Flow of the Ross Ice Shelf, Antarctica, is modulated by the ocean tide

Abstract

The ice streams feeding the Ross Ice Shelf, Antarctica, have large tidally modulated (sinusoidal and stick-slip) flow, but the interaction with the ice shelf is poorly understood. We show that the flow of the Ross Ice Shelf front, up to ∼ ∼650 km from the ice streams, exhibits smooth, sinusoidal motions corresponding to tidal modulation. These observations suggest a possible linking of the ice shelf with the ice streams to form a unified system that responds to small perturbations in stresses associated with ocean tides. If this is the case, the presence of the sinusoidal motion but the absence of stick-slip motion suggests there is damping of very high-frequency signals. The dissimilar signatures of the motions observed in the ice streams and at the front of the ice shelf present challenges to model development aimed at understanding the dynamics of coupled ice-stream/ice-shelf flow and the movement of ice across grounding lines.

Tidally induced velocity variations of the Beardmore Glacier, Antarctica, and their representation in satellite measurements of ice velocity

“…This was instead derived manually from a combination of TerraSAR-X differential interferograms (2012) and ICESat data (2003ICESat data ( -2009) for the area. The two grounding lines differ by less than 2 km, and where ICESat tracks cross the grounding line, data from Brunt et al (2010) using flexure information and Marsh et al (2012) using break of slope and surface deformation distribution also agree well with these grounding lines.…”

“…The frequency and amplitude of the tidally induced response varies with location, with velocity increases between 100 and 300 % of the mean recorded near the calving margins of large ice shelves (Brunt et al, 2010;Makinson et al, 2012) and smaller variations recorded tens of kilometres upstream of the grounding line on fast-flowing ice streams (Gudmundsson, 2006). Variations close to the grounding line have been linked to perturbation in basal shear stress (Bindschadler et al, 2003;, but it is not yet clear how longitudinal stresses are transmitted within the ice shelf (Brunt et al, 2010). Velocity also varies differently depending on the strength of tidal components, with a non-linear response of velocity associated with the semi-diurnal tides and more regular response to diurnal tides (Bindschadler et al, 2003).…”

“…Anandakrishnan et al, 2003;Bindschadler et al, 2003;Gudmundsson, 2006), and when analysing long-term trends it is important not to include bias from these shortterm, unrepresentative velocity variations, or misuse a velocity 'snapshot' taken over a few days to calculate an annual average ice discharge (Doake et al, 2002;Joughin et al, 2005;Gudmundsson, 2006). The frequency and amplitude of the tidally induced response varies with location, with velocity increases between 100 and 300 % of the mean recorded near the calving margins of large ice shelves (Brunt et al, 2010;Makinson et al, 2012) and smaller variations recorded tens of kilometres upstream of the grounding line on fast-flowing ice streams (Gudmundsson, 2006). Variations close to the grounding line have been linked to perturbation in basal shear stress (Bindschadler et al, 2003;, but it is not yet clear how longitudinal stresses are transmitted within the ice shelf (Brunt et al, 2010).…”

Accuracy Assessment of Tide Models in Terra Nova Bay, East Antarctica, for Glaciological Studies of DDInSAR Technique

“…또한 조위는 빙붕 또는 glacier tongue과 육지의 경계선인 지반선(grounding line) 의 이동을 야기하며 (Rignot, 1998), 빙체의 수직운동을 발생시켜 빙하의 흐름속도를 변화시키는데 기여하기도 한다 (Legrésy et al, 2004;Brunt et al, 2010) (Rignot, 1996). DDInSAR 기법은 빙하의 조위변형을 고해상도로 관측할 수 있게 하므로 빙하의 지반선 위치 정의 (Rignot et al, 2011), 지반선의 후퇴 분석 (Rignot, 1998), 조위가 빙하 흐름에 미치는 영 향 해석 (Legrésy et al, 2004 et al, 1995).…”

Tidal bending of ice shelves as a mechanism for large-scale temporal variations in ice flow

“…Ocean tides are known to greatly affect the horizontal flow of both ice shelves and adjoining ice streams, even far upstream of grounding lines (Doake et al, 2002;Brunt et al, 2010;Makinson et al, 2012;Legresy et al, 2004;King et al, 2011;Bindschadler et al, 2003b, a;Anandakrishnan et al, 2003;Alley, 1997;Gudmundsson, 2006;Marsh et al, 2013;Minchew et al, 2016;Rosier 15 et al, 2017). In some cases the ice flow responds at a different frequency to the tidal forcing, for example on the Rutford Ice Stream (RIS) the largest response is at a fortnightly (M sf ) frequency (Gudmundsson, 2006).…”