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L.M. Mitnik and V.A. Dubina
to the sea surface decreases till 2–2.5 m/s when backscatter is absent. As a result,
the corresponding regions have a dark tone on SAR image. Further east, outside of
eddies, the brightness of the image increases, but it is lower than to the west of the
front where SST is higher.
7.2.3 Eddies in the Coastal Zone
Coastal zones are of crucial importance to society. These areas are characterized by
interaction of complex and coupled physical and bio-geo-chemical processes in the
upper ocean and atmospheric boundary layer, at various spatial and temporal scales.
The same areas are strongly influenced also by terrestrial processes, especially by
run-off. A quantitative understanding of the processes impacting the coastal region
is required to determine how wind, waves, current and river discharge variability,
as well as coastal orography, will affect coastal systems. The study of dynamic
phenomena in this zone is difficult, given the wide spectrum of temporal and spatial variability of physical processes occurring, which requires the development of
synergic approaches through the combined use of remote sensing and in-situ data,
together with modeling.
Mesoscale and small-scale features of surface circulation have often the form of
eddies and vortex pairs which are visualized in the ocean color, SST, sea surface
roughness or sea ice fields. Figure 7.4 shows eddies of various scales and warm
water flows in ASAR and AVHRR thermal images of the Japan Sea to the east of
the Korean coastline (Mitnik and Dubina, 2005).
7.3 Okhotsk Sea and Oyashio-Kuroshio Frontal Zone
7.3.1 Eddies in the Soya Warm Current Area
The Soya Warm Current (SWC) flows southeastward along the coast of Hokkaido,
in area with depth less than 150 m (Fig. 7.4). It is formed by Japan Sea waters that
enter the Okhotsk Sea through the Soya (LaPerouse) Strait. The typical width of
the SWC is approximately 50 km. Seasonal variations of monthly-mean velocity of
the SWC are clear pronounced. The velocity reaches a maximum of approximately
100 cm/s in summer (August and September) and became weak in winter (January
and February) (Ebuchi et al., 2009). SWC waters are characterized by high temperature and salinity, and by a sharp front separating them from the lower-temperature
and lower-salinity offshore waters. The distance of the front from the coast is about
35–50 km.
Frequently, radar signatures in the form of eddies, eddy streets and waves are
observed in the SWC area to the southeast of Cape Krilion, north of Hokkaido.
Waves are produced after the flow separates from the cape and propagates downstream. In the region of flow separation, strong horizontal shear induces barotropic
instability, in which the waves are generated (Ohshima and Wakatsuchi, 1990). On
L.M. Mitnik and V.A. Dubina
to the sea surface decreases till 2–2.5 m/s when backscatter is absent. As a result,
the corresponding regions have a dark tone on SAR image. Further east, outside of
eddies, the brightness of the image increases, but it is lower than to the west of the
front where SST is higher.
7.2.3 Eddies in the Coastal Zone
Coastal zones are of crucial importance to society. These areas are characterized by
interaction of complex and coupled physical and bio-geo-chemical processes in the
upper ocean and atmospheric boundary layer, at various spatial and temporal scales.
The same areas are strongly influenced also by terrestrial processes, especially by
run-off. A quantitative understanding of the processes impacting the coastal region
is required to determine how wind, waves, current and river discharge variability,
as well as coastal orography, will affect coastal systems. The study of dynamic
phenomena in this zone is difficult, given the wide spectrum of temporal and spatial variability of physical processes occurring, which requires the development of
synergic approaches through the combined use of remote sensing and in-situ data,
together with modeling.
Mesoscale and small-scale features of surface circulation have often the form of
eddies and vortex pairs which are visualized in the ocean color, SST, sea surface
roughness or sea ice fields. Figure 7.4 shows eddies of various scales and warm
water flows in ASAR and AVHRR thermal images of the Japan Sea to the east of
the Korean coastline (Mitnik and Dubina, 2005).
7.3 Okhotsk Sea and Oyashio-Kuroshio Frontal Zone
7.3.1 Eddies in the Soya Warm Current Area
The Soya Warm Current (SWC) flows southeastward along the coast of Hokkaido,
in area with depth less than 150 m (Fig. 7.4). It is formed by Japan Sea waters that
enter the Okhotsk Sea through the Soya (LaPerouse) Strait. The typical width of
the SWC is approximately 50 km. Seasonal variations of monthly-mean velocity of
the SWC are clear pronounced. The velocity reaches a maximum of approximately
100 cm/s in summer (August and September) and became weak in winter (January
and February) (Ebuchi et al., 2009). SWC waters are characterized by high temperature and salinity, and by a sharp front separating them from the lower-temperature
and lower-salinity offshore waters. The distance of the front from the coast is about
35–50 km.
Frequently, radar signatures in the form of eddies, eddy streets and waves are
observed in the SWC area to the southeast of Cape Krilion, north of Hokkaido.
Waves are produced after the flow separates from the cape and propagates downstream. In the region of flow separation, strong horizontal shear induces barotropic
instability, in which the waves are generated (Ohshima and Wakatsuchi, 1990). On