Brief communication: PICOP, a new ocean melt parameterization under ice shelves combining PICO and a plume model
2018
Abstract. Basal melting at the bottom of Antarctic ice shelves is a major control on
glacier dynamics, as it modulates the amount of buttressing that floating ice
shelves exert onto the ice streams feeding them. Three-dimensional ocean
circulation numerical models provide reliable estimates of basal melt rates
but remain too computationally expensive for century-scale projections. Ice
sheet modelers therefore routinely rely on simplified parameterizations based
on either ice shelf depth or more sophisticated box models. However, existing
parameterizations do not accurately resolve the complex spatial patterns of
sub-shelf melt rates that have been observed over Antarctica's ice shelves,
especially in the vicinity of the grounding line, where basal melting is one
of the primary drivers of grounding line migration. In this study, we couple
the Potsdam Ice-shelf Cavity mOdel (PICO, Reese et al. , 2018 ) to a buoyant
plume melt rate parameterization ( Lazeroms et al. , 2018 ) to create PICOP, a
novel basal melt rate parameterization that is easy to implement in transient
ice sheet numerical models and produces a melt rate field that is in
excellent agreement with the spatial distribution and magnitude of
observations for several ocean basins. We test PICOP on the Amundsen Sea
sector of West Antarctica, Totten, and Moscow University ice shelves in East
Antarctica and the Filchner-Ronne Ice Shelf and compare the results to PICO.
We find that PICOP is able to reproduce inferred high melt rates beneath Pine
Island, Thwaites, and Totten glaciers (on the order of 100 m yr −1 ) and
removes the “banding” pattern observed in melt rates produced by PICO over
the Filchner-Ronne Ice Shelf. PICOP resolves many of the issues contemporary
basal melt rate parameterizations face and is therefore a valuable tool for
those looking to make future projections of Antarctic glaciers.
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