Geology Reference
In-Depth Information
(a)
(b)
12
13
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16
17
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19
20
21
22
23
23
24
25
26
27
28
29
30
31
32
33
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35
4
2
8
1
12
16
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28
32
36
40
44
48
52
56
60
64
68
72
76
80
84
88
92
96
100
January 22, 2003
(c)
(d)
4
8
12
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20
24
28
32
36
40
44
48
52
56
60
64
68
72
76
80
84
88
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96
100
2
3
4
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6
7
8
9
10
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12
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18
19
20
21
22
23
24
25
4
3
1
2
February 22, 2003
Figure 8.8
Examples to demonstrate the effects of surface wind speed and radar incidence angle on the back-
scatter from OW. Total ice concentration assigned to each polygon during the Radarsat image analysis in CIS are
overlaid on a pair of Radarsat‐1 images acquired on (a) 22 January and (c) 22 February 2003. Ellipses representing
the footprints of SSM/I 85 GHz channels are overlaid on the Radarsat‐1 images in (b) and (d). They are color coded
to represent the surface wind speed at 12 m level. Note the difference of the wind speed range between the two
dates. The color bar for the ice concentration is in % and for the wind speed in m/s. (For color detail, please see
color plate section).
subjectively estimated total ice concentration assigned to
each polygon by the analyst. The ice concentration values
are related to the colors as shown in the color bar. The
images on the right side show footprints of the 85 GHz
channel of SSM/I in colors that represent the wind speed
at the 19 m level obtained from SSM/I observations using
the D‐matrix algorithm [
Lo
, 1983]. The time difference
between Radarsat and SSM/I observations was 47 and
33 min for the images of 22 January and 22 February,
respectively. The relation between backscatter and wind
speed is visually demonstrated in the figure. In Figure 8.8a,
the brighter band in the middle of the image corresponds
to OW with a higher wind speed. Note also that backscat-
ter in area 1 is significantly higher compared to area
2 while both represent OW located within approximately
the same incidence angle range. Figure 8.8b confirms
that the wind speed is much higher in area 1. In
Figure 8.8c, the drop in backscatter across areas 1, 2, and
3 is due to an increase in incidence angle and a decrease
of wind speed. Areas 3 and 4 are located within the same
