| 08 Jul 2026
Frequent surface–rotor stability decoupling limits the representativeness of surface-based offshore observations
Abstract. Understanding atmospheric stability throughout the wind turbine rotor layer is critical for predicting wake evolution, power production, wake steering performance, and structural loading. Here, we use sonic anemometer, profiling lidar, and thermodynamic profiler observations collected from an instrumented barge deployed during June–September 2024 as part of the Third Wind Forecast Improvement Project (WFIP3) campaign off the U.S. northeast coast to evaluate how well near-surface measurements represent atmospheric stability at wind turbine hub height. Surface-based and rotor-layer stability classifications disagree more than 30 % of the time, with the dominant decoupling regime characterized by unstable surface conditions beneath a stably stratified rotor layer. The frequency of these decoupling events increases through late summer into fall as hub-height stratification strengthens, while individual events become shorter-lived, indicating frequent transitions between coupled and decoupled states. Decoupling events are characterized by slower wind speeds consistent with weaker turbulent mixing through the marine boundary layer. Surface observations often fail to represent the atmospheric stability experienced by offshore wind turbines during summer marine conditions. Consequently, relying solely on near-surface measurements may underestimate the occurrence of stable rotor-layer conditions that influence wake behavior, offshore wind farm power performance, and estimates of structural loads.
Competing interests: At least one of the (co-)authors is a member of the editorial board of Wind Energy Science.
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This study investigates differences in atmospheric stability between surface and rotor layer heights at an offshore site during WFIP3 campaign and how those differences can lead to misrepresentations in lower-level stability interpretations. This is a timely topic for offshore wind energy research with important implications for both campaign and modeling frameworks. As a whole, the overall story and structure of the presented manuscript are clear and easy to follow. However, there are some major scientific points that require further justification, as well as multiple inconsistencies and misspellings in the writing necessary to address before referring to the manuscript for publication. As such, I recommend major revision; please see the specific comments and suggestions below and address accordingly.
General Comments and Suggestions:
Technical Comments:
Line 61: Since “Section does not appear at the beginning of the sentence, it should be abbreviated as “Sect.” per the journal submission guide.
Line 78: used lidars: Please change “used lidars” to “employed lidars”; it took me a moment to realize you weren’t saying used, as in ‘not new’.
Line 88: “The barge was deployed on tation for a total of 85 days, over the 120 day period, as it was recovered and towed to shore for 2 large wave events events (Table 1)”. Station? Also, the word ‘events’ is repeated.
For the same sentence and the one that follows as, “During the deployed periods, its 16 instruments document the MABL in the region, collecting wind and thermodynamic data, as well as precipitation profiles, and wildlife information (birds and bats),” the tenses switch from past (“recovered”) to present (“document”). Make sure to fix this so it is consistent here and anywhere else this occurs in the text.
Table 2: a border at the bottom of the table would make this table cleaner.
Chapter 2: There are a lot of subsections for Chapter 2 that I think can be organized to be a little easier to digest. Something like this:
Line 109: “Tropospheric Remotely Observed Profiling via Optimal Estimation,…” This needs a reference/references!
Line 118: There should be a comma after altitude, not a period.
Line 124: ‘…relative to water surface assuming a 1.52 m barge draft)”… I think this is good information on the barge height to introduce earlier when first discussing the barge at the beginning of the Chapter, as it was a question I originally had at that section.
Figure 3: the caption needs a period at the end. As an aside, Figure 3 strikes me more as belonging in the Appendix, though that’s personal preference.
Paragraph 145: There are inconsistencies in the use of the full word “minute” and just “min.” Please pick one here and elsewhere – I personally vouch for the full word.
Line 157: Figure 2 shouldn’t be mentioned after Figure 3. I suggest switching them and moving both what is now Figure 2 and Table 1 closer to 2.7 where they are referenced. There are also places where you mention the Figure + panel, such as Figure 4a, before introducing Figure 4 itself, which needs to be avoided.
Figure 4: is there a specific reason you have so many intervals for the wind classifications wind rose? I suggest reducing them to 5 or 6 to better see the differences between heights.
Line 174: In this sentence, make the w in “We” lowercase and add commas before and after the parentheses.
Line 225: In this checklist, please add a space before each / to maintain consistency with the rest of the text. There are also inconsistencies in the section title capitalization throughout (e.g., 3.2 Coupled and Decoupled Stability has all non- text capitalized, but in 3.3 ‘Event identification’, Identification isn’t). According to the journal rules ,
Line 243: There needs to be some sort of introductory sentence into the results. Add a sentence or two about how you begin with assessing meteorological conditions, starting with wind speed shown in Figure 4 wind roses. Otherwise, jumping straight into describing 4a comes out of nowhere for the reader.
Figure 4 caption: Add the word ‘panel’ here before (a) and (b) and any other reference to figure letters.
Line 256: Since you already define MABL, you can just replace atmospheric boundary layer in ‘the resulting destabilization of the lowest portion of the atmospheric boundary layer.’ with MABL. Same with the Obukhov length and Bulk Richardson naming, you already named them L and Ri so just use those.
Line 272: Add comma after 8 and capitalize B in bulk to remain consistent (or, as mentioned above, just use the abbreviations).
Line 286: Remove extra parenthesis
Figure 9-11: the heatmap values are quite small-- I think that can just be solved by increasing the figure size, but also consider removing the decimal places in Figure 10 since they aren’t super necessary. On a semi-related note, three figures would probably be better combined since they’re somewhat connected, which would also fix the abruptness of jumping between them.
Line 301: Take out one of the ‘of decoupling’s.
A stylistic comment throughout: there are quite a few occurrences of short paragraphs. While a few of these might help improve readability, others would arguably serve better as a single paragraph. Some examples of the latter are the last two paragraphs of 3.1, the first two of 4.3, the paragraph at 305 and the single sentence after it.