Overall comments: The manuscript presents a new concept discussing iron solubility of aerosol particles in the Pacific Ocean determined by atmospheric chemistry in East Asia. The work has been discussed in context to previous literature with appropriate references. However, the manuscript needs major revisions to improve clarity and structure for ease of interpretation. Key terminology has not been defined when introduced, with too many terms being used, causing confusion. Several figures have been incorrectly referenced and labeled throughout the publication. While the COVID-19 lockdown has been mentioned in the abstract and introduction, it lacks substantive discussion in the results and implications section, especially with respect to anthropogenic iron sources. Please find my detailed comments below:

Line 104-108: Please add a clarification on when (pre or post sampling) and why filters were hydrophilized and treated with ethanol

Line 136: Explain what (T-Fe/T-Al)_aerosol stands for in the equation? Clarify this term

Line 173: The y-axis should be correctly labeled as EF _T-Fe to be consistent with the text

Line 194: What are JPN+EAout, JPN, and EAout periods? Please specify the dates they comprise, as they have not been mentioned previously.

Line 261 Suggest using %Fe_max instead of [%FeT] for clarity. Avoid using too many terms if possible, as it is confusing.

Line 270: What is S/L ratio?

Line 327: There is no need to indicate bar graph and line graph with axis; this is self-explanatory in the legend.

Line 350: Elaborate on what nss-SO42-/t-Fe represents before using the term. What is its importance?

Line 351: Smallest particle diameter (< 0.39 µm) does not consistently seem to have higher solubility except maybe in Feb 2020, as opposed to what is stated. Please clarify this discrepancy

Line 392: Clarify what figure is being discussed here (Presumably 6b)

Line 402: The figure caption for figure 6 is same as figure 5. Correctly describe Figure 6 and adjust the text accordingly.

Line 405: The yellow regions labeled as the JPN period in fig 5 and 6 are incorrect, which complicates interpreting the results. Fix the labels and discussion accordingly.

Line 410: What is the chemical alteration being referred to? Is it only ocean acidification or other factors as well? Elaborate

Line 427: Please add more discussion on Fesol% from anthropogenic sources during the COVID-19 lockdown period. The datapoint in Figure 6c for the lockdown period is missing. Does anthro-Fe% drop significantly during COVID-19 lockdowns, and what does this imply about the primary sources of soluble anthro-Fe (e.g., industrial vs. vehicular emissions)?

Line 491: The term “Atmospheric Chemical alterations” is too vague. Specify the mechanisms driving Fe dissolution or discuss in more detail

Line 630 and 640: Figures 10b and 10c have been incorrectly discussed as 11b and 11c throughout the text. There is no figure 11c. Please correctly state which figure is being referred to, and review the supporting text for consistency.

Methods Section: The methods are too lengthy and introduce many terms. Consider moving detailed protocols to the SI.

Implications Section: Please reword the implications section to place results in a broader context without introducing new terms like RDF that have not been mentioned previously.

Minor comments:

Line 34: Use another word instead of ‘outside’ (e.g., except).

Line 73, 89: Subscript ‘sol’ in Fe_sol%

Line 596: Correct the spelling of ‘Dissolution’ and ‘Mineral’ in Figures 10a and 10b.

This study presents measurements of size-resolved soluble iron (Fe) content in aerosol particles over the North Pacific Ocean, based on samples collected over a one-year period. The authors distinguish the samples by air mass origin at the sampling site, allowing for a discussion of the potential mechanisms and sources influencing iron solubility across different size fractions. While the study is generally well-structured and clearly written, several points require clarification or further elaboration before publication. These are outlined below.

Specific Comments:

1. Line 130: Please clarify why the extracted solution was evaporated to dryness. What proportion of organically bound soluble Fe is likely to be lost during this procedure? Additionally, why was the residue re-dissolved in 2% HNO₃? The use of nitric acid could potentially increase the dissolved iron content, thereby altering the measured solubility. This methodology seems unconventional and requires justification.

2. Line 159: What is the EFT-Fe value for the second group? Given that the third group is described as being the opposite of the first, it is unclear how the first and second groups can share the same EFT-Fe range. What differentiates them if not the EFT-Fe?

3. Lines 376–380: Please elaborate on the mechanisms that explain the higher iron solubility observed in fine particles when the d-Fe/d-Al ratio is high. A clearer explanation of the processes involved would strengthen the interpretation.

4. Line 444:  please remove the "S" from "Saerosol".

5. Line 493: The statement regarding chemical alterations increasing the solubility of brake ring and tire wear debris requires supporting evidence. Which specific atmospheric processes or reactions contribute to such an increase in solubility? Please provide examples or references to substantiate this claim.

6. Section 3.7: The apparent discrepancy between the lack of a significant iron sulfate source in the PMF analysis and the observed dominance of Fe-sulfate particles in measurements is unclear. If these species play a major role in explaining D-Fe, why are their sources not represented as significant in the PMF results? What is the contribution of iron from the secondary aerosol factor? Could this factor be responsible for the Fe-sulfate signature observed?

7. Figure 10c: The panel is unclear. Does it suggest that there is no mineral-derived soluble Fe when pH > 2? If so, which dissolution pathways or processes are inhibited above this pH threshold? Clarification is needed.

8. Line 640: There is no Figure 11c. Did you mean to refer to Figure 10c instead?