51 
5-3. Discussion on correlation 
When we examined the coincidence of tidal fronts extracted by single band and multi-band 
clustering of NOAA image data with the tidal fronts confirmed by sea truth, it has clear that the 
extent of coincidence was almost the same. Table 4 shows the distance average between the 
tidal fronts obtained from sea truth and NOAA image. 
Table 4: Average distance between the tidal fronts obtained from sea truth and NOAA 
image 
Observation date of sea 
truth 
Observation date of 
satellite NOAA 
Average distance by 
single band data 
Average distance by 
multi-band data 
1992:May 21 
1992:May 21 
4.49 
4.48 
1992:Aug 28_1 
1992:Aug 28 
6.54 
6.60 
1992: Aug 28_2 
1992:Aug 28 
5.59 
5.78 
1991: Sep 3_1 
1991:Sep 3 
0.89 
0.87 
1991: Sep 3_2 
1991 : Sep 3 
1.06 
1.01 
1991: Sep 3_3 
1991:Sep 3 
1.78 
1.75 
1991: Sep 5 
1991:Sep 5 
5.31 
5.31 
1991: Sep 6_1 
1991:Sep 6 
1.07 
0.59 
1991 : Sep 6 2 
1991 : Sep 6 
1.61 
1.92 
Average distance is number of pixel 
It is considered from the above results that the multi-band clustering is not necessarily more 
effective than the single band clustering as the method to classify the water blocks. The tidal 
fronts obtained from NOAA image coincided relatively well with the tidal fronts confirmed by 
sea truth as a whole. However, there are some cases where these tidal fronts were largely 
different. This is considered to be due to the difference of observation date and the influence of 
climate and sea current, etc. It should be necessary to consider the time serial changes including 
those due to climate and sea current to improve the accuracy of tidal front estimation. 
6. Conclusion and problems in the future 
It has become clear from this study that there is a good possibility to estimate the location 
of tidal fronts using relatively simple methods such as preliminary processing of NOAA data 
and applying single band clustering method to temperature distribution data (MCSST). 
However, there are still some problems to be solved in constructing practical method based on 
automatic processing because there is a lack of stability in extracting the tidal fronts as the 
coincidence with the tidal fronts of sea truth is largely deteriorated in some cases and also 
because some methods used in this study necessitate the judgment of specialists. There are 
following problems which should be solved in the future. 
(1) Discussion on the automatic processing method 
In this study, the judgments of specialists were jointly used for establishment of threshold 
for eliminating cloud area and land area and extraction of tidal front on the water block 
classification image. It is necessary to discuss the automatic judgment method which does not 
necessitate the specialist's judgment in developing the practical method.