Fluctuation of the sea surface dynamic topography southeast of Japan as estimated from Seasat altimetry data

Ichikawa, Kaoru; Imawaki, Shiro

doi:10.1007/bf02239003

Cited by 6 publications

(3 citation statements)

References 21 publications

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“…We approximate the mean SSDT lost in the procedure by the mean SSDT field estimated from hydrographic observation data [Willebrand et al, 1990;Ichikawa and Imawaki, 1992]. Ideally, the SSDT should be averaged over the same period as the altimeter measurements.…”

Section: Methodsmentioning

confidence: 99%

“…Geosat altimetry data were distributed as Geophysical Data Records (GDR) by the National Oceanic and Atmospheric Administration (NOAA) [Cheney et al, 1987]. We applied the optimal interpolation method to remove the orbit error as well as to produce synoptic maps of the SSDT fluctuation around the 1-year mean [Wunsch and Zlotnicki, 1984;Ichikawa and Imawaki, 1992]. Details of the method are described in a separate paper (Ichikawa and Imawaki, 1994), so we summarize them shortly in the present paper.…”

Section: Datamentioning

confidence: 99%

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Life history of a cyclonic ring detached from the Kuroshio Extension as seen by the Geosat altimeter

Ichikawa

Imawaki

1994

J. Geophys. Res.

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The sea surface dynamic topography (SSDT; sea surface height relative to the geoid) is approximately estimated by combining the temporal fluctuation of SSDT determined from altimetry data with the climatological mean SSDT calculated from hydrographic data. This approximated SSDT, or composite SSDT, is obtained in the area southeast of Japan for the first year (1986–1987) of the Geosat Exact Repeat Mission. Variations in the Kuroshio Current System are well described by the composite SSDT. In particular, a complete life history of a cyclonic ring is observed for the first time in this region, namely, westward propagation of a southward meander of the Kuroshio Extension, its pinching‐off to form a cyclonic ring, the ring's westward movement, its coalescence with the Kuroshio, and its eastward advection. All available hydrographic data and cloud‐free satellite infrared images support the existence of this series of phenomena.

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Section: Methodsmentioning

confidence: 99%

Section: Datamentioning

confidence: 99%

Life history of a cyclonic ring detached from the Kuroshio Extension as seen by the Geosat altimeter

Ichikawa

Imawaki

1994

J. Geophys. Res.

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“…Satellite altimeters are important marine microwave remote sensors where measured data can be applied to physical oceanography, marine dynamics, marine climates and environments, and sea ice monitoring. For example, the distribution characteristics of regional-and global-scale surface current fields [1], the variation characteristics of mesoscale ocean circulation [2,3] and western boundary currents (such as the Kuroshio and the Gulf Stream) [4,5], the dynamic fluctuation of the sea surface [6], the ocean tidal wave system [7], the propagation of sea surface gravity waves [8], and the role of ocean dynamic phenomena in global climate change and El Niño-Southern Oscillation [9]. Based on the linear relationship between the sea surface pressure gradient force and the sea surface current field, quasi-steady sea surface velocities are derived from altimeters without considering the effect of the sea surface wind stress [10][11][12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Corrections of Mesoscale Eddies and Kuroshio Extension Surface Velocities Derived from Satellite Altimeters

Cao¹,

Qiu²,

Bethel

et al. 2022

Remote Sensing

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Oceanic datasets derived from satellite altimeters are of great significance to physical oceanography and ocean dynamics research and the protection of marine environmental resources. Ageostrophic velocity induced by centrifugal force is not considered in altimeter products. This study introduces an iterative method to perform cyclogeostrophic corrections of mesoscale eddies’ surface velocities derived from satellite altimeters. The corrected eddy velocity field and geostrophic velocity field were compared by combining eddy detection and mathematical statistics methods. The results show that eddies with small curvature radii, high roundness, or Rossby number larger than 0.1 illustrate that cyclogeostrophic correction is required. The cyclogeostrophic velocity is greater (less) than the geostrophic velocity in anticyclonic (cyclonic) eddies. Additionally, the iterative method is applied to cyclogeostrophic-corrected multi-year (1998–2012) Kuroshio surface velocities. The effect of cyclogeostrophic correction is significant for the Kuroshio Extension region, where the maximum relative difference of velocities with and without correction is about 10% and the eddy kinetic energy is 20%.

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Comparison of surface velocities determined from altimeter and drifting buoy data

Ichikawa

Imawaki

Ishii³

1995

J Oceanogr

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Fluctuation of the sea surface dynamic topography southeast of Japan as estimated from Seasat altimetry data

Cited by 6 publications

References 21 publications

Life history of a cyclonic ring detached from the Kuroshio Extension as seen by the Geosat altimeter

Life history of a cyclonic ring detached from the Kuroshio Extension as seen by the Geosat altimeter

Corrections of Mesoscale Eddies and Kuroshio Extension Surface Velocities Derived from Satellite Altimeters

Comparison of surface velocities determined from altimeter and drifting buoy data

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