Better Baltic Sea wave forecasts: improving resolution or introducing ensembles?

Schmith, Torben; Nielsen, Jacob Woge; Rasmussen, Till Andreas Soya; Feddersen, Henrik

doi:https://doi.org/10.5194/os-14-1435-2018

Articles | Volume 14, issue 6

https://doi.org/10.5194/os-14-1435-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/os-14-1435-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 14, issue 6

Research article

|

20 Nov 2018

Research article |

| 20 Nov 2018

Better Baltic Sea wave forecasts: improving resolution or introducing ensembles?

Torben Schmith, Jacob Woge Nielsen, Till Andreas Soya Rasmussen, and Henrik Feddersen

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Final revised paper (published on 20 Nov 2018)
Supplement to the final revised paper
Preprint (discussion started on 31 May 2018)
Supplement to the preprint

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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RC1: 'Review of manuscript “Better Baltic Sea wave forecasts: improving resolution or introducing ensembles?” by Schmith et al.', Anonymous Referee #1, 21 Jun 2018
- AC1: 'Author response to referee #1', Torben Schmith, 20 Jul 2018
RC2: ''Review of manuscript “Better Baltic Sea wave forecasts: improving resolution or introducing ensembles?” by Schmith et al.'', Anonymous Referee #2, 18 Jul 2018
- AC2: 'Author response to referee #2', Torben Schmith, 23 Jul 2018

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

AR by Torben Schmith on behalf of the Authors (23 Aug 2018) Author's response Manuscript

ED: Referee Nomination & Report Request started (03 Sep 2018) by Neil Wells

RR by Anonymous Referee #2 (21 Sep 2018)

RR by Anonymous Referee #1 (26 Sep 2018)

Suggestions for revision or reasons for rejection

The manuscript has improved a lot. I have some minor comments that I suggest to be taken account before publishing the manuscript.

The language of the manuscript should be checked by a native English speaker. There were also some typos.

Line 26: I suggest changing “severe surface waves” to “severe wave conditions”

Lines 72-81: This should be in Discussion-section

Lines 123-125: Is the North Atlantic grid forced by ECMWF-HRES also run 4 times a day? To my understanding the forcing is available only twice a day.

Lines 153-154: If you would only increase grid resolution, not the spectral resolution. How would the computational efforts then compare. If you can not add an exact number, maybe some discussion about this would be appropriate. This experiment setup does not show, whether the possible benefits of the higher resolution comes from increasing horizontal or spectral resolution.

Lines 174-175: I again comment the selection of buoys used for comparison. Your requirement of more than 40% of temporal coverage basically leaves out all the buoys that are in the areas, where the seasonal ice cover typically ranges from Dec/Jan to May, such as the Bothnian Bay and Gulf of Finland. Maybe you should use this criteria in a way that accounts for the time at each buoy location the sea is ice-free.

Line 176: Comment to the ‘sites did not observe the full hour”. WaveRiders, which most of the buoys used in validation were, measure waves for 15-30 min period, and calculate the wave parameters based to that measurements. Did you check, whether the timestamp in the measured data files was the starting time, mid-time, or end time of this measurement period?

Table 4: What about higher values than 5m?

Table 5: Why only Danish stations? I’m not sure that they are the best ones, at least as only ones, to describe the wind field accuracy in the Baltic. At least SMHI and FMI have coastal weather station data available in they open data portals. You should consider using them.

Line 310: According to Björkqvist et aḷthe NB wave buoy measured 8.0 m , not ‘almost 8m’ during the storm

Line 362: I would not state that the performance of LOWENSMEAN and LOWENS were “superior” to HIGH. For sure, it was better in many cases.

Lines 376-386: I would start with informing the readers that these numbers are not directly comparable. Maybe you could start with lines 384-386.

Line 398: I would not call Tuomi et al. 2017 a study, rather a standard product validation procedure performed in CMEMS.

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ED: Publish subject to minor revisions (review by editor) (08 Oct 2018) by Neil Wells

AR by Torben Schmith on behalf of the Authors (26 Oct 2018) Author's response Manuscript

ED: Publish as is (29 Oct 2018) by Neil Wells

Post-review adjustments

AA: Author's adjustment | EA: Editor approval

AA by Torben Schmith on behalf of the Authors (14 Nov 2018) Author's adjustment Manuscript

EA: Adjustments approved (19 Nov 2018) by Neil Wells

Short summary

Using the Baltic Sea as an example, the benefit of increased wave model resolution as opposed to ensemble forecasting is examined, on the premise that the extra computational effort tends to be of the same order of magnitude in both cases. For offshore waters, an ensemble mean is shown to outperform high-resolution modeling. However, for nearshore or shallow waters, where fine-scale depth or coastal features gain importance, this is not necessarily found to be the case.