Isopycnal eddy mixing across the Kuroshio Extension: Stable versus unstable states in an eddying model

TitleIsopycnal eddy mixing across the Kuroshio Extension: Stable versus unstable states in an eddying model
Publication TypeJournal Article
Year of Publication2017
AuthorsChen R., Gille ST, McClean JL
JournalJournal of Geophysical Research-Oceans
Volume122
Pagination4329-4345
Date Published2017/05
Type of ArticleArticle
ISBN Number2169-9275
Accession NumberWOS:000404363600044
Keywordsdiffusivity; drifter data; general-circulation; isopycnal mixing; jets; Kuroshio Extension; Mesoscale eddies; north-atlantic; pacific; southern-ocean; stable and unstable states; surface; time scales; variability
Abstract

The Kuroshio Extension (KE) jet transitions between stable and unstable states on interannual time scales. Cross-jet eddy mixing in the two states is contrasted in the KE region ( 28 degrees-40 degrees N,125 degrees-165 degrees E), using a global eddying 0.1 degrees configuration of the Parallel Ocean Program with online numerical particles. The 4 year period chosen (June 1994 to May 1998) covers a full cycle of the stable state, unstable state and the transition period. Large values of cross-jet eddy diffusivities within the KE jet are concentrated in the upper 1000 m. In the upper ocean, elevated cross-jet mixing within the KE jet is mainly concentrated in the downstream part of the KE jet, where the jet is weak but eddy activity is strong. The simulated time-mean KE jet is more intense and extends further east in the stable state than in the unstable state. Consequently, strong cross-jet mixing within the KE jet is located west of 150 degrees E during June 1996 to May 1997 (a typical unstable state), but east of 150 degrees E during June 1995 to May 1996 (a typical stable state). However, average mixing within the KE jet is indistinguishable in the typical stable and unstable states. In the deep ocean, mixing is strongly influenced by topography, and thus their horizontal structures have less inter-annual variability than in the upper ocean. One caveat is that results here cover one representative cycle of the two states. To obtain the climate mean mixing structures for the stable or unstable state, one would need numerical output covering a period much longer than 4 years.

DOI10.1002/2016jc012164
Short TitleJ Geophys Res-Oceans
Student Publication: 
No