Quantitative Evaluation of Environmental Loading Products and Thermal Expansion Effect for Correcting GNSS Vertical Coordinate Time Series in Taiwan

Round 1

Reviewer 1 Report

Dear Editor and authors,

From my point of view, the manuscript can be accepted to be published after a process of minor revision.
The main weakness of this manuscript is the poor quality of the figures. The figures should help to understand better the text but it's difficult to see them
Also, i would suggest to provide more details about the GNSS data analysis/
My comments and suggestions are included in the attachment.

Regards,

Comments for author File: Comments.pdf

Author Response

Thanks for the valuable comments from you. We have studied the valuable comments carefully, and made some changes to the manuscript. The detailed responses are in the attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

(1) This article focuses on selecting the optimal environmental loading products and investigating the impact of different types of monuments on thermal expansion effects. However, this study does not reveal all physical mechanism of the nonlinear signals. Consider changing the title to make it more appropriate.

(2) Why did the authors only use 2008-2012 data and not considered the most recent data? Also, the link for GPS data acquisition is not accessible.

(3) Simply superimposing the best loading products corresponding to various loading effects cannot draw what is the best combination. The authors are advised to investigate the effect of different combinations of mass loading products on GNSS time series correction.

(4) In most of the results (e.g., Fig. 3), the GNSS data in Taiwan show clear phase differences, whereas various loading products show generally consistent phases. This phenomenon needs to be explained.

(5) The results need to be reorganized and the discussion should be more comprehensive. The authors need to be more cautious when analyzing the causes of various phenomena. Additionally, there are some grammatical errors in the article. Please check and polish carefully.

(6) Lines 10-14: Change “physical driving mechanisms” to “driving factors”. Six kinds of atmospheric loading models (ATML), five kinds of hydrological loading models (HYDL), and three kinds of non-tidal ocean loading models (NTOL) are not “mechanisms” or “factors”. Remove the quantifier and change the “model” to “effect”. In addition, the authors do not discuss the unique effects of various loading effects on different types of sites and relevant statements need to be modified.

(7) Lines 15-16: It is recommended that the authors compare the various mass loading products to demonstrate that the reason is the small area but not the difference between various products.

(8) Lines 22-23: More adequate reasons are needed to explain this phenomenon, such as climate and landscape.

(9) Line 45: Studying mass loading deformation cannot improve GNSS observation accuracy.

(10) Line 125: Change “compared” to “corrected”

(11) Lines 128-129: The authors do not provide a complete summary of the work and the purpose or significance of this study.

(12) Lines 157-170: This paragraph should be placed before GNSS data processing to indicate that the solution process is done after site selection.

(13) Lines 183-184: Note the distinction between mass loading and mass loading displacement. As the authors state, most of these agencies provide loading displacement.

(14) Lines 191-193: This sentence should be placed in the GNSS data processing section.

(15) Lines 248-249: Briefly arise the reason for using “D”.

(16) Lines 250-252: The “n” in Eq. 5 is not declared. In addition, “D” only quantifies the residuals of the two data sets, but not the spatiotemporal correlation. The relevant discussion needs to be revised.

(17) Line 259: Results are similarly described in each subsection. Authors can summarize these results (e.g., D value, RMS reduction rate and its range and mean, etc.) into a table

(18) Lines 261-262: Figure 3a fails to show consistent spatiotemporal patterns.

(19) Line 414: In this section, the authors analyze the driving factors of the hydrological loading effect and investigate its relationship to thermal expansion effects. But these are not the cause of thermal expansion effects.

(19) Lines 416-417: Use annual amplitude for comparison instead of mean displacement when estimating the contribution to the GNSS time series. Readers may be more concerned about the proportion of thermal expansion effect to hydrological load effect.

(20) Lines 432-433: Precipitation data and temperature data can be presented together as meteorological data in section 2.3.

Author Response

Thanks for the valuable comments from you. We have studied the valuable comments carefully, and made some changes to the manuscript. The detailed responses are in the attachment.

Author Response File: Author Response.pdf