Multi-scale satellite observations of Arctic sea ice: new insight into the life cycle of the floe size distribution

Abstract

This study provides a new conceptional framework to understand the life cycle of the floe size distribution of Arctic sea ice and the associated processes. We derived the floe size distribution from selected multi-scale satellite imagery data acquired from different locations and times in the Arctic. Our study identifies three stages of the floe size evolution during summer – ‘fracturing’, ‘transition’ and ‘melt/wave fragmentation’. Fracturing defines the initial floe size distribution ( N ∼ d −α , where d is floe size) formed from the spring breakup, characterized by the single power-law regime over d = 30–3000 m with α ≈ 2. The initial floe size distribution is then modified by various floe fragmentation processes during the transition period, which is characterized by ‘selective’ fragmentation of large floes ( d > 200–300 m) with variable α = 2.5–3.5 depending on the degree of fragmentation. As ice melt intensifies, the melt fragmentation expands the single power-law regime into smaller floes ( d = 70 m) with α = 2.4–3.8, while a significant reduction of small floes ( d < 30–40 m) occurs due to lateral melt. The shape factor shows an overall progression from elongated floes into rounded floes. The effects of scaling and wave-fracture are also discussed. This article is part of the theme issue 'Theory, modelling and observations of marginal ice zone dynamics: multidisciplinary perspectives and outlooks'.

Wave propagation in the marginal ice zone: connections and feedback mechanisms within the air–ice–ocean system

“…The increasing wave activity means that more momentum and energy are transferred into an MIZ that is probably growing in extent [ 7 ]. Assuming canonical attenuation rates, larger waves will reach farther into the ice of the western Arctic, eventually beyond 100 km ( figure 2 ).…”

“…The forecasts of waves within the MIZ are now being used to improve predictions of ice evolution and floe size distributions [ 5 ]. Such two-way coupled wave–ice forecasting systems are essential to accurately representing the polar regions [ 6 ], especially as the extent of the Arctic seasonal MIZ expands with a warming climate [ 7 ].…”

Floes, the marginal ice zone and coupled wave-sea-ice feedbacks

“…This review is not the place to energize the debate over the ‘power law hypothesis’. Still, an apparent consensus has emerged that power-law behaviour holds in regions affected by brittle fracture, such as in the Beaufort or Chukchi Seas [ 29 , 30 , 50 , 51 ]. It is clear that the FSD in the MIZ does not always have a power law tail, influenced as it is by small-spatial-scale processes that do not permit large floes—often the MIZ is comprised of a single peak floe size, or floes all near the same scale.…”

A prognosticative synopsis of contemporary marginal ice zone research

“…FSD is recognized as a determinative ingredient of coupled ocean-wave–sea-ice models of the MIZ, so it is important that an accurate distribution of floe sizes is used and that the physics describing how FSD mutates due to wave-induced flexural and collisional break-up and melting, for example, is accurate. The present volume has three relevant papers: [18] is concerned with modelling, [19] discusses a broken power-law distribution in the context of the physics that creates it, and [20] argues for a lognormal FSD instead of a power law. The informative mini-review by Horvat [21], who re-examines the history and current state of FSD observations and modelling, argues that further high-temporal-resolution investigations of the FSD are needed, e.g.…”