Wind Stress in the Coastal Zone: Observations from a Buoy in Southwestern Norway

Round 1

Reviewer 1 Report

Please see the attached file.

Comments for author File: Comments.pdf

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

This manuscript seeks to expand knowledge of the relationship between the wind stress vector, the mean wind direction, and the sea state in the coastal ocean, where the sea state is subject to coastal processes, such as shoaling and refraction. The authors use ~43 hours of wind at 4 m above surface and wave data from a buoy to characterize 7 idealized cases representing the steering of the wave stress vector by locally generated seas and swell in varying configurations, all limited to sea states where swell is present, the wave speed is greater than the wind speed, and the angle between the mean wind direction and wave direction is non-zero. This work suggests that swell waves steer the wind stress. In comparison with other datasets, there is good agreement of the wind stress estimates except for in cases where there is swell propagating counter to the wind direction. The authors find dependence on the structure of the boundary layer, with influence from adjacent land, and indication that the Monin-Obukhov similarity theory is not applicable to the wind and wave regimes observed.

The manuscript is clear, compelling, and well-written. I recommend publication.

Overall comments:

This dataset is limited to dynamics when the wind speed was <10 m/s and the conclusions have been drawn from 43 hours of data taken during a 5 day period. Though three regimes were defined, I wonder how conclusive the results are and if the regimes are more of a continuum. From a modeling perspective, what is the unifying theory that governs the wind stress direction and the drag coefficient?

Please include a discussion of the potential errors associated with the orientation of the buoy relative to the wind direction (downwind).

The fifth order polynomials are not confidence inspiring. Can you discuss further?

Line 363: what about whitecapping?

Copy edits:

Line 218: height

Line 256: and

Line 313: from

Line 381: data runs

Line 408: typo

Line 501: the

Line 537: within

Line 579: inverse

Line 580: decreasing

Line 855: from

Figure comments:

Figure 2: Right and Left are backwards.

Figure 4: The light grey shading is very difficult to see.

Author Response

Please see attachemet.

Author Response File: Author Response.pdf

Reviewer 3 Report

The paper by Flugge et al describes results from a wind and wave monitoring campaign conducted off the coast of Norway. In particular, they examined how the wind stress fields related to wind speed, direction, and sea state. They defined 7 different combinations of these observed over their field campaign. Overall, the authors found that wind stress often different from wind direction significantly. Surprisingly, the drag coefficients calculated during counter-swell conditions were much lower than expected, which may be due to a land-breeze circulation pattern.

Overall, this is a strong paper that gives highly detailed explanations of the methods, the presented data, and data interpretations. I really liked that the authors defined the variables used throughout the paper (e.g. “off-wind angle a”). Since this paper is a little outside of my field of expertise, it is difficult for me to judge how significant the findings are. However, I think they will be of interest to the readers of this publication.

Below are some minor grammatical errors found in the paper.

Minor edits:

Line 4: “Here we present a new observations…” should be “Here we present new observations…”

Line 50: “…areas has received an increased attention” should be “…areas has received increased attention.”

Line 56: What is meant by “equilibrium-range waves”? Please define.

Line 60: What is a “met-mast”? Please describe.

Line 72: “…Monterey Bay, Canada” should be “…Monterey Bay, California.”

Line 130: “…from a orthogonal wind vector…” should be “…from an orthogonal wind vector…”

Line 168: “…Sullivan et al. [2324])” should be “…, Sullivan et al. [23,24]).”

Line 184: “…Mahrt et al. [1213]” should be “…Mahrt et al. [12,13]”

Figure 2 caption: The words “right” and “left” should be switched (i.e. . “(Left) Site map of the Bergen area showing the locations both of Marstein Fyr and the mooring site on the south-western coast of Norway. (Right) The Fugro Seawatch…

Line 211: “…towards the Faroe Island…” should be “…towards the Faroe Islands…”

Line 217: “…tailor made wave sensor” should be “…tailor-made wave sensor.”

Line 218: “…the buoy has a 3.5 m hight mast…” should be “…the buoy has a 3.5 m high mast…”

Line 256: “…wind direction and and air temperature…” should be “…wind direction and air temperature…”

Line 281: “…due to SST warming of the oversituated air…” I’m not sure if that’s supposed to be “oversaturated” or if “oversituated” is a term I’m not familiar with.

Line 290: “…while the condition…” should be “…while the conditions…”

Line 292: “…over northern Norway has strengthened” should be “…over northern Norway strengthened.”

Line 381: “These data run…” should be “These data runs…”

Line 408: “…have been removed by appsituated the motion correction…” should be “…have been removed by applying the motion correction…”

Line 515: “…the data exhibits an dependency…” should be “…the data exhibits a dependency…”

Line 855: “…form enhanced wind…” should be “…from enhanced wind…”

Line 904: “…the Monin-Obukhov similarity theory is no longer be valid…” should be “…the Monin-Obukhov similarity theory is no longer valid…”

Line 961: “…wage and the wind stress…” should be “…wave age and the wind stress…”

Line 964: “…recorded in this wind regimes…” should be “…recorded in these wind regimes…”

Line 968: “The third wind regimes…” should be “The third wind regime…”

Line 974: “…which reach nearly 3 km offshore” should be “…which reached nearly 3 km offshore.”

Author Response

Please see attachement.

Author Response File: Author Response.pdf