Points) are refered. On this site, the GCPs sampled on a series of small islands of Izu-Ogasawara- 
Ridge are crucial for the turbulence measurements extending hundreds miles off the Pacific-Coast. 
To make clear the spacial structure of mesoscale eddies, some radiometric enhancements 
were applied. As the sea surface temperature differes about 20K in south and north, detailed 
features of each eddies are obscured in the ordinary gray-scale stretching. Through the processing 
of NOAA image shown in Figure 1(a), components of more than 100km in space scale were cutoff. 
1.3 Instantaneous turbulence measurements by SeaMark method 
Figure 1(b) shows the instantaneous turbulence field measured by applying SeaMark 
method to a pair of NOAA/AVHRR data set; i.e. the first set exhibited in Figure 1 and the last one 
obtained about 6hours later. SeaMark method is a sea surface fine feature tracking technique for 
the measurements of sea surface velocity vector distribution (Tanaka et al. 1983). An advantage 
over surface surveys or microwave altimetry is the sampling time of 6 or 12 hours. Owing to such 
a short sampling time, geometrical informations from NOAA image and kinematical ones from 
SeaMark measurements are those gained at the same time, and any data assimilation is unnecessary. 
Synthesizing Figures 1(a) and (b), we gain a quantitative flow visualization of the oceanic 
turbulence. The most energetic is the turbulence proceeding off the Pacific-Coast, which closely 
relates to the Kuroshio. Surely, most oceanographers would interpret a typical pattern of generally 
accepted Kuroshio meandering; i.e. the Kuroshio running near the Pacific-Coast takes a C-type 
meandering path to encircle a coastwise large cold cyclonic watermass inside the Shikoku-Basin. 
Here, we employed another approaching method to focus on the turbulence processes based 
on the coherent structure concept. Kuroshio causes a coastwise turbulent boundary layer, in which 
some cyclonic eddies are being shed into the wakes of the capes. Inside the Shikoku-Basin, a 
dipole is formed by the cyclonic cold watermass in the Enshu-Sea pairing with an anticyclone 
rotating offshore. Their kinetic energy is as in the same level as that of the Kuroshio itself. 
1.4 Tectonic environments and nonlinear turbulence process 
Figure 2 shows the tectonic settings of the energetic oceanic turbulence relating to the two 
northern-hemisphere western boundary currents, Kuroshio and the Gulf-Stream. The Kuroshio is 
located in a convergence zone of 4 sheets of tectonic plate. Coastline is configured by cusped 
capes and arched bays. Space interval of these Giant-Cusps is 100-150km, same order as that of 
mesoscale eddies and as the Rossby's internal radius of deformation. As shown in Figure 1, the 
Giant-Cusps play as the vortex generator which control the growth and decay of boundary layer. 
Another feature is the submarine ridges and seamounts. Linking with the coastline, Kyushu- 
Palau-Ridge and Izu-Ogasawara-Ridge enclose the Shikoku-Basin to form a rotating closed vessel 
of turbulence of 500km in size. On the center of the basin, some discrete seamounts rise in a line. 
In the Gulf-Stream region too, we find Giant-Cusps on the US coast, in the wake of which 
cyclonic eddies have been found (Lugt 1983). About 1,000km downstream of the Cape-Hatteras, 
we also notice the New-England-Seamounts. Overhead these seamounts, Gulf-Stream-Rings are 
formed to migrate westward or to be sometimes trapped there stationary (Richardson 1984). 
Comaparing these, we are led to rationally estimate the tectonic settings in the Kuroshio 
meander, which oceanographers say is unique to the Kuroshio. Although its space scale is same as 
the Gulf-Stream-Rings, time duration of stationariness is much larger. In the Gulf-Stream region, 
hydrodynamics of Rings and coastwise turbulent boundary layer proceed rather linearly. On the 
contrary in the Kuroshio region, hydrodynamics of Giant-Cusps proceeds directly interacting with 
those due to Izu-Ogasawara-Ridge and Kyushu-Palau-Ridge. This nonlinear interaction between 
two energy containing turbulence components is crucial in the Kuroshio hydrodynamics. 
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