Evaluating ice shelf basal melt rates in the Southern Ocean high-resolution model against satellite remote sensing

Ice shelf melt rates by a warm ocean have a critical impact on ice sheet mass balance in Antarctica and in turn on the rates of sea level rise. Validating and tuning modeled ice shelf melt rates is a challenge. Here we discuss the issues by presenting validation of melt rates calculated from the Southern Ocean high-resolution model (SOhi) over the year 2007. SOhi includes full physics, tides, and an updated bathymetric compilation. We compare the model results to two satellite-derived estimates. Overall, we find that the model overestimates ice shelf melt, which we attribute to the ocean model initial (warm) conditions in some areas, bathymetric uncertainties in others, simplified physics on some ice shelves, and also to the inherent limitations of the satellite-derived estimates. The SOhi model nevertheless provides a comprehensive, detailed mapping of ice shelf melt rates around Antarctica; it captures higher melt near grounding lines and ice fronts, areas of freezing versus areas of high melt water production. The identified discrepancies between model and satellite-estimates provide guidelines for model improvements, requirements for additional observations of ice shelf cavities, and assembling of calibration/validation datasets to constrain the models.