Seminar: Dr. Yizhen Li, Woods Hole Oceanographic Institution

Processes regulating formation of low-salinity high-biomass lenses near the edge of the Ross Ice Shelf (Host: John Bane) In situ observations in austral summer of early 2012 in the Ross Sea suggest the presence of low-salinity, high-biomass lenses within cold eddies along the edge of the Ross Ice Shelf (RIS). Idealized model simulations are utilized to examine the processes responsible for ice shelf eddy formation. 3-D model simulations produce similar cold and fresh eddies, although the simulated vertical lenses are quantitatively thinner than observed. Model sensitivity tests show that both basal melting underneath the ice shelf and irregularity of the ice shelf edge facilitate generation of cold and fresh eddies. 2-D model simulations further suggest that both basal melting and downwelling-favorable winds play crucial roles in forming a thick layer of low-salinity water observed along the edge of the RIS. These properties may have been entrained into the observed eddies, whereas that entrainment process was not captured in the specific eddy formation events studied in our 3-D model—which may explain the discrepancy between the simulated and observed eddies, at least in part. Additional sensitivity experiments imply that uncertainties associated with background stratification and wind stress may also explain why the model underestimates the thickness of the low-salinity lens in the eddy interiors. Our study highlights the importance of incorporating accurate wind forcing, basal melting and ice shelf irregularity for simulating ocean dynamics near the RIS edge.