the presented study aimed to produce monthly sea surface pCO2 maps for the South China Sea (SCS). Given SCS is a typical temperate/subtropical maringal sea, the pCO2 sea surface maps for this waters is necessary for understanding the CO2 flux in temperate marginal sea and even global CO2 flux. From this perspective, the study and the data it present is very meaningful. Howeve, the mansucript still have some majors flaws which do not advise me to give a yes to publishing it in its current status. 

Major comments

1. The manuscript was about a dataset generation, but from the abstract and the last section, what kind of data was used as input for the method

was missing. 

2. As I understand EOF  was an important part of the method used for pCO2 maps generation, but in the entire section of methods, no paragraph or sentence was about EOF

3. The language of the manuscript still need some efforts. The current version contains too many redundent phrases and sentences without clear meaning and very difficult to read through and get the logical flow. Readers expect concise and precise expresssion in an acedemica paper. 

and there are some gammar mistake and fuzzy expression.

4. the range of legend in nearly all the map figures were to large and cannot show the spatial gradient of pCO2 distribution, e.g, figure 6, 8, 11, 12,13.

5. what is the intention of including figure 4, if it is the quality of the remote sensing based pCO2 maps included for further pCO2 maps derivation, should the authors just need to include the information from the data distributor?

6. the study site section(2.1) should just serve the question "why mapping pCO2 in SCS is important?", no other information is needed here. 

7. be consitent with the teminology, sometimes it is "in-situ", but "observational data" and "observed data" were present many times. 

8. in the abstract (line 12-14,), the importance of mapping pCO2 in SCS should be addressed before presenting the method, generated data and its quality. 

9 part of the input pCO2 data of the presented  study is from unpublished study (line 158), meaning not peer-reviewed. 

10, line 308: Figure 7, validating the model output with the mdoel training data gives no useful information, suggest removing this part

Minor comments

line 15-17""Using a machine learning-based method facilitated by empirical orthogonal function (EOF)....  between 2003 and 2020" should specifically mention what kind of data was used for the methods input.

linse 17- 20 "We validate our reconstruction with three independent testing datasets where,.... northern basin of the SCS." how independent are the three data set?

line 22 "our reconstructions and observed data" grammar mistake.

Line 27-28 "we  present a new method to assess the uncertainty that includes the bias from the reconstruction and its sensitivity to the features,... quantifies the spatial distribution patterns of uncertainty." then the assessment method should be concisely introduced here. in addition, given this is a data presentation paper, the newly developed method should not in the highlight, unless it is a method presentation paper. 

line 19 "that our reconstruction is effectively captures the main features of both the" ,check the grammar.

line 38,, "22–26%",  I assume it should be 22%–26%. 

line 54-55:  ":The former typically use statistical  interpolations and regression methods" does not  fit with the neighouring sentence, rewrite it or delete it.

line 61- 63 ,"However, because of the complex and dynamic nature of biogeochemical and physical processes in coastal areas, characterization of sea surface pCO2 and subsequently the

air-sea CO2 fluxes both in time and space in marginal seas remains challenging", this sentence is too strong and undermines the motivation of presented  study, rewrite it,

line 67: "clear need", what kind of need is clear need? a need can be strong, urgent, but not clear, need itsself is a clear expression,

line 73:  "(sea surface temperature, SST; chlorophyll a, Chl a),", pay attention to journal requirements on abbrevation 

line 74: "underway "pay attention to the usage of underway, it is ambiguous in the manuscript.

line 82, "the whole China Sea", where is the China Sea? do you mean all the seas in China's territory?

line 84: "(reported in Wang et al., 2021).", pay attention to the format  of the reference citation

line 84:  "Bai et al. (unpublished) subsequently", if the work is not publised, then it should not be cited or discussed, as it is not peer-reviewed.

line 94-96:  include the input data here.

line 137-138 : there is no asterisk in the table and the meaning of the asterisk led note is not clear.

line 144 "Figure 3 shows the spatial and temporal distributions of surface water pCO2.", the spatial distribution of in-situ measurements or data from other source?

line 157:  how the remote sensing-derived pCO2 data were derived?which methods, what is the quality? and output from unpublished study should not be used.

line 184-187: "Wang et al. (in preparation) found a relatively high differential between the....observed data", meaning of this super long sentence is not clear.

line 198 "pCO2 filling method of", should explain the filling method here!

line 201: "pCO2 reconstruction model"  pCO2 reconstruction was used many times in the manuscript, but sea surface pCO2 is not something one can reconstruct, it is a properties or variable of of the sea water, one can measure it ,describe it, retrieve its distribution, but not reconstruct pco2    itself.  So, please pay attention to the verb usage.