The Latitudinal effect on True Height of the Electron Density Profile in the bottom side of the F2 layer of an equatorial region

Ayokunnu, Olalekan David; Ogunsola, Oluseyi Enitan; Adeniyi, Jacob Olusegun; Animasaun, Ismail Adekunle

doi:https://doi.org/10.5194/egusphere-2023-107

Preprints

https://doi.org/10.5194/egusphere-2023-107

Preprints

21 Feb 2023

| 21 Feb 2023

The Latitudinal effect on True Height of the Electron Density Profile in the bottom side of the F2 layer of an equatorial region

Olalekan David Ayokunnu, Oluseyi Enitan Ogunsola, Jacob Olusegun Adeniyi, and Ismail Adekunle Animasaun

Abstract. Abstract. The latitudinal effect in the variations observed values profile of B_o, h_mF2 and N_mF2 for the F2 layer of the equatorial region during the quiet period at low solar activity was studied. Digisonde data for year 2010, a year of low solar activity from three equatorial stations in the African and Southern American sectors namely; Ilorin, Nigeria (8.5° N, 4.5° E, −2.96 dip) Fortaleza, Brazil (3° S, 38° W, −7.03 dip) and Jicamarca, Peru (12° S, 76.8° W, 0.74 dip) were used for the study. During the March equinox; it was observed that the B_o peaks at 1200 hour LT time and the bite-out and the pre-noon peak of N_mF2 were also observed at this same time at Ilorin station. A similar feature was also observed at Fortaleza and at Jicamarca the N_mF2 peaks at 1000 hour LT and B_o peaks at 1500 hour LT. September equinox shows a general deviation from what was observed during the March equinox, at Ilorin and at Fortaleza B_o peaks at 1100 hour LT and at Jicamarca it was observed at 1500 hour LT. During the June solstice at Ilorin, B_o peaks at 1500 hour LT with the bite-out of the N_mF2, and at Fortaleza it was observed at 1200 hour LT with the peak of N_mF2 at 1500 hour LT. There was a shift at Jicamarca, in which two peaks were observed at 1100 and 1500 hour LT respectively. December solstice shows distinct double peaks of B_o at Ilorin and Fortaleza and a different feature was observed at Jicamarca. It was observed that the results from Ilorin and Fortaleza are similar and that of Jicamarca are different from those of other two stations. The peculiarity at Jicamarca is attributed to its closeness to the crest of the equatorial anomaly than these other two stations in the geomagnetic latitude as compared the geographic latitude. This is the second time in our studies that two stations from different latitude will be presented is being having similar profile. These variations observed may be due to effect of the latitudinal differences and the features observed find their explanation in the dynamics of the equatorial ionosphere of the stratospheric-ionospheric couplings.

Received: 04 Feb 2023 – Discussion started: 21 Feb 2023

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this preprint. The responsibility to include appropriate place names lies with the authors.

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Olalekan David Ayokunnu, Oluseyi Enitan Ogunsola, Jacob Olusegun Adeniyi, and Ismail Adekunle Animasaun

Status: closed

RC1:
'Comment on egusphere-2023-107', Anonymous Referee #1, 21 Mar 2023

This paper studied several ionosphere parameters such as B0, HMF2 and NMF2 based on the observation of digisonde over 1 African location and 2 South America locations. The interesting thing is the aspects of the variations of B0, which has been rarely reported based on ionosphere profile from digisonde. However, the paper is far from being ok to be published. The author kept saying the observation is due to latitudinal effects, which is not suitable here. What is latitudinal effect?? Also, there is only one location in Africa, where is the latitudinal variation in Africa?? Also there are principal errors on the description of equatorial ionosphere phenomenon.

The introduction lines 30-54 is a mess and missed a lot of references. When the author introduces items such as ionosphere F1 region, they shall at least give reader a brief introduction of the previous studies and add necessary references, not to mention the typical phenomenon of ionosphere, such as EIA, and equatorial spread F. There are many recent studies on the equatorial ionosphere and here I can provide some for the authors to add.

EIA

Cai, X., Qian, L., Wang, W., McInerney, J. M., Liu, H.-L., & Eastes, R. W. (2022). Hemispherically asymmetric evolution of nighttime ionospheric equatorial ionization anomaly in the American longitude sector. Journal of Geophysical Research: Space Physics, 127, e2022JA030706. https://doi.org/10.1029/2022JA030706

Rajesh, P. K., Lin, C. H., Lin, C. Y.,Chen, C. H., Liu, J. Y., Matsuo, T., et al.(2021). Extreme positive ionosphere storm triggered by a minor magnetic storm in deep solar minimum
revealed by FORMOSAT-7/COSMIC-2 and GNSS observations. Journal of Geophysical Research: Space Physics, 126, e2020JA028261. https://doi.
org/10.1029/2020JA028261

EPB or equatorial spread F

Karan, D. K., Daniell, R. E., England, S. L., Martinis, C. R., Eastes, R. W., Burns, A. G., & McClintock, W. E. (2020). First zonal drift velocity measurement of equatorial plasma bubbles (EPBs) from a geostationary orbit using GOLD data. Journal of Geophysical Research: Space Physics, 125, e2020JA028173. https://doi.org/10.1029/2020JA028173

Aa, E., Zou, S., Eastes, R., Karan, D. K., Zhang, S.-R., Erickson, P. J., & Coster, A. J. (2020). Coordinated ground-based and space-based observations of equatorial plasma bubbles. Journal of Geophysical Research: Space Physics, 125, e2019JA027569. https://doi.org/10.1029/2019JA027569

Line 45, there is a principle error. How can author say that EIA and spread F are resulting from the purely horizontal magnetic field along the geomagnetic equator?? The author shall check some basic knowledge of the EIA and spread F! Magnetic field is only one crucial factor to generate these, but there are more!

Furthermore, from the introduction, I cannot see the necessity to carry out the study in the paper. The author shall emphasize what is their potential advantages over previous studies. For example, a new location with Ne profile??

For fig 2, I cannot see what is the values in x and y axises, please re-draw the fig. Actually the fig appears to be directly cut from the computer screen. The author had better download the data and draw them.

For fig 3, this plot is too coarse. So what is the color that less grey stand for??
For fig 4, there are only 3 stations in the study, so how this plot is generated??

Line 133-135 these 3 papers are too old and may contain errors. The author shall cite some new EIA papers recent years to support their argument.

Line 135-137 this is totally nonsense, magnetic field is only one factor, there are electric field, neutral wind and chemistry that determines the behavior of EIA!

Line 139 this ratio 1.6 is also too coarse, since it is also from an old study. The author had better delete this.

In the discussion, the author just put some discussions on the formation mechanism of EIA. However, what the readers want to see is why B0 variations exhibit the pattern shown in the paper. The author shall re-write their discussions to be correlated with the observations.

Citation: https://doi.org/10.5194/egusphere-2023-107-RC1
- AC1:
  'Reply on RC1', Olalekan David Ayokunnu, 29 Mar 2023
  Response to Referee’s report on: The Latitudinal effect on True Height of the Electron Density Profile in the bottom side of the F2 layer of an equatorial region
  While the authors appreciate the time and expertise of the referee's contributions on this piece of work, I think it is out of place calling a research ‘nonsense’, when you have acknowledged a part of the work has been interesting.
  Nevertheless, we intend to make the following clarification and make necessary corrections in our review work
  Latitudinal effect is the pattern of latitudinal variation with small periodic change from the pole.
  
  This research work is based on stations that are closed to crest of ionization in the equatorial region, where the effect ofequatorial anomalies is usually being observed. The data used is from corresponding author’s base station in the Northern latitude and no other part of this latitude closed to the crest of anomaly has such data for the particular year under study. The choice of corresponding Southern latitude is based on the availability of data. I suppose that the author has right to use data that is available to him.
  
  Line 45:
  
  I did mentioned that the peculiarity of the equatorial region of the ionosphere is from purely horizontal magnetic field along the geomagnetic equator, not what the referee claimed that the phenomenon is caused by EIA and spread F, you can also see that I made reference to another respected author in the field of aeronomy. You can check the citation.
  When the referee made mentioned of a new location with Ne profile, the scope of this work does not cover this, since the work does not go into modeling. Moreover, the results from this work can be made as reference, if such new location falls with the crest of the equatorial anomaly
  I suppose that the referee is not familiar with digisonde data, the plot is virtual height (h’F2) against frequency and it is a raw data of our base station from the software used in exploring the data (automated plots).
  
  The grey line shows the Ne profile of the station under investigation.
  
  Citation: https://doi.org/10.5194/egusphere-2023-107-AC1
RC2:
'Comment on egusphere-2023-107', Anonymous Referee #2, 23 Mar 2023

See the comments attached.

Citation: https://doi.org/10.5194/egusphere-2023-107-RC2
- AC2:
  'Reply on RC2', Olalekan David Ayokunnu, 03 Apr 2023
  Response to Referee’s report on: The Latitudinal effect on True Height of the Electron Density Profile in the bottom side of the F2 layer of an equatorial region
  The authors quite appreciate the constructive critic by our dear referee and we have noted all the area that needs redress and we have therefore respond to every question posed accordingly and all these shall reflect in the upcoming review of the paper.
  Minor correction
  
  Effected
  
  Noted
  
  Noted
  
  Ok
  
  Noted
  
  Ok
  
  Ok
  
  The data was edited
  
  The figs. 1 and 2 are the electron density profiles from the raw data of the stations under investigation, show the typical raw data and night time of the stations. The plot is virtual height h’F2 against the frequency
  
  Noted
  
  Noted, the average of the three months (November, December, January), (February, March, April), (May, June, July) and (August, September, October) were chosen to represents each of the season, the equinoxes and the solstice seasons. Figs. 5 and 6 represent the plot of the variation of the parameter used.
  
  Major comments
  
  Noted
  
  This research work is based on stations that are closed to crest of ionization in the
  
  equatorial region, where equatorial anomalies such spread F, sporadic E, ect. are
  usually observed. The data used is from corresponding author’s base station in the
  Northern latitude and the corresponding Southern latitude that have data of the
  particular year under investigation.
  
  Noted
  
  Citation: https://doi.org/10.5194/egusphere-2023-107-AC2

Status: closed

RC1:
'Comment on egusphere-2023-107', Anonymous Referee #1, 21 Mar 2023

This paper studied several ionosphere parameters such as B0, HMF2 and NMF2 based on the observation of digisonde over 1 African location and 2 South America locations. The interesting thing is the aspects of the variations of B0, which has been rarely reported based on ionosphere profile from digisonde. However, the paper is far from being ok to be published. The author kept saying the observation is due to latitudinal effects, which is not suitable here. What is latitudinal effect?? Also, there is only one location in Africa, where is the latitudinal variation in Africa?? Also there are principal errors on the description of equatorial ionosphere phenomenon.

The introduction lines 30-54 is a mess and missed a lot of references. When the author introduces items such as ionosphere F1 region, they shall at least give reader a brief introduction of the previous studies and add necessary references, not to mention the typical phenomenon of ionosphere, such as EIA, and equatorial spread F. There are many recent studies on the equatorial ionosphere and here I can provide some for the authors to add.

EIA

Cai, X., Qian, L., Wang, W., McInerney, J. M., Liu, H.-L., & Eastes, R. W. (2022). Hemispherically asymmetric evolution of nighttime ionospheric equatorial ionization anomaly in the American longitude sector. Journal of Geophysical Research: Space Physics, 127, e2022JA030706. https://doi.org/10.1029/2022JA030706

Rajesh, P. K., Lin, C. H., Lin, C. Y.,Chen, C. H., Liu, J. Y., Matsuo, T., et al.(2021). Extreme positive ionosphere storm triggered by a minor magnetic storm in deep solar minimum
revealed by FORMOSAT-7/COSMIC-2 and GNSS observations. Journal of Geophysical Research: Space Physics, 126, e2020JA028261. https://doi.
org/10.1029/2020JA028261

EPB or equatorial spread F

Karan, D. K., Daniell, R. E., England, S. L., Martinis, C. R., Eastes, R. W., Burns, A. G., & McClintock, W. E. (2020). First zonal drift velocity measurement of equatorial plasma bubbles (EPBs) from a geostationary orbit using GOLD data. Journal of Geophysical Research: Space Physics, 125, e2020JA028173. https://doi.org/10.1029/2020JA028173

Aa, E., Zou, S., Eastes, R., Karan, D. K., Zhang, S.-R., Erickson, P. J., & Coster, A. J. (2020). Coordinated ground-based and space-based observations of equatorial plasma bubbles. Journal of Geophysical Research: Space Physics, 125, e2019JA027569. https://doi.org/10.1029/2019JA027569

Line 45, there is a principle error. How can author say that EIA and spread F are resulting from the purely horizontal magnetic field along the geomagnetic equator?? The author shall check some basic knowledge of the EIA and spread F! Magnetic field is only one crucial factor to generate these, but there are more!

Furthermore, from the introduction, I cannot see the necessity to carry out the study in the paper. The author shall emphasize what is their potential advantages over previous studies. For example, a new location with Ne profile??

For fig 2, I cannot see what is the values in x and y axises, please re-draw the fig. Actually the fig appears to be directly cut from the computer screen. The author had better download the data and draw them.

For fig 3, this plot is too coarse. So what is the color that less grey stand for??
For fig 4, there are only 3 stations in the study, so how this plot is generated??

Line 133-135 these 3 papers are too old and may contain errors. The author shall cite some new EIA papers recent years to support their argument.

Line 135-137 this is totally nonsense, magnetic field is only one factor, there are electric field, neutral wind and chemistry that determines the behavior of EIA!

Line 139 this ratio 1.6 is also too coarse, since it is also from an old study. The author had better delete this.

In the discussion, the author just put some discussions on the formation mechanism of EIA. However, what the readers want to see is why B0 variations exhibit the pattern shown in the paper. The author shall re-write their discussions to be correlated with the observations.

Citation: https://doi.org/10.5194/egusphere-2023-107-RC1
- AC1:
  'Reply on RC1', Olalekan David Ayokunnu, 29 Mar 2023
  Response to Referee’s report on: The Latitudinal effect on True Height of the Electron Density Profile in the bottom side of the F2 layer of an equatorial region
  While the authors appreciate the time and expertise of the referee's contributions on this piece of work, I think it is out of place calling a research ‘nonsense’, when you have acknowledged a part of the work has been interesting.
  Nevertheless, we intend to make the following clarification and make necessary corrections in our review work
  Latitudinal effect is the pattern of latitudinal variation with small periodic change from the pole.
  
  This research work is based on stations that are closed to crest of ionization in the equatorial region, where the effect ofequatorial anomalies is usually being observed. The data used is from corresponding author’s base station in the Northern latitude and no other part of this latitude closed to the crest of anomaly has such data for the particular year under study. The choice of corresponding Southern latitude is based on the availability of data. I suppose that the author has right to use data that is available to him.
  
  Line 45:
  
  I did mentioned that the peculiarity of the equatorial region of the ionosphere is from purely horizontal magnetic field along the geomagnetic equator, not what the referee claimed that the phenomenon is caused by EIA and spread F, you can also see that I made reference to another respected author in the field of aeronomy. You can check the citation.
  When the referee made mentioned of a new location with Ne profile, the scope of this work does not cover this, since the work does not go into modeling. Moreover, the results from this work can be made as reference, if such new location falls with the crest of the equatorial anomaly
  I suppose that the referee is not familiar with digisonde data, the plot is virtual height (h’F2) against frequency and it is a raw data of our base station from the software used in exploring the data (automated plots).
  
  The grey line shows the Ne profile of the station under investigation.
  
  Citation: https://doi.org/10.5194/egusphere-2023-107-AC1
RC2:
'Comment on egusphere-2023-107', Anonymous Referee #2, 23 Mar 2023

See the comments attached.

Citation: https://doi.org/10.5194/egusphere-2023-107-RC2
- AC2:
  'Reply on RC2', Olalekan David Ayokunnu, 03 Apr 2023
  Response to Referee’s report on: The Latitudinal effect on True Height of the Electron Density Profile in the bottom side of the F2 layer of an equatorial region
  The authors quite appreciate the constructive critic by our dear referee and we have noted all the area that needs redress and we have therefore respond to every question posed accordingly and all these shall reflect in the upcoming review of the paper.
  Minor correction
  
  Effected
  
  Noted
  
  Noted
  
  Ok
  
  Noted
  
  Ok
  
  Ok
  
  The data was edited
  
  The figs. 1 and 2 are the electron density profiles from the raw data of the stations under investigation, show the typical raw data and night time of the stations. The plot is virtual height h’F2 against the frequency
  
  Noted
  
  Noted, the average of the three months (November, December, January), (February, March, April), (May, June, July) and (August, September, October) were chosen to represents each of the season, the equinoxes and the solstice seasons. Figs. 5 and 6 represent the plot of the variation of the parameter used.
  
  Major comments
  
  Noted
  
  This research work is based on stations that are closed to crest of ionization in the
  
  equatorial region, where equatorial anomalies such spread F, sporadic E, ect. are
  usually observed. The data used is from corresponding author’s base station in the
  Northern latitude and the corresponding Southern latitude that have data of the
  particular year under investigation.
  
  Noted
  
  Citation: https://doi.org/10.5194/egusphere-2023-107-AC2

Olalekan David Ayokunnu, Oluseyi Enitan Ogunsola, Jacob Olusegun Adeniyi, and Ismail Adekunle Animasaun

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Short summary

The in-depth study of the ionospheric electron density profile contributes significantly to our understanding of the ionosphere, its dynamic nature and characteristics of radio wave for telecommunication. it was observed that the results from Ilorin and Fortaleza are similar and that of Jicamarca are different from those of other two stations. This is the second time in our studies that two stations from different latitude will be presented as being having similar profile.


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