The ¹⁴C signature of gases trapped in glacial ice contains a wealth of information. Potentially it could be used for determining the age of the gas through radiocarbon dating. Furthermore, the ¹⁴C variations in methane (CH₄) over the last glacial termination can teach us how much destabilization of (¹⁴C depleted) methane clathrates contributed to the CH₄ budget. In the ablation zone of Taylor Glacier, Antarctica, ice with ages between 11.5 and 65 kyr is being exposed. The large ice samples (>500 kg) required for high precision ¹⁴C measurements of trace gas species such as CH₄ and CO can easily be mined from near the glacier surface.

Efforts to interpret ¹⁴C data are complicated by in situ cosmogenic production of ¹⁴C in ice. Production rates fall exponentially with depth, with fast muons producing measurable amounts of ¹⁴C down to a depth of ~200m. Consequently the amount of ¹⁴C in surfacing ice parcels is a function of their flow path in the glacier. Using surface velocity, strain rate and ablation rate measurements we model flow lines of ablating Taylor Glacier ice. On integrating the production rates along the path we obtain a theoretical estimate of the total ¹⁴C production. Our sensitivity study shows that production rate uncertainties as reported in literature are the largest source of uncertainty, followed by ablation rate measurements and flow line modeling.

Measurements in the 2010-2011 field campaign focus on understanding in-situ ¹⁴C production in its own right. Sampling at a depth of ~10 m removes the neutron spallation component, after which we can study muogenic production in isolation. In combination with the exposure history modeling presented here, these measurements should significantly reduce the uncertainties in muogenic production rates reported in literature. In the future this work will serve as a framework for correcting ¹⁴CH₄ measurements for the effects of in situ production, which will allow determination of the true atmospheric signal.