HR: 15:45h
AN: OS52H-06    [PDF]
TI: Impact of a Large Iceberg on Circulation in the Southwestern Ross Sea, Antarctica
AU: * Dinniman, M S
EM: msd@ccpo.odu.edu
AF: Center for Coastal Physical Oceanography, Crittenton Hall, Old Dominion University, Norfolk, VA 23529 United States
AU: Klinck, J M
EM: klinck@ccpo.odu.edu
AF: Center for Coastal Physical Oceanography, Crittenton Hall, Old Dominion University, Norfolk, VA 23529 United States
AU: Smith, W O
EM: wos@vims.edu
AF: Virginia Institute of Marine Science, College of William and Mary, Gloucester Point, VA 23062 United States
AB: Over the last few years, several large icebergs have calved off the Ross Ice Shelf in Antarctica and have drifted around the Ross Sea. In March 2000, the iceberg B-15 was created from the Ross Ice Shelf and a large fragment of this, B-15A ($\approx$6,400 km$^2$), is currently grounded near the east end of Ross Island up against the ice shelf. This iceberg is thought to have a substantial impact on ocean circulation in the southwestern Ross Sea as well as bloom dynamics, primary production, and possibly the entire pelagic ecosystem. An existing high resolution (5 km) three dimensional numerical model of the Ross Sea has been expanded to include the cavity underneath the Ross Ice Shelf and the mechanical and thermodynamic effects of the ice shelf on the water underneath. Two simulations have been run starting from a two year spin-up with a climatological ice shelf. The first simulation continues with the base conditions while the second places an iceberg (over a period of 90 days) representing B-15A and C-16 in the simulation and removes some of the ice shelf that has calved off. Much of the flow in the model is barotropic and the changes in water column thickness due to the iceberg change the circulation patterns in much of the southwestern Ross Sea. This change includes reducing the advection of above freezing surface water into McMurdo Sound during summer which corresponds to observations of unusually extensive sea-ice in McMurdo Sound during the summers of 2002 and 2003. The blocking effect of the iceberg increases the amount of warmer summer surface water from the Ross Sea polynya (a region of lower sea ice concentrations just north of the Ross Ice Shelf) that travels southward just east of Ross Island and underneath the ice shelf, possibly affecting melting of the ice shelf in this area.
DE: 4207 Arctic and Antarctic oceanography
DE: 4255 Numerical modeling
DE: 4540 Ice mechanics and air/sea/ice exchange processes
SC: Ocean Sciences [OS]
MN: 2004 Ocean Sciences Meeting