Measurement of geomagnetic field at sea during JARE-30, 1988-1989

Three components and total intensity of the geomagnetic field were measured by STCM (Shipboard Three Components Magnetometer) and a proton magentometer at the same time at sea during the 30th Japanese Antarctic Research Expedition. The measurements of total intensity of the geomagnetic field by a proton magnetometer showed a variation of noises in harmony with the variation of ship's velocity. This variation of noises may be caused by instability of the sensor due to large velocity of the ship. The measurements of three components of the geomagnetic field by STCM revealed short wavelength noiscs which were caused by small yawing of the ship. Reliable absolute values of three components of the geomagnetic field were obtained by adapting the total intensity of the geomagnetic field measured by a proton magnetometer to the data of three components of the geomagnetic field measured by STCM. In the present state of STCM, it is necessary to measure three components and total intensity of geomagnetic field by STCM and a proton magnetometer simultaneously, in case of obtaining the absolute values of three components of the geomagnetic field. These results suggest that improvement of measurement of the geomagnetic field at sea will be required