A 44 kyr paleoroughness record of the Antarctic surface

Two 788 m conductivity records from ice cores drilled at Dome C, Antarctica, provide an unprecedented opportunity to examine the past roughness of the Antarctic surface. By measuring the distribution of depth differences between synchronous events in the cores, the surface height distribution can be estimated during time intervals in the past. For the first time we publish a record of this type and consider its paleoclimatic implications. The paleoroughness, originating from sastrugi and dunes on the ice sheet surface, is hypothesized to be related to the wind speed, temperature, and accumulation rate during the period of preservation. The roughness record indicates only a slight decrease in the preserved surface roughness from the last glacial period (0.031 m root mean square (r.m.s.) of surface deviation) to the present (0.029 m r.m.s.). This result is surprising given the large change in temperature and accumulation rate that occurred during the last climatic transition. However, it could be consistent with modeling results suggesting low wind speeds on the East Antarctic Plateau during the last ice age if the possible influences of the accumulation and temperature changes are ignored. Additionally, the reliability of the Dome C ice core record is assessed, and the probability of short-term events being missing from the profile is determined. These results are of particular interest when constraining the proportion of events that may be synchronously matched with other ice cores. The principles and results present here allow inferences about the natural variation in ice core records generally.

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