Ice core evidence for secular variability and 200-year dipolar oscillations in atmospheric circulation over East Antarctica during the Holocene

• Published in: Climate Dynamics
• Main Authors: Delmonte, B, Petit, JR, Krinner, G, Maggi, V, Jouzel, J, Udisti, R
• Other Authors: Petit, J
• Format: Article in Journal/Newspaper
• Language: English
• Published: Springer 2005
• Subjects: atmospheric circulation; Holocene; ice core; Antarctic; East Antarctica; Southern Ocean; The Antarctic; Antarc*; Antarctica; EPICA
• Online Access: http://hdl.handle.net/10281/307; https://doi.org/10.1007/s00382-005-0012-9

Two Holocene ice core records from East Antarctica (Vostok and EPICA-Dome C) were analysed for dust concentration and size distribution at a temporal resolution of 1 sample per ∼50 years. A series of volcanic markers randomly distributed over the common part of the ice cores (from 9.8 to 3.5 kyear BP) ensures accurate relative dating (±33 years). Dust-size records from the two sites display oscillations structured in cycles with sub-millennial and secular scale frequencies that are apparently asynchronous. The power spectra of the composite sum (∑) of the two dust-size records display spectral energy mostly for 150- to 500-year periodicities. On the other hand, the 200-year band is common to both records and the 200 year components of the two sites are out-of-phase (100-year lead or lag) over ∼5.5 kyear, a phenomenon also reflected by a significant (>99% conf. lev.) band in the power spectra of the composite difference (Δ) of the two size records. During long-range transport, mineral dust originating from the Southern Hemisphere continents is graded to a variable extent depending on the altitude and duration of atmospheric transport. Relatively coarse dust is associated with air mass penetration from the middle-lower troposphere and conversely relatively fine dust with upper troposphere air masses or the influence of subsidence over the Antarctic plateau, a hypothesis already proposed for the changes that occurred during the Last Glacial Maximum to Holocene transition (Delmonte et al. 2004b). Moreover, we assume that the overall fluctuation of air mass advection over Antarctica depends on the meridional pressure gradient with respect to low latitudes, i.e. the Antarctic Oscillation (AAO). We therefore suggest a regional variability in atmospheric circulation over East Antarctica. The 150-500 year power spectrum of the composite (∑) parameter represents the long term variability of the AAO, imprinted by secular internal oscillations probably related to the southern ocean-climatic system. On the other hand, the ...