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Coastal Ocean Dynamics in the Arctic CODA
Overview
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Sampling Sites
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Arctic coastlines, and in particular the northern coast of Alaska, are eroding at rates of meters per year. Coastal flooding events are becoming more common, as reductions in seasonal sea ice create large fetches for autumn storms. The proposed work concerns the oceanographic factors associated with coastal erosion and flooding, which are distinct from the geologic controls. Key among these oceanographic factors is the previously demonstrated increasing trend in surface wave activity throughout the western Arctic.
Field observations will be collected and a coupled modeling system will be developed that together quantify the wave-ice-ocean interactions along the northern coast of Alaska. This new model will be applied, after calibration and validation with the field observations, to generate a 20-year hindcast. The hindcast will be used to investigate the climate signals in Arctic wave–ice–ocean coupling. The results will determine:
- The significance of coastal protection via scattering and dissipation of waves by sea ice
- The thermodynamic and mechanical effects of increasing wave energy
- The changes in coastal flooding and circulation associated with increasing wave momentum
Making waves with Arctic research
UW Civil + Environmental Engineering News, 24 February 2020 |
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NSF funds wave-ice-ocean research along Arctic Coast
UW Civil + Environmental Engineering News, 16 August 2018 |
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Motivation
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Objectives
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The Arctic coastal region is extensively used for subsistence, e.g., hunting, fishing, and gathering. Commercial activities, such as oil drilling and cargo shipping, are also concentrated along Arctic coasts. Along the northern coast of Alaska, areas such as the National Petroleum Reserve–Alaska (NPRA) and the Teshekpuk Lake Special Area (TLSA) support local In˜upiaq communities and provide undisturbed regions for diverse wildlife.
As the whole Arctic shifts into a modern epoch, with a more seasonal ice cover and warmer temperatures, the Arctic coastal processes are shifting as well. Storm systems with strong wave events now occur more often in the Arctic, with less ice to protect the coast. These storm events cause coastal flooding and erosion, with associated damage to infrastructure.
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The overall goal of this proposal is to improve scientific understanding of wave–ice–ocean interactions along the Arctic coast, with particular attention to the oceanographic parameters that affect erosion. The proposed work will directly observe offshore wave conditions and shoreward wave transformations in the presence of a variety of ice conditions. Results will inform a model capable of resolving wave–ice interactions, coastal circulation, and water temperatures under changing Arctic ice conditions. The specific objectives are to:
- Quantify the role of reduced sea ice in causing increased wave action along the Arctic coast
- Understand the wave–ice dissipation and scattering occurring in the seasonal ice zone along the coast
- Develop hindcast climatology and forecast capability for coastal wave conditions, circulation, and
water temperature
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Media Coverage
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Related Research
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UW study finds disturbing climate change evidence in Arctic Ocean KING5 News, Glenn Farley A joint study between the University of Washington and University of Alaska has uncovered the presence of 'pancake ice' and tall waves in the Arctic Ocean. Photo: John Guillotte |
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21 Jan 2020
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Warm ocean water delays sea ice for Alaska towns, wildlife Associated Press, Dan Joling In the new reality of the U.S. Arctic, open water is the November norm for the Chukchi. Instead of thick, years-old ice, researchers are studying waves and how they may pummel the northern Alaska coastline. |
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19 Nov 2019
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Fall storms, coastal erosion focus of northern Alaska research cruise UW News, Hannah Hickey A University of Washington team is leaving to study how fall storms, dwindling sea ice and vulnerable coastlines might combine in a changing Arctic. The project leaves Thursday, Nov. 7, from Nome, Alaska in the Bering Strait to spend four weeks gathering data during the fall freeze-up season. |
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5 Nov 2019
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Public talks kick off study of ice loss, warming and coastal changes in northern Alaska UW News The northernmost town in the country had its warmest March on record. Utqiagvik, formerly known as Barrow, is among the coastal communities that are feeling the effects of a warming Arctic firsthand. |
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25 Apr 2019
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Worldview Imagery
Persistent measurements of surface waves in landfast ice using fiber optic telecommunication cables
Collaboration with M. Smith at WHOI |
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R/V Sikuliaq 2019 Field Locations
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In November we plan to depart Nome and transit to Flaxman Island to begin three site deployments.
- November 2: Depart Nome
- November 7: Deploy and measure Flaxman Island (site 3)
- November 12: Deploy and measure Jones Islands (site 2)
- November 17: Deploy and measure Icy Cape (site 1)
- November 27: Return to Dutch Harbor
Dates and locations are subject to change based on weather, ice, or subsistence activities.
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Final CODA 2019 Cruise Report (PDF, 9 MB)
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Cruise dates, activities, and stations:
- 6 Nov: Mobilize in Nome, AK
- 7 Nov: Depart, transit north
- 8 Nov: Transit North
- 9 Nov: Deploy mooring line and sampling at Icy Cape (CODA Site 1)
- 10 Nov: Recover/redeploy U Delaware / ONR acoustics mooring
- 11 Nov: GOWEST Fishing in open water
- 12 Nov: Moorings, Stations, and SWIFTs at Jones Islands (CODA Site 2)
- 13 Nov: Moorings, Stations at Flaxman Island (CODA Site 3)
- 14 Nov: GOWEST fishing at the eastern shelfbreak
- 15 Nov: GOWEST fishing in the eastern basin and the mid-slope
- 16 Nov: Stations and redeploy at Jones Is (CODA Site 2)
- 17 Nov: GOWEST fishing at the mid shelf break (with full ice station)
- 18 Nov: GOWEST fishing in the mid basin (and transits West)
- 19 Nov: GOWEST fishing at the western basin (and transits West)
- 20 Nov: GOWEST fishing at the western shelf (and transits South)
- 21–23 Nov: SWIFT buoys and stations at Icy Cape (CODA S1)
- 24 Nov: Turnaround moorings at Icy Cape (CODA S1)
- 25–26 Nov: Transit south *
- 27 Nov: Personnel transfer in Nome
- 28 Nov: Transit south
- 29–30 Nov: Transit south, with pause for SWIFT buoy testing in open water
- 1 Dec: Arrive Dutch Harbor, AK, begin demobilization
* The return transit began early to account for an adverse weather forecast. This amounts to two days of lost science operations from the CODA project.
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December 2019
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December 1: R/V Sikuliaq arrived Dutch Harbor in the morning.
Demobilization. CODA project completed.
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R/V Sikuliaq at dock in Dutch Harbor (Photo: John Guillote)
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November 2019
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November 28–30: Transit South, with pause for SWIFT buoy testing in open water.
There was an extensive field of pancake ice upon arrival near the shore of Icy Cape. Conditions were ideal to monitor interaction of an incoming storm and this new shore ice — 30 knot winds, 3 m (10 ft) seas from the N/NE. Sampling based on moorings placed earlier in the trip in a perpendicular line from the coast at 3, 6, 9, and 12 miles from shore, encompassed myriad ocean conditions from thick pancake ice to open water.
At each station, SASSY (Sediment and Salinity System) was sent through water column a few times. Bottom sediment samples collected and surface ice samples collected.
24-hr/day data collection: Three CODA watch teams, 8-hr shifts per team. SWIFT buoys were deployed and drifted toward coast with the onshore wind. Once their satellite antennas were fully iced (preventing signals to ship), they were recovered, de-iced, and redeployed. Significant amount of data successfully collected.
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SWIFT buoy struggles through thick pancake ice (Photo: John Guillote)
Taking SASSY measurements in pancake ice (Photo: John Guillote)
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November 23–24: Steady snow and windy conditions for the past 3 days.
At S1 (Icy Cape), data was gathered during and after a wind event. All three moorings and the 'sea spider' were retrieved and redeployed. This will augment the data and samples gathered from over 100 stations in the same area.
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Jim Thomson carries a SWIFT buoy toward deployment (Photo: John Guillote)
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November 20, Weather Changes Expected: Weather has been mild over the western arctic this week — winds less than 15 knots and very little wave activity. But, today a significant low pressure system is developing to the south.
Tonight, the R/V Sikuliaq will leave the protection of sea ice and head toward Icy Cape (site 1), to a more coastal area as the storm rolls by. The intended vantage point is near the site of the initial mooring deployment. The science team will observe the storm event three ways: through direct observation, castings off the ship (with the CTD, LISST, and SASSY)*, and anchored moorings.
The storm should peak tomorrow, November 21st, bringing 3–4 m (9–12 ft) waves.
* (respectively: Conductivity–Temperature–Depth, Laser In-Situ Scattering and Transmissiometry, Sediment and Salinity System)
5:35 PM Update: Ship is motoring southwest, about 70 miles west of Barrow, in open water. The wind is still light with a gentle swell.
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(Photo: John Guillote)
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November 11–17, North of Prudhoe Bay in the Beaufort Sea: The science team successfully deployed three additional pressure logger moorings — to measure and record pressure and temperature at varying depths form the sea floor — at a new site located west of the six moorings deployed at two other sites last August. Each site has three moorings, placed 3 miles apart.
The ship transited east to the middle site to retrieve August moorings. All three moorings were successfully retrieved, although the third one did not respond to the acoustic release 'ping' and was manually trawled and caught.
The ship then moved to the last site on an overnight transit eastward encountering thicker than anticipated ice. Progress was slowed to half the expected speed (from 6 knots to 3 knots) and arrived at the first mooring location much later than scheduled. Sikuliaq's thrusters were used to break away ice in order to see the buoy if it surfaced. Retrieval was a lengthy process, requiring much ship maneuvering and crew muscle to clear the ice around the small buoy. Mooring was retrieved. At the second mooring sea conditions were much better, but the acoustic call to release its buoy went 'unconfirmed.' Ship was repositioned for another attempt — still no release. Due to limited daylight, the decision was made to continue retrieval attempt of second mooring and abort retrieval attempt of the third and final mooring at this site. Despite continued efforts, second mooring was not recovered.
Night observations from the deck (Photo: John Guillote)
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Alex de Klerk spots a buoy (Photo: John Guillote)
Moorings ready for deployment (Photo: John Guillote)
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November 10: After two days' transit time from Nome, the science team deployed the first set of moorings near Icy Cape in the Chukchi Sea. The first mooring, a sea floor tripod, was deployed using the ship's A-frame in 30 m of water 12 nautical miles from shore. The next three moorings were placed along a line at 9, 6, and 3 nautical miles from shore. These are simple anchors with pressure loggers and sub-surface thermistor chains that could be deployed by hand.
These four moorings, along with eight more to be deployed in the coming weeks, will record wave properties, water turbulence, temperature, and current data autonomously. They will rest on the seafloor through the fall freeze up, under the winter ice, and through the summer melt, before being retrieved next September.
While on these sites, the team also collected sediment, water samples, and CTD data. All of the deployments went well, aided by settled weather conditions and strong coordination with the ship's crew.
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(Photo: John Guillote)
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November 7: The fully loaded R/V Sikuliaq departed Nome, motoring north at about 10 knots in winds of 35 knots.
November 5: 'SIKULIAQ HEADS NORTH: STORMS, ICE, AND THE FOOD CHAIN' — a joint community presentation by three of the lead scientists for the Strait Science Series, hosted at Nome’s University of Alaska Northwestern campus. Dr. Jim Thomson talked about his focus on understanding wave mechanics and how storm waves affect ice formation and durability along the shore. Dr. Hauke Flores discussed the algae under the ice and the society of creatures it supports. And Dr. Franz Mueter talked about the small but critical Arctic cod populations that depend on that layer of algae.
Early November: R/V Sikuliaq cruised northwest from Newport, Oregon across the Gulf Alaska, then north through the Bering Sea to Nome, Alaska.
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Jim Thomson presents to the Nome community (Photo: John Guillote)
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August 2019
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Early August: The research team worked for several days out of Prudhoe Bay in the R/V Ukpik to deploy seafloor instruments to measure waves and temperatures throughout the open-water summer and into the autumn ice advance. The goal is to observe coastal conditions with and without ice, to understand how the ice protects the coasts from waves.
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(Photo: Lucia Hosekova)
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Arctic Talk & Tour Aboard the Icebreaker Sikuliaq
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Oceanographer Jim Thomson shared his research on Coastal Ocean Dynamics in the Arctic (CODA) during a public open house aboard the R/V Sikuliaq, in Seattle, WA on 16 January 2020. Approximately 50 visitors attended a 2-hr event featuring Jim's discussion about the seasonal cycle of arctic ice and the effect of ocean waves on sea ice and coastal communities along Alaska's north shore, followed by tours of the vessel led by Sikuliaq crew members.
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Sikuliaq Heads North: Storms, Ice, and the Food Chain
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A joint community presentation by three of the lead scientists for the Strait Science Series, hosted at Nome’s University of Alaska Northwestern campus, 5 November 2019. Dr. Jim Thomson talked about his focus on understanding wave mechanics and how storm waves affect ice formation and durability along the shore. Dr. Hauke Flores discussed the algae under the ice and the society of creatures it supports. And Dr. Franz Mueter talked about the small but critical Arctic cod populations that depend on that layer of algae.
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Jim Thomson presents to the Nome community (Photo: John Guillote)
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Research Proposal
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Project Summary and Description (PDF, 43 KB)
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Publications + Data Reports
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Morphology and sediment dynamics of blossom shoals at Icy Cape, Alaska Eidam, E.F., J. Thomson, J.G. Malito, and L. Hošeková, "Morphology and sediment dynamics of blossom shoals at Icy Cape, Alaska," J. Geophys. Res., 129, doi:10.1029/2023JF007398, 2024. |
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More Info
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1 Apr 2024
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Capes and cape-associated shoals represent sites of convergent sediment transport, and can provide points of relative coastal stability, navigation hazards, and offshore sand resources. Shoal evolution is commonly impacted by the regional wave climate. In the Arctic, changing sea-ice conditions are leading to (a) longer open-water seasons when waves can contribute to sediment transport, and (b) an intensified wave climate (related to duration of open water and expanding fetch). At Blossom Shoals offshore of Icy Cape in the Chukchi Sea, these changes have led to a five-fold increase in the amount of time that sand is mobile at a 31-m water depth site between the period 19531989 and the period 19902022. Wave conditions conducive to sand transport are still limited to less than 2% of the year, however, and thus it is not surprising that the overall morphology of the shoals has changed little in 70 years, despite evidence of active sand transport in the form of 1-m-scale sand waves on the flanks of the shoals, which heal ice keel scours formed during the winter. Suspended-sediment transport is relatively weak due to limited sources of mud nearby, but can be observed in a net northeastward direction during the winter (driven by the Alaska Coastal Current under the ice) and in a southwestward direction during open-water wind events. Longer open-water seasons mean that annual net northeastward transport of fine sediment may weaken, with implications for the residence time of fine-grained sediments and particle-associated nutrients in the Chukchi Sea.
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Wave Exposure on the Northern Coast of Alaska Using the SWAN Model with a Sea Ice Parameterization Hošeková, L., W.E. Rogers, and J. Thomson, "Wave Exposure on the Northern Coast of Alaska Using the SWAN Model with a Sea Ice Parameterization," Technical Report, APL-UW TR 2302, Applied Physics Laboratory, University of Washington, Seattle, May 2023, 24 pp. |
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More Info
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8 May 2023
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The presence of sea ice along Arctic coastlines controls the exposure of the coast to wave action. We present a case study from the summer of 2014 to demonstrate the recent addition of ice attenuation in the SWAN (Simulating WAves Nearshore) numerical wave model. Observations from several freely drifting SWIFT (Surface Wave Instrument Float with Tracking) buoys show reduced wave action resulting from remnant sea ice along the coast in early summer. This is well-described by the new model that includes sea ice attenuation, relative to a previous version of the wave model without a sea ice parameterization. The model is sensitive to the sea ice product used for model initialization because some sea ice products do not resolve coastal ice. The difference in the cumulative wave exposure at the coast shows that sea ice attenuation in early summer is a significant seasonal effect.
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Landfast ice and coastal wave exposure in northern Alaska Hošeková, L., E. Eidam, G. Panteleev, L. Rainville, W.E. Rogers, and J. Thomson, "Landfast ice and coastal wave exposure in northern Alaska," Geophys. Res. Lett., 48, doi:10.1029/2021GL095103, 2021. |
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More Info
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28 Nov 2021
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Observations of ocean surface waves at three sites along the northern coast of Alaska show a strong coupling with seasonal sea ice patterns. In the winter, ice cover is complete, and waves are absent. In the spring and early summer, sea ice retreats regionally, but landfast ice persists near the coast. The landfast ice completely attenuates waves formed farther offshore in the open water, causing up to two-month delay in the onset of waves nearshore. In autumn, landfast ice begins to reform, though the wave attenuation is only partial due to lower ice thickness compared to spring. The annual cycle in the observations is reproduced by the ERA5 reanalysis product, but the product does not resolve landfast ice. The resulting ERA5 bias in coastal wave exposure can be corrected by applying a higher resolution ice mask, and this has a significant effect on the long-term trends inferred from ERA5.
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Spurious rollover of wave attenuation rates in sea ice caused by noise in field measurements Thomson, J., Hošeková, L., M.H. Meylan, A.L. Kohout, and N. Kumar, "Spurious rollover of wave attenuation rates in sea ice caused by noise in field measurements," J. Geophys. Res., 126, doi:10.1029/2020JC016606, 2021. |
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More Info
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1 Mar 2021
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The effects of instrument noise on estimating the spectral attenuation rates of ocean waves in sea ice are explored using synthetic observations in which the true attenuation rates are known explicitly. The spectral shape of the energy added by noise, relative to the spectral shape of the true wave energy, is the critical aspect of the investigation. A negative bias in attenuation that grows in frequency is found across a range of realistic parameters. This negative bias decreases the observed attenuation rates at high frequencies, such that it can explain the rollover effect commonly reported in field studies of wave attenuation in sea ice. The published results from five field experiments are evaluated in terms of the noise bias, and a spurious rollover (or flattening) of attenuation is found in all cases. Remarkably, the wave heights are unaffected by the noise bias, because the noise bias occurs at frequencies that contain only a small fraction of the total energy.
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Attenuation of ocean surface waves in pancake and frazil sea ice along the coast of the Chukchi Sea Hošeková, L., M.P. Malila, W.E. Rogers, L.A. Roach, E. Eidam, L. Rainville, N. Kumar, and J. Thomson, "Attenuation of ocean surface waves in pancake and frazil sea ice along the coast of the Chukchi Sea," J. Geophys. Res., 125, doi:10.1029/2020JC016746, 2020.
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More Info
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1 Dec 2020
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Alaskan Arctic coastlines are protected seasonally from ocean waves by the presence of coastal and shorefast sea ice. This study presents field observations collected during the autumn 2019 freeze up near Icy Cape, a coastal headland in the Chukchi Sea of the Western Arctic. The evolution of the coupled air‐ice‐ocean‐wave system during a four‐day wave event was monitored using drifting wave buoys, a cross‐shore mooring array, and ship‐based measurements. The incident wave field with peak period of 2.5 s was attenuated by coastal pancake and frazil sea ice, reducing significant wave height by 40% over less than 5 km of cross‐shelf distance spanning water depths from 13 to 30 m. Spectral attenuation coefficients are evaluated with respect to wave and ice conditions and the proximity to the ice edge. Attenuation rates are found to be three times higher within 500 m of the ice edge, relative to values farther in the ice cover. Attenuation coefficients are in the range of <2.3,2.7> m-1, and follow a power‐law dependence on frequency.
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CODA Moorings Data Report, July 2021
by J. Thomson, E. Eidam, and L. Hosekova (includes single Matlab file with all moorings as separate data structures) |
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CODA Cruise Report, R/V Sikuliaq, SeptemberOctober 2020 (PDF, 9 MB)
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CODA/GO-WEST Cruise Report, R/V Sikuliaq, November 2019 (PDF, 9 MB)
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Implementation of Sea Ice in the Wave Model SWAN
W. Erick Rogers, "Implementation of Sea Ice in the Wave Model SWAN" NRL/MR/7322--19-9874, Naval Research Laboratory, Washington, D.C., April 2019, 30 pp. |
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In the Media
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Using advanced acoustic technology to understand wave conditions and climate change in the Arctic Environment Coastal & Offshore, Torbjørn Goa Thomson’s research in the Arctic has paired Nortek Signature500 acoustic Doppler current profilers (ADCPs) mounted on fixed moorings with drifters equipped with Signature1000 ADCPs to get a complete picture of the Arctic’s changing wave conditions. |
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29 Mar 2021
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TECH FILE: Acoustic tech used to understand climate change in the Arctic Marine Technology News Major changes are occurring in the ocean. Climate change and subsequent melting sea ice are not necessarily good changes. Why are acoustic Doppler current profilers an invaluable tool to get a complete picture of the Arctic’s changing wave conditions in the context of climate change? |
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27 Mar 2021
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Advanced acoustic technology to understand wave conditions and climate change in the Arctic Hydro International Acoustic Doppler current profilers are an invaluable tool to get a complete picture of the Arctic's changing wave conditions in the context of climate change. |
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26 Mar 2021
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Understanding wave conditions and climate change in the Arctic with acoustic technology Ocean News & Technology Moorings equipped with upward-facing Signature500 ADCPs provide a long time series of data. The instruments, which collect data on the waves, currents and sea ice when it is present, are duty-cycled to record data every hour. |
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25 Mar 2021
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