Evaluation of the influence of a facility removed from the Memambetsu Magnetic Observatory site on geomagnetic field measurements in 2013
Shingo NAGAMACHI, Junpei OOGI, Tetsuya SHIMAMURA, Kosuke TAKAHASHI & Ikuko FUJII
We removed an unnecessary facility from the Memambetsu Magnetic Observatory site from August to October 2013. This facility was located at a distance about 130 m from the absolute observation point. To evaluate the amount of artificial magnetic field caused by the facility that we removed, we simulated the artificial magnetic field at the absolute observation point from the data of several 3-component magnetometers and the results of magnetic surveys from around the observatory. To attain an increased level of confidence for the simulation, we considered both the confidence interval of the observation data and the shape of the facility, and we evaluated the confidence interval of the result of the simulation. From the simulation results, we conclude that the influence of the removed facility at the absolute observation point exceeded the ±0.3 nT correction criterion.