the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 25 Jul 2024
ScintPi measurements of low-latitude ionospheric irregularity drifts using the spaced-receiver technique and SBAS signals
Abstract. Previous efforts have used pairs of closely-spaced specialized receivers to measure Global Navigation Satellite System (GNSS) signals and to estimate ionospheric irregularity drifts. The relatively high cost associated with commercial GNSS-based ionospheric receivers limited somewhat their deployment and the estimation of ionospheric drifts. The development of an alternative low-cost GNSS-based scintillation monitor (ScintPi) motivated us to investigate the possibility of using it to overcome this limitation. ScintPi monitors can observe signals from geostationary satellites, which can greatly simplify the estimation of the drifts. We present results of an experiment to evaluate the use of ScintPi 3.0 to estimate ionospheric irregularity drifts. The experiment consisted of two ScintPi 3.0 deployed in Campina Grande, Brazil (7.213° S, 35.907° W, dip latitude ~14° S). The monitors were spaced by 140 m in the magnetic east-west direction and targeted the estimation of the zonal drifts associated with scintillation-causing equatorial spread F (ESF) irregularities. Routine observations throughout an entire ESF season (September 2022 – April 2023) were made as part of the experiment. We focused on results of irregularity drifts derived from geostationary satellite signals. The results show that the local time variation in the estimated irregularity zonal drifts is in good agreement with previous measurements and with the expected behavior of the background zonal plasma drifts. Our results also reveal a seasonal trend in the irregularity zonal drifts. The trend follows the seasonal behavior of the zonal component of the thermospheric neutral winds as predicted by the Horizontal Wind Model (HMW14). This is explained by the fact that low latitude ionospheric F-region plasma drifts are controlled, in great part, by Pedersen conductivity weighted flux tube integrated zonal neutral winds. The results confirm that ScintPi has the potential to contribute to new, cost-effective measurements of ionospheric irregularity drifts in addition to scintillation and total electron content. Furthermore, the results indicate that these new ScintPi measurements can provide insight into the ionosphere-thermosphere coupling.
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RC1: 'Comment on egusphere-2024-2262', Anonymous Referee #1, 26 Aug 2024
The manuscript presents a new way to estimate the zonal drift velocity of scintillation-related equatorial plasma bubbles by utilizing measurements made by low-cost ground-based receivers. The method to derive the zonal drift is well explained, and the results are interesting and promising. The manuscript is well-organized and will be improved after addressing the following comments.
- Line 105, could you use one sentence to summarize the relation between the spacing, irregularity drift, and sampling rate?
- In Figure 3, do you use a threshold of |r| to select high correlation data points? If so, would this method be only applicable during strong scintillation conditions?
- In Figures 4b and c, while it seems that zonal drifts and winds show similarity in the local time and daily variation, it might be better to have a figure to show the correlation between them.
- The IPP calculation considers the altitude of the ionospheric F-region peak density at 450 km. How do different choices of this value impact the estimation of drift velocities? It might be better to have some discussion or background literature on this.
Minor comments:
- Line 267-268, please check “It also shows that scintillation occurrence in most days”.
- Line 274, please check “Eastward drifts around 20-80 m/s in the midnight and post-midnight sector”.
- Line 180, is there any reason to use west receiver instead of east receiver?
- Line 216, could you explain more for the two values in θ?
Citation: https://doi.org/10.5194/egusphere-2024-2262-RC1 -
RC2: 'Comment on egusphere-2024-2262', Anonymous Referee #2, 29 Oct 2024
The manuscript presents a technique for estimating the drift velocity of equatorial plasma bubbles using measurements made by low-cost ground-based receivers. The distinguishing feature of this work is the ability of these monitors to capture signals transmitted by geostationary satellites. The main advantage of using geostationary signals is that the satellite's velocity is not considered in the calculation of ionospheric plasma bubble drift. The methodology is well explained, and the results are interesting. The manuscript is well-structured and will be enhanced after incorporating the following comments.
- In equation (6), a value of 0.899 was obtained. I suggest including the values used to reach this result, perhaps in a table.
- Was a threshold value applied to define a high correlation |r|? Figure 3c suggests that this threshold might be 0.5. If so, this should be explicitly stated in the manuscript.
- The altitude of the ionospheric F-region peak density is mentioned as 450 km several times in the manuscript. Why were 450 km chosen? If there is a specific reason, please provide justification in the text.
Citation: https://doi.org/10.5194/egusphere-2024-2262-RC2 -
RC3: 'Comment on egusphere-2024-2262', Anonymous Referee #3, 12 Nov 2024
The manuscript presents the measurements of the zonal drift of the ionospheric irregularities using two low-cost GNSS-based scintillation monitor(ScintPi) installed 140 m apart in the magnetic east-west direction. The measurements were performed from September 2022 to April 2023 at Campina Grande Brazil using signal from a Geostationary satellite. Even though the data resolution is low 20 HZ and with a low C/N signal the irregularity zonal drifts determined by these ScintPi receivers were in good agreement with previous works that used 50 Hz data resolution and using very expensive GNSS receivers. The methodology used is well explained and the authors even found a seasonal trend in the irregularity zonal drifts that was well correlated with the behavior of the zonal component of the thermospheric neutral winds as predicted by the Horizontal 340 Wind Model (HMW14). Based on the above comment I recommend the manuscript to be accepted as it is.
Citation: https://doi.org/10.5194/egusphere-2024-2262-RC3
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