For a routine observation of surface current by dual-site high-frequency radar(HF and VHF radar), it is absolutely necessary to develop an automatic extraction method of the surface current information from the narrow-beam sea-echo data with stable accuracy and without being checked by an expert. In developing the automatic procedures mentioned above, we took full advantage of the Bragg resonant mechanism, radar measurement's characteristic and statistical analysis. Features of the developed methods are; Surface currents extracted by this process are in good agreement with those measured by current meters at the same time in a bay with a dominant tidal flow, and the distribution mapped by these surface current data illustrate a well-known dominant feature in the bay. The conclusion is that the developed method is valid for the purpose of a routine observation by the radar.
The objective of this research is to carry out a flow analysis in the Japan Sea using the box model method, consisting of three equations of the conservation of mass, salinity and heat, and to study the reproducibility of its result. The input conditions is the water temperature and salinity supplied by JODC, indicate a characteristic distribution in the Japan Sea, including a cold water area, a warm water area and water mass peculiar to the Japan Sea, meteorological data, river flows and flows at straits. The seasonal variation of the nearshore branch of the Tsushima Warm Current along the Japanese coast, the East Korean Warm Current along the Korean Peninsula and the Liman Current along the continent are reproduced in the results of the flow analysis. However, the overshooting of the East Korean Warm Current to the north occur comparing with the analytical result of OGCM/GFDL. The flow in the intermediate layer is anti-clockwise at the west of Yamato Rise and clockwise at the Yamato Basin similar to the analytical result of OGCM/GFDL. The anti-clockwise flow at the Japan Basin and clockwise flow at the Yamato Basin are seen in the deep layer in winter.
Geomagnetic measurements, using a proton precession magnetometer with a short sampling interval of approximately one second, were carried out to investigate a measurement error due to towing attitude of the sensor vehicle. The major results of the measurements are as follows. 1) An increase of towing speed of the sensor does not significant1y affect the magnitude of a measurement noise level, if an available stabilizer is attached to the sensor vehicle. 2) Towing the sensor with a drag rope of 15m long or without any stabilizer causes an increment of noise level in comparison with the case of towing with the available stabilizers. 3) Sea condition is clearly related with the measurement noise level. These results suggest that the error of the sea surface geomagnetic measurements is mainly related with a motion of the towed sensor vehicle.