BEGIN:VCALENDAR VERSION:2.0 PRODID:-//Talks.cam//talks.cam.ac.uk// X-WR-CALNAME:Talks.cam BEGIN:VEVENT SUMMARY:A proxy-constrained history of 20th century atmospheric circulatio n in the Amundsen Sea and implications for glacier retreat - Gemma O'Conno r\, University of Washington DTSTART:20211108T140000Z DTEND:20211108T150000Z UID:TALK164440@talks.cam.ac.uk CONTACT:Dr. Shenjie Zhou DESCRIPTION:Atmospheric circulation around Antarctica is critical to many aspects of the climate system and influences the stability of the Antarcti c ice sheet. In the Amundsen Sea region\, wind-driven upwelling of warm ci rcumpolar deep water enhances glacier retreat. The paucity of climate data around Antarctica before 1979 makes it challenging to interpret recent cl imate activity. We use a proxy-data assimilation framework to reconstruct atmospheric circulation over the Southern Ocean\, with a focus on the Amun dsen Sea region. We use four different climate model priors and a global d atabase of proxy records. The reconstructions show good agreement with ava ilable verification data\, and reveal strengthening Southern Hemisphere we sterlies and a deepening Amundsen Sea Low through the 20th century. The re constructions agree with a subset of ensemble members in the historical "P acemaker" and "Large ensemble" simulations from the CESM climate model\, a llowing us to make inferences about the relative contributions of tropical variability and anthropogenic forcing in the Amundsen Sea region. The rec onstructions also suggest that individual large westerly events in the Amu ndsen Sea region\, such as that associated with the large 1939-1941 El Ni ño event\, may have played an important role in the initiation of glacier retreat. Ongoing work includes high resolution regional ocean modeling\, which can help us understand how ocean circulation responds to events and trends revealed by the reconstructions. LOCATION:British Antarctic Survey\, Zoom/British Antarctic Survey\, semina r room 2 END:VEVENT END:VCALENDAR