Articles | Volume 21, issue 5
https://doi.org/10.5194/os-21-2367-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.Spatiotemporal properties of intrinsic sea level variability along the southeastern United States coastline
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- Final revised paper (published on 08 Oct 2025)
- Preprint (discussion started on 10 Apr 2025)
Interactive discussion
Status: closed
Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor
| : Report abuse
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RC1: 'Comment on egusphere-2025-1571', Marcello Passaro, 14 May 2025
- AC2: 'Reply on RC1', Carmine Donatelli, 13 Aug 2025
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RC2: 'Comment on egusphere-2025-1571', Anonymous Referee #2, 09 Jun 2025
- AC1: 'Reply on RC2', Carmine Donatelli, 13 Aug 2025
Peer review completion
AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload
AR by Carmine Donatelli on behalf of the Authors (13 Aug 2025)
Author's response
Author's tracked changes
Manuscript
ED: Publish as is (15 Aug 2025) by Denise Fernandez

ED: Publish as is (15 Aug 2025) by Mario Hoppema (Co-editor-in-chief)

AR by Carmine Donatelli on behalf of the Authors (15 Aug 2025)
I appreciated the opportunity to review this manuscript. The study presents an engaging analysis and contributes to the ongoing discussion on intrinsic sea level variability. The identification of a connection between along-shore variability and a region across the shelf-break is a noteworthy and potentially valuable insight. I have assigned minor review since further work is needed for the following points:
Please note that the questions raised below are not intended merely for a response to the reviewer, but rather highlight areas where the manuscript lacks sufficient explanation. These should be addressed directly in the main text.
Both major and minor points are described in the line-by-line review below. Note that the comments about the Appendix are anticipated, since I considered that section as a “Data&Method”, which anticipate the results
Line 24:
Could you please clarify what type of predictions are being referred to here? Additionally, over what time scales are these predictions intended to apply?
Lines 25–26:
The phrase “assessment of the capabilities” is somewhat vague in scientific terms. Are you referring to a validation process? Furthermore, when you mention “ocean forecasting,” could you specify the time scales involved?
Line 52:
Earlier, you defined “intrinsic” variability as being generated by the ocean itself, independent of atmospheric forcing. In this context, what exactly do you mean by “sources” of intrinsic sea level variability?
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“APPENDICES”
Why are the Data and Methods sections placed in an appendix?
Given their importance for evaluating the results, I recommend restructuring the manuscript to integrate these sections into the main body of the text.
Appendix A appears to be written for a highly specialized audience, which may limit accessibility. It would be helpful to include a brief explanation of the HR FOSI and HR RYF simulations. Specifically:
What processes do these simulations represent?
What type of ocean models are they based on?
Why were these particular simulations selected over others?
Additionally, please clarify the rationale for applying 32 years of HR RYF data, forced with boundary conditions from a single year (2003–2004). What is the scientific justification for this approach?
Is monthly resolution sufficient to capture the temporal scales of intrinsic sea level variability relevant for forecasting? This question ties back to the earlier point regarding the nature of the forecasts being discussed. Why was the analysis limited to monthly resolution, especially considering the availability of high-frequency observational data such as tide gauge records (e.g., GESLA), daily altimetry grids (noting their limitations in effective temporal resolution)
Why was the Measure dataset selected for gridded sea level data? Measure uses a maximum of two altimeters. How does its spatial resolution compare to more comprehensive products, such as the one provided by Copernicus (SEALEVEL_GLO_PHY_L4_MY_008_047), which incorporates all available altimeters?
Line 219: What is a ball tree algorithm?
A brief explanation would be helpful for readers unfamiliar with this method.
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Figure 1:
The tide gauge (TG) points are currently not visible. Could you clarify why only three tide gauges are shown in this region, which is among the most extensively monitored globally?
Additionally, I suggest adding a panel that shows the difference between panels a and b. For clarity in the subsequent discussion, it would also be helpful to indicate the blue area from Figure 3 within Figure 1.
Line 77:
The statement “the model generally underestimating...” may be influenced by the temporal resolution of the data. This result could differ significantly if daily rather than monthly data were used. It is worth noting that satellite observations typically underestimate high-frequency variance in shelf circulation.
Line 88:
Please clarify that the results discussed here pertain specifically to a region dominated by a western boundary current. This is not a general characteristic of the deep ocean, as illustrated globally in Close et al. (2020), Figure 1c.
Section 2.3:
The propagation described in this section is intriguing and might be better resolved using higher temporal resolution data. The cited study by Close et al. (2020) used “successive 5-day averages.” Could you explain why higher temporal resolution was not used in your analysis, and why it was feasible in other studies?
Line 158:
The finding regarding the along-coast coherence of PC1 is particularly interesting. I recommend expanding the discussion in light of existing observational studies. For example, Oelsmann et al. (2024) (https://doi.org/10.1029/2024jc021120 ) analyzed the along-shore coherence of monthly sea level variability using tide gauges and coastal altimetry. Their Figure 7 shows that, along the U.S. East Coast (a western boundary), the observed clusters do not strongly correlate with interannual variability from typical climate indices, unlike what is observed along eastern boundaries. Your results, consistent with previous work, suggest that these clusters are linked to intrinsic dynamics. Notably, both your model and the observations show a separation at Cape Hatteras.
Line 158 (continued):
Please specify that the “robust 2–3-month lag” refers to the offshore region highlighted in Figure 3.
Lines 160–166:
These statements are somewhat unclear. Figure 3c shows that the lag-correlation of PC1 peaks at around 3 months along the entire shelf. How does this reconcile with the claim that sea level anomalies (SLAs) travel much faster, at sub-monthly scales, once they pass Cape Hatteras, which are “unseen” in your experiments?
Best regards,
Marcello Passaro