TERRAPUB Journal of Oceanography

Journal of Oceanography, Vol. 57 (No. 1), pp. 1-13, 2001

Variability of Sea Surface Circulation in the Japan Sea

Akihiko Morimoto1* and Tetsuo Yanagi2

1Department of Civil and Environmental Engineering, Ehime University, Matsuyama 790-8577, Japan
2Research Institute for Applied Mechanics, Kyushu University, Kasuga 816-8580, Japan

(Received 7 March 2000; in revised form 30 June 2000; accepted 8 August 2000)

Abstract: Composite sea surface dynamic heights (CSSDH) are calculated from both sea surface dynamic heights that are derived from altimetric data of ERS-2 and mean sea surface that is calculated by a numerical model. The CSSDH are consistent with sea surface temperature obtained by satellite and observed water temperature. Assuming the geostrophic balance, sea surface current velocities are calculated. It is found that temporal and spatial variations of sea surface circulation are considerably strong. In order to examine the characteristics of temporal and spatial variation of current pattern, EOF analysis is carried out with use of the CSSDH for 3.5 years. The spatial and temporal variations of mode 1 indicate the strength or weakness of sea surface circulation over the entire Japan Sea associated with seasonal variation of volume transport through the Tsushima Strait. The spatial and temporal variations of mode 2 mostly indicate the temporal variation of the second branch of the Tsushima Warm Current and the East Korean Warm Current. It is suggested that this variation is possibly associated with the seasonal variation of volume transport through the west channel of the Tsushima Strait. Variations of mode 3 indicate the interannual variability in the Yamato Basin.

*Corresponding author E-mail: amorimo@dpc.ehime-u.ac.jp

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