Theory, modelling and observations of marginal ice zone dynamics: multidisciplinary perspectives and outlooks

Abstract

The marginal ice zone (MIZ) is the dynamic interface between the open ocean and sea ice-covered ocean. It is characterized by interactions between surface gravity waves and granular ice covers consisting of relatively small, thin chunks of sea ice known as floes. This structure gives the MIZ markedly different properties to the thicker, quasi-continuous ice cover of the inner pack that waves do not reach, strongly influencing various atmosphere–ocean fluxes, especially the heat flux. The MIZ is a significant component of contemporary sea ice covers in both the Antarctic, where the ice cover is surrounded by the Southern Ocean and its fierce storms, and the Arctic, where the MIZ now occupies vast expanses in areas that were perennial only a decade or two ago. The trend towards the MIZ is set to accelerate, as it reinforces positive feedbacks weakening the ice cover. Therefore, understanding the complex, multiple-scale dynamics of the MIZ is essential to understanding how sea ice is evolving and to predicting its future. This article is part of the theme issue ‘Theory, modelling and observations of marginal ice zone dynamics: multidisciplinary perspectives and outlooks’.

Patterns of wintertime Arctic sea ice leads and their relation to winds and ocean currents

“…The most dominant spatial lead patterns are mainly found in Fram Strait (FS) and in the Barents / Kara Seas (BK), thus close to the marginal ice zone, where the ice pack becomes less dense due to the increased influence of ocean swell and waves (e.g. Bennetts et al, 2022). The lead data shown here indicate, however, that also in the BK region we can spatially distinguish regions with pronounced LFQ that are associated with sea floor channels or ridges.…”

A prognosticative synopsis of contemporary marginal ice zone research

“…Now, with the advent of climate warming, the impact of ocean waves has increased and recognition that it is a major causal element in the establishment and evolution of MIZs, which are also now more pervasive, has been accepted. Accordingly, and capitalizing on the increasing resolution of operational forecasting models, the past decade has witnessed the development of several basin-scale, coupled sea-ice models that have begun to append a contribution from ocean waves, with several papers appearing within this issue [7,8,18,36]. Reciprocally, NOAA’s most recent community wave-modelling framework, normalWAVEWATCH normalIII® [30], includes trial parametrizations of wave attenuation in ice fields.…”

“…Articles [7,8] address this topic, the latter specifically comparing the MIZ width predicted by the state-of-the-art, coupled wave-sea-ice model neXtSIM-WAVEWATCH III with ICESat-2 laser wave data [9], which is further reconciled against an MIZ width based on floe size obtained from satellite altimetry and one based on concentration. Mindful that the model has parameters which can be optimally tuned, the agreements obtained are promising, but, while the rationale undergirding [9] is to establish whether the neXtSIM-WAVEWATCH III model can reproduce observations, it is evident that the question of definition remains unanswered and that greater clarity about how MIZ width should be defined is a pressing practicality of contemporary polar oceans research.…”

The dynamics of unstable waves in sea ice

“…The sea ice properties are intimately linked to ocean wave properties via feedback mechanisms in the marginal ice zone (MIZ) 5 – 7 which around Antarctica, fed by intense Southern Ocean waves all year round 8 , extends for hundreds of kilometers 9 – 11 . Rapid evolution of the polar regions driven by climate change 12 – 14 have revived and energised research activities in understanding waves properties and feedback in the MIZ 7 , 15 , including in the emerging Arctic MIZ 16 .

Figure 1 Example of Southern Ocean waves (wave height m and peak period s) propagating in a MIZ comprised of small ice floes (1–10 m) as seen from the icebreaker S.A. Agulhas II (beam 21.7 m, for visual reference) on the 24 July 2022 at 59 S and 1 E, and schematic of exponential dissipation for a monochromatic wave of unit amplitude propagating from left to right.

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