Presenter: Leonid M. MITNIK

KUROSHIO FRONT AND OCEANIC PHENOMENA NEAR TAIWAN ON ERS SAR IMAGES

Ming-Kuang Hsu, Department of Oceanography, National Taiwan Ocean 
University,  202, Keelung, Taiwan, R.O.C. , hsumk@ind.ntou.edu.tw

Leonid M. Mitnik, Pacific Oceanological Institute, FEB RAS, Vladivostok 
690041, Russia, toi@stv.iasnet.ru

Jian-Hwa Hu, Department of Oceanography, National Taiwan Ocean University, 
202, Keelung, Taiwan, R.O.C., hu@vax.oce.ntou.edu.tw

Cho-Teng Liu, Institute of Oceanography, National Taiwan University, 107, 
Taipei, Taiwan, R.O.C., ctliu@ccms.ntu.edu.tw

The surface manifestations of the Kuroshio, the Taiwan Warm Current and 
diversified oceanic phenomena were studied by analysis of the SAR images 
collected in 1993-1996 over the area 20-27N, 120-124E. SAR signatures 
depend both on oceanic dynamics and wind characteristics. The weather maps, 
wave analysis maps, NOAA AVHRR and ARGOS buoy data were used to interpret 
the brightness variations on the SAR images. Of particular interest were 
the strips of the SAR images which were covered the same areas of about 
100 km x 500-800 km east and west of Taiwan. The complicated structure of 
the currents was clearly visible on each strip. The linear features with 
the increased or decreased values of the normalized radar cross section 
(NRCS) were due to short gravity-wave/current interaction along shear 
and/or
convergence zones within the Kuroshio front. The reduced values of the 
NRCS (dark bands) were often associated with increased concentration of 
slicks aligned along frontal boundaries. Eddy-like and wave-like 
signatures on the SAR images were caused by the interaction of the 
currents with the ambient waters, islands, underwater mountains. Island 
wakes were detected downstream of Lanyu, Lutau and Liuchiu Yu islands. 
Spiral eddies and rips were detected over the underwater mountains and the 
shelf break of the East China Sea. The interaction of the Kuroshio and 
tidal currents with the shelf break resulted also in generation of 
upwelling northeast of Taiwan and packets of rank-ordered internal waves 
propagating both offshore and onshore. High capture rate of the upwelling 
and internal waves by SAR denotes that these phenomena are common for the 
southern East China Sea. Surface manifestations of large-amplitude 
internal solitary waves were observed also in the Luzon Strait and in the 
northern South China Sea. 

Keywords: ERS SAR, Kuroshio, East-China Sea, upwelling, internal waves,
         island wakes

Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry