Research on the Principle of Multi-perspective Solar Magnetic Field Measurement

Solar magnetic field measurements mainly use the Zeeman effect, but this method has two problems, namely, low accuracy of the transverse magnetic field components and a 180° ambiguity. Multi-perspective observations can increase the measurement accuracy and resolve the ambiguity. This study investigates how combined observations from the Sun-Earth L5 point, Sun-Earth line, and solar polar-orbiting satellites improve the accuracy of the transverse solar magnetic field under different satellite positional configurations. A three-satellite model is developed using spherical trigonometry to establish coordinate relationships, and the error propagation formulas are applied to correct transverse field measurement errors. The magnetic field measurement error distribution of the Helioseismic and Magnetic Imager is analyzed, and the magnetograms from the three satellites are simulated. The improvement to the transverse field accuracy under various satellite configurations is then assessed based on simulation results. The results show that multi-perspective measurements can reduce transverse component errors ΔB x to approximately 10% and ΔB y to about 15% compared to the error from a single satellite. An optimally designed polar orbit can decrease the transverse field error by nearly an order of magnitude for 80% of its operation time.