Comprehensive evaluation of the vector magnetic field data from Macau Science Satellite-1A

In this study, we present a comprehensive evaluation of the magnetic field measurements from the Vector Field Magnetometer (VFM) aboard the recently launched Macau Science Satellite-1 (MSS-1). One-year data from November 2, 2023, to November 1, 2024, are considered. The MSS-1 flies with a low inclination (41°) and is designed to provide high-resolution magnetic field measurements, especially for monitoring the evolution of the South Atlantic Anomaly. Earlier studies confirmed the possibility of using MSS-1A data to model the Earth’s main magnetic field (e.g., <xref ref-type="bibr" rid="bJiang2024">Jiang Y et al., 2024</xref>). Therefore, in this study we focus on the magnetic signatures related to the external field, which are primarily associated with magnetospheric and ionospheric currents. The global distributions of the magnetic residuals from MSS-1A show a pattern consistent with that derived from the European Space Agency’s Swarm A satellite. A statistical survey of the conjugated observations (with Δ<italic>t</italic> &lt; 5 min and Δ<italic>R</italic> &lt; 150 km) between the two satellites showed that the difference between their magnetic residuals is within ±3 nanoteslas. By separating the magnetic residuals at the noon and midnight hours, we see that the MSS-1A data can effectively capture features of the magnetospheric and ionospheric currents, such as the magnetospheric ring current and ionospheric equatorial electrojet. Moreover, the magnetic residuals from MSS-1A show a diamagnetic effect caused by post-sunset equatorial plasma bubbles, which also suggests that the MSS-1A data have the potential to reveal the ionospheric structures. The comprehensive evaluations performed within this study demonstrate that the MSS-1A provides high-quality magnetic field data reaching the level of the Swarm satellite, which enables a deeper understanding of the modeling of Earth’s magnetic field as well as monitoring of the magnetic environment.