We thank anonymous reviewer 1 for their careful reading of the manuscript and taking the time to provide numerous constructive suggestions for clarifying our manuscript for a broader audience.

R1- Section 3: the methodology is weak, and more detail is needed on the methods used to correct the data set, while the assessment of uncertainties for the variables is not indicated and is clearly lacking. This is particularly the case for salinity and O2 concentrations, which are sensitive to the effects of biofouling.

I have added three sentences to section 3.1 to give a brief synopsis of the variables measured, their respective uncertainties, and where the detailed methods for the data collection and quality control were described (detailed methods and uncertainties are in the Alin et al 2023 ESSD companion paper and quality control methods are from Jiang et al 2021 ESSD paper on Coastal Data Analysis Product in North America (CODAP-NA), respectively). I believe the language added to this section should address the reviewer’s concern about lack of details of the methodology, which are in the companion paper. I simply failed to spell this out clearly enough in the submitted version.

However, there should be no biofouling concerns regarding salinity and O2 measurements, as these measurements are solely collected from ship-based CTD casts. The sensors were never in the water more than an hour at a time, deployed at a few dozen stations over the span of a few days to a week at most, on each cruise. Bottle/Winkler O2 samples were collected immediately after casts were conducted and were preserved and analyzed on board the ship within a few days of collection.

R1- Section 5.2.3 Provide a brief explanation or context for the term "CO2 storm" to help readers understand its significance and how it differs from typical conditions. This would improve accessibility for a broader audience. 

I added some more detailed language to clarify that the observed “CO2 storm” was the *presence of particularly high fCO2 (and low Ω and pH)* that was not accompanied by particularly low O2 or marine heatwave conditions **in places where these conditions have not been observed to occur in the past**. (The information added to the text is briefly described by the words bounded by asterisks above.)

R1- In this section, the authors do not discuss the evolution of CO2 sinks and sources driven by the temperature change, biomass production and atmospheric forcing. According to the evolution described above, what would be the impact on CO2 fluxes in terms of sources/sinks in these coastal waters?

A brief discussion of these processes was in the original manuscript but was removed when shortening and tightening up. Will add a shorter version back into this section to provide our brief thoughts on this. A detailed treatment of these processes is beyond the scope of what we felt appropriate here, though the information is certainly germane to the topic.

R1- The conclusion is too brief. How to optimize the observations to better observe and understand the evolution of the coastal marine ecosystems in the North Pacific towards acidification and O2 decrease ? What will be the next challenges ? Which data or tools will be important to include for the next study  (eg. better obs. space/time frequencies ? etc...). Consider adding a sentence or two in the conclusion to summarize the key implications or recommendations based on the findings. This would provide a more comprehensive and conclusive end to the abstract.

Really appreciate these comments and will add a few sentences to the conclusion to underscore some of the important points you suggest.

Minor comments: 

R1- Line 83: explain what do you mean by the "time of emergence"

I have added text in this line to explain more fully what “time of emergence” means. In a nutshell, it's the time when anthropogenic trends can be detected to exceed the bounds of natural variability



R1- Figure 1: there is an error of typology

Since the reviewer did not provide details, I am guessing they are referring to the mooring name, which has non-standard symbols in it. I added a few words to the caption to explain that this is a name from a North American tribal language and is typed correctly.

R1- Figures 3 and 4: The raincloud plots are not easy to read. The Fig S4 to S6 are more useful. The authors should explain more the signification the raincloud plots in the text or in the legend. A map with stations acronyms like in Fig S5 would be very useful to understand the trends. Authors should insert a map in the Figures 3 to 4. In these figures MB and SS could be combined as it is shown in Fig. S5 to clarify the figure

I thank the reviewer for their helpful feedback. I appreciate reviewer 1’s comment about the raincloud plots, and I too greatly appreciate the visual format for displaying our oceanographic data as in Figures S4 and S6. However, we had previously received feedback from interdisciplinary colleagues (i.e., non-oceanographers who rely on our results) that those figures were too dense/complex to be readily interpretable, and that they wished to also see some sort of visual statistical summary of the data. I decided on raincloud plots because they reflect the seasonal, spatial, and depth variability across parameters and across this diverse region.  I am aware that they are still complex, and that it is not easy to pick out details. Summarizing this volume of data efficiently, clearly, and intuitively is a major challenge (believe me, I tried many other types of plots on the way to deciding on the raincloud plots!). However, we also provided the ranges of values for each parameter in Table 2, in an effort to ensure all of our end users can find the information they most need. In the companion ESSD paper, we have ALSO provided the detailed depth transects preferred by reviewer 1 for all parameters not included in the supplemental material for this paper. To address reviewer 1’s concern, I have added an explanation to section 3.4 for readers that prefer that form of data visualization, indicating that depth transect plots can be found in the supplemental material of this article and in the companion article and its supplemental material.

R1- Oct 2017 is a very particular month but not shown in Fig. S5 to S8, why ?

Oct 2017 was the cruise month in the Sound to Sea plots (Figures 7A, 8A, and S4) that was very anomalous, but the corresponding measurements in Puget Sound’s Main Basin (Figures 7B, 8B, and S5–S8) were in Sept 2017. I revised the text in the same paragraph where we elaborated on what we meant by “CO2 storm” to clarify this distinction.



R1- The place of figure 5 is bizarre and only discussed in section 4.3

I agree--it felt odd when I put that figure there. Will definitely revisit this when revising the text to ensure the figure is better integrated in the final version.

- Line 828: what are the numerical models discussed here ?

I have added language to clarify that these are 3D physical-biogeochemical ocean models.

Thank you again for your time and thoughtful replies!

We appreciate the helpful and complementary comments from anonymous reviewer 2 that will help further clarify our manuscript for a broader audience.

Major comments

R2: The flow of information in the 2.1 Geographic setting section is challenging to follow; I recommend following a structure similar to that of the article by Alin et al., 2023a, cited in the references section.

Thank you for this comment. I’ve reorganized section 2.1 as suggested, such that I believe it both flows better and follows a more similar structure to the comparable section in our ESSD companion paper.

Minor comments

R2: Line 25: I would also include the utilized study period of the time series in the abstract.

Done.

R2: Line 115: Refer to the Figure 1.

Done.

R2: Line 117: For a better understanding, it would be advisable to refer here to Figure 1 or indicate the location of the Fraser River, as shown later in Line 126.

Done.

R2: Line 121: The abbreviature PS appears before it is explained in Line 122.

I added the abbreviation in location earlier than the first use of PS, as I should have. There was some reorganization of this section, so this line now appears earlier in section 2.1.

R2: Line 125: You could add the abbreviation of the different Puget Sound basins here instead of that in Line 131 (MB), MB repeated in 133 and the remaining in 134.

Good idea. I have added them to the suggested line (which now occurs earlier). I do repeat the full basin names on occasion throughout the paper, as I transition from one basin to another, to help readers less familiar with this region follow the flow.

R2: Figure 1: I recommend including a legend with the abbreviation of the different transects and the associated data point types for a more straightforward interpretation. 

We have revised this figure so that the legend is inside of the figure and will tighten up the caption text accordingly. Thanks for the suggestion.

R2: Line 210: Although it is assumed that the description of the variables analysis methodology, like DIC and TA, is included in the references related to the database, it would be helpful for the reader to add a sentence here indicating the references where they are found again.

I have added three sentences to section 3.1 to give a brief synopsis of the variables measured, their respective uncertainties, and where the detailed methods for the data collection and quality control were described (Alin et al 2023 ESSD companion paper and Jiang et al 2021 ESSD paper on Coastal Data Analysis Product in North America (CODAP-NA), respectively). This addition was in response to a comment by reviewer 1, but if I understood reviewer 2’s comment here, I believe these changes addressed this concern as well.

Thank you again for making your comments complement the previous reviewer's remarks.