Vertical Mixing Approaches to the Ice Shelf-Ocean Boundary Layer

Abstract:

Ice shelf-ocean boundary layer represents “the last meters” of the path that heat takes from the open ocean to the ice-ocean interface. Understanding the structure of this layer can help us estimate how quickly ocean heat can be transferred through the boundary layer up and how quickly the ice can ablate. Recent observations from the Ross Ice Shelf cavity show that the ocean structure is different from those that ocean models predict, including in the boundary layer. Moreover, modelling efforts of the boundary show that low mixing in the boundary layer can drastically reduce the overall meltrates in a cavity. Here we present how various approaches to mixing in the ice shelf-ocean boundary layer can produce different vertical profiles of temperature, salinity and velocity, and the associated meltrate feedbacks. Experiments in an idealised ice shelf-ocean ROMS model incorporate turbulent boundary layer mixing scheme change, meltwater distribution schemes, tidal effects and KPP vertical boundary mixing analysis. We also compare the resulting profiles from the experiments to the CTD profiles from the Ross Ice Shelf cavity.