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

Dataset DOI: [10.5061/dryad.s1rn8pkk5](10.5061/dryad.s1rn8pkk5)

## Description of the data and file structure

Multi-fluid MHD model results from 8 cases as specified in the paper. 

### Files and variables

Fig1a_n3_3d__ful_7_n00040000.dat.zip

Fig1b_n01_3d__ful_7_n00040000.dat.zip

**Description:** 3D MHD data for Fig1a and Fig1b in ascii format. The variable list/unit is given below.

'\"X [R]\" \"Y [R]\" \"Z [R]\" \"r [amu/cm^3]\" \"U_x [km/s]\" \"U_y [km/s]\" \"U_z [km/s]\" \"B_x [nT]\" \"B_y [nT]\" \"B_z [nT]\" \"Pe [nPa]\" \"p [nPa]\" \"B1_x [nT]\" \"B1_y [nT]\" \"B1_z [nT]\" \"E [J/m^3]\" \"J_x [mA/m2]\" \"J_y [mA/m^2]\"_z [mA/m2]\"'

Of these variables:

* **X [R], Y [R], Z [R]** — position in the MSO coordinate system
* **r [amu/cm³]** — total mass density
* **U_x [km/s], U_y [km/s], U_z [km/s]** — plasma velocity components
* **B_x [nT], B_y [nT], B_z [nT]** — total magnetic field components...,

本研究采用最新的火星多流体磁流体动力学（Mars Multi-fluid Magneto-hydrodynamic, MHD）模型，对2022年12月26日火星大气与挥发物演化探测器（Mars Atmosphere and Volatile Evolution, MAVEN）观测到的极端低太阳风密度事件开展了分析。模拟结果表明，太阳风密度在等离子体相互作用过程中起到关键调控作用。在典型太阳风密度条件下，相互作用区域小于2个火星半径（R_M）；当太阳风密度极低（<0.1 cm⁻³）时，沿向日点方向的相互作用区域可扩张至4个火星半径以上，这与该事件期间MAVEN的观测结果一致。在低太阳风密度条件下，离子拾取羽流的规模会缩小，且伴随流速降低。模拟结果还显示，太阳风密度与离子逃逸率之间存在非线性相关关系：当太阳风密度相对较高（>0.2 cm⁻³）时，总离子损失率与太阳风密度呈正相关；但当太阳风密度极低时，离子……

# 数据集来源：《MAVEN观测到的消失太阳风事件的多流体MHD研究：太阳风密度的影响》
数据集DOI：10.5061/dryad.s1rn8pkk5

## 数据与文件结构说明
本数据集包含论文中指定的8组多流体MHD模型模拟结果。

### 文件与变量
数据集文件如下：
Fig1a_n3_3d__ful_7_n00040000.dat.zip
Fig1b_n01_3d__ful_7_n00040000.dat.zip

**文件说明**：包含用于绘制图1a与图1b的三维MHD数据，格式为ASCII。变量列表及单位如下：
"X [R]" "Y [R]" "Z [R]" "r [amu/cm³]" "U_x [km/s]" "U_y [km/s]" "U_z [km/s]" "B_x [nT]" "B_y [nT]" "B_z [nT]" "Pe [nPa]" "p [nPa]" "B1_x [nT]" "B1_y [nT]" "B1_z [nT]" "E [J/m³]" "J_x [mA/m²]" "J_y [mA/m²]" "J_z [mA/m²]"

各变量说明：
* **X [R], Y [R], Z [R]**：火星太阳轨道（Mars Solar Orbital, MSO）坐标系下的空间位置
* **r [amu/cm³]**：总质量密度
* **U_x [km/s], U_y [km/s], U_z [km/s]**：等离子体速度分量
* **B_x [nT], B_y [nT], B_z [nT]**：总磁场分量……