the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 15 Nov 2022
Study of Magnetosphere Dynamics under Various Alfven Mach Numbers for the Northward IMF Condition: 3D Global PIC Simulations
Abstract. For a long time, the interactions of the solar wind with the Earth’s magnetosphere have been analyzed with the help of three-dimensional (3D) global particle-in-cell (PIC) simulation where the interplanetary magnetic field (IMF) is steadily northward. Yet the Earth’s magnetosphere and the Kelvin-Helmholtz Instability (KHI) in a global, dayside and nightside magnetotail configuration using the 3D PIC simulations has not been well examined. In this work, we compared the simulation results for both high and low Alfven Mach numbers of MA=5 and MA=1, respectively. Our results show diverse magnetospheric dynamics by taking into account the various Alfvenic Mach conditions. The relationship between the upstream magnetohydrodynamic (MHD) turbulence in the solar wind and Earth's magnetosphere behavior is investigated. In both the meridian and equatorial planes, the effects of Alfven Mach number on magnetospheric characteristics such as electron/ion densities and current densities are explored. The structure of the magnetosphere is also investigated at high and low Alfven Mach numbers. The solar-terrestrial interaction as a result of various solar activities is investigated in this work utilizing a large-scale global three-dimensional PIC simulation.
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RC1: 'Comment on egusphere-2022-1112', Anonymous Referee #1, 15 Dec 2022
Anonymous referee report on
Study of Magnetosphere Dynamics under Various Alfven Mach Numbers for the
Northward IMF Condition: 3D Global PIC Simulations
by A. Esmaeili and co-authorsIn this study, the authors present work on simulating the global near-Earth space in 3D using a PIC simulation, with northward IMF conditions and for two different solar wind Alfvénic Mach numbers.Â
The paper appears more like a first internal draft than a proper scientific contribution. The language, editing, layout, figures, referencing, methods, results, and conclusions all require major work before they should be considered for publication. Much of the actual content of the draft appears to be rudimentary validation of the (already published) simulation, run with a code not written by the draft authors, so there is no discernable scientific value there either. Thus, I recommend this draft not be accepted for publication. Should the authors wish to rework this draft into a proper manuscript, there is much work needed, and they should most importantly draw quantifiable scientific conclusions from the presented data.
Secondary comments:
MA=5 is not particularly high for near-Earth conditions. MA=1 is ridiculously low. Besides, for a completely tangential IMF, the magnetosonic Mach number is relevant, not the Alfvénic Mach number. Thus, the MA=1 case is questionable at best.
Section 2 is woefully unadequate; the authors state a few basic equations for MHD, but do not describe the PIC model at all. What is the electron mass? What are the boundary conditions? What are the statistics of particles? What is the inner boundary like? How are the two different Alfvénic Mach number cases set up, if the IMF flow-in is pre-prescribed, and (apparently) the flow is set to 400 km/s? What is the solar wind temperature? There is no discussion of how reasonable a 0.5 Re resolution is for the simulated effects or what is gained in comparison with, for example, an MHD simulation.
Further comments:
Contrary to the abstract, there is no discussion of upstream MHD turbulence. Does it even exist in the simulation?
Sect. 2: It's worth stating that you're using cgs units (?)L 51: no  year for Shue et al
L 78: units needed for field
L 76: there is no rotation
L 77-79: numerical simulation steps do not provide the reader with any value unless they are scaled to physical or plasma physics units
eq(3): is not an equation, and even adding =0 at the end would not result in the correct Lorentz acceleration
L93-95: Unfinished draft-like section header editing still visible
L96-100: It is not valid to draw conclusions of magnetospheric dynamics when the solar wind with nonzero IMF has barely moved past the origin. Also, there is no explanation of how the supposed location of dayside reconnection (with a northward IMF?!?) is evaluated.L84-85: Please complete writing your article before submitting it to peer-review
L85-87: incomplete sentence, a missing equation?
L88-92: repetition with corrupted contentsFigures: The spatial unit labels (e.g. 15Re, -10Re, and so on) are much needed but should be used for the actual axes, not placed haphazardly in the approximate place along the axes.
L133-134: a statement of more intense currents has no meaning here - is this simply due to a different solar wind density or velocity? Also, there can be no conclusions about the strength of different ring currents between MA=1 and MA=5 without quantified analysis, as the structures are very different (and, apparently, the supposedly weaker MA=1 case actually peaks higher and in a larger region). Again, the text is not finalized.
Fig. 3 The caption should explain the ovals. The resolution of the figures is too low to distinguish the arrows inside the ovals - a vector graphics image would be better than a bitmap.
L145: KHI should be introduced scientifically via references.
L163-167: The information in the vector plots is insufficient for these statements to be made.
L170-176: Again, without information of how the solar wind speed differs between the runs, this comparison is fruitless.Section 2-4: The fact that there is more compression for a higher Mach number is self-evident and not worthy of publication. There is no new information drawn from the figures, and thus, the scientific value is non-existant.
L178-183: The double cusp structure could warrant further study, but in this context it might as well be a numerical artefact.Fig. 5,6: Apparently panels a have magnetic field lines? Why are they omitted from panels b?
Section 4: What are these new MA=9.4 and 3.64 simulations? They have not been introduced properly. There is no real comparison against the Lavraud simulation, just plots of current density (where the authors have not even included units). Apparently these are in the tail (at what X value?) because the authors state that current sheet bending is not visible in the PIC simulation, but (likely due to the evaluation of results before a tail has properly formed) I would state that there isn't even a current sheet which could bend. There is no discussion of velocities in the text despite including figures (again without units so true comparison of results is impossible).
The reference list contains garbled information.
Citation: https://doi.org/10.5194/egusphere-2022-1112-RC1 -
RC2: 'Comment on egusphere-2022-1112', Anonymous Referee #2, 03 Jan 2023
It is not clear what the contribution of this paper is. Â They ran a PIC model for Earth-solar wind interaction for different Mach numbers and found some similarities with earlier MHD results.Â
The abstract mention solar activity, but that is not discussed in the paper.Â
The paper is clearly an incomplete draft:
- There are many notes inserted: P4, L17. "(Need to be rephrased).". Â P7, L8. "(The figure cite here maybe wrong)". Â P9, L7, "(These sentences are confusing).". Â P16, L10. "(This sentence needs to be rephrased)
- There is repeated text, e.g., P4 "For this simulation, we used the latest version of the 3D Stanford PIC code".
- There is overstriked text, e.g., P5, L9 "zone".
- Figures that are not discussed in the text, e.g., Fig. 10.Â
I do not recommend this paper for publication, and I will not spend more time reading such an incomplete manuscript in detail. Â Even with significant changes I do not think this paper should be published.Â
Citation: https://doi.org/10.5194/egusphere-2022-1112-RC2
Interactive discussion
Status: closed
-
RC1: 'Comment on egusphere-2022-1112', Anonymous Referee #1, 15 Dec 2022
Anonymous referee report on
Study of Magnetosphere Dynamics under Various Alfven Mach Numbers for the
Northward IMF Condition: 3D Global PIC Simulations
by A. Esmaeili and co-authorsIn this study, the authors present work on simulating the global near-Earth space in 3D using a PIC simulation, with northward IMF conditions and for two different solar wind Alfvénic Mach numbers.Â
The paper appears more like a first internal draft than a proper scientific contribution. The language, editing, layout, figures, referencing, methods, results, and conclusions all require major work before they should be considered for publication. Much of the actual content of the draft appears to be rudimentary validation of the (already published) simulation, run with a code not written by the draft authors, so there is no discernable scientific value there either. Thus, I recommend this draft not be accepted for publication. Should the authors wish to rework this draft into a proper manuscript, there is much work needed, and they should most importantly draw quantifiable scientific conclusions from the presented data.
Secondary comments:
MA=5 is not particularly high for near-Earth conditions. MA=1 is ridiculously low. Besides, for a completely tangential IMF, the magnetosonic Mach number is relevant, not the Alfvénic Mach number. Thus, the MA=1 case is questionable at best.
Section 2 is woefully unadequate; the authors state a few basic equations for MHD, but do not describe the PIC model at all. What is the electron mass? What are the boundary conditions? What are the statistics of particles? What is the inner boundary like? How are the two different Alfvénic Mach number cases set up, if the IMF flow-in is pre-prescribed, and (apparently) the flow is set to 400 km/s? What is the solar wind temperature? There is no discussion of how reasonable a 0.5 Re resolution is for the simulated effects or what is gained in comparison with, for example, an MHD simulation.
Further comments:
Contrary to the abstract, there is no discussion of upstream MHD turbulence. Does it even exist in the simulation?
Sect. 2: It's worth stating that you're using cgs units (?)L 51: no  year for Shue et al
L 78: units needed for field
L 76: there is no rotation
L 77-79: numerical simulation steps do not provide the reader with any value unless they are scaled to physical or plasma physics units
eq(3): is not an equation, and even adding =0 at the end would not result in the correct Lorentz acceleration
L93-95: Unfinished draft-like section header editing still visible
L96-100: It is not valid to draw conclusions of magnetospheric dynamics when the solar wind with nonzero IMF has barely moved past the origin. Also, there is no explanation of how the supposed location of dayside reconnection (with a northward IMF?!?) is evaluated.L84-85: Please complete writing your article before submitting it to peer-review
L85-87: incomplete sentence, a missing equation?
L88-92: repetition with corrupted contentsFigures: The spatial unit labels (e.g. 15Re, -10Re, and so on) are much needed but should be used for the actual axes, not placed haphazardly in the approximate place along the axes.
L133-134: a statement of more intense currents has no meaning here - is this simply due to a different solar wind density or velocity? Also, there can be no conclusions about the strength of different ring currents between MA=1 and MA=5 without quantified analysis, as the structures are very different (and, apparently, the supposedly weaker MA=1 case actually peaks higher and in a larger region). Again, the text is not finalized.
Fig. 3 The caption should explain the ovals. The resolution of the figures is too low to distinguish the arrows inside the ovals - a vector graphics image would be better than a bitmap.
L145: KHI should be introduced scientifically via references.
L163-167: The information in the vector plots is insufficient for these statements to be made.
L170-176: Again, without information of how the solar wind speed differs between the runs, this comparison is fruitless.Section 2-4: The fact that there is more compression for a higher Mach number is self-evident and not worthy of publication. There is no new information drawn from the figures, and thus, the scientific value is non-existant.
L178-183: The double cusp structure could warrant further study, but in this context it might as well be a numerical artefact.Fig. 5,6: Apparently panels a have magnetic field lines? Why are they omitted from panels b?
Section 4: What are these new MA=9.4 and 3.64 simulations? They have not been introduced properly. There is no real comparison against the Lavraud simulation, just plots of current density (where the authors have not even included units). Apparently these are in the tail (at what X value?) because the authors state that current sheet bending is not visible in the PIC simulation, but (likely due to the evaluation of results before a tail has properly formed) I would state that there isn't even a current sheet which could bend. There is no discussion of velocities in the text despite including figures (again without units so true comparison of results is impossible).
The reference list contains garbled information.
Citation: https://doi.org/10.5194/egusphere-2022-1112-RC1 -
RC2: 'Comment on egusphere-2022-1112', Anonymous Referee #2, 03 Jan 2023
It is not clear what the contribution of this paper is. Â They ran a PIC model for Earth-solar wind interaction for different Mach numbers and found some similarities with earlier MHD results.Â
The abstract mention solar activity, but that is not discussed in the paper.Â
The paper is clearly an incomplete draft:
- There are many notes inserted: P4, L17. "(Need to be rephrased).". Â P7, L8. "(The figure cite here maybe wrong)". Â P9, L7, "(These sentences are confusing).". Â P16, L10. "(This sentence needs to be rephrased)
- There is repeated text, e.g., P4 "For this simulation, we used the latest version of the 3D Stanford PIC code".
- There is overstriked text, e.g., P5, L9 "zone".
- Figures that are not discussed in the text, e.g., Fig. 10.Â
I do not recommend this paper for publication, and I will not spend more time reading such an incomplete manuscript in detail. Â Even with significant changes I do not think this paper should be published.Â
Citation: https://doi.org/10.5194/egusphere-2022-1112-RC2
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