the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
The response of ionospheric currents to different types of magnetospheric fast flow bursts using THEMIS observations
- 1University of California Los Angeles, Atmospheric and Oceanic Sciences, Math Sciences Building, Los Angeles, CA 90095-1565, United States
- 2Department of Earth, Planetary and Space Sciences, University of California Los Angeles, California 90095, USA
- 3Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, Colorado 80303, USA
- 1University of California Los Angeles, Atmospheric and Oceanic Sciences, Math Sciences Building, Los Angeles, CA 90095-1565, United States
- 2Department of Earth, Planetary and Space Sciences, University of California Los Angeles, California 90095, USA
- 3Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, Colorado 80303, USA
Abstract. The magnetotail earthward fast flow bursts can transport most of the magnetic flux and energy into the inner magnetosphere. These fast flow bursts are generally an order of magnitude higher than the typical convection speeds, that are azimuthally localized (1–3RE) and are flanked by plasma vortices which map to ionospheric plasma vortices of the same sense of rotation. This study uses multipoint analysis of conjugate magnetospheric and ionospheric observations to investigate the magnetospheric and ionospheric responses to the fast flow bursts that are associated with both substorms and pseudobreakups. We study in detail what properties control the differences in the magnetosphere-ionosphere responses between substorm and pseudobreakup conditions, and how such differences lead to the different ionospheric responses. The fast flow bursts and pseudobreakup events were observed by the Time History of Events and Macroscale Interaction during Substorms (THEMIS), when the satellites were at least 6RE from the Earth in radial distance, and a magnetic local time (MLT) region of ±5 hours from local midnight. The results show that the magnetosphere and ionosphere response to substorm fast flow bursts are much stronger and more structured compared to pseudobreakups, which is more likely to be localized, transient, and weak in the magnetosphere. The magnetic flux in the tail is much stronger for strong substorms and much weaker for pseudobreakup events. The Blobe decreases significantly for substorm fast flow bursts compared to pseudobreakup events. The curvature force density for pseudobreakups are much smaller than substorm fast flow events, indicating that the pseudobreakups may not be able to penetrate deep into the inner magnetosphere. This association can help us study the properties and activity of the magnetospheric earthward flow vortices from ground data.
Homayon Aryan et al.
Status: final response (author comments only)
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RC1: 'Comment on angeo-2022-3', Anonymous Referee #1, 25 Feb 2022
This paper shows conjugate ionosphere-magnetosphere observations that suggest that substorm fast flows travel more earthward in comparison to fast flows related to pseudobreakups. Despite being a more localized event than substorms, pseduobreakup-related fast flows also produce an ionospheric response but they are weaker than those produced by substorm-related fast flows.
Though the conclusions arrived in this work are not new, it strengthens them by presenting multiple conjugate ionosphere and magnetosphere measurements of fast flows and their effects. Furthermore, pairs of pseudobreakup and substorm fast-flows were selected such that they were within 5 hours of each other, attempting to make the background conditions as similar as possible.
Major
- Line 70-72: The paper suggests that it looks into what properties control the differences in the magnetosphere-ionosphere responses between substorm and pseudobreakup conditions, and how such differences lead to the different ionospheric responses. This goal is not completely met by the rest of the paper. Perhaps a deeper analysis of the observations pointed out in the observations section can do this goal justice.
- There seems to be missing text after Lines 118 and Lines 230. Perhaps a Latex formatting error. (The line numbers are also not coherent in the pdf, so I am referring to the line numbers mentioned in the margins.)
- A claim is made at the end of the abstract and end of the conclusions: ‘This association can help us study the properties and activity of the magnetospheric earthward flow vortices from ground data.’ I think it’ll be very useful if the authors can briefly explain how this may help future studies so that readers may immediately recognize the potential of this work.
- Figures: It will be very useful for the readers if the authors can label aspects of the figure with arrows and texts that are being referred to in the main text of the manuscript. This is especially needed in figures 5 and 6 to point out vortex directions and Figures 7 and 8.
- A supplementary file containing the figures that show the ionospheric response, and additional GOES measurements, for the cases not shown in the main manuscript - will go a long way to benefit the ideals of data availability and transparency.
Minor
- Regarding the title: As the paper does not focus nor go into detailed analysis about the response of the ionospheric currents to magnetospheric fast flows, perhaps a better title for this work would be more closely tied to its novelty or conclusions. For e.g., Multiple conjugate observations of different types of magnetospheric fast flow bursts.
- In the abstract, since a major feature of this study is the ‘conjugate magnetospheric and ionospheric observations’, it might be useful to mention that the primary ionospheric observations were made by all-sky cameras and magnetometer-based equivalent ionospheric currents.
- Line 37: The acronym MPB - mid-latitude-positive bay should be defined here, as it's the first occurrence.
- Line 81-82: Authors say that they have analyzed 11 years of data. However, in 110, they note that the unique configuration lasted only for 3 months. Perhaps, the phrase “11 years of observations” can be omitted as it does not really reflect the final range of data used in this study.
- Line 152-153: The authors say that the y-coordinates of the satellites were almost the same, so all the differences in the measurements are due to separation in the (x,z) plane. I think the authors are saying that the distance between the spacecrafts in this plane does not exceed 1000 km. If so, perhaps it can be made clearer by also including an additional plot in Figure 4 of the X-Z plane as well.
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AC1: 'Reply on RC1', Homayon Aryan, 12 Apr 2022
The comment was uploaded in the form of a supplement: https://angeo.copernicus.org/preprints/angeo-2022-3/angeo-2022-3-AC1-supplement.pdf
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AC3: 'Reply on RC1', Homayon Aryan, 12 Apr 2022
The comment was uploaded in the form of a supplement: https://angeo.copernicus.org/preprints/angeo-2022-3/angeo-2022-3-AC3-supplement.pdf
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AC5: 'Reply on RC1', Homayon Aryan, 12 Apr 2022
The comment was uploaded in the form of a supplement: https://angeo.copernicus.org/preprints/angeo-2022-3/angeo-2022-3-AC5-supplement.zip
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RC2: 'Comment on angeo-2022-3', Anonymous Referee #2, 07 Mar 2022
This manuscript presents 3 cases studies of pair of events, where in each pair the first event is a pseudo breakup and the second a substorm onset. The events are studied by conjugate observations in the magnetosphere and ionosphere, offered by the THEMIS satellites and the THEMIS network of magnetometers and all-sky cameras in the American sector.
The main conclusion is that the effects of substorm-associated fast flow bursts in the magnetosphere and ionosphere are much stronger and more structured compared to those that are observed during pseudo breakups. In the ionosphere intensified currents and current vortices were observed both during pseudo breakups and substorms, but they were stronger in the latter case. The magnetospheric differences between the two groups were clearly seen in the electron fluxes and changes of the lobe magnetic field.
I need to point out that the manuscript seems to have been hastily submitted, and would have benefited from a final round of polishing and checking. Now the incomplete sentences, unfinished citations and other small errors give an unnecessarily negative impression of the whole manuscript.
In summary, the manuscript presents rather interesting multipoint studies of substorms and pseudo breakups, and may be accepted for publication after some corrections and clarifications.
MAJOR COMMENTS
As noted, there are several annoying errors in the text that tell of poor quality control and lack of polishing. For example
- incomplete sentences missing some or several words, at least on lines 112, 119, 238, 241
- use of parenthesis in the citations
- missing citations in line 35, 66, 109
- Case 4 is not in figure 1, lines 163-165
Taken individually the errors are reasonably minor, but their large number gives an unprofessional impression of the whole work. I recommend that you go through the manuscript very carefully before resubmitting.Line 54: It's better to say "mostly Pedersen" and "mostly Hall", as also Hall current may have divergence and therefore connect to FACS, and Pedersen current may have some contribution to the electrojets.
Lines 87-92. It's true that there are both curl-free and divergence-free SECS, but only the divergence-free type is used in the ground magnetometer analysis. You should clarify this point and also more carefully describe the meaning of the current amplitudes (i.e. the magnitudes of the divergence-free SECS) that are shown on the right side panels of Figs 5 and 5. In lines 190-192 and 197 you seem to identify the amplitudes with FAC, so it is necessary to list the assumptions that are involved there.
The selection criteria in Section 3 should be discussed more carefully. For example, what were the criteria for the SML index? Were the all-sky camera images used in the selection, i.e. do you require visible auroral activity in all pseudo breakups?
When discussing Figures 5-6 it would be good to mark the areas of interest to the panels, as now it is bit hard to follow which features are discussed, and should one look at the arrows on the left panels or the amplitudes on the right panels.
You study 3 event pairs, but detailed data are shown only for couple selected events. I recommend that you would collect the key parameters (e.g. magnitude of ionospheric currents, changes in lobe magnetic field, particle fluxes etc) from all events to a table. This would strengthen your conclusions and give the readers a firm understanding of the common features.
It's bit unclear to me which results are new and which agree or disagree with previous studies. Also the implications on and future potential to "study the properties and activity of the magnetospheric earthward flow vortices" remains rather vague. I recommend that you add some discussion of these points to Section 5.
Acknowledgments:: Check the omniweb address. SuperMAG web page gives specific sentences that should be used when utilizing the SuperMAG substorm lists and the SuperMAG indexes.
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AC2: 'Reply on RC2', Homayon Aryan, 12 Apr 2022
The comment was uploaded in the form of a supplement: https://angeo.copernicus.org/preprints/angeo-2022-3/angeo-2022-3-AC2-supplement.pdf
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AC4: 'Reply on RC2', Homayon Aryan, 12 Apr 2022
The comment was uploaded in the form of a supplement: https://angeo.copernicus.org/preprints/angeo-2022-3/angeo-2022-3-AC4-supplement.pdf
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AC6: 'Reply on RC2', Homayon Aryan, 12 Apr 2022
The comment was uploaded in the form of a supplement: https://angeo.copernicus.org/preprints/angeo-2022-3/angeo-2022-3-AC6-supplement.zip
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AC2: 'Reply on RC2', Homayon Aryan, 12 Apr 2022
Homayon Aryan et al.
Homayon Aryan et al.
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