A Comparison of Modeled and Observed Dayside Bow Shock Locations in 8 Years of MMS Data

@article{wenli2025bowshock,
author = {Mo, Wenli and Raptis, Savvas and Toy-Edens, Vicki and Yeakel, Kiley and Turner, Drew L.},
title = {A Comparison of Modeled and Observed Dayside Bow Shock Locations in 8 Years of MMS Data},
journal = {Journal of Geophysical Research: Space Physics},
volume = {130},
number = {11},
pages = {e2025JA033966},
keywords = {bow shocks, mms},
doi = {https://doi.org/10.1029/2025JA033966},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2025JA033966},
eprint = {https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2025JA033966},
note = {e2025JA033966 2025JA033966},
abstract = {Abstract The interplay between Earth's magnetic field and the solar wind provides a natural laboratory to study the physics of shock waves in collisionless plasmas. 3D parameterized shape models of Earth's bow shock boundary quantify how this interaction depends on upstream solar wind parameters. Using 2,063 bow shocks observed with the Magnetospheric Multiscale (MMS) mission over 8 years, we investigate the relationship between the observed and parameterized bow shock location with solar wind parameters. We find that the observed bow shock location is strongly correlated with the solar wind density, plasma \$\beta \$, and Mach number. In addition, we provide updated fitting parameters to bow shock models from literature derived empirically or using magnetohydrodynamic (MHD) simulations. Models provide a reasonable fit to the data after updating the fit with MMS-observed bow shocks, with coefficient of determination \$\left({R}^{2}\right)\$ scores between \$0.836-0.878\$. However, we find that observed locations can still deviate significantly from model predictions under extreme solar wind conditions. We also explore the models' variability under different interplanetary magnetic field (IMF) clock angles (Northward and Southward) and shock geometries (quasi-perpendicular and quasi-parallel). While we observe no discernible difference in the bow shock shape as a function of IMF direction, we find that quasi-parallel bow shocks are systematically closer to Earth than quasi-perpendicular, with a disparity of as much as \${\sim} 1\$ \${R}\_{E}\$ in bow shock stand-off distance between the two bow shock types.},
year = {2025}
}