the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 17 Aug 2023
Ionospheric density depletions around crustal fields at Mars and their connection to ion frictional heating
Abstract. Mars’ ionosphere is formed through ionization of the neutral atmosphere by solar irradiance, charge exchange, and electron impact. Observations by Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft have shown a highly dynamic ionospheric layer at Mars impacted by loss processes including ion escape, transport, and electron recombination. The crustal fields at Mars can also significantly modulate the ionosphere. We use MAVEN data to perform a statistical analysis of ionospheric density depletions around crustal fields. Events mostly occur when the crustal magnetic field are radial, outward, and with a mild preference towards east in the planetocentric coordinates. We show that events near crustal fields are typically accompanied by an increase in suprathermal electrons within the depletion, either throughout the event or as a short-lived electron beam. However, no correlation between the changes in the bulk electron densities and suprathermal electron density variations is observed. Our analysis indicates that the temperature of the major ionospheric species, O2+, increases during most of the density depletion events, which could indicate that some ionospheric density depletions around crustal fields are a result of ion frictional heating.
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Notice on discussion status
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
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Preprint
(1280 KB)
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
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- Final revised paper
Journal article(s) based on this preprint
Interactive discussion
Status: closed
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RC1: 'Comment on egusphere-2023-1799', Isabela de Oliveira, 15 Sep 2023
General Comments
- Interesting approach, followed by an interesting and relevant discussion.
- I miss O+ also being cited in the Abstract.
Scientific Questions
- Line 27: Explain "stand-off distance", or change it to another word. This may not be obvious to non-native English speakers, like myself, and can cause confusion even within the field of research.
- Lines 89-90: "In deriving Equation 1, effects of generic similarities between time series (constant arrays), singularities, and absolute strength of the fields are also considered." > How are these effects considered exactly?
- Line 95: "The minimum accepted quality flag in LPW data is 50." > What does that mean, considering that the data never reached the density of 50 cm-3? What I interpreter from this is that the whole dataset should not be accepted? Or is it the opposite? Also, write the units after "50".
- Figure 1: Are you showing an example of electron depletion that is actually associated to regions of strong crustal magnetic fields? I can see from Panel a that the measurements of Bx and Bz are lower than the predicted (modeled) values. Probably the measured |B| will also be lower than the modeled |B|. How does that relate to your proximity parameter for this event? Is it considered high or low?
- Line 100: "down select": Do you mean you eliminate profiles with proximity parameter less than 5, or the opposite? "Down select" sounds ambiguous here, please use something like "eliminate", or rather "we select only", depending on what you mean.
- It would be interesting to see a map of crustal magnetic fields at Mars overlayed by the locations of the depletion events you analyse. I assume your proximity parameter could also catch events in the Northern hemisphere, far away from intense crustal fields.
- Figure 2: Are Br, Btheta and Bphi values that are measured by the spacecraft or values from the crustal magnetic field model?
- Figures 3 and 4: Please insert a scale bar next to the histograms showing number/probability of events. Right now, the histograms are only qualitative.
- Line 129/Figure 3: "depletions are found more likely around crustal magnetic fields pointing eastward". What is the physical explanation for that? Does it have to do with the preferential direction of the solar wind magnetic field, perhaps?
- Line 131/Figure 4: "(i.e., exiting the Martian surface)". Why do you think we do not see as many events for Br/|B| = -1, i.e., when the field is entering the surface?
- Line 161/Figure 6: "There is a shift towards higher O2+ variations with increase in ∆ne,s (the Colorbar)." What shift? Do you mean density variations of O2+ are larger than of O+? The sentence is confusing. Also, you say ∆ne,s but the colorbar shows ∆ne,c.
- Line 195: It lacks a sentence saying why we do not see even stronger variations in ion temperatures at altitudes higher than 400 km. Is it because the abundance of neutrals decreases? Or simply because there are not as many depletion events above 400 km?
Technical Corrections
The manuscript contains several typos. Please, carefully proofread it and fix them.
- Line 12: "crustal magnetic fields are..."
- Line 24: "~200 km"
- Line 27: "make"
- Line 54: "night"
- Line 54: (Cao et al., 2022) should be an inline citation.
- Line 72: " in Section 2"
- Line 79: "time series"
- Lines 78-79: "As such, we identified these events visually and when the density measurements exhibit sharp depletions both in timeseries and altitude profile data." > You identified the events both visually **and** when the density measurements exhibit sharp depletions? Is this correctly phrased?
- Lines 91, 93, 96: You write Panel (a), Panel b, Panel c, and Panel d. Please, be consistent.
- Line 94: "UTC"
- Figure 1: The texts of X, Y, Z, and hhmm are not corresponding to the label rows.
- Line 125: "Figure 3"
- Line 126: "... are shown below each plot."
- Line 144: "electron"
- Line 184: "ions and neutrals"
- Line 208: "due to"
- Line 209: "are listed"
- Line 230: "removes caused"?
Citation: https://doi.org/10.5194/egusphere-2023-1799-RC1 - AC1: 'Reply on RC1', Hadi Madanian, 07 Nov 2023
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RC2: 'Comment on egusphere-2023-1799', Anonymous Referee #2, 24 Nov 2023
The authors investigate how density depletions in the ionosphere of Mars are correlated with the crustal fields and show how said depletions might be connected to ion frictional heating. The paper is well written and presents different aspects of the topic taking advantage of the available MAVEN observations from several instruments. The authors define certain parameters which then use to quantify the correlation between the crustal fields and the ionospheric depletions and their connection to ion frictional heating. The plots are clear and help the reader to understand the main points of the paper. There are some parts in the paper though that need further clarification.
-
AC2: 'Reply on RC2', Hadi Madanian, 23 Dec 2023
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2023/egusphere-2023-1799/egusphere-2023-1799-AC2-supplement.pdf
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AC2: 'Reply on RC2', Hadi Madanian, 23 Dec 2023
Interactive discussion
Status: closed
-
RC1: 'Comment on egusphere-2023-1799', Isabela de Oliveira, 15 Sep 2023
General Comments
- Interesting approach, followed by an interesting and relevant discussion.
- I miss O+ also being cited in the Abstract.
Scientific Questions
- Line 27: Explain "stand-off distance", or change it to another word. This may not be obvious to non-native English speakers, like myself, and can cause confusion even within the field of research.
- Lines 89-90: "In deriving Equation 1, effects of generic similarities between time series (constant arrays), singularities, and absolute strength of the fields are also considered." > How are these effects considered exactly?
- Line 95: "The minimum accepted quality flag in LPW data is 50." > What does that mean, considering that the data never reached the density of 50 cm-3? What I interpreter from this is that the whole dataset should not be accepted? Or is it the opposite? Also, write the units after "50".
- Figure 1: Are you showing an example of electron depletion that is actually associated to regions of strong crustal magnetic fields? I can see from Panel a that the measurements of Bx and Bz are lower than the predicted (modeled) values. Probably the measured |B| will also be lower than the modeled |B|. How does that relate to your proximity parameter for this event? Is it considered high or low?
- Line 100: "down select": Do you mean you eliminate profiles with proximity parameter less than 5, or the opposite? "Down select" sounds ambiguous here, please use something like "eliminate", or rather "we select only", depending on what you mean.
- It would be interesting to see a map of crustal magnetic fields at Mars overlayed by the locations of the depletion events you analyse. I assume your proximity parameter could also catch events in the Northern hemisphere, far away from intense crustal fields.
- Figure 2: Are Br, Btheta and Bphi values that are measured by the spacecraft or values from the crustal magnetic field model?
- Figures 3 and 4: Please insert a scale bar next to the histograms showing number/probability of events. Right now, the histograms are only qualitative.
- Line 129/Figure 3: "depletions are found more likely around crustal magnetic fields pointing eastward". What is the physical explanation for that? Does it have to do with the preferential direction of the solar wind magnetic field, perhaps?
- Line 131/Figure 4: "(i.e., exiting the Martian surface)". Why do you think we do not see as many events for Br/|B| = -1, i.e., when the field is entering the surface?
- Line 161/Figure 6: "There is a shift towards higher O2+ variations with increase in ∆ne,s (the Colorbar)." What shift? Do you mean density variations of O2+ are larger than of O+? The sentence is confusing. Also, you say ∆ne,s but the colorbar shows ∆ne,c.
- Line 195: It lacks a sentence saying why we do not see even stronger variations in ion temperatures at altitudes higher than 400 km. Is it because the abundance of neutrals decreases? Or simply because there are not as many depletion events above 400 km?
Technical Corrections
The manuscript contains several typos. Please, carefully proofread it and fix them.
- Line 12: "crustal magnetic fields are..."
- Line 24: "~200 km"
- Line 27: "make"
- Line 54: "night"
- Line 54: (Cao et al., 2022) should be an inline citation.
- Line 72: " in Section 2"
- Line 79: "time series"
- Lines 78-79: "As such, we identified these events visually and when the density measurements exhibit sharp depletions both in timeseries and altitude profile data." > You identified the events both visually **and** when the density measurements exhibit sharp depletions? Is this correctly phrased?
- Lines 91, 93, 96: You write Panel (a), Panel b, Panel c, and Panel d. Please, be consistent.
- Line 94: "UTC"
- Figure 1: The texts of X, Y, Z, and hhmm are not corresponding to the label rows.
- Line 125: "Figure 3"
- Line 126: "... are shown below each plot."
- Line 144: "electron"
- Line 184: "ions and neutrals"
- Line 208: "due to"
- Line 209: "are listed"
- Line 230: "removes caused"?
Citation: https://doi.org/10.5194/egusphere-2023-1799-RC1 - AC1: 'Reply on RC1', Hadi Madanian, 07 Nov 2023
-
RC2: 'Comment on egusphere-2023-1799', Anonymous Referee #2, 24 Nov 2023
The authors investigate how density depletions in the ionosphere of Mars are correlated with the crustal fields and show how said depletions might be connected to ion frictional heating. The paper is well written and presents different aspects of the topic taking advantage of the available MAVEN observations from several instruments. The authors define certain parameters which then use to quantify the correlation between the crustal fields and the ionospheric depletions and their connection to ion frictional heating. The plots are clear and help the reader to understand the main points of the paper. There are some parts in the paper though that need further clarification.
-
AC2: 'Reply on RC2', Hadi Madanian, 23 Dec 2023
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2023/egusphere-2023-1799/egusphere-2023-1799-AC2-supplement.pdf
-
AC2: 'Reply on RC2', Hadi Madanian, 23 Dec 2023
Peer review completion
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Hadi Madanian
Troy Hesse
Firdevs Duru
Marcin Pilinski
Rudy Frahm
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
(1280 KB) - Metadata XML