3D Asymmetric Magnetopause Modeling from Support Vector Regression Machine and MineTool

As the inner boundary of the magnetosheath, the magnetopause is the location for energy, mass, and momentum transfer between the solar wind and the magnetosphere. The location of the magnetopause as well as its dependence on solar wind and geophysical conditions is critical for solar wind-magnetosphere interaction and global magnetosphere dynamics. Since the first theoretical solution of the shape and size of the magnetopause, many models have been proposed for magnetopause location. However, none of these models make use of new magnetopause crossings with much better coverage of high-latitude magnetopause and the cusps, as well as solar wind conditions. Previous studies also usually mandated analytical descriptions of magnetopause shape, which were then fit to subsets of crossings. This leaves much room for improvement, especially for unusual upstream conditions. In this study, we use the biggest magnetopause crossing database ever used by magnetopause modeling, including both older magnetopause crossings mainly from Space Physics Data Facility (SPDF) and earlier studies, and new magnetopause crossings from Cluster, THEMIS, Wind, Geotail, Polar, and Interball-1 with better high-latitude magnetopause and cusp coverage and corresponding solar wind conditions. Advanced machine learning technique, Support Vector Regression Machine (SVRM), and machine learning tool, MineTool, are used in this study to explore this big database for the control of the magnetopause locations by various solar wind and geophysical factors, including Earth's dipole tilt, the vector solar wind velocity, and the vector IMF, solar wind dynamic pressure, Beta, and Alfven Mach number. Comparison of our new magnetopause model with some leading earlier models shows that the new model has the smallest error, very well captures the subsolar magnetopause, high-latitude magnetopause, and cusps. Behavior of the new magnetopause model, including its asymmetry, magnetopause and cusp locations, is further studied under various typical solar wind conditions.