Recent accumulation variability in northwest Greenland from ground-penetrating radar and shallow cores along the Greenland Inland Traverse

Abstract

ABSTRACT. Accumulation is a key parameter governing the mass balance of the Greenland ice sheet. Several studies have documented the spatial variability of accumulation over wide spatial scales, primarily using point data, remote sensing or modeling. Direct measurements of spatially extensive, detailed profiles of accumulation in Greenland, however, are rare. We used 400 MHz ground-penetrating radar along the 1009 km route of the Greenland Inland Traverse from Thule to Summit during April and May of 2011, to image continuous internal reflecting horizons. We dated these horizons using ice-core chemistry at each end of the traverse. Using density profiles measured along the traverse, we determined the depth to the horizons and the corresponding water-equivalent accumulation rates. The measured accumulation rates vary from $0.1 m w.e. a

Annual Greenland accumulation rates (2009–2012) from airborne snow radar

“…First, to characterize density across the GrIS, we extract the snow/firn density measurements ranging in depth from the snow surface to 15 m (the depth to which MAR predicts firn density), which contains over 1500 measurements from snow pits and cores at 62 sites. At each site, the number of measurements ranges in number between 8 and 170 and maximum depths range from 1 to 15 m. (Koenig et al, 2014;Koenig and SUMup, 2015;Miège et al, 2013;Mosley-Thompson et al, 2001;Hawley et al, 2014;Baker, 2012) (Fig. 1).…”

“…Mosley-Thompson et al, 2001). A recent traverse and study by Hawley et al (2014) reports a 10 % increase in accumulation rate since the 1950s and highlights the need to monitor how Greenland precipitation is evolving in the midst of ongoing climate change. Although many other accumulation-rate measurements exist, they are more limited in either space or time (e.g.…”

“…Although many other accumulation-rate measurements exist, they are more limited in either space or time (e.g. Dibb and Fahnestock, 2004;Hawley et al, 2014).…”

Multi-Channel Ground-Penetrating Radar for the Continuous Quantification of Snow and Firn Density, Depth, and Accumulation

“…The stratigraphic horizons within the firn of the dry-snow accumulation zone are known to be isochronous -depositional surfaces of a constant age (Jacobel & Hodge, 1995;Siegert et al, 1998;Eisen et al, 2004;Hawley et al, 2014;Macgregor et al, 2015). Though, the radiostratigraphy does not necessarily represent annual histories from buried melt-refreeze or hoar layers forming during the summer-fall transition, as reported in this work (Section 3.3.1).…”

“…Mechanical characteristics of the snow/firn density and pore structure give rise to the stratigraphy sensed in the electromagnetic domain (Arcone et al, 2004). The continuous nature of the snow/firn layers allows for large spatial correlation of the stratigraphic depth-age scale (Hawley et al, 2014;Macgregor et al, 2015).…”