Reprinted from CLIMATE OF THE ARCTIC Printed in U. S. A. Temperature Measurements on Black Rapids Glacier, Alaska, 1973*
As part of reconnaissance work on Black Rapids Glacier, we measured near-surface temperatures in early April and July, 1973, at three sites. The highest site is at 1860 m altitude in the accumulation area. In April the 0 C isotherm was found at a depth of 9 m below the 1972 summer surface; by July t...
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.482.9046 http://ak.water.usgs.gov/glaciology/black_rapids/reports/1975 Temperature measurements on Bk Rapids - Harrison - Climate of Arctic.pdf |
| Summary: | As part of reconnaissance work on Black Rapids Glacier, we measured near-surface temperatures in early April and July, 1973, at three sites. The highest site is at 1860 m altitude in the accumulation area. In April the 0 C isotherm was found at a depth of 9 m below the 1972 summer surface; by July the snow and fim were isothermal at 0 C at all depths of temperature measurement. It is fairly likely that this condition is typical of the entire accumulation area. The second site is at an altitude of 1550 m, about 7 km below the equilibrium line. There the April and July temperatures were, respectively,-1.0 and-1.7 C at 10 m below the 1972 summer surface. The third site is at 1140 m in the ablation area and the temperatures were-0.6 and-1.2 C. Our measurements favor the classification of Black Rapids Glacier as temperate, except for the colder surface layer. In this case its surge behavior would not be due to thermal instability associated with alterna-tion between freezing and melting conditions at the bed. Several hundred glaciers in Alaska periodically flow at speeds 10 to 100 times greater than their "normal" flow rate; these are called surging glaciers. To date no satisfactory explanation of this surging behavior exists. A leading hypothesis (Robin, 1955; Hoffman and Clarke, 1972) states that a surging glacier is normally frozen to its bed and that surging recurs periodically when the bed is warmed to 0 C as the ice in the "ice reservoir " area gradually thickens while the glacier recovers from its previous surge. The in-[J ( PLANATION G> /'73 GO,A",. " I,MPEltlf,vRE SrAr,.",. o fO KllOH£T~RS |
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