Sensitivity assessment of wave heights to surface forcing in Cook Inlet, Alaska

Gaurav Singhal, Vijay G. Panchang, James A. Nelson

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Abstract

Strong tidal forcing combined with complex winds and currents make wave modeling quite challenging in Cook Inlet (CI), Alaska. Using a coupled wind-wave-current modeling approach, we conducted a sensitivity analysis of the environmental factors that impact the modeling predictive skill for waves. A depth-averaged circulation model forced by the winds, tides, and river input was shown to replicate measured flow velocities (NOAA data obtained in 2005) with high correlation coefficients (R2>0.8). Wave-current interaction is examined by one-way and two-way coupling of the wave and circulation models for a 12-day period that included multiple storm events. On average, it is found that significant wave heights (SWHs), which were originally<2m, increase by about 0.5m in the presence of currents (with speeds up to 3m/s). While the effect of currents on larger SWHs (>2m) was found to be minimal. On the other hand, the effect of waves on the currents was found to be marginal, which indicated that two-way coupling between the models may be unnecessary. Artificial adjustment to the currents (to account for possible errors and uncertainties in the circulation model such as baroclinic forcing, winds, and other effects) had only a small effect on the predicted SWHs resulting from the coupled model (<10cm, on average). On the other hand, errors in the wind-fields and wave open boundary conditions resulted in substantial errors in the modeled SWHs. Overall, the experiments carried out here suggest that for forecasting purposes, one-way coupling would be adequate; two-way coupling, albeit incorporating better physics, has less of an effect on the accuracy of the forecast than improved wind-fields.

Original languageEnglish
Pages (from-to)S50-S62
JournalContinental Shelf Research
Volume63
DOIs
Publication statusPublished - 5 Jul 2013

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Keywords

  • Cook Inlet
  • Coupled wind-wave-current modeling
  • Environmental fluid dynamics code (EFDC)
  • Sensitivity analysis
  • Simulating waves nearshore (SWAN)

ASJC Scopus subject areas

  • Oceanography
  • Aquatic Science
  • Geology

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