69 
degrees step. We employed two HF ocean radars at Sawara site and Kinaoshi site in 
order to observe current vectors (Fig. 1). Sea echoes over the range of 90 km can be 
detected by our system in good conditions(Ohno et al., 1993). A doppler spectrum 
obtained at every 1.5 km in the range direction. Ocean currents of all radar beam 
directions were obtained every two hours. In order to study COC, we made maps of 
daily-mean ocean current vectors with neglecting of tidal components by operation of 25 
hours running mean.. 
2.2 Satellite observation and image analysis 
NOAA-12 Advanced Very High Resolution Radiometer (AVHRR) data were 
collected from January to March 1995. These data were received at the Meteorological 
Satellite Center of Japan Meteorological Agency. For the AVHRR thermal infrared data, 
in-flight calibration was first carried out and the calibrated data then processed to remove 
geometric distortions by use of an procedure described by Saitoh (1995). A digitized 
coast line and geographical mark were superimposed on the geometric corrected image. 
By using infrared images, It is able to identify Coastal Oyashio water mass because it is 
relatively low temperature to warm adjacent waters. 
3. Results and Discussion 
The data shown in Fig.2 of the synoptic views of surface currents provided by the 
radar system from January 21 to 24, 1995. Distribution of Coastal Oyashio water is 
shown in Fig.3 in January 22 and 24, 1995. On January 22, COC flows with speed of 10 
cm/s to 20 cm/s from the east to the west in the mouth of the Funka Bay (Fig.2 b). On 
January 22, Coastal Oyashio water do not reach to offshore of Muroran (Fig. 3a). After 
two days, Coastal Oyashio water arrives to the mouth of the Funka Bay and some water 
intrudes to the Bay (Fig. 3b). There is a time lag of about two days between the 
movement of Coastal Oyashio water and the change of COC, then we can identify the 
intrusion of Coastal Oyashio water from infrared images on January 24. 
Fig. 4 and Fig.5 are also time series views of surface currents and distribution of 
Coastal Oyashio water in the period of early March, 1995, respectively. COC flows 
with speed of over 50 cm/s from the east to the west in the mouth of the Funka Bay in 
March 1 (FIg.4 b). There is also a time lag of about two days between the appearance of 
strong westward surface currents and the intrusion of Coastal Oyashio water to the 
Funka Bay. These are at least two evidences of the intrusion of Coastal Oyashio water 
to the Bay in the period of this study. 
The time series of daily averaged surface currents at PI is compared with daily