kness 
asure. 
  
  
a boat. 
5. COMPARISON OF ICE THICKNESS WITH RSI DATA 
On February 26, 2011, the most part of Saroma Lake 
were frozen except around the two small mouths of the 
lake to the Sea of Okhotsk as shown in the FORMOSAT- 
2 RSI image on Figure 6(a). We performed ice thickness 
measurement from a small boat at the marginal ice area 
near the first mouth of the lake (See Figure 4(a)). This 
was quite successful. But, the thickness of ices which we 
could measure from the boat were around 15 to 20cm. So, 
we performed similar experiment on February 25, 2012 at 
the Monbetsu Bay(See Figure 4(b)). At that time, we 
could measure many thin sea ices which thicknesses less 
than 15cm. The ice thickness of each point were 
measured several times and averaged. 
  
(a) Enterlance of Saroma Lake (Feb. 26, 2011) 
  
(b) Monbetsu Bay (Feb. 25, 2012) 
Figure 4. Measured points plotted on RSI images 
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 5 shows the relationship between the ice 
thickness and the radiance derived from RSI band 3 and 4 
data measured at the points shown in Figure 4(a) and (b). 
The linear relationships were observed between the ice 
thickness and the radiance acquired by RSI for the thin 
ice area around the mouth of the lake when the ice 
thicknesses were less than 20cm. This suggests the 
possibility of estimating ice thickness of thin ice with high 
resolution optical sensor such as RSI under the snowless 
and cloud free condition. Since the data were taken in two 
different places with one year interval, the result also 
suggested the stability and reliability of RSI data. As for 
the ice thicker than 20cm, our previous study (Cho et. al., 
2011) suggested the difficulty of estimating ice thickness 
with optical sensors. 
  
BANDS3 (0.63-0.69um) 
y = 2.2326% +51.17 : 
110 - hé =0 {ff 
  
  
  
  
~~ 
  
  
so rl 
i t 
+ 
  
  
  
Badianre (Wim^92/umisr) 
8 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
10 15 20 25 
Lee thickness (cm) 
(a) BAND3 
BANDA4 (0.76-0.90um) 
y=1.7106x + 30.056 
E:=07797 
Am 
8 
N 
< 
B 
E 
8 
s 
"x 
"n 
e 
0 5 10 15 20 25 
Ice thickness (cm) 
(b BAND4 
Figure 5. Relationship between ice thickness and RSI data 
^