Multi-Channel Ice Penetrating Radar Traverse for Estimates of Firn Density in the Percolation Zone, Western Greenland Ice Sheet

TitleMulti-Channel Ice Penetrating Radar Traverse for Estimates of Firn Density in the Percolation Zone, Western Greenland Ice Sheet
Publication TypeConference Proceedings
Year of Conference2017
AuthorsMeehan, Tate, Bradford John, Marshall H.P., Osterberg Erich, Hawley Bob, Hawley Bob, Overly Thomas, Lewis Gabe, Graeter Karina, and McCarthy Forrest
Conference Name85th Annual Western Snow Conference
Date Published2017
Conference LocationBoise, Idaho
Abstract

To better predict the response of the Greenland Ice Sheet (GrIS) to future warming, leading edge Regional
Climate Models (RCM) must be calibrated with in situ measurements of recent snow accumulation and ablation.
Mass balance estimates averaged across the entire Greenland Ice Sheet (GrIS) vary between models by more than 30
percent, and regional comparisons of mass balance reconstructions in Greenland vary by 100 percent or more.
Greenland Traverse for Accumulation and Climate Studies (GreenTrACS) is a multi-year and multi-disciplinary
science traverse in the western percolation zone of GrIS. During spring 2016, we used multi-channel 500MHz radar
in a multi-offset configuration to survey more than 800 km from Raven Camp towards Summit Station. Multi-offset
radar measurements can provide high precision electromagnetic (EM) velocity estimates of the firn to within ±0.003
m/ns. EM velocity, in turn, can be used to estimate firn density. Using the CRIM equation we estimate the average
firn density to a depth of ~25 meters. Preliminary radar-derived average density estimates agree with cumulative
average density estimates from a firn core measurement (~40 kg.m-3), despite the spatial heterogeneity of the firn.
(KEYWORDS: multi-offset, GPR, Greenland, Ice Sheet, GreenTrACS, firn, density)

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