A Novel Technique for High-Precision Ionospheric VTEC Estimation and Prediction at the Equatorial Ionization Anomaly Region: A Case Study over Haikou Station
and Bin Xu 2Round 1
Reviewer 1 Report
see attached report.
Comments for author File: 
Comments.pdf
must be improved on before resubmission.
Author Response
Thank you very much for your professional view.
I have made modifications to your view.
Please see the attachment for the coverletter.
Author Response File: 
Author Response.docx
Reviewer 2 Report
This paper proposes a Kriging-Kalman method to estimate the ionospheric vertical total electron content (VTEC) using GNSS observation data, and evaluates its accuracy in the equatorial anomaly region. Also, it introduces a long short term memory network (LSTM) for predicting the occurrence time of the ionospheric equatorial anomaly and VTEC changes, which outperforms other models, which provides valuable insights into accurately estimating ionospheric VTEC in the challenging equatorial anomaly region.
And here are some advice and questions:
1. Line 9: Please verify if the email address of the 3rd author is correct, which might be @whu.edu.cn instead of @whn.edu.cn.
2. Though the model prediction in the paper yields a good result, what are the advantages of the NN model and the LSTM ? Why are these two models picked to be applied in predicition ? The mechanism differences between them may need to be illustrated briefly in the text to explain why they are choosed among other models to be applied to predict the VTEC.
Author Response
Thank you very much for your professional view.
I have made modifications to your view.
Point 1: Line 9: Please verify if the email address of the 3rd author is correct, which might be @whu.edu.cn instead of @whn.edu.cn.
Response 1: I have replaced @whu.edu.cn with @whn.edu.cn on Line 9.
Point 2: Though the model prediction in the paper yields a good result, what are the advantages of the NN model and the LSTM ? Why are these two models picked to be applied in predicition ? The mechanism differences between them may need to be illustrated briefly in the text to explain why they are choosed among other models to be applied to predict the VTEC.
Response 2: Many scholars have conducted research on the NN model and used it for ionospheric VTEC prediction. The author wants to compare the predicted results with the LSTM model. Ionospheric VTEC data are essentially time-series data. The article chose the LSTM model mainly because it performs well in processing time series data.
Reviewer 3 Report
1. Suggest to give references to “ionospheric TEC results obtained using the above system hardware delay solution method cannot accurately reflect the real changes in the ionospheric TEC in the region” in line 60~61, or give some more explanation.
2. There are some typing errors, such as: the I^i in equation 5~8; (p1-p2) in equeation 9; an unnecessary ‘1’ in the last row of equation 16，and an unnecessary ‘1’ in the last colunm of equation 17.
3. Suggest to give references to “and VTEC at different ionospheric pierce points no longer satisfies the linear relationship between longitude and latitude; therefore, ?????(?) in equation (14) can no longer be used as the calculated receiver VTEC value.” in line 156~158, or give some more explanation.
Can you compare the Kalman method and the Kriging-Kalman method for VTEC estimation in Qingdao?
4. Please check the “zej” in equation 18.
5. Suggest to introduce the “calculation method of ?” briefly in line 163.
6. Check the subheading number 3.2 à 2.2.2 in line 175; 3.3à 2.3 in line 184; 2.3à 2.4 in line202
7. Suggest to change the “truth values” to “reference values”.
8. What is the standard of high precision estimation for VTEC?
Author Response
Dear Reviewer:
Thank you very much for your comments.
I have made modifications based on your comments.
Please see the attachment.
Author Response File: Author Response.docx
Round 2
Reviewer 3 Report
No further suggestions for Authors.
Author Response
Thank you very much for your comments！
