J/ApJ/903/125 MHD simulations cases; Martian bow shock model (Wang+, 2020)
A 3D Parametric Martian Bow Shock Model with the Effects of Mach Number, Dynamic
Pressure, and the Interplanetary Magnetic Field.
Wang M., Xie L., Lee L.C., Xu X.J., Kabin K., Lu J.Y., Wang J., Li L.
<Astrophys. J., 903, 125 (2020)>
=2020ApJ...903..125W 2020ApJ...903..125W
ADC_Keywords: Solar system; Magnetic fields
Keywords: Planetary bow shocks ; Interplanetary magnetic fields ; Mars ;
Solar wind
Abstract:
Using global MHD simulations, we construct a 3D parametric Martian bow
shock model that employs a generalized conic section function defined
by seven parameters. Effects of the solar wind dynamic pressure (Pd),
the magnetosonic Mach number (MMS), and the intensity and the
orientation of the interplanetary magnetic field (IMF) on the seven
parameters are examined based on 250 simulation cases. These 250 cases
have a Pd range of 0.36-9.0nPa (the solar wind number density varying
from 3.5 to 12/cm3 and the solar wind speed varying from 250 to
670km/s), an MMS range of 2.8-7.9, and an IMF strength range from zero
to 10nT. The results from our parametric model show several things.
(1) The size of the Martian bow shock is dominated by Pd. When Pd
increases, the bow shock moves closer to Mars, and the flaring of the
bow shock decreases. (2) The MMS has a similar effect on the bow shock
as Pd but with different coefficients. (3) The effects of IMF
components on the bow shock position are associated with the draping
and pileup of the IMF around the Martian ionosphere; hence, we find
that both the subsolar standoff distance and the flaring angle of the
bow shock increase with the field strength of the IMF components that
are perpendicular to the solar wind flow direction (BY and BZ in the
MSO coordinate system). The parallel IMF component (BX) has little
effect on the subsolar standoff distance but affects the flaring
angle. (4) The cross section of the bow shock is elongated in the
direction perpendicular to the IMF on the Y-Z plane, and the
elongation degree is enhanced with increasing intensities of BY and
BZ. The north-south (dawn- dusk) asymmetry is controlled by the cone
angle when the IMF is on the X-Z (X-Y) plane. These results show a
good agreement with the previous empirical and theoretical models. The
current parametric model is obtained under solar maximum conditions
with the strongest Martian crustal magnetic field located at the
subsolar point. In fact, the bow shock shape can also be affected by
both the solar extreme ultraviolet radiation and the orientation of
crustal magnetic anomalies to the Sun, which should be considered in
future models.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 149 250 Supplementary information of the simulation cases
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See also:
J/A+A/578/A63 : MHD shock code mhd_vode (Flower+, 2015)
J/ApJS/230/21 : Solar wind 3D magnetohydrodynamic simulation (Chhiber+, 2017)
J/ApJ/854/78 : Magnetohydrodynamic (MHD) simulations. II. (Finley+, 2018)
J/A+A/645/A101 : 3D MHD models angular quadratures (Jaume Bestard+, 2021)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Case [1/250] Case number
5- 10 F6.3 /cm3 n [1.0/12] Solar wind number density (1)
12- 18 F7.2 km/s Ux [-671/-250] Solar wind velocity (1)
20- 25 F6.4 nPa Pd [0.26/9] Solar wind dynamic pressure (1)
27- 34 F8.4 nT Bx [-10/10] X coordinate interplanetary magnetic field
strength (1)
36- 43 F8.4 nT By [-10/10] Y coordinate interplanetary magnetic field
strength (1)
45- 52 F8.4 nT Bz [-10/10] Z coordinate interplanetary magnetic field
strength (1)
54- 55 I2 nT Bt [0/10] Interplanetary magnetic field magnitude (1)
57- 61 F5.3 --- MMS [2.81/7.92] Magnetosonic Mach number (1)
63- 67 F5.3 rad mu [0/3.15] Interplanetary magnetic field cone angle
(1)
69- 74 F6.3 rad lambda [-3.15/3.15] Interplanetary magnetic field clock
angle (1)
76- 80 F5.3 --- r0 [1.47/1.98] Bow shock subsolar standoff distance;
Mars radii (2)
82- 87 F6.4 --- a0 [0.65/0.84]? Flaring degree (2)
89- 96 F8.6 --- a1 [0.001/0.11]? Elongation degree (2)
98-107 F10.7 --- a2 [-0.17/0.13]? North-South asymmetry degree (2)
109-118 F10.7 --- a3 [-0.1/0.13]? Dawn-dusk asymmetry degree (2)
120-128 F9.6 rad w [-4.74/2.72]? Twisting angle of cross-section (2)
130-135 F6.4 --- R2 [0.95/1]? Coefficient of determination for case
fitting (2)
137-142 F6.4 --- R2mod [0.47/1]? Coefficient of determination (3)
144-149 F6.4 --- RMSE [0.05/0.96]? Root mean squared error Mars radii (3)
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Note (1): These are the input solar wind conditions for each case. The upstream
solar wind ion and electron temperatures are set to be 5e4 and 3e5K,
respectively. The solar wind velocities UY and UZ are chosen to
be 0. The solar maximum condition and the strongest crustal field
located in the subsolar region are fixed in all the cases.
Note (2): These are the fitting results of model construction parameters. The
eccentricity of the conic section function is fixed to 1.05.
Note (3): These are associated with the identified locations of bow shock from
simulations and the final model functions (Equation (6)-(11) and
Table 1) for each case.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 01-Mar-2022