Investigation of historical severe storms and storm tides in the German Bight with century reanalysis data

Meyer, Elke Magda Inge; Gaslikova, Lidia

doi:https://doi.org/10.5194/nhess-24-481-2024

Articles | Volume 24, issue 2

https://doi.org/10.5194/nhess-24-481-2024

© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

Special issue:

Hydro-meteorological extremes and hazards: vulnerability,...

https://doi.org/10.5194/nhess-24-481-2024

© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 24, issue 2

Research article

|

14 Feb 2024

Research article |

| 14 Feb 2024

Investigation of historical severe storms and storm tides in the German Bight with century reanalysis data

Elke Magda Inge Meyer and Lidia Gaslikova

Download

Final revised paper (published on 14 Feb 2024)
Preprint (discussion started on 19 Sep 2023)

Interactive discussion

Status: closed

RC1:
'Comment on egusphere-2023-2068', Anonymous Referee #1, 13 Oct 2023

The modelling of storm tide events is highly important for understanding extreme sea levels and coastal flooding, especially from a climatic perspective (past and future). Moreover, because of its complex dynamics, long-term modelling and analysis are challenging. The paper presents the analysis of different reanalysis forcing for storm tide modelling in the North Sea. The paper is well written and well structured, and results are clearly presented, with figures and tables being all relevant.
I compliment the authors for their huge amount of modelling work. I suggest the author use such a database of model results for performing a deeper analysis and discussion on the uncertainty in reproducing extreme events using ensembles (20CRv2c and 20CRv3).

Citation: https://doi.org/10.5194/egusphere-2023-2068-RC1
- AC1: 'Reply on RC1', Elke Meyer, 13 Dec 2023
  
  The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2023/egusphere-2023-2068/egusphere-2023-2068-AC1-supplement.pdf
  
  Citation: https://doi.org/10.5194/egusphere-2023-2068-AC1
RC2:
'Comment on egusphere-2023-2068', Anonymous Referee #2, 23 Oct 2023

This is a case-study type paper, examining what would happen to flood risk if particular types of historical storms occurred coincidentally with higher tide levels, on the German Bight coastline. It's not particularly novel scientifically, but these studies can be useful as evidence building for local impacts work so I would recommend publishing after some minor revisions. It summarises model runs of storm surges forced by a variety of met reanalyses. It appears to be sound in terms of method and results but doesn't communicate specific messages very well.

The abstract is very bland. Obviously reanalysis can be useful, obviously total water levels depend on tidal phase. I suggest the authors make clearer, and more positive statements - which reanalysis models? How much higher? How much accuracy? What is new about the experiments with different tidal phase - is the result any different from just adding the difference of tide-only height? Who should read this paper, and why?

The paper would be easier to read with more headings, for example at line 383 the new section needs a subheading. Elsewhere as well, consider what the reader is supposed to learn from the information presented. Eg fig 7 - the top and bottom panels are pretty similar events, so what are we looking for?

Watch out for undue caution in statements like "flood risk may increase with climate change" - it's pretty unequivocal that sea level rise is happening, will happen, and will increase coastal flood risk.

I find the consistent lower response of ERA5 quite surprising, and I'd like to know more about why this is seen, to know more about whether we should be using it elsewhere. In Fig 5, ERA5 appears to be lower than the other models outside of the storm window. What is the alignment like when there is no storm? Does it vary seasonally? It would be good to check in case there is just a constant bias that could be corrected easily.

Related, line 420: The study hasn't accounted for mean SLR. Would it be hard to do so, eg add a mean SL estimate to the model data? If not, when in time is it correct - would you expect the model to be too low now or too high at some date in the past?

If the storm type is important I suggest arranging fig A1 by the 3 clusters.

Then also sort by these clusters in other figs (eg Fig 6) so we can compare them more easily.

Minor points

What is the pink line in Fig A1?

Mostly the English is fine but there's some small grammar errors for a copy edit, eg Line 273 & 403, affect. Line 304, line 382.

Citation: https://doi.org/10.5194/egusphere-2023-2068-RC2
- AC2: 'Reply on RC2', Elke Meyer, 13 Dec 2023
  
  We would like to thank the two reviewers for taking the time to review our manuscript and for their valuable comments and suggestions to improve our manuscript. We have written our responses below their points in blue., see the supplement.
  
  Citation: https://doi.org/10.5194/egusphere-2023-2068-AC2
CC1:
'Comment on egusphere-2023-2068', Chu-En Hsu, 27 Oct 2023

Respected colleagues,
Thanks for your time and consideration. While the authors have done an excellent job of investigating historical severe storm tides in the North Sea, I would like to draw attention to the relevant analyses and discussions on storm surges and wave runup during three historical hurricanes (Matthew 2016, Dorian 2019, and Isaias 2020) studied by Hsu et al. (2023; https://doi.org/10.5194/nhess-2023-49) using a different modeling system (i.e., COAWST; Warner et al., 2010). Along the South Atlantic Bight, the relative contributions of storm surge and wave runup were analyzed. Hsu et al. (2023) also studied the connection between storm characteristics (e.g., storm translation speed and wind speed) and variations in the water level components.
It'll be fascinating to see if these findings can also be reviewed and discussed further in the present work.
Best wishes,

Chu-En Hsu

Citation: https://doi.org/10.5194/egusphere-2023-2068-CC1
- AC3: 'Reply on CC1', Elke Meyer, 13 Dec 2023
  
  Thank you for drawing our attention to this really interesting paper. However, the topic focused on tropical cyclones and different components contributing to total water level is beyond the scope of our paper, which is primarily aimed at the assessment of different atmospheric reanalyses in connection with extra-tropical water level extremes.
  
  Citation: https://doi.org/10.5194/egusphere-2023-2068-AC3

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload

ED: Publish subject to minor revisions (review by editor) (13 Dec 2023) by Francesco Marra

AR by Elke Meyer on behalf of the Authors (15 Dec 2023) Author's response Author's tracked changes Manuscript

ED: Publish as is (16 Dec 2023) by Francesco Marra

ED: Publish as is (22 Dec 2023) by Paolo Tarolli (Executive editor)

AR by Elke Meyer on behalf of the Authors (30 Dec 2023)

Short summary

Storm tides for eight extreme historical storms in the German Bight are modelled using sets of slightly varying atmospheric conditions from the century reanalyses. Comparisons with the water level observations from the gauges Norderney, Cuxhaven and Husum show that single members of the reanalyses are suitable for the reconstruction of extreme storms. Storms with more northerly tracks show less variability within a set and have more potential for accurate reconstruction of extreme water levels.