Crustal thickness of Antarctica estimated using data from gravimetric satellites

Muriel Llubes,Sean Bruinsma,Frédérique Rémy,Lucia Seoane

doi:10.5194/se-9-457-2018

Abstract

Abstract. Computing a better crustal thickness model is still a necessary improvement in Antarctica. In this remote continent where almost all the bedrock is covered by the ice sheet, seismic investigations do not reach a sufficient spatial resolution for geological and geophysical purposes. Here, we present a global map of Antarctic crustal thickness computed from space gravity observations. The DIR5 gravity field model, built from GOCE and GRACE gravimetric data, is inverted with the Parker–Oldenburg iterative algorithm. The BEDMAP products are used to estimate the gravity effect of the ice and the rocky surface. Our result is compared to crustal thickness calculated from seismological studies and the CRUST1.0 and AN1 models. Although the CRUST1.0 model shows a very good agreement with ours, its spatial resolution is larger than the one we obtain with gravimetric data. Finally, we compute a model in which the crust–mantle density contrast is adjusted to fit the Moho depth from the CRUST1.0 model. In East Antarctica, the resulting density contrast clearly shows higher values than in West Antarctica.

Highlights

The surface topography of Antarctica has already been determined precisely by various altimetric missions: ERS1/2, EnviSat, ICESat, Cryosat-2 (Zwally et al, 2002; Rémy and Parouty, 2009; Helm et al, 2014) and more recently by the SARAL or Sentinel-3 satellites (Verron et al, 2015)
The higher values are not always located in the areas completed by satellite gravity in BEDMAP 2 because the large set of new data included during the computation really improved the model
We provide a regional map of crustal thickness covering the entire Antarctic continent

Summary

Introduction

The surface topography of Antarctica has already been determined precisely by various altimetric missions: ERS1/2, EnviSat, ICESat, Cryosat-2 (Zwally et al, 2002; Rémy and Parouty, 2009; Helm et al, 2014) and more recently by the SARAL or Sentinel-3 satellites (Verron et al, 2015). Satellites are the only way to obtain information when gravimetric ground data are lacking Such observations have provided to glaciologists the thickness of the ice cover and the temporal tracking of the ice sheet. Launched in 2002, the GRACE mission provides monthly or 10-day temporal grids (Lemoine et al, 2007; Foerste et al, 2008; Landerer and Swenson, 2012) It allows for the computation of mass balance, annual or seasonal cycles (Ramillien et al, 2006; Llubes et al, 2007; Peng et al, 2016; Ramillien et al, 2006; Williams et al, 2014). Space gravimetry is used to separate snow and ice contributions (Memin et al, 2014)

Objectives

Findings

Discussion

Conclusion