Ablation (Glacier)

Ablation is the sum of all mass-loss processes that remove ice and snow from a glacier: surface and basal melt, sublimation, wind scour, and frontal calving. It is the debit side of the glacier mass balance, set against accumulation from snowfall. The equilibrium line altitude separates the upper accumulation zone from the lower ablation zone where net loss occurs. Surface ablation is driven mostly by the energy balance, with absorbed shortwave radiation and turbulent sensible heat dominating in summer. For tidewater and marine-terminating glaciers, calving and submarine melt at the grounding line add large dynamic ablation terms that the surface energy balance alone misses.