Satellite Clock Batch Estimation Accuracy Analysis and Its Impacts on PPP
Round 1
Reviewer 1 Report
This work investigates the issues that impact batch estimation accuracy of the ultra-rapid satellite clock, as well as the impacts on PPP convergence and accuracy. The topic is interesting, while there are still some issues which seems confusing to the reader.
1． Definitions of ICB and TDB should be further clarified. It seems they are proposed by the authors. The clearest definitions I can find are below Eq. (10), Combining the interpretation below Eq. (2), I conclude that both ICB and TDB are the estimated satellite clock bias. The only difference are ICB is the satellite clock error at the initial epoch i0, and TDB is the estimated satellite clock at the ith epoch.
2． Line 416, there is “s0 is the reference satellite” and Line 418, there is “ … the mean value of all satellite clocks is selected as the reference.” Do you mean s0 is actually not a satellite indicator, but means the mean value of all satellite clock bias?
3． Please distinguish “satellite clock”, “satellite clock bias”, “satellite clock error”. Do you use them arbitrarily? Or there are significantly differences between any two of them?
4． Simulations in Section 3.2 need further explanation. Do you mean, by simulating the impacts of ICB, a constant bias is added into each satellite clock bias at all epochs? The constant biases at different satellites are different, and obtained from a normal distribution. While for the impact of TDB, a random error is added into each satellite clock bias at each epoch. Therefore, differences between the two are the former is invariant along time, while the later is variant.
If my understanding is correct, could you clarify this clearer.
5． The analyses on observation redundancy are quite simple. Only the numbers of stations are discussed. How about the results if 40 stations with different distributions are used? Would this impact the estimation results?
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Reviewer 2 Report
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Reviewer 3 Report
The paper presents very interesting research in terms of the source of the satellite clock bias in PPP method. The manuscript is very well written and should be published.
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