Abstract
JOURNAL OF GEOPHYSICAL RESEARCH,
VOL. 114,
D11112,
14 PP., 2009
doi:10.1029/2008JD010475
Tropical Pacific–high latitude south Atlantic teleconnections as seen in δ18O variability in Antarctic coastal ice cores
Norwegian Polar Institute, Tromsø, Norway
Norwegian Polar Institute, Tromsø, Norway
Norwegian Polar Institute, Tromsø, Norway
Department of Mathematics and Statistics, University of Tromsø, Tromsø, Norway
Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany
Institute of Meteorology and Geophysics, University of Innsbruck, Innsbruck, Austria
Centre for Ice and Climate, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
Institute for Marine and Atmospheric Research, Utrecht University, Utrecht, Netherlands
Institute for Marine and Atmospheric Research, Utrecht University, Utrecht, Netherlands
We use a network of eight ice cores from coastal Dronning Maud Land (DML), Antarctica, to examine the role of the tropical ENSO (El Niño-Southern Oscillation) in the temporal variability of δ 18O in annual accumulation. The longest record from the S100 ice core covering the period 1737–1999 is used to analyze the teleconnections between the tropical Pacific and coastal DML on decadal scales and longer. A shorter stacked coastal DML δ 18O series spanning 1955–1999 is constructed to assess the variability of ENSO teleconnection on interannual scales. Results suggest that, on typical ENSO timescales of 2–6 years, the strength of the teleconnection varies in time, being stronger for years with generally negative phase of the Southern Annular Mode (SAM). On the timescales of approximately two decades (bidecadal), positive isotope anomalies are associated with oceanic warming and a westward sea surface temperature (SST) gradient in the equatorial Pacific. Bidecadal variability in SAM, forced by the tropical Pacific, is proposed as a critical element in the teleconnection. Our analysis suggests that a multidecadal positive trend in the annual mean δ 18O values from the analyzed cores can be indicative of the atmospheric warming that begun in this part of the DML already in the 1910s. The trend in δ 18O, quantified in terms of long-term surface air temperature (SAT) changes, is consistent with the instrumental data. Yet, we speculate that the accurate estimation of SAT trends requires an assessment of the potential role of secular SAM and sea ice extent changes in shaping the isotopic signal.
Received 22 May 2008; accepted 16 April 2009; published 9 June 2009.
Citation: (2009), Tropical Pacific–high latitude south Atlantic teleconnections as seen in δ18O variability in Antarctic coastal ice cores, J. Geophys. Res., 114, D11112, doi:10.1029/2008JD010475.
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