Coast-to-interior gradients and recent trends in physical and chemical properties of near-surface snow and firn in northwest Greenland
Abstract
The Greenland Ice Sheet (GIS), which holds enough ice to raise global sea levels by approximately 7 m, is a major driver of Arctic and global climate. Observations over the past two decades have documented changes including notable increases in ice discharge, significant warming in coastal regions, and expanded areal extent of annual surface melt (e.g., Rignot and Thomas, 2002; Mote, 2007; Hanna and others, 2008). In contrast, observations document little change in temperature or accumulation in the central regions of the ice sheet (Hanna and others, 2008, 2011). The 1120 km-long Greenland Inland Traverse (GrIT), between Thule Air Base in northwest Greenland and Summit Station in central Greenland, is a logistics traverse that follows a nearly identical route taken by Carl Benson and the US Army Snow, Ice and Permafrost Research Establishment (SIPRE) between 1952 and 1955 (Benson, 1962). Observations from the SIPRE and GrIT traverses provide two snapshots of surface conditions across the northwest region of the GIS separated by 56 years. Hawley and others (in review) observe an increase in snow accumulation rates along the GrIT traverse route based on internal reflecting horizons in radar data dated with firn cores, with larger accumulation increases observed in the coastal region near Thule. Here we expand upon the analysis of Hawley and others (in review) by determining coast-to-interior gradients in snow accumulation, density, hardness (Rammsonde), and snow chemistry using samples from 18 snow pits and 3 firn cores collected during the 2010 and 2011 GrIT traverses. Snow pit and firn core samples were analyzed for trace element (23Na, 24Mg, 27Al, 32S, 39K, 44Ca, 47Ti, 51V, 52Cr, 55Mn, 56Fe, 59Co, 63Cu, 66Zn, 75As, 88Sr, 111Cd, 133Cs, 138Ba, 139La, 140Ce, 141Pr, 208Pb, 209Bi, 238U) concentrations and stable water isotope ratios (δD, δ18O), and were dated by seasonal oscillations in chemical concentrations and isotope ratios. We compare the GrIT data to those of Benson to determine changes in physical parameters over the past 56 years. Firn cores collected from coastal (2Barrel; 76.9317° N, 63.1467° W) and interior (Galen, 74.4223° N, 39.2943° W; Owen, 72.6° N, 38.5° W) locations along the traverse provide a multi-decadal context to the snow pit snapshots, and allow us to investigate temporal trends in accumulation. Furthermore, we utilize climate reanalysis data to investigate associated changes over the past half-century in surface temperature, atmospheric circulation (e.g., North Atlantic Oscillation) and sea ice extent.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2013
- Bibcode:
- 2013AGUFM.C13B0677W
- Keywords:
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- 0724 CRYOSPHERE Ice cores;
- 0736 CRYOSPHERE Snow;
- 0770 CRYOSPHERE Properties;
- 0726 CRYOSPHERE Ice sheets