Abstract:

Icebergs constitute half the mass loss from the Greenland and Antarctic ice sheets. Understanding their impact on global ocean circulation requires accurate models of iceberg melting. We test previous parameterisations in a series of laboratory experiments and find that they underestimate melting and neglect the central importance of iceberg geometry. To understand these geometric effects we turn to simulation, developing a high-order phase-field spectral code. The phase-field approach allows us to dynamically couple the evolving iceberg shape with temperature and salt fluxes at the boundary. The simulations reproduce side-dependent melt patterns and reveal that
1. at high speeds vortex generation doubles localised melt rates
2. at low speeds double-diffusive convection can enhance iceberg melting.
We propose parameterisations that correct for iceberg geometry before discussing some bigger questions for modelling ice-ocean interactions.