Master thesis defense by Estelle L. Ngoumtsa

Title: A new reconstruction of climatic impurities in the Sub-Antarctic region
-Continuous Flow Analysis of the SubICE firn cores: Mertz, Siple, Bouvet, Peter-First, Young

Abstract: Paleoclimatic records from the Sub-Antarctic region are extremely sparse [King et al. 2019]. Investigation into this region offers a unique insight into mechanisms of Southern Hemisphere climate that are not yet well understood. This thesis details impurity reconstructions for five Sub-Antarctic firn cores, analysed by means of Continuous Flow Analysis (CFA) method. The cores were drilled during leg 2 and 3 of the Antarctic Circumpolar Expedition (ACE), and constitute the Sub-Antarctic Ice Core Expedition (SubICE). The cores are situated in ideal locations to capture changes in Circumpolar Westerly Winds (CWW) and the Antarctic Circumpolar Current (ACC); two of the key processes responsibe for the mixing and ventilation of the deep ocean. The SubICE cores: Mertz, Siple, Young, Bouvet and Peter-First were melted in the CFA system at The University of Copenhagen in June 2018. The system was setup in order to detect insoluble dust particles, Ca2+, NH+ 4 , H2O2, H+ and electrolytic meltwater conductivity. We present a high-resolution chemical analyses of the SubICE cores on a depth scale. Where data was available, we also include stable water isotopes, melt layer profiles, MSA and Na+ measurements provided by the British Antarctic Survey. In general, the cores exhibit vast amounts of melt and/or substantial dust deposition, in some cases, compromising the signal recorded in the lab. Despite these complexities, we hypothesise potential sources of distinct features in the data and discuss charecteristics such as accumulation, dust transport, sea ice extent and biotic influence across the islands. However, it is important to note that there is not enough evidence to make any solid claims here and further investigation is needed in these critical and fascinating locations.