45 
Study on the Estimation of Tidal Front at Coastal Sea Area 
based on the NOAA Image Analysis 
Yukio AKAMATSU, Naoki SHIRAI (Kokusai Kogyo Co., Ltd.) 
Tadashi ASAI, Kazuo MURAKAMI 
(Port and Harbour Research Institute, the Ministry of Transport) 
1. Introduction 
It is required for the conservation of oceanic environment and safe navigation of vessels to 
grasp the distribution of floating garbage for effective garbage collection. Since the floating 
garbages are incessantly changing their positions under the influence of oceanic and 
meteorological conditions, it is necessary to develop the method to extract the area of the 
floating garbage distribution at real time. The floating garbage has a nature to concentrate along 
the tidal front, so it shows the possibility to estimate the area of floating garbage distribution by 
identifying the location of the tidal front. 
From the above point of view, the authors developed the tidal front estimation model based 
on the NOAA image analysis and applied this model to Osaka Bay, Japan. This study has been 
done for the purpose to find out the analysis method of NOAA image suitable for identifying 
the location of tidal front. 
2. Tidal front estimation model based on automatic processing 
The goal of this study is to estimate the location 
of tidal front through the image processing, 
eventually automatize the estimation by adding 
the information of time serial changes, and 
construct the system which can be put to 
practical use. Figure 1 shows the research plan of 
the model development. 
In this study,as one of the methods to estimate 
the location of tidal front by automatic processing, 
we discussed the method to extract the tidal front 
through the satellite image processing. Fig. 1: Research plan of the model development 
3. Study area and Data used for analysis 
We decided the whole area of Osaka Bay as the 
study area for analysis. Figure 2 shows the scope of 
study area. 
The data used for the analysis are the visible,near 
infrared and atmospheric correction added sea 
surface temperature data (MCSST) of artificial 
satellite NOAA data from 1991 to 1992.These 
pixel size is about 1.5km.We established the 
following selection guideline to discuss the 
possibility of identifying the location of tidal front. 
Fig. 2: Study area for analysis 
Estimation of tidal front 
location by image processing 
Consideration on time serial change 
Automatization 
Practical system