012
(R2=0.94).
> thickness
condition.
> estimated
AMSR-E
hin sea ice
However,
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Thus, the
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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XXXIX-B8, 2012
XXII ISPRS Congress, 25 August — 01 September 2012, Melbourne, Australia
Figure 10 shows scatter plots of 19GHz versus 37GHz at
vertical polarization brightness temperatures of AMSR-E used
in Bootstrap Algorithm for the sample areas. This characteristic
domain is used for calculating ice concentrations in Bootstrap
Algorithm. It is clear that the thin ice area ( ?) can’t be
identified with the ice floe(consolidated ice #) in this scatter
plots. So, the authors have introduced the scatter plots of
AMSR-E (19GHz V-19GHz H) versus 37GHzV as shown on
Figure 11. Since thin ice areas are likely to be wet, the
polarization difference of 19GHz brightness temperature in thin
ice area increases than big ice floe (consolidated ice). As a
result, the thin ice area(<*) could be discriminated from big ice
floe(#) in the scatter plots on Figure 11. The authors have
introduced following two equations for extracting thin ice area.
TB(19GHzV — 19GHzH) +TB(37GHzV)>300K (1)
TB(19GHzV)>245K (2)
The meshed area represents the area extracted with equation (1).
Equation (2) is used to reject the sea ice area which
concentration is less than approx. 80%. The red area in Figure
12(a) are the “thin ice areas” extracted with this method. The
extracted areas were overlaid on the MODIS image for
evaluation as shown on Figure 12(b) and (c). It is clear that
most of the thin ice areas which are appearing in dark purple in
the MODIS image are successfully extracted with the proposed
method. Up to now, we have applyed this method to around ten
AMSR-E scenes for the Sea of Okhotsk with success.
>
E : : Sagat. ol :
@ Gan Sea of Okhotsk
x 19 p eot # A-ice floe
i e ee i s od + B-Thin ice
À C-Mixed zone
3$ D-Mixed zone
+ E-Qpen water
200 ne 220 230 240 250 260
AMSR-E T837V
Fig.10 Scatter plots of 19GHz vs 37GHz at V polarization
(Sea of Okhotsk, 2009/02/07)
80
76
t.
3 90
n
3 5
x Sea of Okhotsk
E ao
ui
n 3$ A-ice floe
P
2% ssThinice
20 à C-Mixed zone
zm & D-Mixed zone
x E-Open water
0
200 210 220 230 240 250 260
AMSR-E Te37V
Fig.11 Scatter plots of Tg(19GHzV-19GHzH) versus
Tp(37GHzV)
=
(a) AMSR-E image (Red: extracted area)
(b)MODIS image
(c) Expansion of the extracted area overlaid on MODIS
image
Fig.12 Thin ice area extraction result