A time-dependent three-dimensional magnetopause model based on quasi-elastodynamic theory

The interaction between the solar wind and the Earth’s magnetosphere is one of the most important research topics in space weather and space plasma physics. The finding of the exact magnetopause position significantly enhances our knowledge of magnetospheric response to solar wind variations. While numerous magnetopause models have been constructed in the past decades, a substantial portion of them remains time-independent models, posing limitations in elucidating the dynamic movement of the magnetopause under varying solar wind conditions. This study pioneers the establishment of a time-dependent three-dimensional magnetopause model grounded in the quasi-elastodynamic pressure theory, named the POS (Position, Overall oscillation and Surface wave like-structure) model. In contrast to the existing time-dependent magnetopause models (except for numerical simulations), the POS model transcends the one-dimensional framework, providing a real-time depiction of magnetopause position and shape alterations. The model's validity is substantiated through comparisons with satellite observation. Based on an extensive dataset of satellite magnetopause crossings (exceeding 40,000 magnetopause crossing events), the POS model exhibits superior predictive accuracy (as evaluated by root-mean-square error) compared to six widely employed magnetopause models. Remarkably, the POS model demonstrates heightened efficacy under highly disturbed solar wind conditions as well as in high-latitude and flank region of magnetopause and it possesses characteristics as predictive accuracy, concise formulation, and fast computational speed. The introduction of a time-dependent three-dimensional dynamic magnetopause model not only advances our comprehension of the physical processes in space plasma and enhances our predictive capabilities for space weather on the Earth but also provides valuable insights into the dynamic processes in the magnetospheres of other planets.