Nonlinear influence of the Earth’s rotation on iceberg melting

Abstract

The calving of icebergs accounts for a significant fraction of the mass loss from both the Antarctic and Greenland ice sheets. Iceberg melting affects the water properties impacting sea ice formation, local circulation and biological activity. Laboratory experiments have investigated the effects of the Earth’s rotation on iceberg melting and the possible formation of Taylor columns (TCs) underneath icebergs. It is found that at high Rossby number,$Ro$, when rotation is weak compared to advection, iceberg melting is unaffected by the background rotation. As$Ro$decreases, the melt rate shows an increasing trend, which is expected to reverse for very low$Ro$. This behaviour is explained by considering the integrated horizontal velocity at the base of the iceberg. For moderate$Ro$, a partial TC is formed and its effective blocking accelerates the flow under the remainder of the iceberg, which increases the melt rate since the melting is proportional to the flow velocity. It is expected that for very low$Ro$the melt rate decreases because, with the expansion of the TC, the region of flow acceleration occurs away from the base of the iceberg. For low free stream velocity the freshwater produced by the ice melting introduces another dynamical effect. It is observed that there is a threshold free stream velocity below which the melt rate is constant. This is explained with the formation of a gravity current at the base of the iceberg that insulates it from the free flow and controls its melting.