Historical Antarctic station-based pressure changes in austral summer during the 20th century

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Sunday, 4 January 2015
Grant A. Witte, Ohio University, Athens, OH; and R. L. Fogt

Several recent studies point to a profound influence of stratospheric ozone depletion on the Antarctic pressure variations over the last 30 years. Yet, as with much of Antarctic data, researchers are left with neither long-term point (station) measurements of pressure variations across Antarctica, nor gridded pressure data from reanalyses or models that can be deemed reliable, given very little in situ data to constrain the solution across the high southern latitudes. Thus, it is not clear how unique these changes are in a longer historical context spanning the entire 20th century. Using reconstructions of Antarctic pressure based on the method of principal component regression, pressure variations across the austral summer since 1905 are examined for the first time. Notably, the reconstruction skill is the highest in austral summer compared to other seasons, allowing for a detailed investigation of the historical pressure variability. The poster will present several reconstructions from East Antarctica, the Antarctic interior, and the Antarctic Peninsula. It will be shown that there are significant negative pressure trends at many stations, most marked in East Antarctica, over the last 30 years. In the newly afforded historical context, these trends are the strongest they have been over the last century, highlighting the uniqueness of stratospheric ozone depletion on the austral summer Antarctic circulation. Future work includes examining other seasons as well as comparing the reconstructions to climate model simulations with different forcing mechanisms.