FHD磁力仪分量线圈装置误差对磁偏角观测的影响分析

Study on the influence of the directional error of the vector coil on the declination of FHD vector proton precession magnetometer

根据FHD磁力仪观测磁偏角的原理,计算了分量线圈不水平导致的磁偏角观测值误差,发现分量线圈仅在EW方向的倾斜对磁偏角观测产生误差。文中将理论分析结果与实际观测结果进行了对比分析,发现由于分量线圈底座水平的长期漂移,仪器的垂直分量及磁偏角观测误差也会发生长期漂移,长期漂移变化的周期约2～4个月,对垂直分量其幅度约3.5～11.0nT,而磁偏角的幅度约0.1′～1.0′,因此认为在将该仪器观测值用作绝对观测值进行地震异常分析时,应注意回避这种长期漂移变化。

This paper studied the influence of the directional error of vector coil on the declination of FHG vector proton precession magnetometer in theory. The result indicates that only the directional error of the vector coil in east-west direction has the influence on the declination. This paper also analyzed the error of observation data with the theoretical result, and finds that there is long-period drift about the error of observation data of declination and horizontal intensity of this magnetometers with the drift of directional error of the vector coil. The estimated drift cycle ranges 2～4 months, the drift quantity of vertical intensity is about 3.5～11.0 nT, the declination is 0.1′～ 1.0′. The suggestion is also proposed that the drift must be avoided in analysis of seismomagnetic precursor.