Download or read book The net transport of the Antarctic Circumpolar Current through Drake Passage written by T. Whitworth and published by . This book was released on 1982 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book On the transport of the Antarctic Circumpolar Current through Drake Passage and its relation to wind written by R.G. PETERSON and published by . This book was released on 1988 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book On the Variability of the Antarctic Circumpolar Current written by Ray George Peterson and published by . This book was released on 1987 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Assessing If the Antarctic Circumpolar Current Transport Through Drake Passage is Changing written by Morgan Dibb and published by . This book was released on 2019 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Structure and transport of the Antarctic Circumpolar Current at Drake Passage from short term measurements written by W.D. NOWLIN and published by . This book was released on 1977 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Determining the Temporal Variability of the Antarctic Circumpolar Current Transport Through Drake Passage from in Situ Observations written by Ceri Whitelegg and published by . This book was released on 2014 with total page 39 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Deriving a Novel Time Series of Total Transport in the Antarctic Circumpolar Current in Drake Passage written by Victoria L. Frith and published by . This book was released on 2011 with total page 55 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Antarctic Circumpolar Current in the Drake Passage written by Ramiro Ferrari and published by . This book was released on 2013 with total page 129 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis examines Antarctic Circumpolar Current (ACC) circulation and the mechanisms of meridional heat transport in Drake Passage. In order to achieve these goals we used in situ measurements collected during the DRAKE project (from January 2006 to March 2009; DRAKE 2006-9), available observations from the historical DRAKE 79 experiment, satellite altimetry data (since 1993) and high resolution model outputs (ORCA 12, MERCATOR). DRAKE 2006-9 current meter records, obtained from a current meter array deployed on the eastern side of the Shackleton Fracture Zone (SFZ), suggested the existence of a permanent strong deep cyclonic circulation in the northeastern part of the Yaghan Basin and in the Ona Basin. Mooring data also revealed a vertical consistency of the velocity and temperature variations. However, the rotation of the mean velocity vector with depth indicated consistent downwelling through the entire water column practically all along the mooring line. Near-surface current meter velocities provided an unprecedented opportunity to evaluate the altimetric velocities in this region. Comparison between in situ velocities and velocities derived from altimetry has shown good agreement allowing to further interpret observations at isolated mooring sites and to put them in the context of the 18-year-long satellite record. Altimetry helped to identify a dominant spatial structure associated to the presence of a strong southward meander of the Subantarctic Front in Yaghan Basin. Furthermore, it provided an accurate documentation concerning how the major topographic features control the mean location and meandering of the Antarctic Circumpolar Current frontal branches. In situ temperature and velocity time series from the DRAKE 2006-9 project were combined with the year-long historical DRAKE 79 experiment data set in order to analyse the eddy and mean flow contributions to the meridional heat flux across in the Drake Passage. Estimated cross-stream heat fluxes caused by the rotation of the mean flow with depth were found to be at least an order of magnitude larger than eddy heat fluxes. Equatorward heat fluxes caused by the mean flow found downstream the SFZ were in agreement with the general downwelling observed along the DRAKE 2006-9 project mooring array. Upstream the SFZ, however, the distribution of equatorward and poleward fluxes was puzzling. This distribution was analyzed using model outputs. Heat flux estimates due to the mean flow from the model outputs were similar to those obtained from in situ data and exhibited small spatial scales. The rough topography in Drake Passage likely promotes associated small spatial scales of vertical velocities and heat fluxes. The model-estimated heat flux due to the mean flow across the Southern ACC Front in Drake Passage (covering about 3% of the circumpolar longitudes between 48°W and 64°W) is thus on the order of 10% of the heat lost to the atmosphere south of 60°S.

Download or read book Structure and Variability of the Antarctic Circumpolar Current written by Ėduard Iosifovich Sarukhani︠a︡n and published by . This book was released on 1985 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Structure and Dynamical Balance of the Antarctic Circumpolar Current in Drake Passage written by Yvonne L. Firing and published by . This book was released on 2012 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis investigates the structure and dynamics of the Antarctic Circumpolar Current (ACC) in Drake Passage using observations that resolve spatial scales from 100 m to 1000 km and temporal scales from inertial to interannual. The structure and variability of the current, the eddy and mean contributions to the vorticity balance, and the patterns of internal wave activity are examined. The two primary sources of data are a long time series (2005-present) of upper ocean currents from the ARSV Laurence M. Gould (LMG) shipboard acoustic Doppler current profiler (SADCP), and a four-year process study (cDrake) providing time series of near-bottom currents, bottom pressures, and bottom-surface sound travel times as well as bathymetry, lowered ADCP, and CTD data from five yearly cruises. The vertical structure in the upper 1000 m is equivalent barotropic, with variable vertical length scale. The mean transport in the upper 1000 m is 95±2 Sv. Transport variability is approximately equally divided between shear and depth-mean components. Eddy kinetic energy decreases with depth faster than mean kinetic energy, reinforcing the view of the ACC as a barrier to mixing. Using empirical relationships determined from historical hydrography, travel time data from the cDrake array in the PFZ can be converted to baroclinic streamfunction. The near-bottom current and bottom pressure measurements provide the barotropic reference velocity. Streamfunction derivatives can be computed by objective mapping. We used independent measurements and simulated idealized fields to validate the objectively mapped fields and error estimates. Mean and eddy nonlinear vorticity advection and bottom pressure torque dominate the mean vorticity balance. The residual is first order. SOSE has the same balance and similar scales, with the residual accounted for by sub-grid-scale dissipation. In the southeastern Pacific a Rossby-wave-like balance between mean relative vorticity advection and planetary vorticity advection is observed. Downward-propagating internal wave energy and shear-strain ratios consistent with near-inertial frequencies predominate over deep waters and in the surface layer. Over shallower topography upward-propagating energy and supra-inertial frequencies dominate. The seasonal cycles in wind stress and internal wave energy south of the Polar Front are aligned; the seasonal cycle north of the Polar Front matches that in surface-layer stratification.

Download or read book Dynamics of the Antarctic Circumpolar Current written by Sarah Tragler Gille and published by . This book was released on 1995 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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 Geosat altimeter, without assuming prior knowledge of the geoid. For this study, an automated technique has been developed to estimate mean sea surface height for each satellite ground track using a meandering Gaussian jet model, and errors have been estimated using Monte Carlo simulation. The results are objectively mapped to produce a picture of the mean Subantarctic and Polar Fronts, which together comprise the major components of the ACC. The locations of the fronts are consistent with in situ observations and indicate that the fronts are substantially steered by bathymetry. The jets have an average Gaussian width of about 44 km in the meridional direction and meander about 75 km to either side of their mean locations. The width of the fronts is proportional to 1/f, indicating that with constant stratification, the width is proportional to the baroclinic. Rossby radius. The average height difference across the Subantarctic Front (SAF) is 0.7 m and across the Polar Front (PF) 0.6 m. The mean widths of the fronts are correlated with the size of the baroclinic Rossby radius. The meandering jet model explains between 40% and 70% of the height variance along the jet axes. Bathymetric constrictions are associated with increased eddy variability, a smaller percentage of which may be explained by the meandering of the ACC fronts, indicating that propagating eddies and rings may be spawned at topographic features. Detailed examination of spatial and temporal variability in the altimeter data indicates a spatial decorrelation scale of 85 km and a temporal e-folding scale of 34 days. The sea surface height variability is objectively mapped using these scales to define autocovariance functions. The resulting maps indicate substantial evidence of mesoscale eddy activity. Over 17-day time intervals, meanders of the PF and SAF appear to elongate, break off as rings, and propagate. Statistical analysis of ACC variability from altimeter data is conducted using empirical orthogonal functions (EOFs). The first mode EOF describes 16% of the variance in total sea surface height across the ACC; reducing the domain into basin scales does not significantly increase the variance represented by the first EOF, suggesting that the scales of motion are relatively short, and may be determined by local instability mechanisms rather than larger basin scale processes. Likewise, frequency domain EOFs indicate no statistically significant traveling wave modes. The momentum balance of the ACC has been investigated using both output from a high resolution primitive equation model and sea surface height measurements from the Geosat altimeter. In the Semtner-Chervin general circulation model, run with approximately quarter-degree resolution and time varying ECMWF winds, topographic form stress is the dominant process balancing the surface wind forcing. Detailed examination of form stress in the model indicates that it is due to three large topographic obstructions located at Kerguelen Island, Campbell Plateau, and Drake Passage. In order to reduce the effects of standing eddies, the model momentum balance is considered in stream coordinates; vertically integrated through the entire water column, topographic form drag is the dominant balance for wind stress. However, at mid-depth the cross-stream momentum transfer is dominated by horizontal biharmonic friction. In the upper ocean, horizontal friction, mean momentum flux divergence, transient momentum flux divergence, and mean vertical flux divergence all contribute significantly to the momentum balance. Although the relative importance of individual terms in the momentum balance does not vary substantially along streamlines, elevated levels of eddy kinetic energy are associated with the three major topographic features. In contrast, altimeter data show elevated energy levels at many more topographic features of intermediate scales, suggesting that smaller topographic effects are better able to communicate with the surface in the real ocean than in the model. Transient Reynolds stress terms play a small role in the the overall momentum balance; nonetheless, altimeter and model measurements closely agree, and suggest that transient eddies tend to accelerate the mean flow, except in the region between the major fronts which comprise the ACC. Potential vorticity is considered in the model output along Montgomery streamfunction. Even at about 1000 m depth, it varies in response to wind forcing, largely as a result of changes in vertical stratification, indicating that forcing and dissipation do not locally balance in the Southern Ocean. In order to compare model and altimeter potential vorticity estimates, two different proxies for potential vorticity on surface streamlines are considered. Both proxies show very similar results for model and altimeter, suggesting that differences in surface streamlines estimated by the altimeter and the model are not significant in explaining the Southern Ocean flow. The proxies are both roughly conserved along surface height contours but undergo substantial jumps near topographic features. However, they cannot capture stratification changes which may be critically important to the overall potential vorticity balance.

Download or read book Monitoring the Antarctic Circumpolar Current in the Drake Passage written by M.A. Morales Maqueda and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Antarctic Sector of the Pacific written by G.P. Glasby and published by Elsevier. This book was released on 1989-02-07 with total page 415 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Antarctic Sector of the Pacific covers the area between Australia and South America south of about 45°S. The region comprises about 6% of the Earth's surface and is amongst the most remote, hostile and least studied of the world's oceans. The scientific importance of the region is derived from its role in the reconstruction of Gondwanaland, its influence on Pacific climate and palaeoclimate and its biological productivity. No systematic surveys of the region have been undertaken since the work of the U.S.N.S. Eltanin (1962-1972). The comprehensive reassessment of whale stocks by the International Whaling Commission in 1990 and problems with ratification of the Antarctic Minerals Regime attest to the importance of Antarctic matters at present.The book will stimulate scientific activity in the region and serve as a handbook for future research. It should also appeal to oceanographers and Polar scientists.

Download or read book Proceedings of the Estonian Academy of Sciences Physics and Mathematics written by and published by . This book was released on 2004-12 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Antarctic Circumpolar Current at Drake Passage written by P. Challenor and published by . This book was released on 1996 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Temporal Variability of the Antarctic Circumpolar Current Through Drake Passage and the Scotia Sea written by M. P. Meredith and published by . This book was released on 1994 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Antarctic Circumpolar Current written by D.J. BAKER and published by . This book was released on 1977 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: