Niels Bohr Institutet > Kalender - det sker på NBI > 2010 > Master's Thesis Defense
Master's Thesis Defense
Monday, April 12th, Christopher Stowasser defends his Master's thesis. The title of the thesis is "A novel laser-based technique for continuous measurements of methane concentrations from deep ice cores".
Supervisor: Thomas Blunier
Censor: Peter Aakjær
Abstract:
The analysis of stable water isotopes, gas bubbles and impurities trapped in ice provides knowledge of earth's past climate. Deep ice cores from Greenland act as climate archives for more than the last 123,000 years covering the Holocene, the last glacial period and parts of the previous interglacial period called the Eemian.
This thesis presents preparation and first field tests of a novel laser-based method for measuring methane concentrations from deep ice cores with high precision and high temporal resolution. Measurements are carried out by a near-infrared cavity ring-down spectrometer which is connected to the field-deployable Continuous Flow Analysis system from the University of Bern. Here, air bubbles are continuously extracted from the melted ice core samples and are forwarded into the spectrometer for methane concentration measurements.
During the 2009 field season of the North Greenland Eemian Ice Drilling project (NEEM) methane concentrations were measured along 12.1 meters of ice core from the early Holocene period. These experiments showed that the method is suited for field measurements and yields an unprecedented temporal resolution. However, the precision of the method is not yet comparable to conventional discrete methods for measuring methane concentrations from ice cores and needs to be improved. Experiences from this first test season helped to locate the problem of precision and improvements are presented which will be implemented before the 2010 field season.