RELATIONSHIP BETWEEN THE SOUTHERN WESTERLY WINDS AND GLACIAL DYNAMICS AT THE SABRINA COAST, EAST ANTARCTICA AS DETERMINED BY BERYLLIUM ISOTOPE RATIOS

The Southern Westerly Winds which circulate clockwise around Antarctica are unique in that they have been largely unimpeded by landmasses since ca. 34 Ma, as opposed to the Northern Hemisphere winds which cross large continental masses as they circulate the globe. The unobstructed interaction of the Southern Westerly Winds with the Southern Ocean allows for ocean-atmosphere interaction. Variability in these interactions is largely related to the latitudinal position of the Southern Westerly Winds and the Antarctic Circumpolar Current fronts, systems which may shift depending on the temperature gradient in the atmosphere and ocean. The temperature gradients change along with glacial-interglacial cycles, though the manifestation of the resulting climate signal often differs by location.

The Sabrina Coast region of East Antarctica hosts the Totten Glacier, one of the largest East Antarctic glaciers most susceptible to climate change and a major outlet glacier of the Aurora Subglacial Basin. This subglacial basin is one of the largest in East Antarctica, holding 3 to 4 m sea level equivalent of ice. Marine sediment cores extracted from the continental slope and rise off the Sabrina Coast extend to at least 350 ka, containing records of multiple glacial-interglacial cycles. Here, beryllium-10 and beryllium-9 isotope ratios (¹⁰Be/⁹Be), along with grain size analysis and regional and global proxy data, are used to investigate the timing of glacial advance and retreat in this region of East Antarctica resulting from changes in the position of the Southern Westerly Winds from the last glacial period to the present.

The ¹⁰Be/⁹Be values fluctuate very little during the glacial period, indicating a relatively stable glacial system associated with a more northerly position of the Southern Westerly Winds during the glacial period. A southward shift of the Southern Westerly Winds after the Last Glacial Maximum induces large-scale glacial retreat in the Sabrina Coast region, as revealed by an abrupt increase in ¹⁰Be/⁹Be related to a sudden influx of fresh meltwater from the Antarctic continent. The results presented here demonstrate beryllium isotope ratios may be used as a proxy for Southern Westerly Wind position due to the relationship between shifts in the Southern Westerly Winds and Antarctic glacial dynamics.