TERRAPUB Journal of Oceanography

Journal of Oceanography, Vol. 52 (No. 4), pp. 457-474, 1996

Eddy Activities of the Surface Layer in the Western North Pacific Detected by Satellite Altimeter and Radiometer

Shigeru Aoki1 and Shiro Imawaki2

1Department of Earth System Science and Technology, Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga, Fukuoka 816, Japan
2Research Institute for Applied Mechanics, Kyushu University, Kasuga, Fukuoka 816, Japan

(Received 5 October 1994; in revised form 4 November 1995; accepted 12 January 1996)

Abstract: Geosat radar altimeter data during the first year (from November 1986 to November 1987) of its Exact Repeat Mission are analyzed to estimate the eddy kinetic energy and propagation characteristics of anomalies of sea surface dynamic topography (SSDT) for the western North Pacific. SSDT anomalies are compared with anomalies of sea surface temperature (SST) derived from NOAA satellite radiometer data. The eddy kinetic energy (Ke) is large in the Kuroshio stationary meander region and Kuroshio Extension region. In the downstream region of the Kuroshio Extension, Ke is especially large on the upstream and downstream sides of prominent bathymetric features. In the interior region of the subtropical gyre is found a zonal tongue of large Ke at around 20-23°N. Westward propagation is dominant in the SSDT and SST anomaly field at mid-latitudes. Longitude-time lag correlation diagrams reveal the coincidence of SSDT and SST anomalies statistically, which fact suggests the baroclinic nature of the anomalies. Zonal phase speeds of SSDT anomalies are approximately equal to the theoretical speeds of baroclinic first-mode long Rossby waves, but the meridional variation of observed phase speeds does not follow the simple theoretical variation of decreasing speeds monotonously with increasing latitudes.

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