31 Jan 2023
 | 31 Jan 2023
Status: this preprint is open for discussion.

Can rifts alter ocean dynamics beneath ice shelves?

Mattia Poinelli, Michael Schodlok, Eric Larour, Miren Vizcaino, and Riccardo Riva

Abstract. Land ice discharge from the Antarctic continent into the ocean is restrained by ice shelves, floating extensions of grounded ice that buttress the glacier outflow. The ongoing thinning of these ice shelves – largely due to enhanced melting at their base in response to global warming – is known to accelerate the release of glacier meltwater into the world oceans, augmenting global sea level. Mechanisms of ocean heat intrusion under the ice base are therefore crucial to project the future of Antarctic ice shelves. Furthermore, ice shelves are weakened by the presence of km-wide full-thickness ice rifts, which are observed all around Antarctica. However, their impact on ocean circulation around and below ice shelves has been largely unexplored as ocean models are commonly characterized by resolutions that are too coarse to resolve their presence. Here, we apply the Massachusetts Institute of Technology general circulation model at high resolution to investigate the sensitivity of sub-shelf ocean dynamics and ice shelf melting to the presence of a km-wide rift in proximity of the ice front. We find that (a) the rift curtails water and heat intrusion beneath the ice shelf base and (b) basal melting of a rifted ice shelf is on average 20 % lower than for an intact ice shelf under identical forcing. We therefore posit that rifts and their impact in the sub-shelf dynamics are important to consider in order to accurately reproduce and project pathways of heat intrusion into the ice shelf cavity.

Mattia Poinelli et al.

Status: open (until 28 Mar 2023)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-75', Anonymous Referee #1, 02 Mar 2023 reply
  • RC2: 'Comment on egusphere-2023-75', Anonymous Referee #2, 14 Mar 2023 reply

Mattia Poinelli et al.

Mattia Poinelli et al.


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Short summary
Rifts are fractures on ice shelves that connect atmosphere-exposed ice with the ocean underneath. The impact of rifts on ocean circulation below Antarctic ice shelves has been largely unexplored as ocean models are commonly ran at resolutions that are too coarse to resolve their presence. Our model simulations show that a km-wide rift near the ice shelf front modulates heat intrusion beneath the ice and inhibits basal melt. These processes are therefore worthy of further investigation.