HR: 08:30h
AN: C41A-03 INVITED     [PDF]
TI: Melting and Freezing Under the Ross Ice Shelf: Lessons From an Impacted Cavity
AU: * Jacobs, S S
EM: sjacobs@ldeo.columbia.edu
AF: Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964 United States
AU: Smethie, W M
AF: Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964 United States
AU: Assmann, K M
AF: Alfred Wegener Institute for Polar and Marine Research, Postfach 12 01 61, Bremerhaven, D-27515 Germany
AU: Holland, D M
AF: Courant Institute of Mathematical Sciences, New York University, New York, NY 10012 United States
AU: Bergamasco, A
AF: National Research Council, Institute of Marine Sciences, San Polo 1364, Venice, I-30125 Italy
AB: The dimensions of ice shelves are strongly influenced by the temperature and circulation of the underlying ocean. Inflow temperatures vary by about three degrees, with most ice shelves floating in seawater near the in situ freezing point. Circulation under the ice depends on modifications of the thermohaline field by melting, freezing and tidal mixing, which determine the vertical stratification and heat flux. Observations near ice fronts have previously been used to estimate the amount of meltwater present in outflows from ice shelf cavities. While limited by the seasonality and dynamic range of the measurements, along with discrete sampling methods and uncertain source water assumptions, geochemical data add valuable information to the more commonly utilized temperature and salinity fields. Here we evaluate repeat chlorofluorocarbon and thermohaline sections in a region that has experienced a multidecadal decline in shelf water salinity. Inferences about net basal melting are compared with results from numerical models and bottom-moored instruments. Ice shelf cavities are sinks for much of the high salinity shelf water produced by sea ice formation. Outflows from those cavities reflect the properties of shelf water inflows, and affect the salinity and density of downstream bottom water production. We suggest future work that could help to better understand ocean forcing of ice shelf change in an evolving climate.
DE: 1863 Snow and ice (1827)
DE: 4207 Arctic and Antarctic oceanography
DE: 4271 Physical and chemical properties of seawater
DE: 4283 Water masses
DE: 4842 Modeling
SC: Cryosphere [C]
MN: 2003 Fall Meeting