58 research outputs found
A thin plate approximation for ocean wave interactions with an ice shelf
A variational principle is proposed to derive the governing equations for the
problem of ocean wave interactions with a floating ice shelf, where the ice
shelf is modelled by the full linear equations of elasticity and has an
Archimedean draught. The variational principle is used to form a thin-plate
approximation for the ice shelf, which includes water--ice coupling at the
shelf front and extensional waves in the shelf, in contrast to the benchmark
thin-plate approximation for ocean wave interactions with an ice shelf. The
thin-plate approximation is combined with a single-mode approximation in the
water, where the vertical motion is constrained to the eigenfunction that
supports propagating waves. The new terms in the approximation are shown to
have a major impact on predictions of ice shelf strains for wave periods in the
swell regime.Comment: 19 pages, 7 figure
Model predictions of wave overwash extent into the marginal ice zone
A model of the extent of wave driven overwash into fields of sea ice floes is
proposed. The extent model builds on previous work modelling wave overwash of a
single floe by regular waves by including irregular incoming waves and random
floe fields. The model is validated against a laboratory experiment. It is then
used to study the extent of wave overwash into marginal ice zones consisting of
pancake and fragmented floe fields. The effects of wave conditions and floe
geometry on predicted extents are investigated. Finally, the model is used to
predict the wave overwash extent for the conditions observed during a winter
(July) 2017 Antarctic voyage in which the sea surface was monitored by a
stereo-camera system
Evolution of Directional Wave Spectra Through Finite Regular and Randomly Perturbed Arrays of Scatterers
An idealized wave–ice interaction model without subgrid spatial or temporal discretizations
Interactions between irregular wave fields and sea ice: A physical model for wave attenuation and ice breakup in an ice tank
Irregular, unidirectional surface water waves incident on model ice in an ice tank are used as a physical model of ocean surface wave interactions with sea ice. Results are given for an experiment consisting of three tests, starting with a continuous ice cover and in which the incident wave steepness increases between tests. The incident waves range from causing no breakup of the ice cover to breakup of the full length of ice cover. Temporal evolution of the ice edge, breaking front, and mean floe sizes are reported. Floe size distributions in the different tests are analyzed. The evolution of the wave spectrum with distance into the ice-covered water is analyzed in terms of changes of energy content, mean wave period, and spectral bandwidth relative to their incident counterparts, and pronounced differences are found between the tests. Further, an empirical attenuation coefficient is derived from the measurements and shown to have a power-law dependence on frequency comparable to that found in field measurements. Links between wave properties and ice breakup are discussed
Wind, waves, and surface currents in the Southern Ocean:Observations from the Antarctic Circumnavigation Expedition
The Southern Ocean has a profound impact on the Earth's climate system. Its strong winds, intense currents, and fierce waves are critical components of the air-sea interface and contribute to absorbing, storing, and releasing heat, moisture, gases, and momentum. Owing to its remoteness and harsh environment, this region is significantly undersampled, hampering the validation of prediction models and large-scale observations from satellite sensors. Here, an unprecedented data set of simultaneous observations of winds, surface currents, and ocean waves is presented, to address the scarcity of in situ observations in the region-https://doi.org/10.26179/5ed0a30aaf764 (Alberello et al., 2020c) and https://doi.org/10.26179/5e9d038c396f2 (Derkani et al., 2020). Records were acquired underway during the Antarctic Circumnavigation Expedition (ACE), which went around the Southern Ocean from December 2016 to March 2017 (Austral summer). Observations were obtained with the wave and surface current monitoring system WaMoS-II, which scanned the ocean surface around the vessel using marine radars. Measurements were assessed for quality control and compared against available satellite observations. The data set is the most extensive and comprehensive collection of observations of surface processes for the Southern Ocean and is intended to underpin improvements of wave prediction models around Antarctica and research of air-sea interaction processes, including gas exchange and dynamics of sea spray aerosol particles. The data set has further potentials to support theoretical and numerical research on lower atmosphere, air-sea interface, and upper-ocean processes.
Three-dimensional imaging of waves and floes in the marginal ice zone during a cyclone
The marginal ice zone is the dynamic interface between the open ocean and consolidated inner pack ice. Surface gravity waves regulate marginal ice zone extent and properties, and, hence, atmosphere-ocean fluxes and ice advance/retreat. Over the past decade, seminal experimental campaigns have generated much needed measurements of wave evolution in the marginal ice zone, which, notwithstanding the prominent knowledge gaps that remain, are underpinning major advances in understanding the region’s role in the climate system. Here, we report three-dimensional imaging of waves from a moving vessel and simultaneous imaging of floe sizes, with the potential to enhance the marginal ice zone database substantially. The images give the direction–frequency wave spectrum, which we combine with concurrent measurements of wind speeds and reanalysis products to reveal the complex multi-component wind-plus-swell nature of a cyclone-driven wave field, and quantify evolution of large-amplitude waves in sea ice
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