| Acoustic Doppler Current Profiler (ADCP) employs a magnetic compass for obtaining direction of the sensor， which indicates that most of the observed values are relying on appropriate values by the compass. In an actual river， which is authors’ field of measurements， there are a number of sources which disturbs natural magnetic field， such as waterway bridges， forepoles along the river， H-steel structures， even in a tethered ADCP platform. For better understanding an actual situation， the authors conducted field measurements with ADCP and external compass. In this paper， the authors describe the results which were affected by local magnetic fields. Also we propose the observational method with external， non-magnetic compass for solving the problem. |
