关键词: 大地电磁观测, 强电磁干扰, 远参考处理, 非Robust

Abstract: Abstract With the development of national economic construction, high-speed railway, wind power, and photovoltaic power stations, high voltage power grids are Widely distributed. Under these strong electromagnetic interference environments, whether or how to obtain high-quality magnetotelluric（MT） observation data is a practical problem. We have carried out MT observation in Yinchuan, Yuncheng, Hebi, and Zhangjiakou in the past two years. Based on the data acquisition and processing results of about 500 MT stations in these four survey areas, we have sorted out 45 typical MT stations under strong electromagnetic interference environment, such as high-speed railway, electrified railway, wind power stations, photovoltaic power stations, high voltage power grids. After fine processing, the curves of apparent resistivity and impedance phase of 44 MT stations are reasonable. From the curves, it can be seen that the frequency band near-field interference of MT data near the high-speed railway, electrified railway, and photovoltaic power stations is apparent, and the influence of wind power stations on electromagnetic interference is small. The comprehensive electromagnetic interference phenomenon of high voltage power grids, colliery, and the city is shown as single or multi outliers. Especially with uncertainty and diversity of interference sources, the full band data are affected mainly due to the complex electromagnetic interference environment in coal mines and cities. The results show that long period data can be guaranteed by lengthening observation time in a strong electromagnetic interference environment. Remote-reference technique with high-quality remote-reference station data can suppress the near-field effect. The non-Robust method is more useful to suppress outliers than Robust in the data processing. Carefully selected spectral data can make apparent resistivity and impedance phase curves more consistent with actual curve characteristics. The above methods are effective in helping to obtain high-quality MT data.

Key words: magnetotelluric observatio, strong electromagnetic interference, remote-reference, non-Robust