Data from: Multi-fluid MHD study of the disappearing solar wind event observed by MAVEN: Effects of solar wind density

Using the latest Mars Multi-fluid Magneto-hydrodynamic (MHD) model, we
examined the extremely low solar wind density event observed by Mars
Atmosphere and Volatile Evolution (MAVEN) on December 26, 2022. Simulation
results show that the solar wind density plays a crucial role in plasma
interactions. The interaction region expands significantly from less than
2 RM under typical solar wind density conditions to more than 4 RM along
the subsolar line for extremely low solar wind density (< 0.1
cm^-3^), consistent with MAVEN observations during the event. Under low
solar wind density conditions, the ion pickup plume becomes smaller and is
associated with a lower flow speed. Model results also show a nonlinear
correlation between the solar wind density and the ion escape rates.
Specifically, when the solar wind density is relatively high (> 0.2
cm^-3^), the total ion loss rate positively correlates with the solar wind
density. However, when the solar wind density is extremely low, ion escape
rates are nearly constant despite further decreases in solar wind density.
For this event, the solar wind density dropped by over an order of
magnitude, while the MHD model predicts the total ion escape rate reduced
by approximately a factor of ~3. Additionally, we investigated possible
reasons for the sudden drop in magnetic field strength during the inbound
segment of two consecutive orbits and found that a sudden change of the
interplanetary magnetic field (IMF) direction to radial configuration
could also contribute to the observed field decrease.