GPS-derived velocity and strain fields around Dome Argus, Antarctica

Yuande Yang,Lianzhong Wang,Zemin Wang,Yujun Du,Bo Sun,Cheinway Hwang,Songtao Ai,Minghu Ding,Dongchen E

doi:10.3189/2014jog14j078

Abstract

AbstractKnowledge of the surface topography, velocity field and strain field at an ice-core site is critical to the accurate interpretation of ice-core records. At Dome Argus (Dome A), where a Chinese deep ice-core drilling project is being carried out, we have produced an accurate surface digital elevation model from GPS measurements in January 2013 at 47 sites. We identify two peaks at Dome A, with the northern peak ~7 cm higher than the southern peak. Repeat GPS measurements at 12 sites in 2008 and 2013 provide a surface velocity field around the dome. The surface velocity ranges from 3.1±2.6 to 29.4±1.2 cm a–1, with a mean of 11.1 ~2.4 cm a–1. The surface flow directions are near perpendicular to the surface elevation contours. Velocities from GPS are lower than derived from satellite radar interferometry (InSAR). From GPS velocities, the accuracy of velocity from the existing InSAR velocity field is determined, resulting in a standard deviation of 0.570 m a–1 in speed and 117.5º in direction. This result is consistent with the reported accuracy of InSAR, showing the value of in situ GPS measurements for assessing and correcting remote-sensing results. A surface strain field for the drilling site over Dome A is calculated from 24 strain triangles, showing north–south extension, east– west compression and vertical layer thinning.

Highlights

The ongoing deep ice-core drilling at Dome Argus (Dome A) is vital to the understanding of climate change in Antarctica
Information about ice thickness, ice velocity, surface topography, snow accumulation history and strain field is needed in order to assess the age of the deep ice here
There exist two peaks in the study region, which may be due to the existence of bedrock mountains and steep valley walls in the region shown in Cui and others (2010, Fig. 2. (a) Surface topography, and surface velocity field from GPS

Summary

Introduction

The ongoing deep ice-core drilling at Dome Argus (Dome A) is vital to the understanding of climate change in Antarctica. The ice-core record may extend the paleoclimatic record to $1 Ma BP (Xiao and others, 2008). Information about ice thickness, ice velocity, surface topography, snow accumulation history and strain field is needed in order to assess the age of the deep ice here. In 2008, the ice-sheet thickness and bed topography were measured by ground-based, ice-penetrating radar during the 24th Chinese National Antarctic Research Expedition (CHINARE; Sun and others, 2009), exhibiting a 3139 m thickness at the core location (Cui and others, 2010). Steep bedrock valley walls beneath Dome A were reported, and freezing from the base has important impacts on ice thickness and ice flow over Dome A (Bell and others, 2011). The surface topography of Dome A was GPS-surveyed in January 2004 (Zhang and others, 2007) and January 2007 (Cheng and others, 2009)

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Conclusion