Parallel electric fields produced by ionospheric injection

Saka, Osuke

doi:https://doi.org/10.5194/angeo-41-369-2023

Articles | Volume 41, issue 2

https://doi.org/10.5194/angeo-41-369-2023

© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/angeo-41-369-2023

© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 41, issue 2

Regular paper

|

19 Sep 2023

Regular paper |

| 19 Sep 2023

Parallel electric fields produced by ionospheric injection

Osuke Saka

Download

Final revised paper (published on 19 Sep 2023)
Preprint (discussion started on 12 Jan 2023)

Interactive discussion

Status: closed

RC1:
'Comment on angeo-2023-1', Anonymous Referee #1, 01 Apr 2023

General comments:
The paper proposes a scenario of field-aligned electric potential generation. The author hypothesizes the existence of an electric field pointing downward to the ionosphere due to the breakdown of charge neutrality at a thin layer around altitude of 80km to 140km. This electric field may cause shifting of the electron mirror point to larger L shell (higher altitude), which leads to much less electron loss than the protons in the flux tube. The author uses a 1D model to demonstrate that the charge imbalance of the electron and protons could cause an electric field parallel to the electric field.
As a general opinion from the reviewer, this paper has a few major flaws, in both science merit and in scientific writing quality, which makes the paper unable to meet the standard of publication.
Major weakness 1: The main idea of the paper is based on an assumption of the existence of a thin layer where charge neutrality breaks down which leads to a vertical potential within the layer. However, this assumption is unfounded. The author didn’t provide any evidence or cite related work in either observation or simulation indicating the proposed scenario could be real.
Major weakness 2: The example cases are against common sense and observations. In the deduction of the parallel electric field, the author simply chose two cases of half empty and entirely empty loss cone. However, these two cases can hardly happen or the author didn’t point it out under what time scale this could happen. As a matter of fact, during the substorm or storm, electron and ion fluxes keep coming across the plasma sheet and wave-particle interaction scatters particles and refills the loss cone constantly. The author needs to provide evidence that the proposed cases could actually happen. Furthermore, if the ions get lost through the loss cone much more than the electrons as like the author suggests, then we should have observed much stronger ion precipitation than the electrons, but in reality, it is quite the opposite.
Major weakness 3: The language of the paper could be improved to make the idea clearer to the reader. Some sentences are very vague and confusing to the reviewer. The writer could use figure or diagram to help describe the idea.
Specific comments:
Line 37-40: What is the exact direction mentioned in the “one direction”? Where do the electrons accumulate? The reviewer finds these descriptions quite confusing. It will be very helpful to put a diagram of all the mentioned species and variable so reader can get the idea much clearer.
Line 53-54: The author should define “vertical”, “downward”, etc., in a scientific way, e.g., by providing the description of a coordinate system.
Line 59: The author derives the parallel electric field following Persson 1963, but the storm/substorm time condition may not applicable to Persson’s scenario. The half empty or entirely empty loss cone is very unlikely to persist, because during substorm or storm time, the electron/ion flux keeps coming into the inner magnetosphere and wave-particle interaction refills the flux tube constantly.
Line 122-125: The description is unclear. The author needs to mark x1, x2 in a figure or a diagram.
Technical corrections:
Line 81-87: What does the alpha mean here in the equations? The alpha was the pitch angle in the paragraph above, but now it becomes a ratio.

Citation: https://doi.org/10.5194/angeo-2023-1-RC1
- AC1: 'Reply on RC1', Osuke Saka, 09 Apr 2023
  
  Author Comment to Referee 1
  
  AC to RC1
  A variation of ionospheric potential may appear in the global current circuit of ionosphere-atmosphere-earth system. The currents in this circuit are generated in the atmosphere by charge separation processes in tropical convective storms. Nevertheless, the current influenced by the ionospheric potential can be picked up in this global circuit by monitoring vertical component (Bz) of the ground magnetometer data. Bz on the ground was reduced in association with the decrease of atmospheric electric field on the ground [Minamoto and Kadokura, 2011]. Such correlation would occur in association with the potential drop of the ionosphere at above the ground station [Saka, abstract presented in JpGU 2021].
  
  References
  Minamoto, Y., and Kadokura, A.: Extracting fair-weather data from atmospheric electric-field observations at Syowa Station, Antarctica, Polar Sci., 5, 313-318, 2011.
  Saka, O., Effects of auroral Ionosphere on atmospheric electricity, PEM11-P06, Abstract presented in JpGU2021.
  
  AC to RC2
  It is assumed that localized ionospheric potential drop and associated vertical electric fields directed into the ionosphere (downward) grows in the polar ionosphere prior to the auroral evolution arising out of the onset arc. When the downward electric field amplitudes become sufficient, the electric fields displaced mirror point of electrons to higher altitudes. Disagreed pitch angle distributions between electron and ions produced space charge along the field lines. Deposited space charges produce parallel electric fields pointing out of the ionosphere, i.e., upward electric fields. The upward electric fields initiate auroral evolution. Downward electric fields are shielded by the space charge deposited. The lifetime of the downward electric fields may be of the order of few second, bounce periods of electrons. However, upward electric fields produced at the onset are steady-state solutions in converging field geometries [Persson, 1966; Knight, 1973; Chiu and Schulz, 1978]. Upward fields may persist as far as ionospheric generator is activated and trapped populations exceed those in the loss cone. Populations in loss cone are assumed to be empty or filled one-half of the trapped ones. This may happen prior to the onset of upward electric fields.
  
  References
  Persson, H.: Electric field parallel to the magnetic field in a low-density plasma, Phys. Fluids, 9, 1090-1098, 1966.
  Knight, S.: Parallel electric fields, Planet. Space Sci., 21, 741-750, 1973.
  Chiu, Y.T., and Schulz, M.: Self-consistent particle and parallel electrostatic field distributions in the Magnetospheric-Ionospheric auroral region, J. Geophys. Res., 83, 629-642, 1978.
  
  AC to RC3
  To study in more realistic conditions, we considered negative charge sheet (1280km in longitudes and 128km in latitudes) grew in the polar ionosphere. The thickness of the sheet is assumed to be 60km corresponding to the thickness of the ionosphere (80km – 140km). Emerged charge density was 5x10^2 m^-3 in the sheet. Vertical electric fields generated by this negative sheet is directed into the ionosphere or downward. Altitude profiles of the downward electric fields at the center of the sheet is presented in Red in Figure 1(A-1). For references, magnetic mirror force in mV/m is presented in Black. Magnetic moment for this case is calculated assuming 1keV_perp at 1Re. Force arising from electrostatic fields exceed the magnetic mirror force below 3643km in altitudes. When the spatial scale of the negative charge sheet decreased to 640km x 64km, the crossover altitudes of two forces decreased to 1830km (Figure 1(B-1)).
  
  As a result of the downward electric field, electrons moving toward the ionosphere change their pitch angle trajectories by decelerating the parallel velocities. Mirror height moved to 1407km (Figure 1(A-2)). For the smaller scale charge sheet, new mirror height is 590km (Figure 1(B-2)). Pitch angle trajectories (sin^2(alf)-X plots) with new mirror height bend clockwise as shown in Figure 1(A-2 and B-2)) in Red.
  
  From this new mirror height, electrons start bouncing. Ions do not change their pitch angle because ions that moved mirror point to lower altitudes enter the loss cone. As a result, there appeared three regions in the pitch-angle plane in Figure 1(A-2, B-2); (A) electrons and ions are in loss cone, (B) ions are trapped but electrons from loss cone decelerated by downward electric fields filled this region due to magnetic mirroring, (C) electrons and ions are trapped. In these localized potential cases, pitch-angel disagreement appears in region (B).
  
  Normalized density difference and parallel electric fields calculated by integrating the density difference along field lines are presented in Figure 1(A-3, B-3) and Figure 1(A-4, B-4), respectively. To evaluate the parallel electric fields, we assumed that trapped electrons repelled from both hemispheres would build up the electron rich regions in the magnetosphere.
  
  Specific comments
  “One direction”
  Motions of electron/ion differed in a thin layer composed of collisionless electrons and collisional ions. “One direction” indicates ExB direction in such an anisotropic medium.
  
  “Vertical, downward”
  Please refer to AC to RC2.
  
  “Persson’s scenario”
  Please refer to AC to RC2.
  
  “X1 and X2”
  Marks X1 and X2 are removed because there are no figures related to X1 and X2.
  Technical corrections
  It is corrected, and numbers are added to the equations.
  
  Citation: https://doi.org/10.5194/angeo-2023-1-AC1
- AC3: 'Reply on RC1', Osuke Saka, 12 Apr 2023
  
  Author Comment to Referee 1
  
  AC to RC1
  A variation of ionospheric potential may appear in the global current circuit of ionosphere-atmosphere-earth system. The currents in this circuit are generated in the atmosphere by charge separation processes in tropical convective storms. Nevertheless, the current influenced by the ionospheric potential can be picked up in this global circuit by monitoring vertical component (Bz) of the ground magnetometer data. Bz on the ground was reduced in association with the decrease of atmospheric electric field on the ground [Minamoto and Kadokura, 2011]. Such correlation would occur in association with the potential drop of the ionosphere at above the ground station [Saka, abstract presented in JpGU 2021].
  
  References
  Minamoto, Y., and Kadokura, A.: Extracting fair-weather data from atmospheric electric-field observations at Syowa Station, Antarctica, Polar Sci., 5, 313-318, 2011.
  Saka, O., Effects of auroral Ionosphere on atmospheric electricity, PEM11-P06, Abstract presented in JpGU2021.
  
  AC to RC2
  It is assumed that localized ionospheric potential drop and associated vertical electric fields directed into the ionosphere (downward) grows in the polar ionosphere prior to the auroral evolution arising out of the onset arc. When the downward electric field amplitudes become sufficient, the electric fields displaced mirror point of electrons to higher altitudes. Disagreed pitch angle distributions between electron and ions produced space charge along the field lines. Deposited space charges produce parallel electric fields pointing out of the ionosphere, i.e., upward electric fields. The upward electric fields initiate auroral evolution. Downward electric fields are shielded by the space charge deposited. The lifetime of the downward electric fields may be of the order of few seconds, bounce periods of electrons. However, upward electric fields produced at the onset are steady-state solutions in converging field geometries [Persson, 1966; Knight, 1973; Chiu and Schulz, 1978]. Upward fields may persist as far as ionospheric generator is activated and trapped populations exceed those in the loss cone. Populations in loss cone are assumed to be empty or filled one-half of the trapped ones. This may happen prior to the onset of upward electric fields.
  
  References
  Persson, H.: Electric field parallel to the magnetic field in a low-density plasma, Phys. Fluids, 9, 1090-1098, 1966.
  Knight, S.: Parallel electric fields, Planet. Space Sci., 21, 741-750, 1973.
  Chiu, Y.T., and Schulz, M.: Self-consistent particle and parallel electrostatic field distributions in the Magnetospheric-Ionospheric auroral region, J. Geophys. Res., 83, 629-642, 1978.
  
  AC to RC3
  To study in more realistic conditions, we considered negative charge sheet (1280km in longitudes and 128km in latitudes) grew in the polar ionosphere. The thickness of the sheet is assumed to be 60km corresponding to the thickness of the ionosphere (80km – 140km). Emerged charge density was 5x10^2 m^-3 in the sheet. Vertical electric fields generated by this negative sheet is directed into the ionosphere or downward. Altitude profiles of the downward electric fields at the center of the sheet is presented in Red in Figure 1(A-1). For references, magnetic mirror force in mV/m is presented in Black. Magnetic moment for this case is calculated assuming 1keV_perp at 1Re. Force arising from electrostatic fields exceed the magnetic mirror force below 3643km in altitudes. When the spatial scale of the negative charge sheet decreased to 640km x 64km, the crossover altitudes of two forces decreased to 1830km (Figure 1(B-1)).
  
  As a result of the downward electric field, electrons moving toward the ionosphere change their pitch angle trajectories by decelerating the parallel velocities. Mirror height moved to 1407km (Figure 1(A-2)). For the smaller scale charge sheet, new mirror height is 590km (Figure 1(B-2)). Pitch angle trajectories (sin^2(alf)-X plots) with new mirror height bend clockwise as shown in Figure 1(A-2 and B-2)) in Red.
  
  From this new mirror height, electrons start bouncing. Ions do not change their pitch-angle trajectories because of a large mass ratio (M/m). As a result, there appeared three regions in the pitch-angle plane in Figure 1(A-2, B-2); (A) electrons and ions are in loss cone, (B) ions are trapped but electrons from loss cone decelerated by downward electric fields filled this region due to magnetic mirroring, (C) electrons and ions are trapped. In these localized potential cases, pitch-angel disagreement appears in region (B).
  
  Normalized density difference and parallel electric fields calculated by integrating the density difference along field lines are presented in Figure 1(A-3, B-3) and Figure 1(A-4, B-4), respectively. To evaluate the parallel electric fields, we assumed that trapped electrons repelled from both hemispheres would build up the electron rich regions in the magnetosphere.
  
  Specific comments
  “One direction”
  Motions of electron/ion differed in a thin layer composed of collisionless electrons and collisional ions. “One direction” indicates ExB direction toward lower latitudes where electrons accumulate. Please refer schematic illustration of ionospheric injection scenario in [Saka, O.: Ionospheric control of space weather, Ann Geophys., 39, 455-460, 2021]. This is presented in the supplement (Figure 2).
  
  “Vertical, downward”
  Please refer to AC to RC2.
  
  “Persson’s scenario”
  Please refer to AC to RC2.
  
  “X1 and X2”
  Marks X1 and X2 are removed because there are no figures related to X1 and X2.
  Technical corrections
  It is corrected, and numbers are added to the equations.
  
  Citation: https://doi.org/10.5194/angeo-2023-1-AC3
- AC5: 'Reply on RC1', Osuke Saka, 12 Apr 2023
  
  Please delete AC1. New comment AC3 is posted.
  
  Citation: https://doi.org/10.5194/angeo-2023-1-AC5
RC2:
'Comment on angeo-2023-1', Anonymous Referee #2, 02 Apr 2023

Since I have the pricilege of reading the 1. reviewers paper I see no need to provide a new synopsis of the paper; the 1. referee did a fine job.
I also agree with the first referee's assessment. However, I thik it should be stronger. Specifically:
1. The argujmentation is circular. Supposedly, the primary electric field (whatever cause) would cause charge separation that sustains those fields (line 39ff). Electrostatic fields work exactly the opposite way, i.e., forces on the cahrged particles are such as to reduce the charge separation.
2. As pointed out by the other referee, the assumptions for the equations (which should be numbered) have no basis. They are completely arbitrary and may lead to any result one desires. The use of the quantity alpha is not defined, or differently in different places. It remains unclear what it means on line 86.
3. Discussion: What injection? How would plasma be injected onto auroral field lines? And what is a 'local breakdow?' The entire meager discussion is nothing but handwaving. There is no discussion of prior work. In particular, parallel electric fields on ionosphere field lines are understood to be the result of FAC, and the theory has been worked out in detail by Knight, Lyuon, and others, but there is no reference here.
The paper is fundamentally flawed and should not be published.

Citation: https://doi.org/10.5194/angeo-2023-1-RC2
- AC2: 'Reply on RC2', Osuke Saka, 09 Apr 2023
  
  Author Comment to Referee 2
  
  Two types of electrostatic fields:
  It is assumed that localized ionospheric potential drop and associated vertical electric fields directed into the ionosphere (downward) grows in the polar ionosphere (referred to as local breakdown of the ionosphere) prior to the auroral evolution arising out of the onset arc. When the downward electric field amplitudes become sufficient, the electric fields displaced mirror point of electrons to higher altitudes. Disagreed pitch angle distributions between electron and ions produced space charge along the field lines. Deposited space charges produce parallel electric fields pointing out of the ionosphere, i.e., upward electric fields. The upward electric fields initiate auroral evolution. Downward electric fields are shielded by the space charge deposited. The lifetime of the downward electric fields may be of the order of few second, bounce periods of electrons. However, upward electric fields produced at the onset are steady-state solutions in converging field geometries [Persson, 1966; Knight, 1973; Chiu and Schulz, 1978]. Upward fields may persist as far as ionospheric generator is activated and trapped populations exceed those in the loss cone.
  
  References
  Persson, H.: Electric field parallel to the magnetic field in a low-density plasma, Phys. Fluids, 9, 1090-1098, 1966.
  Knight, S.: Parallel electric fields, Planet. Space Sci., 21, 741-750, 1973.
  Chiu, Y.T., and Schulz, M.: Self-consistent particle and parallel electrostatic field distributions in the Magnetospheric-Ionospheric auroral region, J. Geophys. Res., 83, 629-642, 1978.
  
  Equations and the use of the quantity alpha
  All equations are numbered. The equation, sin^2(alf)=B/Br is a key equation in the ionospheric driver scenario. This equation shows that if reflection point changes, pitch-angle at any point B also changes, i.e., a change of reflection point generates space charges.
  Transient downward electric fields change the reflection point and yield space charges along the field lines. Space charges generate parallel electric field out of the ionosphere (upward), opposite to the transient ones. Upward electric fields are steady-state solutions in the converging field geometry [Persson, 1966; Knight, 1973; Chui and Schulz, 1978].
  Populations in loss cone are assumed to be empty or filled one-half of the trapped ones. This may happen prior to the onset of upward electric fields.
  
  Discussion of prior work and meaning of ionospheric injection:
  Generators that build up space charges are supposed to exist in the distant magnetosphere. Parallel potentials related to the magnetospheric driver scenario were discussed by Knight [1973], Chiu and Schulz, 1978, Lyons [1980], and [Stern, 1981 and references therein].
  In the polar ionosphere, the Cowling channel becomes ionospheric generator when the Pedersen currents closed to the field-aligned currents [Baumjohann, 1983]. Part of upward field-aligned currents are carried by ions injected out of the ionosphere to avoid complete neutralization of the ionospheric plasmas. The downward field-aligned currents are carried by the electrons injected out of the ionosphere, from the positive potential rise.
  
  References
  Baumjohann, W.: Ionospheric and field-aligned current systems in the auroral zone: a concise review, Adv. Space Res., 2, 55-62, 1983.
  Chiu, Y.T., and Schulz, M.: Self-consistent particle and parallel electrostatic field distributions in the Magnetospheric-Ionospheric auroral region, J. Geophys. Res., 83, 629-642, 1978.
  Knight, S.: Parallel electric fields, Planet. Space Sci., 21, 741-750, 1973.
  Lyons, L.R.: Generation of large-scale regions of auroral currents, electric potentials, and precipitation by the divergence of the convection electric field, J. Jeophys. Res., 85, 17-24, 1980.
  Stern, D.P.: One-dimensional models of quasi-neutral parallel electric fields, J. Geophys. Res., 86, 5839-5860, 1981.
  
  Citation: https://doi.org/10.5194/angeo-2023-1-AC2
- AC4: 'Reply on RC2', Osuke Saka, 12 Apr 2023
  
  Author Comment to Referee 2
  
  Two types of electrostatic fields:
  It is assumed that localized ionospheric potential drop and associated vertical electric fields directed into the ionosphere (downward) grows in the polar ionosphere (referred to as local breakdown of the ionosphere) prior to the auroral evolution arising out of the onset arc. When the downward electric field amplitudes become sufficient, the electric fields displaced mirror point of electrons to higher altitudes. Disagreed pitch angle distributions between electron and ions produced space charge along the field lines. Deposited space charges produce parallel electric fields pointing out of the ionosphere, i.e., upward electric fields. The upward electric fields initiate auroral evolution. Downward electric fields are shielded by the space charge deposited. The lifetime of the downward electric fields may be of the order of few seconds, bounce periods of electrons. However, upward electric fields produced at the onset are steady-state solutions in converging field geometries [Persson, 1966; Knight, 1973; Chiu and Schulz, 1978]. Upward fields may persist as far as ionospheric generator is activated and trapped populations exceed those in the loss cone.
  
  References
  Persson, H.: Electric field parallel to the magnetic field in a low-density plasma, Phys. Fluids, 9, 1090-1098, 1966.
  Knight, S.: Parallel electric fields, Planet. Space Sci., 21, 741-750, 1973.
  Chiu, Y.T., and Schulz, M.: Self-consistent particle and parallel electrostatic field distributions in the Magnetospheric-Ionospheric auroral region, J. Geophys. Res., 83, 629-642, 1978.
  
  Equations and the use of the quantity alpha
  All equations are numbered. The equation, sin^2(alf)=B/Br is a key equation in the ionospheric driver scenario. This equation shows that if reflection point changes, pitch-angle at any point B also changes, i.e., a change of reflection point generates space charges if electrons and ions differed.
  Transient downward electric fields change the reflection point of electrons and yield space charges along the field lines. Space charges generate parallel electric field out of the ionosphere (upward), opposite to the transient ones. Upward electric fields are steady-state solutions in the converging field geometry [Persson, 1966; Knight, 1973; Chui and Schulz, 1978].
  Populations in loss cone are assumed to be empty or filled one-half of the trapped ones. This may happen prior to the onset of upward electric fields.
  
  Discussion of prior work and meaning of ionospheric injection:
  Generators that build up space charges are supposed to exist in the distant magnetosphere. Parallel potentials related to the magnetospheric driver scenario were discussed by Knight [1973], Chiu and Schulz, 1978, Lyons [1980], and [Stern, 1981 and references therein].
  In the polar ionosphere, the Cowling channel becomes ionospheric generator when the Pedersen currents closed to the field-aligned currents [Baumjohann, 1983]. In the present scenario, part of upward field-aligned currents is carried by ions injected out of the ionosphere from negative potential region. The downward field-aligned currents are carried by the electrons injected out of the ionosphere, from positive potential.
  
  References
  Baumjohann, W.: Ionospheric and field-aligned current systems in the auroral zone: a concise review, Adv. Space Res., 2, 55-62, 1983.
  Chiu, Y.T., and Schulz, M.: Self-consistent particle and parallel electrostatic field distributions in the Magnetospheric-Ionospheric auroral region, J. Geophys. Res., 83, 629-642, 1978.
  Knight, S.: Parallel electric fields, Planet. Space Sci., 21, 741-750, 1973.
  Lyons, L.R.: Generation of large-scale regions of auroral currents, electric potentials, and precipitation by the divergence of the convection electric field, J. Jeophys. Res., 85, 17-24, 1980.
  Stern, D.P.: One-dimensional models of quasi-neutral parallel electric fields, J. Geophys. Res., 86, 5839-5860, 1981.
  
  Citation: https://doi.org/10.5194/angeo-2023-1-AC4
- AC6: 'Reply on RC2', Osuke Saka, 12 Apr 2023
  
  Please delete AC2. New comment AC4 is posted.
  
  Citation: https://doi.org/10.5194/angeo-2023-1-AC6

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload

ED: Reconsider after major revisions (further review by editor and referees) (11 May 2023) by Dalia Buresova

AR by Osuke Saka on behalf of the Authors (21 May 2023) Author's response Author's tracked changes Manuscript

ED: Referee Nomination & Report Request started (06 Jun 2023) by Dalia Buresova

RR by Anonymous Referee #3 (15 Jul 2023)

Suggestions for revision or reasons for rejection

This study addresses the formation of the parallel electric fields in the ionosphere. The authors first discuss the excitation of the transient electric fields due to the breakdown of the charge neutrality, and then discuss a steady state solution of the parallel electric fields. Despite the fact that the research topic is important, the arguments of the two types of electric fields in the manuscript are not convincing, and I cannot recommend the publication of the paper. There are several reasons as I describe below. I recommend the rejection of the paper, but I encourage the authors to write a full-length paper with more physical discussions and detailed descriptions about how to obtain the electric field and the densities using equations.

1. Section 2.1 discusses the excitation of transient electric fields. The authors assume that there is a negatively charged sheet in the ionosphere, 1280km in longitudes, 128km in latitudes, located between the altitude of 80 km and 140 km. In Figure 3-1, the electric field E as a function of X is shown. However, it is not clear how to calculate the electric field. Is it simply the solution of the electrostatic field based on the sheet of the negative charge, surrounded by the neutral plasma? If so, why does the electric field E decrease so sharply from 10 mV/m around X=0.6 to almost zero around X=1? If we simply consider a uniformly charged sheet, a 1D solution of the electric field becomes constant in both sides of the sheet. This case is 3D, so I understand that a 1D solution should not be applied here, and the electric field should decrease as we move away from the localized sheet. However, even when we consider a point charge, the electric field has 1/r^2 dependence, where r is the distance from the charge. In Fig. 3-1, the electric field E rapidly decreases with a distance X, more rapidly than 1/r^2 dependence. Since there is no physical explanation and the derivation of E for Fig. 3-1, it is hard to grasp the result. I suspect that this rapid decay of E could be due to the shielding by the positive charges, but there is no explanation about how to obtain Fig. 3-1.

2. Fig. 3-3 shows the density difference ni-ne, but this is also hard to understand. How did the authors calculate ni-ne? There is Eq. (3), but how the authors calculate ni-ne is not explained in the manuscript. There is an argument about the trapping particles and the loss cone population (i.e. passing particles) in lines 95 to 109, but it was not possible for me to understand how to obtain ni-ne. Should we assume c=0 to calculate ni-ne? If we assume c=0, Eq. (3) just tells that ni= ne; therefore, I am perplexed. Also why is the density of ions becomes larger than the density of electrons? According to the calculation for Fig. 3-1, I thought that the negatively charged sheet is assumed, but why ni-ne>0?

3. Section 2.2 discusses a steady state solution, but I do not understand what is written in this section. Does Fig.3-4 show the electric field produced by the density separation ni-ne shown in Fig. 3-3? Fig. 3-3 shows a very strong charge separation, almost 60%, but why is the amplitude of the electric field in Fig. 3-4 very small, 0.5 mV/m, compared with the electric field in Fig. 3-1, which is of the order of 1 to 10 mV/m? Also, it is stated that the geometrical factor sqrt(B_s1/B_s0) was multiplied to E_para(s_1), but I do not understand why we should do it. In addition, I do not understand the logical flow between Section 2.1 (transient electric fields) to Section 2.2 (steady state solution). Section 2.2 must have more detailed explanations about what is going on.

4. The authors must check English in the manuscript. There are many nouns that lack articles. For example, line 17 (New scenario), line 22 (double layer)(electrostatic shock), and line 32 (generator) lack articles. There are plenty of such errors in the text, as well as other types of grammatical errors.

Hide

RR by Anonymous Referee #4 (07 Aug 2023)

ED: Publish as is (15 Aug 2023) by Dalia Buresova

AR by Osuke Saka on behalf of the Authors (17 Aug 2023)

Short summary

Transverse electric fields transmitted from the magnetosphere and those generated by the neutral winds yield a local breakdown of the charge neutrality at the boundaries between the thermosphere and mesosphere. The breakdown may create parallel electric fields in the thermosphere to produce spiral auroras and outflows. This explanation supposes an auroral generator located not in a distant space, but rather in our much nearer upper atmosphere.