A laboratory study of iceberg side melting in vertically sheared flows

Abstract

An earlier study indicates that the side melting of icebergs subject to vertically homogeneous horizontal velocities is controlled by two distinct regimes, which depend on the melt plume behavior and produce a nonlinear dependence of side melt rate on velocity. Here, we extend this study to consider ice blocks melting in a two-layer vertically sheared flow in a laboratory setting. It is found that the use of the vertically averaged flow speed in current melt parameterizations gives an underestimate of the submarine side melt rate, in part because of the nonlinearity of the dependence of the side melt rate on flow speed but also because vertical shear in the horizontal velocity profile fundamentally changes the flow splitting around the ice block and consequently the velocity felt by the ice surface. An observational record of 90 icebergs in a Greenland fjord suggests that this effect could produce an average underestimate of iceberg side melt rates of 21%.