An Update to the 'Barrier or Blender' Model of the Gulf Stream, Based on Lagrangian Analysis of Aviso Altimetry

Finite-time Lyapunov exponent (FTLE) is calculated from 22 years of Aviso geostrophic velocity to identify Lagrangian coherent structure (LCS) in the Gulf Stream region. The coherent structures in and around the Gulf Stream are delineated by the both positive- and negative-time FTLE ridges, and represent boundaries between dynamically distinct regions with characteristic transport and mixing processes. Alternating positive- and negative-time FTLE ridge patterns are found to line the meandering jet, which indicate the regions of entrainment and detrainment along the jet.

This LCS pattern compares well with the Bower kinematic model of a meandering jet, although it is clear that the kinematic model is an over-simplification of the jet dynamics, and studying the dynamics of vortex interaction with the jet is important for more fully understanding fluid transfer in the Gulf Stream region. A new conceptual model for the Gulf Stream is proposed, including a mechanism for the generation of the observed region of largest mean mixing efficiency. There is large variability in mixing efficiency in the ‘wavemaker’ region, where standing Rossby waves are important.

Back to: Mesoscale and Submesoscale Processes: Characterization, Dynamics, and Representation VI Posters