Removing of vehicle noise events observed in magnetic fields by fitting of magnetotelluric time series data

초록

Nowadays, urbanisation is rapid. Therefore, distorted magnetotelluric (MT) data due to electromagnetic cultural noise around the site is unavoidable. In particular, the development of traffic causes a distorted time series of MT surveys by moving vehicles. In this study, we numerically calculated the horizontal component of a moving vehicle's magnetic field by simulating the vehicle as a magnetic dipole. The model used constant horizontal and vertical distances between the MT site and the road. The magnetic field was calculated using three variables: the direction of the magnetic dipole induced on the vehicle by the Earth's magnetic field, the magnitude of the vehicle's magnetic moment, and the velocity of the moving vehicle. Modelling and fitting was performed for 10 observed vehicle horizontal component noise events. We calculated very close waveforms to the observed vehicle noise events through the modeling and fitting process. Additionally, by using the calculated waveform that closely matched the observed vehicle noise events with minimal error, it was possible to infer the direction of the magnetic dipole, the magnitude of the moment, and the speed of the vehicle. The vehicle noise fitting method used in this study is expected to effectively remove vehicle noise waveforms observed MT data. © NSG 2023.All rights reserved.