Effects of Projected Changes in Wind, Atmospheric Temperature, and Freshwater Inflow on the Ross Sea

Abstract

AbstractA 5-km horizontal resolution regional ocean?sea ice?ice shelf model of the Ross Sea is used to examine the effects of changes in wind strength, air temperature, and increased meltwater input on the formation of high-salinity shelf water (HSSW), on-shelf transport and vertical mixing of Circumpolar Deep Water (CDW) and its transformation into modified CDW (MCDW), and basal melt of the Ross Ice Shelf (RIS). A 20% increase in wind speed, with no other atmospheric changes, reduced summer sea ice minimum area by 20%, opposite the observed trend of the past three decades. Increased winds with spatially uniform, reduced atmospheric temperatures increased summer sea ice concentrations, on-shelf transport of CDW, vertical mixing of MCDW, HSSW volume, and (albeit small) RIS basal melt. Winds and atmospheric temperatures from the SRES A1B scenario forcing of the MPI ECHAM5 model decreased on-shelf transport of CDW and vertical mixing of MCDW for 2046?61 and 2085?2100 relative to the end of the twentieth century. The RIS basal melt increased slightly by 2046?61 (9%) and 2085?2100 (13%). Advection of lower-salinity water onto the continental shelf did not significantly affect sea ice extent for the 2046?61 or 2085?2100 simulations. However, freshening reduces on-shelf transport of CDW, vertical mixing of MCDW, and the volume of HSSW produced. The reduced vertical mixing of MCDW, while partially balanced by the reduced on-shelf transport of CDW, enhances the RIS basal melt rate relative to the twentieth-century simulation for 2046?61 (13%) and 2085?2100 (17%).