Recent advances in the reconstruction of the Antarctic Oscillation: The used of regional well-replicated tree-ring chronologies

VILLALBA R.; LARA A.; MASIOKAS M.; BONINSEGNA J.; COOK E.; LUCKMAN B.; SCHNEIDER D.; ARAVENA J.; MORALES M.; CHRISTIE D.; URRUTIA R.; MUNDO I.; HOLZ A.; ARANEO D.; NUEKOM R.; FENWICK P.; PALMER J.

Valdivia, Chile

Otro; Third Science meeting, IAI Collaborative Research Network 2047; 2010

IAI

The Antarctic Oscillation (AAO) is the dominant pattern of climate variability at mid- to high-latitudes in the Southern Hemisphere (SH). AAO anomalies are related to climate changes over Antarctica and temperate regions of South America, New Zealand, Australia and South Africa. The positive phase of the AAO is associated with a cooling across E Antarctica and central Australia, and a warming over the Antarctic Peninsula, S Patagonia, Tasmania and S New Zealand. This positive phase is also related to anomalously dry conditions over SW South America, New Zealand and Tasmania and to wet conditions over much of Australia and South Africa. A high-resolution proxy network from mid- to high-latitudes in the SH was used to reconstruct past variations in the AAO. 338 tree-ring chronologies from South America, New Zealand, and Tasmania, were grouped into regional, well-replicated records. Tree-ring records were complemented with annually-resolved ice cores from Antarctica. Conservative standardization methods were used to preserve low-frequency oscillations in the reconstructions. The reconstructions explain over 50 % of the total variance in the instrumental AAO in the interval 1949-2001. Consistent with observational records, most reconstructions show a positive trend in the AAO during the past 50 years, suggesting significant changes in the atmospheric circulation in the SH.