Windblown diatoms at Little Dome C and their potential for reconstructing Southern Hemisphere Westerly Winds during the MPT

The Southern Hemisphere Westerly Winds play a crucial role in the Earth's climate system and may have influenced the physical and biological processes that drove CO2 exchange in the Southern Ocean during the Mid-Pleistocene Transition (MPT). Numerous paleoclimate archives have been utilised to reconstruct past westerly winds over different timescales; however, many are limited by their reliance on precipitation or temperature proxies to infer SHWW changes. Marine diatoms found in Antarctic ice core layers have recently established as a reliable proxy for directly reconstructing historical changes in wind strength and atmospheric circulation within the Southern Hemisphere Westerly Wind belt.

In this study, we present diatom records preserved in two snow pits from Little Dome C and in Holocene samples from the EPICA Dome C ice core. The annual abundance of diatoms preserved in Little Dome C snow layers strongly correlates with wind strength over South America and the South Atlantic sector of the Southern Ocean. Backward trajectory analyses enable us to trace the pathways of air masses before reaching the Little Dome C site, aiming to identify potential primary source regions for the Little Dome C diatoms. The strong positive correlation between Little Dome C diatoms and wind strength in South America and the South Atlantic highlights the potential to use diatoms preserved in the BE-OI as a proxy for reconstructing past changes in mid-latitude winds. This study lays the groundwork for further exploration of diatom records preserved in excess meltwater collected during the BE-OI slow CFA campaign.