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Snow accumulation across Ekströmisen and Ritscherflya

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Citation:
Oerter, H. (2003): Snow accumulation across Ekströmisen and Ritscherflya , 21. Internationale Polartagung, Deutsche Gesellschaft für Polarforschung, Kiel, 17 March 2003 - 22 March 2003 .
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Abstract:

Snow accumulation is an important glaciological parameter for various kinds of studies in Antarctica. A traverse route runs from Neumayer station (70° 38.6S, 8° 15.5W) at the coast across Ekströmisen and Ritscherflya towards Kottasberge, Heimefrontfjella (Kottas camp 74° 12.3S, 9° 44.8W). This 410 km long route was marked in 1985/86 for the first time by bamboo stakes with a spacing of 500 m as route markers. From the beginning the stakes were used for accumulation studies as well. The stake line was re-established in the 1996/97 season starting at a waypoint in 9 km distance from the Neumayer station. Since then it was read and maintained each year. Only with the availability of GPS it was possible to locate the stakes precisely enough to correlate unambiguously the readings of two successive years. The accumulation profile shows great variability depending on surface topography and wind field. There are also considerable yearly variations. Near surface density (0-1 m depth) values obtained from snow pit studies allow to convert the stake readings to accumulation values in water equivalent units.The traverse route was subdivided into 9 sections. Section 1 represents the ice shelf area from the starting point (9 km distance to Neumayer station) to waypoint 70 km, section 2 the remaining ice shelf area to the grounding line, section 3 the first 48 km of the ascend to Ritscherflya. Sections 4, 5 and 6 are the next 45, 55, and 45 km, respectively. Section 7 represents the remaining 94 km towards Kottas camp, in front of Kottasberge. Section 8 runs from Kottas camp to Strømmebakken, the gate to cross Kottasberge. Section 9, finally, runs along Strømmebakken towards Amundsenisen. In total the stake line is 454 km long and in the 2001/02 season 911 stakes were used to calculate accumulation rates. The table shows the results for the 5years period 1997-2001: Distance along the 9 profile sections, the measured change in snow height related to a 1-year period and averaged for each section, the mean near surface density, and the mean accumulation rate. The standard deviation is a measure for the year to year variability.Section 1* 2** 3 4 5 6 7 8 9**Distance (km) 57 56 48 45 55 45 94 20 34Snow height (cm/a) 71.7 57.5 69.2 45.4 12.0 28.2 38.8 64.1 108.5Density (kg m-3) 423 440 455 425 500 418 365 385 370Mean accumulation (kg m-2 a-1) 249 199 240 157 42 98 135 223 376Standard deviation during 1997-2001 39 35 36 14 25 32 58 63* only 2000-2001, ** only 1998-2001The poster shows in addition the graphs of the stake readings for the years 1997 to 2001, and the results of the snow pit studies. It is remarkable that within section 5 the accumulation rates decreases to 43 kg m-2 a-1 only. Here one still can find the original stakes from 1984/85, which had been marked in the 1986/87 season by a tape 120 m above ground. Thus, theses very low accumulation values can be confirmed even over a period of 15 years. The decrease of accumulation must be due to the prevailing strong (katabatic) winds in this area.

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