Aspect ratio affects iceberg melting

TL;DR

This study investigates how iceberg aspect ratio influences melting rates through combined experimental and numerical methods, revealing significant face-dependent variations and proposing corrections to existing models.

Contribution

It introduces novel insights into the impact of iceberg shape on melting, highlighting the importance of aspect ratio and flow conditions, and proposes improved parameterisations.

Findings

Melting varies significantly across different iceberg faces.

High flow velocities increase side melting and vortex-induced basal melt rates.

Existing models fail to accurately capture the influence of aspect ratio on melting.

Abstract

Iceberg meltwater is a critical freshwater flux from the cryosphere to the oceans. Global climate simulations therefore require simple and accurate parameterisations of iceberg melting. Iceberg shape is an important but often neglected aspect of iceberg melting. Icebergs have an enormous range of shapes and sizes, and distinct processes dominate basal and side melting. We show how different iceberg aspect ratios and relative ambient water velocities affect melting using a combined experimental and numerical study. The experimental results show significant variations in melting between different iceberg faces, as well as within each iceberg face. These findings are reproduced and explained with novel multiphysics numerical simulations. At high relative ambient velocities melting is largest on the side facing the flow, and mixing during vortex generation causes local increases in basal melt rates of over 50%. Double-diffusive buoyancy effects become significant when the relative ambient velocity is low. Existing melting parameterisations do not reproduce our findings. We propose several corrections to capture the influence of aspect ratio on iceberg melting.