EGU2020-16421
https://doi.org/10.5194/egusphere-egu2020-16421
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

The impact of Arctic sea ice cover on seasonal modulation of the M2 tide

Inger Bij de Vaate1,3, Amey Vasulkar2,3, Cornelis Slobbe1, and Martin Verlaan2,3
Inger Bij de Vaate et al.
  • 1Civil Engineering and Geosciences, Technical University of Delft, Netherlands
  • 2Delft Institute of Applied Mathematics, Technical University of Delft, Netherlands
  • 3Deltares, Delft, Netherlands

The impact of Arctic sea ice decline on future global tidal and storm surge extreme water levels is unknown. Regional studies show that the impact can be substantial; causing increased erosion and posing higher risks to fragile Arctic ecosystems in low-lying areas. Since Arctic tides and surges influence global water levels, consequences of Arctic sea ice decline will be noticed across the globe. In the ongoing FAST4Nl project, an Arctic Total Water Level model will be used to quantify this impact. The model will be developed as an extension of the operational Global Tide and Surge Model (GTSM) and includes the effect of sea ice on tides.

Here we present the results of a study on the seasonal variability of the M2 tide with respect to differences in sea ice cover. The effect of sea ice on the M2 amplitude was modelled for minimal and maximal sea ice configurations. In addition, tidal harmonic analysis was performed on a global tide gauge data set, supplemented by SAR altimeter derived water levels from the Arctic region. The high along-track resolution of SAR altimeters (300 m) enables to derive water levels from leads in the sea ice. Here, the retrieved sea surface heights within a given region were stacked, in order to obtain a sufficiently large data set for analysis of the predominantly ice-covered areas. This allowed to gain insight in the seasonal modulation of both local and global tides and directly relate these processes to variations in sea ice.

How to cite: Bij de Vaate, I., Vasulkar, A., Slobbe, C., and Verlaan, M.: The impact of Arctic sea ice cover on seasonal modulation of the M2 tide, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-16421, https://doi.org/10.5194/egusphere-egu2020-16421, 2020

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Presentation version 1 – uploaded on 01 May 2020
  • CC1: Comment on EGU2020-16421, Mattias Green, 04 May 2020

    Thanks Inger for a neat piece of work. Is it possible that the cahnges you see on the European Shelf is solely due to changes in seasonal startification?

    • AC1: stratification, Inger Bij de Vaate, 04 May 2020

      Thanks Mattias, yes we also think that in some areas stratification has an important part in the seasonal modulation we observe. We are currently including an additional baroclinity term in the model and preliminary results show that this contributes up to a 0.1m difference in amplitude. This seems especially important in the Hudson bay area.

  • CC2: drift ice, Roman Sulzbach, 04 May 2020

    I wonder if frictional terms originating from drifting ice could account for the remaining inconsistencies between modeled and observed seasonal M2-variability. Do you have an estimate if this effect could reach a comparable seasonal amplitude (as friction with fast ice)?

    • AC2: drift ice, Inger Bij de Vaate, 04 May 2020

      We do think that drift ice can influence the tides to some extent. We expected this to be mainly the case in bays or narrow areas where the drift ice has low velocity and behaves as pseudo-fast ice. Incorporating this in the model did not yet solve the disagreement with observations. Including atmospheric forcing in the model, floating ice could have a larger effect on tides, we are working on that. Besides ice, there are other processes that can cause seasonal modulation of tides in this region, such as baroclinity and variations in atmospheric pressure...