A Firn Densification Process in the High Accumulation Dome of Southeastern Greenland. Issue 1 (1st February 2017)

• Record Type: Journal Article
• Authors: Iizuka, Yoshinori; Miyamoto, Atsushi; Hori, Akira; Matoba, Sumito; Furukawa, Ryoto; Saito, Takeshi; Fujita, Shuji; Hirabayashi, Motohiro; Yamaguchi, Satoru; Fujita, Koji; Takeuchi, Nozomu
• Is Part Of: Arctic, antarctic, and alpine research. Volume 49:Issue 1(2017)
• Page Start: 13
• Page End: 27
• Publication Date: 2017-02-01
• Subjects: Polar regions -- Periodicals; Alpine regions -- Periodicals; Alpine regions; Cold Climate; Arctic Regions; Electronic journals; Periodicals; 570.998
• DOI: 10.1657/AAAR0016-034
• Languages: English
• ISSNs: 1523-0430

Abstract

ABSTRACT: We examine a firn core from a dome in southeast Greenland that exhibits distinct firn densification. The ice was −20.9 °C at 20 m depth, and the core gives an average accumulation rate of 1.0 m w.e. yr −1 in water equivalent. However, the close-off density of 830 kg m −3 occurs at 83.4–86.8 m depth, which is about 20-m shallower than that obtained from two empirical models. Where the density ρ > 750 kg m −3, the densification appears faster than that from the empirical models. As a result, compared to the empirical coefficient, the actual compactive viscosity coefficient is nonlinear and decreases at ρ > 750 kg m −3, indicating that the firn with a higher density is softer than that from the empirical result. We argue here that the high accumulation rate creates a high overburden pressure in a short time. Thus, the relative softness of the firn may arise from (1) there being not enough time to form bonds between grains as strong as those in a lower accumulation-rate area, and similarly, (2) the dislocation density in the firn being relatively high.