2015 Arctic

This project will further the understanding of ocean-ice-atmosphere interaction around the Jakobshavn Isbrae and Disko Bay region of west Greenland, with a particular focus on the role of sea surface temperature and sea ice variability in modulating past outlet glacier behavior and ice sheet/cap mass balance (snowfall and melt) over the past two centuries. The PIs will reconstruct past environmental conditions in the Disko and Baffin Bay region based on new glaciochemical and stratigraphic records from three 100-m deep ice cores, several firn cores, and geophysical studies from three sites surrounding Disko Bay.

This project will investigate the potential of carbon-14 in ice cores as an absolute dating tool, as a tracer of the past cosmic ray flux and as a recorder of the past fossil fraction of the global methane budget. Cosmic ray particles produce carbon-14 from oxygen-16 directly within near-surface glacial ice and firn. This in-situ produced carbon-14 quickly reacts to form 14C-containing carbon dioxide, carbon monoxide, and methane in the ice matrix. Some or all of the resulting 14C-bearing gases may be lost from the firn to the atmosphere. The proposed work will provide a thorough characterization of in-situ cosmogenic 14C in glacial firn and shallow ice in the Summit region of Greenland. It will examine the retention of cosmogenic 14C in ice grains at all depth levels in the firn column, the partitioning of 14C between carbon dioxide, carbon monoxide, and methane, as well as the production rates and accumulation of cosmogenic 14C in shallow ice below firn close-off.

This project will follow up on the serendipitous recent discovery that liquid water is present year-round within the firn layer of the southern Greenland Ice Sheet. This discovery complicates understanding of the relationship of surface melting on the ice sheet to sea level rise by revealing another pathway for meltwater to take. Even the most fundamental questions about the firn aquifer remain unanswered. This proposal will address three essential research questions: (1) What are the pathways and connections of the firn aquifer with the broader Greenland hydrologic system and what is the aquifer's effect on sea level rise? (2) What is the mass/volume of the liquid water stored in the Greenland firn aquifer? (3) What are the rates and patterns of water flow in the aquifer? These questions will be addressed using standard groundwater sampling techniques, seismic sounding, nuclear magnetic resonance, and ice core measurements.

This project will collect a new large diameter ice core near Summit, Greenland using the Blue Ice Drill (BID), providing ice from 80 to 170 meters depth (air age from about 1960 to about 1600 AD). The ice core will be analyzed to establish the first reliable record of pre-industrial carbon monoxide (CO) concentration and stable isotope composition in the Arctic atmosphere, which would also be representative of a large part of the Northern Hemisphere.

This project involves the seasonal (winter) acquisition of cores from ice-covered northern (U.S. Midwest) temperate lakes and rivers to investigate the spatial and temporal distribution of planktonic ice nucleating activity in freshwater ecosystems.