Climatic signals from 76 shallow firn cores in Dronning Maud Land, East Antarctica

• Main Author: Altnau, Sebastian
• Format: Master Thesis
• Language: English
• Published: 2014
• Subjects: Massenbilanz; Wasser; Isotop; Dronning Maud Land; East Antarctica; shallow firn cores; stable isotopes; surface mass balance; signal-to-noise ratio; climatic signals; SAM; Neumayer; Neumayer Station; Antarc*; Antarctica; Ice Shelf
• Online Access: https://resolver.obvsg.at/urn:nbn:at:at-ubi:1-636

The spatial and temporal distribution of SMB and δ18O were investigated utilizing a set of 76 firn cores retrieved by various expeditions during the past three decades in Dronning Maud Land, East Antarctica. It was the first comprehensive study of this unique data set. The large number of cores was used to calculate stacked records of SMB and δ18O, which considerably increased the signal-to-noise ratio compared to earlier studies and facilitated the detection of climatic signals. Considerable differences between cores from the interior plateau and the coastal cores were found. Whereas the δ18O of both the plateau and the ice shelf cores exhibit a slight positive trend in both surface mass balance and δ18O over the second half of the 20th century, the SMB has a negative trend in the ice shelf cores, but increases on the plateau in the corresponding period. Comparison with meteorological data from Neumayer Station revealed that for the ice shelf regions atmospheric dynamic effects are more important than thermodynamics, while on the plateau, the temporal variations of SMB and δ18O occur mostly in parallel, thus can be explained by thermodynamic effects. The Southern Annular Mode (SAM) exhibits a positive trend since the mid-1960s, which is assumed to lead to a cooling of East Antarctica. This is not confirmed by the firn core data. Changes in the atmospheric circulation that result in a changed seasonal distribution of precipitation/accumulation could partly explain the observed features in the ice shelf cores. by Sebastian Altnau Innsbruck, Univ., Masterarb., 2014