Identification

Title

Divergent eddy heat fluxes in the Kuroshio Extension at 144°-148°E. Part II: Spatiotemporal variability

Abstract

The Kuroshio Extension System Study (KESS) provided 16 months of observations to quantify divergent eddy heat flux (DEHF) from a mesoscale-resolving array of current- and pressure-equipped inverted echo sounders. KESS observations captured a regime shift from a stable to unstable state. There is a distinct difference in the spatial structure of DEHFs between the two regimes. The stable regime had weak downgradient DEHFs. The unstable regime exhibited asymmetry along the mean path with strong downgradient DEHFs upstream of a mean trough at ~147°E. The spatial structure of DEHFs resulted from episodic mesoscale processes. The first 6 months were during the stable regime in which fluxes were associated with eastward-propagating 10-15-day upper meanders. After 6 months, the Kuroshio Extension underwent a regime shift from a stable to unstable state. This regime shift corresponded with a red shift in mesoscale phenomena with the prevalence of ~40-day deep externally generated eddies. DEHF amplitudes more than quadrupled during the unstable regime. Cold-core ring (CCR) formation, CCR–jet interaction, and coupling between ~40-day deep eddies were responsible for asymmetry in downgradient fluxes in the mean maps not observed during the stable regime. The Kuroshio Extension has prominent deep energy associated with externally generated eddies that interact with the jet to drive some of the biggest DEHF events. These eddies play an important role in the variability of the jet through eddy–mean flow interactions. The DEHFs that result from vertical coupling act in accordance with baroclinic instability. The interaction is not growth from an infinitesimal perturbation, but from the start is a finite-amplitude interaction.

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document

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http://n2t.net/ark:/85065/d7w37x6r

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eng

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geoscientificInformation

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publication

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2016-01-01T00:00:00Z

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publication

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2013-11-01T00:00:00Z

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Copyright 2013 American Meteorological Society (AMS). Permission to use figures, tables, and brief excerpts from this work in scientific and educational works is hereby granted provided that the source is acknowledged. Any use of material in this work that is determined to be "fair use" under Section 107 or that satisfies the conditions specified in Section 108 of the U.S. Copyright Law (17 USC, as revised by P.L. 94-553) does not require the Society's permission. Republication, systematic reproduction, posting in electronic form on servers, or other uses of this material, except as exempted by the above statements, requires written permission or license from the AMS. Additional details are provided in the AMS Copyright Policies, available from the AMS at 617-227-2425 or amspubs@ametsoc.org. Permission to place a copy of this work on this server has been provided by the AMS. The AMS does not guarantee that the copy provided here is an accurate copy of the published work.

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OpenSky Support

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UCAR/NCAR - Library

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PO Box 3000

Boulder

80307-3000

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opensky@ucar.edu

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http://opensky.ucar.edu/

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