TERRAPUB Journal of Oceanography

Journal of Oceanography, Vol. 66 (No. 5), pp. 709-717, 2010

Distribution of Deep Near-Inertial Waves Observed in the Kuroshio Extension

Jae-Hun Park1*, Kathleen A. Donohue1, D. Randolph Watts1 and Luc Rainville2

1Graduate School of Oceanography, University of Rhode Island, Narragansett, RI 02882-1197, U.S.A.
2Applied Physics Laboratory, University of Washington, Seattle, WA 98105-6698, U.S.A.

(Received 27 May 2010; in revised form 11 August 2010; accepted 11 August 2010)

Abstract: The distribution of deep near-inertial waves (NIWs) is investigated using data mainly from an array of 46 near-bottom acoustic current meter sensors spanning a 600 km × 600 km region as part of the Kuroshio Extension System Study during 2004-2006. The deep NIW distribution is interpreted in the context of both upper-layer and near-bottom mapped circulations. The wintertime-mean mixed-layer NIW energy input, modeled from observed wind stress, has the same range of values north and south of the Kuroshio Extension in this region. Yet, the wintertime-mean deep NIW energy distribution reveals a sharp factor-of-5 decrease from north to south of the Kuroshio jet. This direct observational evidence shows that the Kuroshio Extension blocks the equatorward propagation of NIWs. The NIW energy that does reach the sea floor within the subset of wintertime observations in the subtropical gyre arrives with patchy spatial and temporal distribution. Elevated NIW energy in deep water is associated with anticyclones in the deep barotropic flow and unassociated with upper layer eddies.

*Corresponding author E-mail: jpark@gso.uri.edu

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