Klimaforskning - hjemmeside
Startet av Jostemikk, november 29, 2011, 16:34:55 PM
SitatSea-ice conditions are now reported regularly in marinesynoptic observations, as well as by special reconnaissanceflights, and coastal radar. Especially importantly, satelliteobservations have been used to map sea-ice extentroutinely since the early 1970s. The American Navy JointIce Center has produced weekly charts which have beendigitised by NOAA. These data are summarized in Figure7.20 which is based on analyses carried out on a 1° latitudex 2.5° longitude grid. Sea-ice is defined to be present whenits concentration exceeds 10% (Ropelewski, 1983). Sinceabout 1976 the areal extent of sea-ice in the NorthernHemisphere has varied about a constant climatologicallevel but in 1972-1975 sea-ice extent was significantly less.
SitatThis tells us that 1974 Arctic ice coverage was similar to current coverage, which is also about two million km^2 less than 1979. But it is worse than it seems. The CIA published the document below in 1974, which tell us that prior to 1974, Arctic ice coverage was an additional 10% lower.
Sitat"Meridional flows" from the north at Spitzbergen (Svalbard) are also mentioned in that reference. These are a result of an Arctic Dipole. They also write of an average annual increase of shipping access to the island from 94 days to 157 days over the period from 1918 to 1939. The year with the most southern sea ice was 1917.
SitatThe 1905-1906 expedition Roosevelt in the Hudson-Fulton parade in 1909Peary's next expedition was supported by a $50,000 gift by George Crocker, who was the youngest son of Charles Crocker. Peary then used the money for a new ship. Peary's new ship Roosevelt battled its way through the ice between Greenland and Ellesmere Island to an American hemisphere farthest north by ship.
SitatIn 1907, Arctic explorer Robert Peary traveled along the northern coast of Canada's Ellesmere Island on a dog sled and described a "glacial fringe" along the island's northern coast. Modern glaciologists have deduced that this ice fringe formed roughly 4,500 years ago and, in Peary's time, was likely a continuous ice shelf covering some 8,900 square kilometers (almost 3,500 square miles). By the 1950s, much of that ice had disintegrated.By July 2008, what had once been a massive ice fringe along the northern Ellesmere coast had been reduced to five isolated ice shelves: Serson, Petersen, Milne, Ward Hunt, and Markham. (The Ayles Ice Shelf broke free in 2005.) These five ice shelves constituted the last remaining ice shelves in Canada.
Sitat fra: Jostemikk på mars 17, 2012, 22:24:13 PMDette er området der Peary seilte nordover mellom Grønland og Ellesmere Island. Nøyaktig hvor han ankret opp på nordsiden av Ellesmere Island har jeg ikke klart å finne ut, men jeg har markert det første stedet nord for øya som er så langt nord som 83 grader. Den andre pila markerer bare det faktum at det er på 83 grader nord.