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Definition:
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The transition from being grounded to being afloat, made when the pressure w gd exerted by water of depth d on adjacent ice of thickness h = d + hflot becomes just equal to the weight i gh of the ice; w is the density of the water, i is the depth-averaged density of the ice (allowing for example for crevasses and possibly snow or firn) and hflot is the freeboard, that is, the elevation of the ice surface above the water level. The definition neglects tidal flexure and some other lesser phenomena. It represents mutual hydrostatic equilibrium of the column of water and the adjacent column of ice the water below d supports the weight of both columns, which are at rest with respect to each other. If the two densities are known, a measurement of the freeboard of floating ice is a measurement of ice thickness, which is required for the calculation of ice discharge. The condition for flotation is d = h i / w. A condition for being afloat is d
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