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The Deuterium Excess record from the Siple Dome ice core. Annalisa Schilla, James White, Eric Steig, Ed Brook. Overview. Regional variation among Antarctic deuterium excess records Extra-Antarctic/Pacific climate signal in Siple Dome deuterium excess
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The Deuterium Excess record from the Siple Dome ice core Annalisa Schilla, James White, Eric Steig, Ed Brook
Overview • Regional variation among Antarctic deuterium excess records • Extra-Antarctic/Pacific climate signal in Siple Dome deuterium excess • A Holocene precession signal in the Ross Sea region?
Background • Deuterium excess is defined as: d=δD-8*δ18O (indexed to MWL) • Measure of kinetic fractionation, primarily SST (actual T change?) • Distinct signal from raw isotopes
Various Antarctic Moisture Sources Modified from Vimeux et al., 2001
Pacific as Siple Moisture Source Region • GCM and simple model results: coastal sites have > contribution from proximal ocean basin • Siple Dome moisture is dominated throughout the year by Pacific sources, from ~30ºS to the sea ice edge • Siple Dome • Siple Dome Delaygue et al., 2000
Siple d vs. Pacific Records • Siple d shares variability on several timescales with Pacific records
b) a) • Siple Dome • Siple Dome • Taylor Dome • Taylor Dome Precession at Siple Dome? • Moisture flux during (a) 1980 (normal year) and (b) 1982 (El Nino year). From Cullather et al., 1996. • Did ENSO variability really increase in the mid-Holocene (e.g., per Clement et al., 2000, Rodbell et al. 1999, Moy et al. 2000)?
Summary • Deuterium excess varies dramatically across Antarcticavarious moistures source regions • Moisture source region for Siple participates in global climate changes separately from Antarctica at a variety of timescales • Siple-Taylor isotope divergence through Holocenea precession signal?