Antarctica - Siple Station

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Records of the concentrations of dust, 18O, and SO42- for the last 550 years were obtained from a 302-m core drilled in 1985/86 at Siple Station (75o55'S; 84o15'W; 1054 m a.s.l.). The 302-m core was cut into 5757 samples for dust and 18O and 3492 samples for SO42-. The small sample size, and hence large number of samples, coupled with the well-preserved seasonality in both 18O and SO42- contributed to the excellent time scale estimated to have an accuracy of ± 5 years at A.D. 1435.

The excellently preserved stratigraphic sequences at Siple result from the high annual accumulation rate ( 0.54 m H2O eq.). This is illustrated in the photograph showing the drill tower extending out of the trench. The drilling, core processing and core storage was done in the trench because the accumulating and drifting snow buried everything on the surface within minutes.

The 550-year records of 18O and dust concentrations from Siple Station, Antarctica suggest warmer and less dusty atmospheric conditions from 1600 to 1830 A.D. which encompasses much of the northern hemisphere Little Ice Age (LIA). Dust and 18O data from South Pole Station indicate that the opposite conditions (e.g. cooler and more dusty) were prevalent there during the LIA. Meteorological data from 1945-85 show that the LIA temperature opposition between Amundsen-Scott and Siple, inferred from 18O, is consistent with the present spatial distribution of surface temperatures. There is some observational evidence suggesting that under present conditions stronger zonal westerlies produce a temperature pattern similar to that of the LIA. These regional differences demonstrate that a suite of spatially distributed, high resolution ice-core records will be necessary to characterize the LIA in Antarctica.

Dai, J., E. Mosley-Thompson and L.G. Thompson, 1991. Ice core evidence for an explosive tropical volcanic eruption 6 years preceding Tambora. Journal of Geophysical Research, 96(D9), 17,361-17,366.

Mosley-Thompson, E., L.G. Thompson, P. Grootes, and N. Gundestrup, 1990. Little Ice Age (Neoglacial paleoenvironmental conditions at Siple Station, Antarctica. Annals of Glaciology, 14, 199-204.

Mosley-Thompson, E. and L.G. Thompson, 1991. Spatial and temporal characteristics of the Little Ice Age: The Antarctic ice core record. In: The Role of the Polar Regions in Global Change. Ed: G. Weller (Symposium Volume for Conference), 606-610.

Mosley-Thompson, E., J. Dai, L.G. Thompson, P.M. Grootes, J.K. Arbogast, and J.F. Paskievitch, 1991. Glaciological studies at Siple Station (Antarctica): potential ice core paleoclimatic record. Journal of Glaciology, 37(125), 11-22.

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Last Updated: 7/26/96