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ing to the value of the current velocity. The area bound by the light lines
7
and
8
was characterized by a small positive radar contrast against the sur-
rounding waters (Figure 1a), which supports this conclusion. The flow
13
bends around eddy
10
and turns to the west in area
14
. In this area the di-
rections of the wind speed and surface current coincide. The relative wind
speed here was lower and the area
14
looks darker in Figure 1a. Moreover,
it should be noted that the brightness variations over the mesoscale eddy
could be partly due to sea surface temperature variations and the corre-
sponding variations in the stability of the boundary layer of the atmos-
phere. Likely, it was just these factors which would explain the positive
radar contrast of the Kuroshio waters in Figure 1a (Mitnik and Lobanov
1992).
The step-like features in area
15
can also be interpreted as current-
induced. The arrows in Figure 1b show the directions of surface currents in
a small-scale elliptical eddy. These currents were responsible for the
westward and eastward displacements of the spill band. This cyclonic eddy
has a low radar contrast without distinct boundaries similar to the current
shift lines
7
and
8
. The different scaled eddy-like structures and also the
eddy streets were earlier detected in ERS SAR images of the Kuroshio east
of Taiwan (Hsu et al. 1997 1998, Mitnik et al. 1996, Mitnik and Hsu
1998).
Case 2.
The ERS-2 SAR image shown in Figure 4 was acquired on December 29,
1997, at 02:26 UTC (orbit 14071, frame 3141) during a descending pass
when the satellite was flying towards 192.9 qN and the SAR antenna was
looking towards 282.9 qN. The mountainous Taiwan coast and the island
of Lutao are clearly seen on the image.
On this day the seas surrounding Taiwan were under the influence of
weak (3-6 ms
-1
) northern winds, as shown in the weather maps of the JMA
for 00:00 and 06:00 UTC. Two ships
1
and
2,
moving to the north and one
ship
3
moving to the south are distinguishable in the upper right hand part
of the image. Ship
1
was the cause of the appearance of a spill band
4
. A
turbulent ship wake behind the ship and the northern part of the spill repre-
sented a straight line
5
parallel to the turbulent wake behind ship
2
.
A light (with increased Vq values) band
6
crosses the image from north
to south. The band divides the warmer surface Kuroshio waters
7
from the
colder waters
8
bordering the Taiwan coast. The difference in sea surface
temperature between the Kuroshio and coastal waters is indicated by their
brightness (the values of the NRCS). The higher NRCS values of the Ku-
roshio waters can be explained by the joint influence of two factors. The
