Wave-Ice Interaction for Regional Applications: SWAN Developments and
Validations
Abstract
Interaction between surface gravity waves and sea-ice in the marginal
ice zone is complex, and most of the prior research focus has been in
deeper oceans. Here, the regional wave model Simulating WAves Nearshore
(SWAN) is configured to simulate reduced wind-generation and wave
dissipation in the presence of sea-ice. The wind-generation process is
modified by scaling the generation terms with the open-water fraction,
while wave dissipation in the presence of sea-ice is simulated as an
exponential energy decay as function of ice concentration, wave
frequency and empirical coefficients determined from prior experiments.
Modified SWAN is used to simulate interaction between regional sea-ice
and a swell event in the Barents Sea. The simulation accounting for
wave-ice interaction reasonably agrees with field measured significant
wave height and the energy spectral density. Additional simulations are
conducted for the shallow seas of Gulf of Bothnia, located in the
northernmost reach of the Baltic sea. Modeled wave dynamics in this
region agrees well with satellite altimetry based measurements. This
model setup is further investigated to understand fetch scaling in the
marginal ice zone, and non-dimensional energy scales well with a
non-dimensional fetch determined from a cumulative fetch dependent on
ice concentration. Additional implications for Stokes drift and Stokes
drift shear are also discussed for the Bothnian bay. Finally
recommendations for including dissipation due to ice thickness, and
plans for future model coupling are considered.