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The paper, "Determination of the Chemical Equator from GEOS-Chem Model Simulation: A Focus on the Tropical Western Pacific Region" by Xiaoyu Sun et al., proposes a method to identify the hemispheric boundary of air mass transport known as the chemical equator, which has not been extensively studied. The study concentrates on the Tropical West Pacific region and utilizes artificial tracers simulated by the GEOS-Chem model to determine the chemical equator's location. The authors investigate the chemical equator's vertical structure and compare it to the tropical rain belt and wind field convergence. The article fits within the scope of ACP, but significant revisions are necessary before it can be published. To improve the manuscript, the following revisions are suggested. Clarify the vertical level of the chemical equator's results to better understand the location of air mass transport between the hemispheres. Strengthen the justification for the chemical equator determination method by providing a more detailed explanation of the reasoning behind the methodology used. Provide additional evidence to support the interpretation of some results. This can be achieved through the inclusion of further analysis or data that reinforces the conclusions drawn from the results. Apply the chemical equator concept to gain a better understanding of inter-hemispheric air transport. This could include investigating how the chemical equator affects atmospheric composition or analyzing how it may influence global climate patterns.

The following revisions are proposed:

1. To better understand the inter-hemispheric transport of pollutants/tracers, the manuscript should investigate the relationship between the chemical equator's location and atmospheric compositions such as CO, CH4, and SF6. This analysis could utilize satellite observations or model output to provide a comprehensive understanding of the differences in tracer distribution between the northern and southern hemispheres. Including a TransCom simulation analysis (i.e. Krol et al., GMD, 2018) in the discussion would be a valuable addition to the manuscript.

2. The manuscript should discuss the unique features of the chemical equator over the Tropical Western Pacific region compared to other regions. This could include a detailed analysis of the chemical equator's behavior and characteristics in the context of the Western Pacific Monsoon and other regional circulations.

3. To better understand air mass transport, the manuscript should include the distribution of artificial tracers from 30◦ N - 90◦ N and 30◦ S - 90◦ S. This will provide insight into the relative contributions from source domains and air mass inter-hemispheric transport.

4. The manuscript should clarify the vertical level on which the results are based to obtain the chemical equator. This information should be provided in both the methods and results sections to ensure that the reader can understand the study's findings.

5. To improve the manuscript's clarity, it is recommended to conduct a thorough review to identify inaccuracies, misprints, and errors. These revisions will enhance the text's readability and improve the manuscript's overall quality.