Accumulation patterns around Dome C, East Antarctica, in the last 73 kyr

Marie G P Cavitte,Frédéric Parrenin,Frédéric Parrenin,Frédéric Parrenin,Frédéric Parrenin,Donald D Blankenship,Brice Van Liefferinge,Catherine Ritz,Catherine Ritz,Catherine Ritz,Catherine Ritz,Massimo Frezzotti,Duncan A Young,Jason L Roberts,Jason L Roberts,Jason L Roberts

doi:10.5194/tc-12-1401-2018

Abstract

Abstract. We reconstruct the pattern of surface accumulation in the region around Dome C, East Antarctica, since the last glacial. We use a set of 18 isochrones spanning all observable depths of the ice column, interpreted from various ice-penetrating radar surveys and a 1-D ice flow model to invert for accumulation rates in the region. The shallowest four isochrones are then used to calculate paleoaccumulation rates between isochrone pairs using a 1-D assumption where horizontal advection is negligible in the time interval of each layer. We observe that the large-scale (100s km) surface accumulation gradient is spatially stable through the last 73 kyr, which reflects current modeled and observed precipitation gradients in the region. We also observe small-scale (10 s km) accumulation variations linked to snow redistribution at the surface, due to changes in its slope and curvature in the prevailing wind direction that remain spatially stationary since the last glacial.

Highlights

The Dome C region, located on the East Antarctic interior plateau, has long been the focus of extensive research: it is the site of the oldest continuous ice core as yet retrieved, the EPICA Dome C ice core, dating to ∼ 800 ka (Parrenin et al, 2007)
Superimposed, we observe a number of regions ∼ 20 km wide that show a ∼ 25 % accumulation increase over the Little Dome C Massif” (LDCM), to ∼ 50 km wide or more east of the Concordia Ridge (CR) with a ∼ 75 % increase
By setting a limit on the maximum horizontal advection allowed for each age interval, the described accumulation patterns and variations are reasonably unaffected by the 1-D assumption

Summary

Introduction

The Dome C region, located on the East Antarctic interior plateau, has long been the focus of extensive research: it is the site of the oldest continuous ice core as yet retrieved , the EPICA Dome C ice core, dating to ∼ 800 ka (Parrenin et al, 2007). Modern surface precipitation on the Dome C plateau is extremely low (∼ 25 mm yr−1, Stenni et al, 2016), with infrequent storm events representing more than 50 % of the total annual precipitation (Frezzotti et al, 2005). Present-day moisture-bearing air mass trajectories (Scarchilli et al, 2011; Genthon et al, 2016) point to a western Indian Ocean provenance for the snow precipitation at Dome C (85 % of the precipitation), and suggest this could have persisted through glacial–interglacial cycles. Whillans (1975) details how wind speed and direction can affect total mass balance in Marie Byrd Land.

Methods

Results

Discussion

Conclusion