Collaborative Research: Reconstruction and Understanding of Antarctic Circulation Variability and Trends since 1905

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Patterns of variability in sea level pressure (SLP) are a potential diagnostic of the Antarctic atmospheric circulation, and may be used to model polar forcing mechanisms such as stratospheric ozone depletion, greenhouse gas (GHG) increases, tropical SST changes and intrinsic extra-tropical climate dynamics. Previous work has shown some skill in gridded reconstructions of temperature over Antarctica, yet no similar Antarctic-focused data sets exist for SLP. A few studies have recognized the fact that SLP variability over the Antarctic is the largest of any comparably sized region on Earth. This implies low signal-to-noise ratios. For both modeling and observation-based studies, long time periods need to be considered, not just the data-rich instrumented period since ~1979, in order to assess the roles of various types of forcing and to detect their signals. The project seeks to answer two sets of questions: (1) How has the Antarctic circulation changed during the last century, both at individual stations and across the continent? Are changes in the past three decades unique in the last 100+ years? (2) What mechanisms are associated with these changes, both in the zonal mean and regional circulation patterns? What is the range of natural (internal) variability, and what role do changes in SSTs, GHG forcing, and/or ozone depletion play in driving any of these changes?