Master Thesis defence - Luca Foresta – Niels Bohr Institute - University of Copenhagen

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Master Thesis defence - Luca Foresta

An attempt of obtaining a chronologically correct reconstruction of the NEEM disturbed section.

The North Greenland Eemian Ice Drilling (NEEM) project was specifically aimed at retrieving ice spanning the entire previous interglacial period, the Eemian. Such period is highly interesting because the temperature was ∼5°C warmer with respect to present conditions and models estimate a temperature rise of 2-6°C by the end of the century (NGRIPmembers et al., 2004; IPCC, 2007). Drilling activities ended in 2010 when bedrock was reached at 2537.36m depth. The last section of the core contains clear evidence of Eemian ice characterized by 'high' d18O values, far above the average level of the younger glacial ice. Nevertheless, below ∼2200m depth, the stratigraphy appears to be corrupted, as it was at Summit (GISP2 and GRIP ice cores, Greenland).

The aim of this work is to investigate the possibility to obtain a chronologically consistent representation of the deepest part of the NEEM ice core. The  disturbed data were broken into intervals, rearranged by the use of selected operations in order to create candidate solutions. Each possible solution was compared to a reference profile, a function built by combining real data (NGRIP) to a reconstruction of Greenland d18O variability from Barker et al, 2011 (an application of the inverse bipolar seesaw model).  In order to perform the comparisons, a dedicated algorithm, originally used in the image registration field,  was developed. Such routine estimates the scale and translation factors which best align two any given functions, not necessarily ice core data. Finally, the method was also applied to the Summit disturbed data sections in order to check whether common features might arise.

Supervisors: P. Ditlevsen and P. Langen