A New Method to Calculate the Fluxgate Magnetometer Offset in the Interplanetary Magnetic Field: 2. Using Mirror Mode Structures

Abstract

AbstractAccurate magnetic field measurement is of great significance to the development of space exploration. The fluxgate magnetometer (FGM) is a magnetic field measuring instrument commonly used on the spacecraft. The zero offset of the spaceborne FGM varies slowly with time, thus it needs to be regularly calibrated. Here, we develop a new method to determine the zero offset of the FGM using mirror mode structures. This method is based on an assumption that the magnetic depression of mirror mode structures is only in the maximum variance direction. We find that each mirror mode structure has an optimal offset line (OOL), which is determined by the minimum strength of the modified magnetic field in the plane perpendicular to the maximum variance direction in an offset cube. The OOL is approximately parallel to the maximum variance direction and passes through the zero offset in the offset cube. The common intersection of at least two non‐parallel OOLs can be regarded as the zero offset, which accuracy tends to be higher with more events. Our method can simultaneously use the mirror modes and Alfvén waves, and is able to be applied to many regions, such as solar wind, planetary magnetosheaths and magnetospheres.