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

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'.