Iceberg free drift

The free-drift velocity of an iceberg follows from air and water drag, the Coriolis force, pressure gradients, currents and other external forces. Large submerged area and mass make its wind response weak compared with that of a thin floe.

For a constant wind force $\mathbf{F}$, still water, and linear water drag force $-m\gamma \mathbf{v}$, let $J\mathbf{v}=\hat{\mathbf{z}}\times \mathbf{v}$. The Coriolis parameter $f$ gives equilibrium ${\mathbf{v}}_{\infty }=(\gamma \mathbf{F}-fJ\mathbf{F})/[m({\gamma }^2+f^2)]$. The deviation evolves as $e^{-\gamma t}R(-ft)(\mathbf{v}(0)-{\mathbf{v}}_{\infty })$, a damped inertial oscillation. Actual drag is commonly quadratic, so this is a linear illustrative model rather than a universal iceberg speed law.

Water drag on a large iceberg can exceed a tug force by many orders of magnitude; the relevant area is the immersed horizontal base when the quoted coefficient is an equivalent water-drag coefficient.