Variability in the Deep Western Boundary Current : local versus remote forcing
Joyce, Terrence M.
Toole, John M.
MetadataShow full item record
Horizontal velocity, temperature and salinity measurements from the Line W array for the period 2004–2008 show large changes in the water mass structure and circulation of the Deep Western Boundary Current (DWBC). Fluctuations in the flow with periods from 10 to 60 days are bottom intensified: signals most likely associated with topographic Rossby waves (TRW). A fraction (∼15%) of the DWBC transport variability is caused by Gulf Stream rings and meanders. These flow anomalies are surface intensified and fluctuate at frequencies lower than the TRW. Interannual variability in the velocity field appears to be related to changes in the hydrographic properties. The dominant mode of variability is characterized by an overall freshening, cooling, a potential vorticity (PV) increase in the deep Labrador Sea Water (dLSW) and a PV decrease in the Overflow Water (OW). The variability in the flow associated with these property changes is not spatially homogeneous. Offshore (water depths larger than 3500 m) changes in the velocity are in phase with PV changes in the OW: a decrease in the OW PV is accompanied by an increase in the southward (negative) transport. Conversely, variations of the inshore flow are in phase with changes in the dLSW PV (increasing PV and decreasing transport). This trend, true for most of the record, reverses after the winter of 2007–2008. A sudden decrease of the dLSW PV is observed, with a corresponding intensification of the flow in the inner DWBC as well as a northward shift in the Gulf Stream axis.
Author Posting. © American Geophysical Union, 2012. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 117 (2012): C12022, doi:10.1029/2012JC008369.
Suggested CitationJournal of Geophysical Research 117 (2012): C12022
Showing items related by title, author, creator and subject.
Climate variability in the equatorial Pacific Ocean induced by decadal variability of mixing coefficient Huang, Chuan Jiang; Wang, Wei; Huang, Rui Xin (American Meteorological Society, 2007-05)The circulation in the equatorial Pacific Ocean is studied in a series of numerical experiments based on an isopycnal coordinate model. The model is subject to monthly mean climatology of wind stress and surface thermohaline ...
Trend and interannual variability in southeast Greenland Sea Ice : impacts on coastal Greenland climate variability Moore, G. W. K.; Straneo, Fiamma; Oltmanns, Marilena (John Wiley & Sons, 2014-12-02)We describe the recent occurrence of a region of diminished sea ice cover or “notch” offshore of the Kangerdlugssuaq Fiord, the site of the largest tidewater glacier along Greenland's southeast coast. The notch's location ...
Decadal variability of the upper ocean heat content in the East/Japan Sea and its possible relationship to northwestern Pacific variability Na, Hanna; Kim, Kwang-Yul; Chang, Kyung-Il; Park, Jong Jin; Kim, Kuh; Minobe, Shoshiro (American Geophysical Union, 2012-02-09)The upper ocean heat content variability in the East/Japan Sea was investigated using a 40 year temperature and salinity data set from 1968 to 2007. Decadal variability was identified as the dominant mode of variability ...