As I tried to explain in Reply #18, I believe that the current downward fluctuation in Antarctic Sea Ice Extent if likely associated with the influence of our currently strong El Nino on the average location of the Amundsen Bellingshausen Sea Low, ABSL.
As discussed in both the reference in Reply #18 & the immediate following linked reference, during the satellite era the ABSL has largely been more westward (i.e. it is now more frequently centered nearer the eastern side of the Ross Sea where it more frequently promotes sea ice production) than its historic mean local (which is historically nearer to the ASE). Thus as we have now entered a positive PDO cycle, we can expect the ABSL to more frequently reposition eastward (back towards the Amundsen & Bellingshausen Seas). Indeed, during La Nina the ABSL is on average moved more westward closer to 140W, while during El Nino's the ABSL is on average moved more eastward closer to about 115W. The attached figure from Bertler et al 2006 (see reference at bottom of this post), which shows pictorially the relationship between the location of the Amundsen Sea Low (or Amundsen Bellingshausen Sea Low), ASL (or ABSL) and either a La Nina or an El Nino event.
Nerilie J. Abram, Robert Mulvaney, Françoise Vimeux, Steven J. Phipps, John Turner and Matthew H. England, (2014), "Evolution of the Southern Annular Mode during the past millennium", Nature Clim. Change (2014); doi:10.1038/nclimate2235
http://www.nature.com/nclimate/journal/v4/n7/full/nclimate2235.htmlAbstract: "The Southern Annular Mode (SAM) is the primary pattern of climate variability in the Southern Hemisphere, influencing latitudinal rainfall distribution and temperatures from the subtropics to Antarctica. The positive summer trend in the SAM over recent decades is widely attributed to stratospheric ozone depletion; however, the brevity of observational records from Antarctica—one of the core zones that defines SAM variability—limits our understanding of long-term SAM behaviour. Here we reconstruct annual mean changes in the SAM since AD 1000 using, for the first time, proxy records that encompass the full mid-latitude to polar domain across the Drake Passage sector. We find that the SAM has undergone a progressive shift towards its positive phase since the 15th century, causing cooling of the main Antarctic continent at the same time that the Antarctic Peninsula has warmed. The positive trend in the SAM since ~AD 1940 is reproduced by multimodel climate simulations forced with rising greenhouse gas levels and later ozone depletion, and the long-term average SAM index is now at its highest level for at least the past 1,000 years. Reconstructed SAM trends before the 20th century are more prominent than those in radiative-forcing climate experiments and may be associated with a teleconnected response to tropical Pacific climate. Our findings imply that predictions of further greenhouse-driven increases in the SAM over the coming century also need to account for the possibility of opposing effects from tropical Pacific climate changes."
Bertler, N.A., Naish, T.T., Mayewski, P.A. and Barrett, P.J., (2006), "Opposing oceanic and atmospheric ENSO influences on the Ross Sea Region, Antarctica", Advances in Geosciences, 6, pp 83-88, SRef-ID: 1680-7359/adgeo/2006-6-83.
