Although it has been speculated that the lognormal distribution of iceberg sizes observed away from glacial calving fronts is the product of the mechanisms by which icebergs fracture and disintegrate 7, the absence of appropriate methods with which to study free-floating iceberg disintegrations has limited efforts to study the mechanics of this phenomenon. Although iceberg drift-decay models exist 5, our mechanical understanding of iceberg disintegration remains unable to explain the size-frequency distributions of icebergs commonly observed most notably the discrepancy between the power-law distributed icebergs sizes observed at glacial calving fronts 6 and the lognormal iceberg-size distributions observed globally within open waters 7, 8. The rate at which icebergs drift and disintegrate influences the risk of collisions with high-latitude hydrocarbon infrastructure and shipping 1, the extent of zones of nutrient-enhanced carbon sequestration 2, 3, and the interpretation of palaeoclimate indicators such as ice-rafted debris 4. Consequently, the size-frequency distribution required to model iceberg distributions accurately must vary according to distance from the calving front. We suggest that changes in the characteristic size-frequency scaling of icebergs can be explained by the emergence of a dominant set of driving processes of iceberg degradation towards the open ocean. Our results indicate that the shift in the size-frequency distribution of iceberg sizes observed is a product of fracture-driven iceberg disintegration and dimensional reductions through melting. Here we use passive seismic monitoring to examine mechanisms of iceberg disintegration as a function of drift. Fundamentally, there is a discrepancy between iceberg power-law size-frequency distributions observed at glacial calving fronts and lognormal size-frequency distributions observed globally within open waters that remains unexplained.
Although the size-frequency distributions of icebergs can provide insight into how they disintegrate, our understanding of this process is incomplete.
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