Preprints
https://doi.org/10.5194/nhess-2020-100
https://doi.org/10.5194/nhess-2020-100

  24 Apr 2020

24 Apr 2020

Review status: a revised version of this preprint was accepted for the journal NHESS and is expected to appear here in due course.

Non-stationary analysis of water level extremes in Latvian waters, Baltic Sea, during 1961–2018

Nadezhda Kudryavtseva1, Tarmo Soomere1,2, and Rain Männikus1 Nadezhda Kudryavtseva et al.
  • 1Wave Engineering Laboratory, Department of Cybernetics, School of Science, Tallinn University of Technology, Akadeemia 21, Tallinn, 12618, Estonia
  • 2Estonian Academy of Sciences, Kohtu 6, Tallinn, 10130, Estonia

Abstract. Analysis and prediction of water level extremes in the eastern Baltic Sea is a difficult task because of the contribution of various drivers to the water level, the presence of outliers in time series and possibly non-stationarity of the extremes owing to the changes in the atmospheric forcing. Non-stationary modelling of extremes was performed to the block maxima of water level derived from the time series at six locations in the Gulf of Riga and one location in the Baltic proper, Baltic Sea, during 1961–2018. Several parameters of the Generalised Extreme Value distribution of the measured water maxima both in the Baltic proper and in the interior of the Gulf of Riga exhibit statistically significant changes over these years. The most considerable changes occur to the shape parameter ξ. All stations in the interior of the Gulf of Riga experienced a regime shift: a drastic abrupt drop of the shape parameter from ξ ≈ 0.03 ± 0.02 to ξ ≈ −0.36 ± 0.04 around 1986 followed by an increase of a similar magnitude around 1990. This means a sudden switch from a Fréchet distribution to a three-parameter Weibull distribution and back. The water level extremes at Liepaja in the Baltic proper and Kolka at the entrance to the Gulf of Riga reveal significant linear trends in the location and scale parameters. This pattern indicates a different course of the water level extremes in the Baltic proper and the interior of the Gulf of Riga. The described changes may lead to greatly different projections for long-term behaviour of water level extremes and their return periods based on data from different intervals.

Nadezhda Kudryavtseva et al.

 
Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement
 
Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement

Nadezhda Kudryavtseva et al.

Nadezhda Kudryavtseva et al.

Viewed

Total article views: 604 (including HTML, PDF, and XML)
HTML PDF XML Total BibTeX EndNote
490 98 16 604 23 30
  • HTML: 490
  • PDF: 98
  • XML: 16
  • Total: 604
  • BibTeX: 23
  • EndNote: 30
Views and downloads (calculated since 24 Apr 2020)
Cumulative views and downloads (calculated since 24 Apr 2020)

Viewed (geographical distribution)

Total article views: 503 (including HTML, PDF, and XML) Thereof 502 with geography defined and 1 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 

Cited

Latest update: 12 Apr 2021
Download
Short summary
The paper demonstrates a finding of a very sudden change in the nature of water level extremes in the Gulf of Riga. The shape of the distribution is variable with time, it abruptly changed for several years and then suddenly got restored. If similar sudden changes happen in other places in the world, then not taking into account the non-stationarity can lead to a significant underestimation of the future risks potentially caused by the water level extreme events.
Altmetrics