Processes regulating formation of low-salinity, high-biomass lenses along the edge of Ross Ice Shelf

In situ observations in austral summer of early 2012 in the Ross Sea suggested the presence of low-salinity, high-biomass lenses within the 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 ice shelf edge may have facilitated the cold and fresh eddy generation. 2-D model simulations further suggest that both basal melting and time-varying, downwelling-favorable wind play crucial roles in forming the fresh lens on the RIS edge. Additional sensitivity experiments imply that uncertainties associated with background stratification and wind stress may explain why the model underestimates observed surface lens thickness. Our study highlights the importance of incorporating accurate wind forcing, basal melting and ice shelf edge roughness on understanding ocean dynamics near the RIS edge.