Two modes of Gulf Stream variability revealed in the last two decades of satellite altimeter data
MetadataShow full item record
KeywordAtlantic Ocean; Circulation/ Dynamics; Boundary currents; Indices; Ocean dynamics; Observational techniques and algorithms; Altimetry; Mathematical and statistical techniques; Empirical orthogonal functions
Monthly mapped sea level anomalies (MSLAs) of the NW Atlantic in the region immediately downstream of the Gulf Stream (GS) separation point reveal a leading mode in which the path shifts approximately 100 km meridionally about a nominal latitude of 39°N, producing coherent sea level anomaly (SLA) variability from 72° to 50°W. This mode can be captured by use of a simple 16-point index based on SLA data taken along the maximum of the observed variability in the region 33°–46°N and 45°–75°W. The GS shifts between 2010 and 2012 are the largest of the last decade and equal to the largest of the entire record. The second group of EOF modes of variability describes GS meanders, which propagate mainly westward interrupted by brief periods of eastward or stationary meanders. These meanders have wavelengths of approximately 400 km and can be seen in standard EOFs by spatial phase shifting of a standing meander pattern in the SLA data. The spectral properties of these modes indicate strong variability at interannual and longer periods for the first mode and periods of a few to several months for the meanders. While the former is quite similar to a previous use of the altimeter for GS path, the simple index is a useful measure of the large-scale shifts in the GS path that is quickly estimated and updated without changes in previous estimates. The time-scale separation allows a low-pass filtered 16-point index to be reflective of large-scale, coherent shifts in the GS path.
Author Posting. © American Meteorological Society, 2014. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 44 (2014): 149–163, doi:10.1175/JPO-D-13-0136.1.
Showing items related by title, author, creator and subject.
High-frequency acoustic scattering from turbulent oceanic microstructure : the importance of density fluctuations Lavery, Andone C.; Schmitt, Raymond W.; Stanton, Timothy K. (Acoustical Society of America, 2003-11)Acoustic scattering techniques provide a unique and powerful tool to remotely investigate the physical properties of the ocean interior over large spatial and temporal scales. With high-frequency acoustic scattering it is ...
Rypina, Irina I.; Kirincich, Anthony R.; Lentz, Steven; Sundermeyer, Miles A. (American Meteorological Society, 2016-06-29)This paper aims to test the validity, utility, and limitations of the lateral eddy diffusivity concept in a coastal environment through analyzing data from coupled drifter and dye releases within the footprint of a ...
Ross, Tetjana; Lavery, Andone C. (Acoustical Society of America, 2011-12-20)A weak-scattering model that allows prediction of acoustic scattering from oceanic pycnoclines (and the accompanying sound speed gradients) based on hydrographic profiles is described. Model predictions, based on profiles ...