Siobhan O’Farrell: The influence of ocean waves on Antarctic sea-ice albedo and seasonal melting, and potential coupled physical and biological feedbacks
Dr Robert Massom
Australian Antarctic Division, Australian Antarctic Program Partnership, and Australian Centre for Excellence in Antarctic Science
Dr Phil Reid
Australian Antarctic Division, and Australian Antarctic Program Partnership
Dr Steve Warren
University of Washington, USA
Dr Bonnie Light
University of Washington, USA
Dr Don Perovich
Dartmouth College, USA
Prof Luke Bennetts
University of Melbourne, Australia
Dr Petteri Uotila
University of Helsinki, Finland
Presenting author
Dr Siobhan O’Farrell
University of Melbourne, Australia
siobhan.ofarrell@unimelb.edu.au
Dr Michael Meylan
University of Newcastle, Australia
Dr Klaus Meiners
Australian Antarctic Division, Australian Antarctic Program Partnership, and Australian Centre for Excellence in Antarctic Science
Dr Pat Wongpan
IMAS, Australia
Dr Alex Fraser
IMAS and Australian Antarctic Program Partnership, Australia
Dr Alessandro Toffoli
University of Melbourne, Australia
Dr Giulio Passerotti
University of Melbourne, Australia
Dr Pete Strutton
IMAS and Australian Centre for Excellence in Antarctic Science, Australia
Dr Sean Chua
Australian Antarctic Division and Australian Antarctic Program Partnership
Dr Melissa Fedrigo
Australian Antarctic Division
Abstract:
This study identifies wave driven processes that can accelerate the seasonal melting of sea ice both in the marginal ice zone (MIZ) and in open water areas within the interior sea-ice zone (SIZ). It builds on the long-held view that seasonal Antarctic sea-ice ablation is primarily driven by ice-floe lateral and basal melting enhanced in the MIZ by wave breakup of ice floes, by demonstrating that ocean waves play important additional roles in generating surface and interior melting (termed “wave melting”) via three sets of processes: “wave flooding”, “wave pulverisation”, and “wave greening” (involving algal proliferation in wave-modified ice). Based on existing observations and simple one-dimensional modelling, these wave processes are estimated to reduce ice albedo by 0.38–0.64 compared to snow-covered ice, resulting in vertical melt-rate enhancements of 0.9–5.2 cmd−1 amplified by wave greening to1.1 6.1cmd−1.
The study also identifies five positive feedback and sub-feedback mechanisms that likely accelerate the ice melting further. It addresses a gap in current climate and Earth system models, which account for wave effects on floe size distributions but overlook these coupled wave-driven dynamic, contribute to explaining why and how Antarctic sea ice can melt back so rapidly each summer. An intention of this foundational study is to stimulate further targeted investigation aimed at quantifying the role of wave melting in the annual sea-ice cycle–as well as the contribution of wave greening to primary production in the sea-ice zone and its role in key bio geochemical processes that feedback to climate.
Audience: Earth system modellers, processes modellers
Key words: Sea ice, wave melting, albedo, bio geochemical feedback