the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 25 Jan 2021
Performance of BDS B1 frequency standard point positioning during the main phase of different classes of geomagnetic storms in China and its surrounding area
Abstract. Geomagnetic storms are one of the space weather events. The radio signals transmitted by modern navigation systems suffer from the effects of storms which can degrade the performance of the whole system. In this study, the performance of BeiDou Navigation Satellite System (BDS) B1 frequency standard point positioning in China and its surrounding area during different classes of storms is investigated for the first time. The analysis of the results revealed that BDS B1 frequency standard point positioning accuracy was deteriorated during the storms. The probability of the extrema in the statistics of positioning errors during strong storms is the largest, followed by moderate and weak storms. The positioning accuracy for storms of a similar class is found not to be at the same level. The root mean square error (RMSE) in position for the different classes of storms could be at least tens of centimeters in the East, North and Up directions.
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Interactive discussion
Status: closed
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RC1: 'Comment on angeo-2021-5', Anonymous Referee #1, 24 Feb 2021
The paper analyzes the BeiDou B1 frequency standard point positioning in China and its surrounding area during selected magnetic storm events from 2015 to 2018 and they pointed out that positioning accuracy was deteriorated during the storm. The positioning error was larger for stronger magnetic storms. The root mean square error (RMSE) in position for the different magnetic storms in the East, North and Up directions were also presented. This topic has been discussed previously in the literature and the original contribution of this paper is the fact that the data were from Beidou B1 frequency. Some improvements and clarifications need to be done before the paper could be accepted to Annales Geophysicae. Please see the below comments. - The authors just analyzed the Bias and the bias RMSE (Figures 1-3 and Tables 4 â 6). They did not provide the precision of the positioning, that come from the Covariance matrix; - Would be quite important also to show the precision from the adjustment, as well as the quality control of the adjustment; - Why the standard deviation was not shown? The coordinate obtained has an uncertainty, which in some cases may even be greater than discrepancy. In this case, it appears that the uncertainty (standard deviation) was considered to be zero or disregarded. Not being zero, the standard deviation impacts in the coordinate accuracy; - What is the Klobuchar model contribution to the positioning error since it corrects about 40 to 50% of the ionospheric effect? A discussion or even some quantitative values should be presented in the paper; - Figure 2: there is no data for LHAZ between day 86 and day 87 during the moderate storm. Mention this fact and explain the reason of this lack of data; - Figure 4: I would expect it to be explored in the paper; - Figures 1 to 3: plot in the top the simultaneous DST or even better, if available, the SYM H (instead of Dst) that has a time resolution of 1 minute; - Explain in details what could be the ionospheric activity at low latitudes mentioned at line 145 and include the explanation in the paper; - The title should include recovery phase since results from this storm phase are also presented. As a suggestion, even though it is too large (try to shorten it) : âPerformance of BDS B1 frequency standard point positioning during the main and recovery phases of different classes of geomagnetic storms in China and its surrounding areaâ; - Are there severe storms according to Astafyeva et al., 2014 classification (Dst<-250) during the analyzed period ? The severe storm effects on positioning should be larger. Line Comments/Suggestions/questions 013 motivated >>> caused 019 include here the Aarons paper (see reference below) * 104 check if there is Solar Radio Burst (SRB) around 01 LT since SRBs can cause positioning errors 119 What is the effect of different versions of the receiver hardware on the positioning calculations? 125 Table 4 â Table 6 (just missing one space) 131 1 â 4 m (just missing one space) 138 range of 1 â 3 m (just missing one space) 148 same of line 104: check the possibility of Solar Radio Burst (SRB) occurrence 163 complicated >>> complex * Aarons J (1991) The role of the ring current in the generation or inhibition of equatorial F-layer irregularities during magnetic storms. Radio Sci 26:1131â1149
Citation: https://doi.org/10.5194/angeo-2021-5-RC1 - AC1: 'Reply on RC1', Junchen Xue, 24 Apr 2021
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RC2: 'Comment on angeo-2021-5', Anonymous Referee #2, 22 Aug 2021
The authors assess the positioning accuracy of BDS using B1 frequency and Standard Point Positioning under the effect of a variety of geomagnetic storms. They provide a nice analysis however the study is incomplete in many ways and needs to be improved before the publication in Annales Geophysicae. First, the motivation of the paper is not clear. Does it target single-frequency users of GNSS and try to give lessons for the future use of the system? Does it aim to compare BDS B1 frequency results with the L1 SPP frequency of the GPS? Or, does it aim to compare the findings of the study with those of the BDS studies which were previously published? Neither a literature review nor comparisons of results to previous studies are provided relating to the above questions. Furthermore, the motivation of the study is not clearly stated in the abstract ad in the introduction. Then, the sampling strategy is not discussed well in the beginning and the weaknesses related to those are stated in the conclusion! Was that possible to adopt a better sampling strategy from the rich IGS network!? In addition, the authors determined that some days with strong storms do not affect positioning accuracy but the authors do not refer to literature and include discussion for possible underlying facts. These are serious weaknesses of the paper and need to be improved for the next submission. Other detailed comments are given in the reviewer’s attachment and need to be carefully answered and revised by the authors.
- AC2: 'Reply on RC2', Junchen Xue, 09 Sep 2021
Interactive discussion
Status: closed
-
RC1: 'Comment on angeo-2021-5', Anonymous Referee #1, 24 Feb 2021
The paper analyzes the BeiDou B1 frequency standard point positioning in China and its surrounding area during selected magnetic storm events from 2015 to 2018 and they pointed out that positioning accuracy was deteriorated during the storm. The positioning error was larger for stronger magnetic storms. The root mean square error (RMSE) in position for the different magnetic storms in the East, North and Up directions were also presented. This topic has been discussed previously in the literature and the original contribution of this paper is the fact that the data were from Beidou B1 frequency. Some improvements and clarifications need to be done before the paper could be accepted to Annales Geophysicae. Please see the below comments. - The authors just analyzed the Bias and the bias RMSE (Figures 1-3 and Tables 4 â 6). They did not provide the precision of the positioning, that come from the Covariance matrix; - Would be quite important also to show the precision from the adjustment, as well as the quality control of the adjustment; - Why the standard deviation was not shown? The coordinate obtained has an uncertainty, which in some cases may even be greater than discrepancy. In this case, it appears that the uncertainty (standard deviation) was considered to be zero or disregarded. Not being zero, the standard deviation impacts in the coordinate accuracy; - What is the Klobuchar model contribution to the positioning error since it corrects about 40 to 50% of the ionospheric effect? A discussion or even some quantitative values should be presented in the paper; - Figure 2: there is no data for LHAZ between day 86 and day 87 during the moderate storm. Mention this fact and explain the reason of this lack of data; - Figure 4: I would expect it to be explored in the paper; - Figures 1 to 3: plot in the top the simultaneous DST or even better, if available, the SYM H (instead of Dst) that has a time resolution of 1 minute; - Explain in details what could be the ionospheric activity at low latitudes mentioned at line 145 and include the explanation in the paper; - The title should include recovery phase since results from this storm phase are also presented. As a suggestion, even though it is too large (try to shorten it) : âPerformance of BDS B1 frequency standard point positioning during the main and recovery phases of different classes of geomagnetic storms in China and its surrounding areaâ; - Are there severe storms according to Astafyeva et al., 2014 classification (Dst<-250) during the analyzed period ? The severe storm effects on positioning should be larger. Line Comments/Suggestions/questions 013 motivated >>> caused 019 include here the Aarons paper (see reference below) * 104 check if there is Solar Radio Burst (SRB) around 01 LT since SRBs can cause positioning errors 119 What is the effect of different versions of the receiver hardware on the positioning calculations? 125 Table 4 â Table 6 (just missing one space) 131 1 â 4 m (just missing one space) 138 range of 1 â 3 m (just missing one space) 148 same of line 104: check the possibility of Solar Radio Burst (SRB) occurrence 163 complicated >>> complex * Aarons J (1991) The role of the ring current in the generation or inhibition of equatorial F-layer irregularities during magnetic storms. Radio Sci 26:1131â1149
Citation: https://doi.org/10.5194/angeo-2021-5-RC1 - AC1: 'Reply on RC1', Junchen Xue, 24 Apr 2021
-
RC2: 'Comment on angeo-2021-5', Anonymous Referee #2, 22 Aug 2021
The authors assess the positioning accuracy of BDS using B1 frequency and Standard Point Positioning under the effect of a variety of geomagnetic storms. They provide a nice analysis however the study is incomplete in many ways and needs to be improved before the publication in Annales Geophysicae. First, the motivation of the paper is not clear. Does it target single-frequency users of GNSS and try to give lessons for the future use of the system? Does it aim to compare BDS B1 frequency results with the L1 SPP frequency of the GPS? Or, does it aim to compare the findings of the study with those of the BDS studies which were previously published? Neither a literature review nor comparisons of results to previous studies are provided relating to the above questions. Furthermore, the motivation of the study is not clearly stated in the abstract ad in the introduction. Then, the sampling strategy is not discussed well in the beginning and the weaknesses related to those are stated in the conclusion! Was that possible to adopt a better sampling strategy from the rich IGS network!? In addition, the authors determined that some days with strong storms do not affect positioning accuracy but the authors do not refer to literature and include discussion for possible underlying facts. These are serious weaknesses of the paper and need to be improved for the next submission. Other detailed comments are given in the reviewer’s attachment and need to be carefully answered and revised by the authors.
- AC2: 'Reply on RC2', Junchen Xue, 09 Sep 2021
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