scholarly journals Break-up of sea ice by ocean waves

1998 ◽  
Vol 27 ◽  
pp. 438-442 ◽  
Author(s):  
Patricia J. Langhorne ◽  
Vernon A. Squire ◽  
Colin Fox ◽  
Timothy G. Haskell
Keyword(s):  
Flexural Strength ◽  
Sea Ice ◽  
Field Experiments ◽  
Endurance Limit ◽  
Ocean Waves ◽  
Fatigue Behaviour ◽  
Induced Motion ◽  
Break Up ◽  
Ice Failure ◽  
Wave Induced

The manner in which sea ice breaks up determines its floe-size distribution. This, together with any redistribution due to ocean currents or winds, alters the fluxes between the atmosphere and the underlying ocean. Many materials fail at stresses well below their flexural strength when subject to repeated bending, such processes being termed fatigue. in some materials a stress exists below which the material will maintain its integrity even if subjected to an infinite number of load cycles. This stress is termed the endurance limit. We report a scries of field experiments to investigate the fatigue behaviour of first-year sea ice that subjected in situ cantilever beams to repeated bending with zero mean stress. These tests suggest that an endurance limit exists for sea ice, and that it is approximately 60% of the flexural strength. Using theory and data from wave experiments performed in similar conditions to the fatigue experiments, estimates are made of the conditions under which wave-induced break-up occurs. These indicate that fatigue may be a neglected ingredient of sea-ice failure due to wave-induced motion.

scholarly journals Strong and highly variable push of ocean waves on Southern Ocean sea ice

2018 ◽  
Vol 115 (23) ◽  
pp. 5861-5865 ◽  
Author(s):  
Justin E. Stopa ◽  
Peter Sutherland ◽  
Fabrice Ardhuin
Keyword(s):  
Southern Ocean ◽  
Sea Ice ◽  
Numerical Models ◽  
Poor Performance ◽  
Ocean Waves ◽  
Ice Dynamics ◽  
High Resolution Imagery ◽  
Average Wind ◽  
Break Up ◽  
Synthetic Aperture Radars

Sea ice in the Southern Ocean has expanded over most of the past 20 y, but the decline in sea ice since 2016 has taken experts by surprise. This recent evolution highlights the poor performance of numerical models for predicting extent and thickness, which is due to our poor understanding of ice dynamics. Ocean waves are known to play an important role in ice break-up and formation. In addition, as ocean waves decay, they cause a stress that pushes the ice in the direction of wave propagation. This wave stress could not previously be quantified due to insufficient observations at large scales. Sentinel-1 synthetic aperture radars (SARs) provide high-resolution imagery from which wave height is measured year round encompassing Antarctica since 2014. Our estimates give an average wave stress that is comparable to the average wind stress acting over 50 km of sea ice. We further reveal highly variable half-decay distances ranging from 400 m to 700 km, and wave stresses from 0.01 to 1 Pa. We expect that this variability is related to ice properties and possibly different floe sizes and ice thicknesses. A strong feedback of waves on sea ice, via break-up and rafting, may be the cause of highly variable sea-ice properties.

scholarly journals Drivetrains on floating offshore wind turbines: lessons learned over the last 10 years

2021 ◽  
Author(s):  
Amir R. Nejad ◽  
Jone Torsvik
Keyword(s):  
Wind Turbines ◽  
Field Experiments ◽  
Structure Design ◽  
Lessons Learned ◽  
Offshore Wind ◽  
Wind Loading ◽  
Floating Offshore Wind Turbines ◽  
Induced Motion ◽  
Research Findings ◽  
Wave Induced

AbstractThis paper presents lessons learned from own research studies and field experiments with drivetrains on floating wind turbines over the last ten years. Drivetrains on floating support structures are exposed to wave-induced motions in addition to wind loading and motions. This study investigates the drivetrain-floater interactions from two different viewpoints: how drivetrain impacts the sub-structure design; and how drivetrain responses and life are affected by the floater and support structure motion. The first one is linked to the drivetrain technology and layout, while the second question addresses the influence of the wave-induced motion. The results for both perspectives are presented and discussed. Notably, it is highlighted that the effect of wave induced motions may not be as significant as the wind loading on the drivetrain responses particularly in larger turbines. Given the limited experience with floating wind turbines, however, more research is needed. The main aim with this article is to synthesize and share own research findings on the subject in the period since 2009, the year that the first full-scale floating wind turbine, Hywind Demo, entered operation in Norway.

scholarly journals Aerial observations of sea ice break-up by ship waves

2021 ◽  
Author(s):  
Elie Dumas-Lefebvre ◽  
Dany Dumont
Keyword(s):  
Sea Ice ◽  
Flexural Rigidity ◽  
Temporal Analysis ◽  
Coast Guard ◽  
Modal Shape ◽  
Lawrence Estuary ◽  
Ship Waves ◽  
Break Up ◽  
Ice Floes ◽  
Wave Induced

Abstract. We provide the first in situ observations of floe size distributions (FSD) resulting from wave-induced sea ice break-up. In order to obtain such data, an unmanned aerial vehicle was deployed from the Canadian Coast Guard Ship Amundsen as it sailed in the vicinity of large ice floes in Baffin Bay and in the St. Lawrence Estuary, Canada. When represented as probability density functions weighted by the surface of ice floes, the FSDs exhibit a strong modal shape which confirms the preferential size hypothesis debated in the scientific community. Both FSDs are compared to a flexural rigidity length scale, which depends on ice properties, and with the wavelength scale. This comparison tends to show that the maximal distance between cracks is preferentially dictated by sea ice thickness and elasticity rather than by the wavelength. Temporal analysis of one fracture event is also done. Results show that the break-up advances almost as fast as the wave energy and that waves responsible for the break-up propagate following the mass loading dispersion relation. Moreover, our experiments show that thicker ice can attenuate wave less than thinner ice. This method thus provides key information on the wave-induced FSD, clarifies theoretical aspects from the construction of the FSD to its implementation in models and brings new knowledge regarding the temporal evolution of sea ice break-up.

scholarly journals Wave–sea-ice interactions in a brittle rheological framework

2021 ◽  
Vol 15 (1) ◽  
pp. 431-457
Author(s):  
Guillaume Boutin ◽  
Timothy Williams ◽  
Pierre Rampal ◽  
Einar Olason ◽  
Camille Lique
Keyword(s):  
Sea Ice ◽  
Barents Sea ◽  
Ocean Waves ◽  
Ice Cover ◽  
The Arctic ◽  
Sea Ice Extent ◽  
Ice Dynamics ◽  
Coupled Modelling ◽  
Wave Induced ◽  
The Impact

Abstract. As sea ice extent decreases in the Arctic, surface ocean waves have more time and space to develop and grow, exposing the marginal ice zone (MIZ) to more frequent and more energetic wave events. Waves can fragment the ice cover over tens of kilometres, and the prospect of increasing wave activity has sparked recent interest in the interactions between wave-induced sea ice fragmentation and lateral melting. The impact of this fragmentation on sea ice dynamics, however, remains mostly unknown, although it is thought that fragmented sea ice experiences less resistance to deformation than pack ice. Here, we introduce a new coupled framework involving the spectral wave model WAVEWATCH III and the sea ice model neXtSIM, which includes a Maxwell elasto-brittle rheology. This rheological framework enables the model to efficiently track and keep a “memory” of the level of sea ice damage. We propose that the level of sea ice damage increases when wave-induced fragmentation occurs. We used this coupled modelling system to investigate the potential impact of such a local mechanism on sea ice kinematics. Focusing on the Barents Sea, we found that the internal stress decrease of sea ice resulting from its fragmentation by waves resulted in a more dynamical MIZ, particularly in areas where sea ice is compact. Sea ice drift is enhanced for both on-ice and off-ice wind conditions. Our results stress the importance of considering wave–sea-ice interactions for forecast applications. They also suggest that waves likely modulate the area of sea ice that is advected away from the pack by the ocean, potentially contributing to the observed past, current and future sea ice cover decline in the Arctic.

scholarly journals WIFF1.0: A hybrid machine-learning-based parameterization of Wave-Induced sea-ice Floe Fracture

2021 ◽  
Author(s):  
Christopher Horvat ◽  
Lettie A. Roach
Keyword(s):  
Sea Ice ◽  
Climate Models ◽  
Ocean Surface ◽  
Ocean Waves ◽  
Ocean Surface Waves ◽  
Marginal Ice Zone ◽  
Ice Floes ◽  
Global Statistics ◽  
Surface Wave Field ◽  
Wave Induced

Abstract. Ocean surface waves play an important role in maintaining the marginal ice zone, a heterogenous region occupied by sea ice floes with variable horizontal sizes. The location, width, and evolution of the marginal ice zone is determined by the mutual interaction of ocean waves and floes, as waves propagate into the ice, bend it, and fracture it. In previous work, we developed a one-dimensional “superparameterized” scheme to simulate the interaction between the stochastic ocean surface wave field and sea ice. As this method is computationally expensive and not bitwise reproducible, here we use a pair of neural networks to accelerate this parameterization, delivering an adaptable, computationally-inexpensive, reproducible approach for simulating stochastic wave-ice interactions. Implemented in the sea ice model CICE, this accelerated code reproduces global statistics resulting from the full wave fracture code without increasing computational overheads. The combined model, Wave-Induced Floe Fracture (WIFF v1.0) is publicly available and may be incorporated into climate models that seek to represent the effect of waves fracturing sea ice.

scholarly journals Experimental evidence for a universal threshold characterizing wave-induced sea ice break-up

2020 ◽  
Author(s):  
Joey Voermans ◽  
Jean Rabault ◽  
Kirill Filchuk ◽  
Ivan Ryzhov ◽  
Petra Heil ◽  
...  
Keyword(s):  
Sea Ice ◽  
Field Observations ◽  
Forecasting Models ◽  
Operational Forecasting ◽  
Wide Range ◽  
Quantitative Manner ◽  
Field Campaigns ◽  
Break Up ◽  
Wave Induced ◽  
Promising Avenue

Abstract. Waves can drastically transform a sea ice cover by inducing break-up over vast distances in the course of a few hours. However, relatively few detailed studies have described this phenomenon in a quantitative manner, and the process of sea ice break-up by waves needs to be further parameterized and verified before it can be reliably included in forecasting models. In the present work, we discuss sea ice break-up parameterization and demonstrate the existence of an observational threshold separating breaking and non-breaking cases. This threshold is based on information from two recent field campaigns, supplemented with existing observations of sea ice break-up. The data used cover a wide range of scales, from laboratory-grown sea ice to polar field observations. Remarkably, we show that both field and laboratory observations tend to converge to a single quantitative threshold at which the wave-induced sea ice break-up takes place, which opens a promising avenue for robust parametrization in operational forecasting models.

scholarly journals Impacts of a lengthening open water season on Alaskan coastal communities: deriving locally relevant indices from large-scale datasets and community observations

2018 ◽  
Vol 12 (5) ◽  
pp. 1779-1790 ◽  
Author(s):  
Rebecca J. Rolph ◽  
Andrew R. Mahoney ◽  
John Walsh ◽  
Philip A. Loring
Keyword(s):  
Sea Ice ◽  
Large Scale ◽  
Climate Model ◽  
Regional Climate ◽  
Open Water ◽  
Ocean Waves ◽  
Coastal Communities ◽  
Time Period ◽  
Break Up ◽  
Wind Events

Abstract. Using thresholds of physical climate variables developed from community observations, together with two large-scale datasets, we have produced local indices directly relevant to the impacts of a reduced sea ice cover on Alaska coastal communities. The indices include the number of false freeze-ups defined by transient exceedances of ice concentration prior to a corresponding exceedance that persists, false break-ups, timing of freeze-up and break-up, length of the open water duration, number of days when the winds preclude hunting via boat (wind speed threshold exceedances), the number of wind events conducive to geomorphological work or damage to infrastructure from ocean waves, and the number of these wind events with on- and along-shore components promoting water setup along the coastline. We demonstrate how community observations can inform use of large-scale datasets to derive these locally relevant indices. The two primary large-scale datasets are the Historical Sea Ice Atlas for Alaska and the atmospheric output from a regional climate model used to downscale the ERA-Interim atmospheric reanalysis. We illustrate the variability and trends of these indices by application to the rural Alaska communities of Kotzebue, Shishmaref, and Utqiaġvik (previously Barrow), although the same procedure and metrics can be applied to other coastal communities. Over the 1979–2014 time period, there has been a marked increase in the number of combined false freeze-ups and false break-ups as well as the number of days too windy for hunting via boat for all three communities, especially Utqiaġvik. At Utqiaġvik, there has been an approximate tripling of the number of wind events conducive to coastline erosion from 1979 to 2014. We have also found a delay in freeze-up and earlier break-up, leading to a lengthened open water period for all of the communities examined.

scholarly journals Experimental evidence for a universal threshold characterizing wave-induced sea ice break-up

2020 ◽  
Vol 14 (11) ◽  
pp. 4265-4278
Author(s):  
Joey J. Voermans ◽  
Jean Rabault ◽  
Kirill Filchuk ◽  
Ivan Ryzhov ◽  
Petra Heil ◽  
...  
Keyword(s):  
Sea Ice ◽  
Field Observations ◽  
Forecasting Models ◽  
Operational Forecasting ◽  
Wide Range ◽  
Quantitative Manner ◽  
Field Campaigns ◽  
Break Up ◽  
Wave Induced ◽  
Promising Avenue

Abstract. Waves can drastically transform a sea ice cover by inducing break-up over vast distances in the course of a few hours. However, relatively few detailed studies have described this phenomenon in a quantitative manner, and the process of sea ice break-up by waves needs to be further parameterized and verified before it can be reliably included in forecasting models. In the present work, we discuss sea ice break-up parameterization and demonstrate the existence of an observational threshold separating breaking and non-breaking cases. This threshold is based on information from two recent field campaigns, supplemented with existing observations of sea ice break-up. The data used cover a wide range of scales, from laboratory-grown sea ice to polar field observations. Remarkably, we show that both field and laboratory observations tend to converge to a single quantitative threshold at which the wave-induced sea ice break-up takes place, which opens a promising avenue for robust parametrization in operational forecasting models.

scholarly journals A device for measuring wave-induced motion of ice floes in the Antarctic marginal ice zone

2015 ◽  
Vol 56 (69) ◽  
pp. 415-424 ◽  
Author(s):  
Alison L. Kohout ◽  
Bill Penrose ◽  
Scott Penrose ◽  
Michael J.M. Williams
Keyword(s):  
Sea Ice ◽  
Measurement Unit ◽  
First Year ◽  
Large Wave ◽  
Antarctic Sea Ice ◽  
Induced Motion ◽  
Wave Heights ◽  
Ice Floes ◽  
Wave Induced ◽  
The Antarctic

AbstractA series of wave instruments was deployed on first-year Antarctic sea ice during SIPEX (Sea Ice Physics and Ecosystem Experiment) II. Here we describe the hardware and software design of these instruments and give an overview of the returned dataset. Each instrument consisted of a high-resolution accelerometer coupled with a tri-axis inertial measurement unit, which was located using GPS. The significant wave heights measured near the ice edge were predominately between 1 and 2 m. During the 6 weeks of data capture, several large wave events were measured. We report here a selection of events, highlighting the complexities associated with measuring wave decay at individual frequencies.

scholarly journals Effects of Wave-Induced Sea Ice Break-Up and Mixing in a High-Resolution Coupled Ice-Ocean Model

2021 ◽  
Vol 9 (4) ◽  
pp. 365
Author(s):  
Junde Li ◽  
Alexander V. Babanin ◽  
Qingxiang Liu ◽  
Joey J. Voermans ◽  
Petra Heil ◽  
...  
Keyword(s):  
High Resolution ◽  
Sea Ice ◽  
Ice Cover ◽  
Ocean Model ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Ice Melt ◽  
Arctic Sea ◽  
Break Up ◽  
Wave Induced

Arctic sea ice plays a vital role in modulating the global climate. In the most recent decades, the rapid decline of the Arctic summer sea ice cover has exposed increasing areas of ice-free ocean, with sufficient fetch for waves to develop. This has highlighted the complex and not well-understood nature of wave-ice interactions, requiring modeling effort. Here, we introduce two independent parameterizations in a high-resolution coupled ice-ocean model to investigate the effects of wave-induced sea ice break-up (through albedo change) and mixing on the Arctic sea ice simulation. Our results show that wave-induced sea ice break-up leads to increases in sea ice concentration and thickness in the Bering Sea, the Baffin Sea and the Barents Sea during the ice growth season, but accelerates the sea ice melt in the Chukchi Sea and the East Siberian Sea in summer. Further, wave-induced mixing can decelerate the sea ice formation in winter and the sea ice melt in summer by exchanging the heat fluxes between the surface and subsurface layer. As our baseline model underestimates sea ice cover in winter and produces more sea ice in summer, wave-induced sea ice break-up plays a positive role in improving the sea ice simulation. This study provides two independent parameterizations to directly include the wave effects into the sea ice models, with important implications for the future sea ice model development.

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