Overview

The overall goal of KESS is to identify and quantify the dynamic and thermodynamic processes governing the variability of and the interaction between the Kuroshio Extension and the recirculation gyre. The objectives of KESS.


Objective 1

To understand processes coupling the baroclinic and barotropic circulation and variability of the Kuroshio Extension System.

Working Hypotheses

  • As in the canonical baroclinic instability process, meandering of the Kuroshio Extension couples the baroclinic front to deep eddies, that, in turn steer the baroclinic front.
  • The baroclinic and barotropic coupling differ in the Kuroshio compared to the Gulf Stream due to differing topography, stratification and potential vorticity (PV).
  • The backgroud PV field favors mixed baroclinic/barotropic instability.
  • Mesoscale processes are punctuated by episodic large-amplitude events, which dominate the statistics of eddy fluxes and their divergences.

Objective 2

To determine and quantify cross-frontal exchange processes in the Kuroshio Extension.

Working Hypotheses

  • Mesoscale processes including meanders, rings, and barotropic eddies drive cross-frontal fluxes of heat, salt, momentum, and PV.
  • Meander crests and troughs play symmetric roles in the cross-frontal exchange processes.
  • Stirring processes strain waters injected across the front into thin streamers and facilitate the final mixing process.

Objective 3

To determine the processes that govern the strength and structure of the recirculation gyre - its position, elongation, stratification, and subtropical mode water formation within the gyre.

Working Hypotheses

  • Meanders and mesoscale instabilities result in PV-fluxes that drive recirculation.
  • Modulation of the recirculation gyre is due to changing PV structure of the Kuroshio Extension (Spall (1996) hypothesis).
  • Sea-surface temperature (SST) changes are moderated by the enormous heat capacity of Subtropical Mode Water (STMW) lenses which are sequestered reservoirs of heat.
  • Mean and eddy fluxes of heat by the Kuroshio Extension play a role in the variation of SST in the Kuroshio Extension region.

Full proposal including: Summary, Description, and References (pdf version)


Spall, Michael A., 1996. Dynamics of the Gulf Stream/Deep Western Boundary Current Crossover. Part II: Low-frequency internal oscillations. Journal of Physical Oceanography, 26(10), 2169-2182.