Dynamics of the Antarctic Circumpolar Current. Evidence for Topographic Effects from Altimeter Data and Numerical Model Output.

• Main Author: Gille, Sarah T.
• Other Authors: MASSACHUSETTS INST OF TECH CAMBRIDGE
• Format: Text
• Language: English
• Published: 1995
• Subjects: Physical and Dynamic Oceanography; *OCEAN CURRENTS; *EDDIES(FLUID MECHANICS); *OCEANOGRAPHIC DATA; HEAT TRANSFER; PRESSURE GRADIENTS; MATHEMATICAL MODELS; POLAR REGIONS; SPATIAL DISTRIBUTION; OCEAN SURFACE; ANALYSIS OF VARIANCE; THESES; INPUT OUTPUT PROCESSING; VORTICES; HIGH RESOLUTION; CONTINENTAL SHELVES; BATHYMETRY; KINETIC ENERGY; ALTIMETERS; DRAG; MARINE CLIMATOLOGY; HYDROGRAPHY; STRATIFICATION; OCEAN MODELS; GEOSTROPHIC WIND; OCEAN BOTTOM TOPOGRAPHY; REYNOLDS NUMBER; WIND STRESS; EQUATIONS OF STATE; FRONTS(OCEANOGRAPHY); ANTARCTIC REGIONS; MOMENTUM TRANSFER; JET STREAMS; SCIENTIFIC SATELLITES; SOUTHERN OCEAN; Antarctic; Southern Ocean; The Antarctic; Antarc*
• Online Access: http://www.dtic.mil/docs/citations/ADA305871; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA305871

Geosat altimeter data and numerical model output are used to examine the circulation and dynamics of the Antarctic Circumpolar Current (ACC). The mean sea surface height across the ACC has been reconstructed from height variability measured by the altimeter, without assuming prior knowledge of the geoid. The results indicate locations for the Subantarctic and Polar Fronts which are consistent with in situ observations and indicate that the fronts are substantially steered by bathymetry. Detailed examination of spatial and temporal variability indicates a spatial decorrelation scale of 85 km and a temporal e-folding scale of 34 days. Empirical Orthogonal Function analysis suggests that the scales of motion are relatively short, occuring on 1000 km length-scales rather than basin or global scales. The momentum balance of the ACC has been investigated using output from the high resolution primitive equation model in combination with altimeter data. In the Semtner-Chervin quarter-degree general circulation model topographic form stress is the dominant process balancing the surface wind forcing. In stream coordinates, the dominant effect transporting momentum across the ACC is bibarmonic friction. Potential vorticity is considered on Montgomery streamlines in the model output and along surface streamlines in model and altimeter data. (AN) Prepared in cooperation with Woods Hole Oceanographic Inst., MA.