A Comprehensive Analysis of Environmental Loading Effects on Vertical GPS Time Series in Yunnan, Southwest China

Round 1

Reviewer 1 Report

Comments on “A Comprehensive Analysis of Environmental Loading Effects on Vertical GPS Time Series in Yunnan, Southwest China” by Hu et. al.

This paper is dedicated to analyze the contribution and correction effect of HYDL, ATML, and NTOL environmental loading products from different organizations on the GPS time series in Yunnan, China, and gives the optimal combination of products that can help to obtain more accurate GPS time series in the future. However, there are some inappropriate or inaccurate descriptions in this paper. Below are my comments and suggestions to improve the paper. I hope that the authors find them helpful and consider them in the future version.

Major comments:

1. The GPS time series are not always in phase with the individual environmental loading time series, so the reduction in RMS values cannot be used as an indicator to quantitatively assess the effects of environmental loading on the GPS time series. Therefore, many descriptions in this paper are not rigorous, for example, “ATML and NTOL may be unnecessary for correcting seasonal variations” and “HYDL was the main factor responding for seasonal variations at most stations in Yunnan (NTAL is also large but only out-of-phase to GPS data)”.

Detailed comments:

1. Line 29, First, the meaning of "best environmental load" is not clear. It may be more appropriate to express it as "HYDL contributes the most to the environmental load". Secondly, ATML is also important for the correction of seasonal variation of GPS, which cannot be expressed as "unnecessary".

2. Line 44, “Seasonal variation signals are often regarded as noise in GPS observation”. This statement is inaccurate. The seasonal signals in GPS time series are also widely used to study changes in border mass loading, such as changes in terrestrial water storage and atmospheric loading. But noise is usually of little use.

4. Line 90, change "however" to "therefore".

5. Line 160, change "Figure 2" to " Figure 3".

6. Line 176, there is an error in numerator of formula 2.

7. Line 184, change “have” to “has”.

8. Line 219, “which implied that HYDL was the main factor causing the seasonal variations at most stations”. This is an inappropriate description. Because there is no comparison between HYDL, ATML and NTOL here, it cannot be stated that "HYDL was the main factor". It is suggested to change it to "HYDL has a significant effect on the seasonal variation of the GPS time series".

9. Line 249, “Above the correction and RMS reduction, the 5 ATML products cannot correct the seasonal variations in vertical GPS time series”. As stated in the Major comments, this expression is inappropriate because the RMS reduction cannot assess the correction effect of ATML on the GPS time series.

10. Line 313, the expression “while the GPS and ATML, NTOL, their combination time series were only located in a small time” is not clear.

11. Line 316, what is “technical error”.

12. Line 329, “implying that ATML and NTOL were not the main factor causing the annual variations”. It is not recommended to express it in this way, because the impact of ATML is also relatively great.

13. Line 397, add "poroelastic deformation".

Author Response

I have carefully revised the manuscript.

Author Response File: Author Response.pdf

Reviewer 2 Report

Introduction:

Line 47 paragraph: the results of the works of references 11 and 12, are expressed in amplitude, percentage or rms and are not easily comparable if I understand correctly.

Data and methods:

2.1.2. Environmental Loading Model

I think “ERA-interim” is not properly referenced.

As shown in Figure 161 3, the HYDL and ATML time series had a significant
annual variation correlated with the 162 vertical GPS time series
Process options of GAMIT/Globk (2.1.1) should be indicated to check if this
affirmation is relevant or not.

Results:

I don't understand when you refer to a negative reduction of RMS.
 According to formula 2, is the result worse? It is nor sense even to study it then.




In general I miss a better detailed explanation of the process

Author Response

I have carefully revised the manuscript.

Author Response File: Author Response.pdf