in the space of three weeks during Feb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antarctica Glacier Flow Rate
Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest continent, being about 40% larger than Europe, and has an area of . Most of Antarctica is covered by the Antarctic ice sheet, with an average thickness of . Antarctica is, on average, the coldest, driest, and windiest of the continents, and it has the highest average elevation. It is mainly a polar desert, with annual Climate of Antarctica#Precipitation, precipitation of over along the coast and far less inland. About 70% of the world's freshwater reserves are frozen in Antarctica, which, if melted, would raise global sea levels by almost . Antarctica holds the record for the Lowest temperature recorded on Earth, lowest measured temperature on Earth, . The coastal regions can reach temperatures over in summer. Native Wildlife of Antarctica, spe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Green Glacier
Green Glacier () is a glacier on the east side of Graham Land, Antarctica, long and wide, flowing from the plateau northeast between Dugerjav Peak and Rugate Ridge, and then east into Vaughan Inlet next north of Pirne Peak and south of the terminus of Hektoria Glacier. It was surveyed by the Falkland Islands Dependencies Survey (FIDS) in 1955, and was named by the UK Antarctic Place-Names Committee for John R. Green, FIDS leader at Deception Island in 1950 and at the Argentine Islands The Argentine Islands are a group of islands in the Wilhelm Archipelago of Antarctica, situated southwest of Petermann Island, and northwest of Cape Tuxen on Kyiv Peninsula in Graham Land. They were discovered by the French Antarctic Expeditio ... in 1951. References Glaciers of Oscar II Coast {{OscarIICoast-glacier-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aerial Photo Of Monte Rosa Massif - Wallis - Switzerland (cropped)
Aerial may refer to: Music * ''Aerial'' (album), by Kate Bush * ''Aerials'' (song), from the album ''Toxicity'' by System of a Down Bands *Aerial (Canadian band) * Aerial (Scottish band) * Aerial (Swedish band) Performance art * Aerial silk, apparatus used in aerial acrobatics *Aerialist, an acrobat who performs in the air Recreation and sport * Aerial (dance move) *Aerial (skateboarding) *Aerial adventure park, ropes course with a recreational purpose * Aerial cartwheel (or side aerial), gymnastics move performed in acro dance and various martial arts *Aerial skiing, discipline of freestyle skiing *Front aerial, gymnastics move performed in acro dance Technology Antennas *Aerial (radio), a radio ''antenna'' or transducer that transmits or receives electromagnetic waves **Aerial (television), an over-the-air television reception antenna Mechanical *Aerial fire apparatus, for firefighting and rescue *Aerial work platform, for positioning workers Optical *Aeri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dansgaard–Oeschger Event
Dansgaard–Oeschger events (often abbreviated D–O events), named after palaeoclimatologists Willi Dansgaard and Hans Oeschger, are rapid climate fluctuations that occurred 25 times during the last glacial period. Some scientists say that the events occur quasi-periodically with a recurrence time being a multiple of 1,470 years, but this is debated. The comparable climate cyclicity during the Holocene is referred to as Bond events. Evidence The best evidence for Dansgaard–Oeschger events remains in the Greenland ice cores, which only go back to the end of the last interglacial, the Eemian interglacial (about 115,000 years ago). Ice core evidence from Antarctic cores suggests that the Dansgaard–Oeschger events are related to the so-called Antarctic Isotope Maxima by means of a coupling of the climate of the two hemispheres, the Polar see-saw. If this relationship holds also for the previous glacials, Antarctic data suggest that D-O events were present in previous glacia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Periodic Function
A periodic function is a function that repeats its values at regular intervals. For example, the trigonometric functions, which repeat at intervals of 2\pi radians, are periodic functions. Periodic functions are used throughout science to describe oscillations, waves, and other phenomena that exhibit periodicity. Any function that is not periodic is called aperiodic. Definition A function is said to be periodic if, for some nonzero constant , it is the case that :f(x+P) = f(x) for all values of in the domain. A nonzero constant for which this is the case is called a period of the function. If there exists a least positive constant with this property, it is called the fundamental period (also primitive period, basic period, or prime period.) Often, "the" period of a function is used to mean its fundamental period. A function with period will repeat on intervals of length , and these intervals are sometimes also referred to as periods of the function. Geometrically, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hartmut Heinrich
Hartmut Heinrich (born 5 March 1952 in Northeim, Lower Saxony) is a German marine geologist and climatologist. Heinrich was Head of the Marine Physics Department at the Federal Maritime and Hydrographic Agency (''BSH'') in Hamburg until September 2017. He was actively involved in global Argo Ocean Observing Programme, environmental research and administration, and adaptation to climate change. In 1988 he described the suddenly occurring climate changes in the history of the Earth, which have since been named after him, Heinrich events. Since October 2017 he is freelancer (10°E maritime consulting) for climate and environment. In October 2017 the Free and Hanseatic City honoured his important contribution to climatic research with the title "Professor ''honoris causa''". Heinrich studied geology at the University of Göttingen and attained a doctorate at the University of Kiel in marine geology. The discovery that was named for him, Heinrich events, periods of substantial ice ou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heinrich Events
A Heinrich event is a natural phenomenon in which large groups of icebergs break off from glaciers and traverse the North Atlantic. First described by marine geologist Hartmut Heinrich (Heinrich, H., 1988), they occurred during five of the last seven glacial periods over the past 640,000 years (Hodell, et al., 2008). Heinrich events are particularly well documented for the last glacial period but notably absent from the penultimate glaciation (Obrochta et al., 2014). The icebergs contained rock mass that had been eroded by the glaciers, and as they melted, this material was dropped to the sea floor as ice rafted debris (abbreviated to "IRD") forming deposits called Heinrich layers. The icebergs' melting caused vast quantities of fresh water to be added to the North Atlantic. Such inputs of cold and fresh water may well have altered the density-driven, thermohaline circulation patterns of the ocean, and often coincide with indications of global climate fluctuations. Various me ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ice Rafted Debris
Ice rafting is the transport of various materials by ice. Various objects deposited on ice may eventually become embedded in the ice. When the ice melts after a certain amount of drifting, these objects are deposited onto the bottom of the water body, e.g., onto a river bed or an ocean floor. These deposits are called ice rafted debris (IRD) or ice rafted deposits. Ice rafting was a primary mechanism of sediment transport during glacial episodes of the Pleistocene when sea levels were very low and much of the land was covered by large masses (sheets) of ice. The rafting of various size sediments into deeper ocean waters by icebergs became a rather important process. Ice rafting is still a process occurring today, although its impact is significantly less and much harder to gauge. The melting of large icebergs deposits sediment of various sizes, usually referred to as glacial marine sediment, onto the shelf and deeper marine areas. Ice rafting may be used for analysis of ice drif ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Laurentide Ice Sheet
The Laurentide Ice Sheet was a massive sheet of ice that covered millions of square miles, including most of Canada and a large portion of the Northern United States, multiple times during the Quaternary glacial epochs, from 2.58 million years ago to the present. The last advance covered most of northern North America between c. 95,000 and c. 20,000 years before the present day and, among other geomorphological effects, gouged out the five Great Lakes and the hosts of smaller lakes of the Canadian Shield. These lakes extend from the eastern Northwest Territories, through most of northern Canada, and the upper Midwestern United States (Minnesota, Wisconsin, and Michigan) to the Finger Lakes, through Lake Champlain and Lake George areas of New York, across the northern Appalachians into and through all of New England and Nova Scotia. At times, the ice sheet's southern margin included the present-day sites of coastal towns of the Northeastern United States, and cities such as Bos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Milankovitch Cycles
Milankovitch cycles describe the collective effects of changes in the Earth's movements on its climate over thousands of years. The term was coined and named after Serbian geophysicist and astronomer Milutin Milanković. In the 1920s, he hypothesized that variations in eccentricity, axial tilt, and precession combined to result in cyclical variations in the intra-annual and latitudinal distribution of solar radiation at the Earth's surface, and that this orbital forcing strongly influenced the Earth's climatic patterns. Earth's movements The Earth's rotation around its axis, and revolution around the Sun, evolve over time due to gravitational interactions with other bodies in the Solar System. The variations are complex, but a few cycles are dominant. The Earth's orbit varies between nearly circular and mildly elliptical (its eccentricity varies). When the orbit is more elongated, there is more variation in the distance between the Earth and the Sun, and in the amount of S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Insolation
Solar irradiance is the power per unit area (surface power density) received from the Sun in the form of electromagnetic radiation in the wavelength range of the measuring instrument. Solar irradiance is measured in watts per square metre (W/m2) in SI units. Solar irradiance is often integrated over a given time period in order to report the radiant energy emitted into the surrounding environment (joule per square metre, J/m2) during that time period. This integrated solar irradiance is called solar irradiation, solar exposure, solar insolation, or insolation. Irradiance may be measured in space or at the Earth's surface after atmospheric absorption and scattering. Irradiance in space is a function of distance from the Sun, the solar cycle, and cross-cycle changes.Michael Boxwell, ''Solar Electricity Handbook: A Simple, Practical Guide to Solar Energy'' (2012), p. 41–42. Irradiance on the Earth's surface additionally depends on the tilt of the measuring surface, the height ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Circumpolar Deep Water
Circumpolar Deep Water (CDW) is a designation given to the water mass in the Pacific and Indian oceans that is a mixing of other water masses in the region. It is characteristically warmer and saltier than the surrounding water masses, causing CDW to contribute to the melting of ice shelves in the Antarctic region. Physical Properties CDW, the greatest volume water mass in the Southern Ocean, includes the North Atlantic Deep Water (NADW), the Antarctic Bottom Water (AABW), Antarctic Intermediate Water (AAIW), as well as recirculated deep water from the Indian and Pacific Oceans. A distinguishing characteristic of the CDW is that the water is not formed at the surface, but rather by a blending of other water masses. CDW sits at a depth of around 500 meters, approximately at the depth of the continental shelf. There are two types of CDW: Upper Circumpolar Deep Water (UCDW) and Lower Circumpolar Deep Water (LCDW). UCDW originates in the Indian and Pacific Oceans and has lower o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
