Ice stream D flow speed is strongly modulated by the tide beneath the Ross Ice Shelf

Abstract

[1] The flow velocity of ice stream D, West Antarctica has been measured to vary by a factor of three over the course of a day. These fluctuations are measured at the grounding line as well as upstream of the grounding line in the ice plain of ice stream D. The diurnal velocity fluctations appear to be driven by the tide beneath the Ross Ice Shelf. These results suggest that there is significant, and heretofore poorly understood, influence of the ocean tide and of the ice shelf on the dynamics of ice stream flow.

Diurnal and semidiurnal tide‐induced lateral movement of Ronne Ice Shelf, Antarctica

“…On RIS, which experiences the largest tidal range around Antarctica of up to 7 m, the oscillations in velocity and strain are much larger than on smaller ice shelves. The oscillating ice shelf stresses, which will be zero at the ice front and greatest toward grounding lines, will influence the horizontal force balance of the inflowing ice streams and the phase relationship between ice stream flow and the tidal forcing, particularly ice streams with low-friction beds [e.g., Anandakrishnan et al, 2003;Bindschadler et al, 2003;Thomas, 2007]. For parts of RIS where its length exceeds 600 km and the thickness ranges from 300 m at the ice front, to over 1200 m at the grounding lines, the horizontal elastic stresses could exceed AE20 kPa, which is approaching the stress perturbations caused by the tidally varying height of the water column.…”

Glacier change along West Antarctica's Marie Byrd Land Sector and links to inter-decadal atmosphere–ocean variability

“…Indeed, all GL retreat within the central and western sectors of Getz Ice Shelf occurred directly upstream of well-surveyed, deep (> 400 m) bathymetric depressions north of the ice fronts (Fig. 1), which transect the continental shelf and route warm modified-CDW from the CSB to the sub-ice shelf cavity (Wåhlin et al, 2010;Arneborg et al, 2012;Jacobs et al, 2013; see also our Fig. 6a).…”

“…Brunt et al, 2010Brunt et al, , 2011Joughin et al, 2016;Scheuchl et al, 2016). Additional confounding variables such as diurnal tidal variability and atmospheric forcing -previously recognized as important controls on GL migration over much shorter temporal baselines (Anandakrishnan et al, 2003;Fricker et al, 2009;Brunt et al, 2010) -are assumed to be negligible over the timescales we consider (cf. Milillo et al, 2017).…”

Increased rate of acceleration on Pine Island Glacier strongly coupled to changes in gravitational driving stress

“…Short-term modulations of velocity, such as those caused by semi-diurnal, diurnal and fortnightly oceanic tides (e.g. Anandakrishnan et al, 2003;Bindschadler et al, 2003;Gudmundsson, 2007), cannot always be resolved, and there is a risk that some of these components may introduce bias. Also there are limited InSAR data available >100 km inland, therefore it has been difficult to assess the extent of the recent acceleration.…”