South Georgia sits amidst the furious if not screaming fifties latitude belt, the circum Antarctic westerlies. This region is famous for the endless march of storms parading around Antarctica. The island is south of the Antarctic Convergence, preventing any truly warm season from persisting. The cool maritime climate leads to numerous glaciers covering a majority of the island and quite low equilibrium line altitudes. Sugden, Clapperton and Pelto (1989-sorry no good link to this paper, one of the first I worked on), 1989 noted the ELA of Neumayer Glacier at 550 m. The tidewater glaciers of South Georgia in general maintained fairly advanced positions unitl 1980. Gordon et al., (2008) observed that larger tidewater and sea-calving valley and outlet glaciers generally remained in relatively advanced positions until the 1980s. After 1980 most glaciers receded; some of these retreats have been dramatic and a number of small mountain glaciers will soon disappear. Neumayer Glacier is one of the large tidewater glaciers on South Georgia. Maps from the British Antarctic Survey (BAS) and satellite imagery are used here to assess the changes in this glacier terminus position. A view of the entire glacier in 2006 from Google Earth, from beyond its calving terminus, indicates indicates the glacier remains vigorous with extensive crevassing at the calving front and extensive snowcover above the ELA. The BAS has a mapping function that provides glacier front positions since early in the 20th century. For Neumayer Glacier the 1938 position is 3.5 km down fjord from the 2006 position. There was essentially no retreat up to 1974 and limited retreat up to 1993. . In 2004 and 2009 NASA provided two images of Neumayer Glacier indicating retreat from 2004 when the glacier extended to the down fjord edge of a tributary glacier from the south. By 2009 the glacier has retreated upglacier of this now former tributary, this retreat is 1300 m. Landsat Image from 1999 to 2014 indicates retreat of 4800 m from the red to the green arrow , this is 320 m/year. The glacier appears to have retreated into a deeper section of the fjord then where it ended from 1970-2002. This will enhance calving from the glacier, and promote additional mass loss and retreat. This retreat will impact Konig Glacier which is connected to the Neumayer Glacier. Calving rate increases with water depth and the degree of glacier. Pelto and Warren (1991) provided an expanded version of the relationship first quantified by Brown and others (1982). In the you would have never guessed it category, is the glacier retreat has been an aid to the rat population, as the glacier tongues used to corner populations.
I was taught: roaring forties, furious fifties and screaming sixties… But I have no cite for that!
In this case which is worse furious or screaming? Furious sounds more punishing in terms of storms and screaming more persistent in terms of harshness.
I think it has more to do with alliteration… 😉
And here’s someone who agrees with me!
ELA = Equilibrium Line Altitude: The long term balance point along a glacier. The ELA is where the amount of accumulated snow and ablated water are equal (http://gemini.oscs.montana.edu/~geol445/hyperglac/systems1/).
Antarctic Convergence = a curve continuously encircling Antarctica where cold, northward-flowing Antarctic waters meet the relatively warmer waters of the subantarctic. Antarctic waters predominantly sink beneath subantarctic waters, while associated zones of mixing and upwelling create a zone very high in marine productivity, especially for Antarctic krill. This line, like the Arctic tree line, is a natural boundary rather than an artificial one, like a line of latitude. It not only separates two hydrological regions, but also separates areas of distinctive marine life associations and of different climates (wikipedia).
— Robert (n00b)
Well put the ELA often refers to the balance point for a particular year. The annual equilibrium line altitude is a good first assessment of the annual balance. If the annual ELA is above the long term ELA necessary for an equilibrium balance the glacier has a negative balance, if the annual ELA is lower a positive balance. An annual ELA can fall above the top of a glacier a