Two Modes of Gulf Stream Variability Revealed in the Last Two Decades of Satellite Altimeter Data

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 degrees N, producing coherent sea level anomaly...

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Bibliographic Details
Published in:Journal of Physical Oceanography
Main Authors: Pérez Hernández, María Dolores, Joyce, Terrence M.
Other Authors: 50861902200, 34975057000, 3057975, 264375, WOS:Perez-Hernandez, MD, WOS:Joyce, TM
Format: Article in Journal/Newspaper
Language:English
Published: 2014
Subjects:
North-Atlantic Oscillation
Western Boundary Current
Cape-Hatteras
Circulation Models
Propagation
Path
Meanders
Position
Shifts
East
Atlantic Ocean
Circulation
Dynamics
Boundary Currents
Ocean Dynamics
Observational Techniques And Algorithms
Altimetry
Mathematical And Statistical Techniques
Empirical Orthogonal Functions
Separation Point
North Atlantic
North Atlantic oscillation
Online Access:http://hdl.handle.net/10553/72507
https://doi.org/10.1175/JPO-D-13-0136.1
Description
Summary: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 degrees N, producing coherent sea level anomaly (SLA) variability from 72 degrees to 50 degrees 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 degrees-46 degrees N and 45 degrees-75 degrees 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. 163 149 15

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