Sea ice floe size: its impact on pan-Arctic and local ice mass and required model complexity

Abstract. Sea ice is composed of discrete units called floes. Observations show that these floes can adopt a range sizes spanning orders magnitude, from metres to tens kilometres. Floe size impacts the nature and magnitude interactions between sea ice, ocean, atmosphere including lateral melt rate momentum heat exchange. However, large-scale geophysical models employ continuum approach traditionally either assume constant or do not include an explicit treatment floe size. In this study we apply novel observations analyse two alternative approaches modelling distribution (FSD) within state-of-the-art CICE model. The first model considered prognostic size–thickness where shape emergent feature assumed priori. second considered, WIPoFSD (Waves-in-Ice module Power law Size Distribution) model, assumes follows power with exponent. We introduce parameterisation motivated by idealised in-plane brittle fracture demonstrate inclusion scheme enables achieve reasonable match against for mid-sized (100 m–2 km). While neither FSD results in significant improvement ability simulate pan-Arctic metrics stand-alone configuration, larger be seen over regional scales concentration thickness. find particularly enhances early season, whereas increase occurs primarily during late season. then differences explained considering effective size, metric used characterise given FSD. Finally, discuss advantages disadvantages different note although unable represent potentially important features annual evolution it less computationally expensive produces better fit derived 2 m resolution MEDEA imagery, possibly making stronger candidate climate models.