Preprints
https://doi.org/10.5194/tc-2021-343
https://doi.org/10.5194/tc-2021-343

  29 Nov 2021

29 Nov 2021

Review status: this preprint is currently under review for the journal TC.

The effect of changing sea ice on nearshore wave climate trends along Alaska’s central Beaufort Sea coast

Kees Nederhoff1, Li Erikson2, Anita Engelstad2, Peter Bieniek3, and Jeremy Kasper4 Kees Nederhoff et al.
  • 1Deltares USA, 8601 Georgia Ave., Silver Spring, MD 20910, USA
  • 2U.S. Geological Survey Pacific Coastal and Marine Science Center, 2885 Mission St., Santa Cruz, CA 95060, USA
  • 3International Arctic Research Center, University of Alaska, Fairbanks, PO Box 757340, Fairbanks, AK 99775-7340, USA
  • 4Alaska Center for Energy and Power, University of Alaska Fairbanks, Fairbanks, AK 99775, USA

Abstract. Diminishing sea ice is impacting the wave field across the Arctic region. Recent observation and model-based studies highlight the spatiotemporal influence of sea ice on offshore wave climatologies, but effects within the nearshore region are still poorly described. This study characterizes the wave climate in the central Beaufort Sea coast from 1979 to 2019 by utilizing a wave hindcast model that uses ERA5 winds, waves, and ice concentrations as input. The spectral wave model SWAN is calibrated and validated based on more than 10,000 in situ measurements collected over a 13-year time period across the region, with friction variations and empirical coefficients for newly implemented empirical ice formulations for the open water season. Model results and trends are analyzed over the 41-year time period using the non-parametric Mann-Kendall test, including an estimate of Sen’s slope. The model results show that the reduction of sea ice concentration correlates strongly with increases in average and extreme wave conditions. In particular, the open water season extended by ~96 days over the 41-year time period (~2.4 days/yr), resulting in a five-fold increase of the yearly cumulative wave power. Moreover, the open water season extends later into the year, resulting in relatively open-water conditions during fall storms with high wind speeds. The later freeze-up results in an increase of the annual offshore median wave heights of 1 % per year and an increase in the average number of rough wave days (defined as days when maximum wave heights exceed 2.5 m) from 1.5 in 1979 to 13.1 days in 2019. Trends in the nearshore areas deviate from the patterns offshore. Model results indicate a non-breaking depth-induced saturation limit for high wave heights in the shallow areas of Foggy Island Bay. Similar patterns are found for yearly cumulative wave power.

Kees Nederhoff et al.

Status: open (until 24 Jan 2022)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on tc-2021-343', Jim Thomson, 17 Dec 2021 reply
  • RC2: 'Comment on tc-2021-343', Anonymous Referee #2, 22 Dec 2021 reply

Kees Nederhoff et al.

Data sets

Wave model results of the central Beaufort Sea coast, Alaska Anita C. Engelstad, Kees Nederhoff, and Li E. Erikson https://doi.org/10.5066/P990NDMQ

Kees Nederhoff et al.

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Short summary
Diminishing sea ice is impacting waves across the Arctic region. Recent work shows the effect of the sea ice on offshore waves, however, effects within the nearshore are less known. This study characterizes the wave climate in the central Beaufort Sea coast of Alaska. We show that the reduction of sea ice correlates strongly with increases in the average and extreme waves. However, found trends deviate from offshore since part of the increase in energy is dissipated before reaching the shore.