High-resolution subglacial topography around Dome Fuji, Antarctica, based on ground-based radar surveys conducted over 30 years

Abstract

Abstract. The retrieval of continuous ice core records of more than 1 Myr is an important challenge in palaeo-climatology. For identifying suitable sites for drilling such ice, the knowledge of the subglacial topography and englacial layering is crucial. For this purpose, extensive ground-based ice radar surveys were done over Dome Fuji in the East Antarctic plateau during the 2017–2018 and 2018–2019 austral summers by the Japanese Antarctic Research Expedition, on the basis of ground-based radar surveys conducted over the previous ~ 30 years. High-gain Yagi antennae were used to improve the antenna beam directivity and thus attain a significant decrease in hyperbolic features in the echoes from mountainous ice-bedrock interfaces. We combined the new ice thickness data with the previous ground-based data, recorded since the 1980s, to generate an accurate high-spatial-resolution (up to 0.5 km between survey lines) ice thickness map. This map revealed a complex landscape composed of networks of subglacial valleys and highlands, which sets substantial constraints for identifying possible locations for new drilling. In addition, our map was compared with a few bed maps compiled by earlier independent efforts based on airborne radar data to examine the difference in features between sets of the data.

Fractionation of O<sub>2</sub>∕N<sub>2</sub> and Ar∕N<sub>2</sub> in the Antarctic ice sheet during bubble formation and bubble–clathrate hydrate transition from precise gas measurements of the Dome Fuji ice core

“…Theoretical works including molecular dynamics simulations for different gases and ice conditions may shed light on the different relationships between δO 2 /N 2 and δAr/N 2 in different zones. Finally, the International Partnership for Ice Core Sciences regards the retrieval of an ice core containing ice older than 1 million years as highest priority (Fisher et al, 2013;Tsutaki et al, 2021). Our constraints on the permeation coefficients of the gases in ice might be useful for predicting the magnitude of diffusive smoothing of air composition in such an ice core.…”

Development of crystal orientation fabric in the Dome Fuji ice core in East Antarctica: implications for the deformation regime in ice sheets

“…Figure 1(b) demonstrates that the ice coring site was very close (within 10 km) to the present dome summit. At the present time with the Holocene climate, DF is associated with a steep north-south surface mass balance gradient (Fujita et al, 2011;Tsutaki et al, 2021). We suggest that this morphology demonstrates that the DF summit has migrated along this gradient in the north-south direction during glacial and interglacial periods over which the accumulation rate changed dramatically (e.g., Parrenin et al, 2016).…”

Development of crystal orientation fabric in the Dome Fuji ice core in East Antarctica: implications for the deformation regime in ice sheets

“…Although the precise thicknesses of thin sections are not provided in Wang et al (2003) or Durand et al (2007Durand et al ( , 2009 (missing data are indicated by the # symbol in this table), it can be assumed that the thicknesses of sections prepared for optically based COF measurements were approximately 0.5 mm or less. , 2011;Tsutaki et al, 2022). We suggest that this morphology demonstrates that the DF summit has migrated along this gradient in the north-south direction during glacial and interglacial periods over which the accumulation rate changed dramatically (e.g., Parrenin et al, 2016).…”