DATE: Friday, March 29, 2019 TIME: 2:30 pm (refreshments at 2:15 pm) PLACE: ENR building, room 223 14 College Farm Road, New Brunswick, NJ
Ryan Fogt
Geography Department, Ohio University
A 20th century perspective of Antarctic pressure marked by variability, extremes, and change
During the late 20th Century, the Antarctic atmospheric circulation has changed and significantly influenced the overall Antarctic climate, through processes including a poleward shift of the circumpolar westerlies. However, little is known about the full spatial pattern of atmospheric pressure over the Antarctic continent prior to 1979. This presentation investigates surface pressure changes across the entire Antarctic continent back to 1905 from a newly developed station and spatial pressure reconstructions poleward of 60°S. The greatest reconstruction skill is in austral summer, which will be the primary focus. Historically, the reconstructions indicate that during the summer of the race for the South Pole in 1911-1912, Antarctica experienced both unusually high pressure and warm temperatures, quite differently impacting each polar party. Consistent with the relatively short observations, Antarctic pressure is marked with considerable interannual and multidecadal variability throughout the 20th century.
Climate models indicate a strong forced response in austral summer emerging after 1980, consistent with ozone depletion with a secondary, but important, role from tropical SSTs. Models also indicate a weaker forced response in austral autumn, and all seasons are characterized by above average pressure anomalies in the middle twentieth century. While these new datasets expand our knowledge of historical Antarctic climate, the skill is too low in the South Pacific / Amundsen Sea region to precisely understand long-term variations there, despite it being an important area of variability and ongoing change.