Improving Earth’s Magnetic Field Measurements by Numerical Corrections of Thermal Drifts and Man-Made Disturbances

Figure 4

The power spectral density of 1 Hz magnetic data (vertical component, diurnal variation removed) at BDV (a), PLM (b), and KEL (c) shows that the anthropogenic repeats on a daily-scale, with quiet night periods and noise bursts in the daytime.