Effect of near-terminus subglacial hydrology on tidewater glacier submarine melt rates

Submarine melting of Greenlandic tidewater glacier termini is proposed as a possiblemechanism driving their recent thinning and retreat. We use a general circulation model, MITgcm, tosimulate water circulation driven by subglacial discharge at the terminus of an idealized tidewater glacier.We vary the spatial distribution of subglacial discharge emerging at the grounding line of the glacier andexamine the effect on submarine melt volume and distribution. We find that subglacial hydrology exerts animportant control on submarine melting; under certain conditions a distributed system can induce a factor5 more melt than a channelized system, with plumes from a single channel inducing melt over only alocalized area. Subglacial hydrology also controls the spatial distribution of melt, which has the potential tocontrol terminus morphology and calving style. Our results highlight the need to constrain near-terminussubglacial hydrology at tidewater glaciers if we are to represent ocean forcing accurately.