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  • 1
    Keywords: lithosphere ; tectonics ; circum-Arctic tectonics ; Arctic Ocean
    Description / Table of Contents: Circum-Arctic lithosphere evolution / V. Pease and B. Coakley / Geological Society, London, Special Publications, 460, 1-6, 31 August 2017, https://doi.org/10.1144/SP460.19 --- Greenland–Canada --- Integrated crustal–geological cross-section of Ellesmere Island / R. Stephenson, K. Piepjohn, C. Schiffer, W. Von Gosen, G. N. Oakey and G. Anudu / Geological Society, London, Special Publications, 460, 7-17, 23 May 2017, https://doi.org/10.1144/SP460.12 --- Regional crustal architecture of Ellesmere Island, Arctic Canada / Christian Schiffer and Randell Stephenson / Geological Society, London, Special Publications, 460, 19-32, 12 June 2017, https://doi.org/10.1144/SP460.8 --- Structural transect through Ellesmere Island (Canadian Arctic): superimposed Palaeozoic Ellesmerian and Cenozoic Eurekan deformation / Karsten Piepjohn and Werner von Gosen / Geological Society, London, Special Publications, 460, 33-56, 24 May 2017, https://doi.org/10.1144/SP460.5 --- Alaska and Chukotka --- Circum-Arctic Lithosphere Evolution (CALE) Transect C: displacement of the Arctic Alaska–Chukotka microplate towards the Pacific during opening of the Amerasia Basin of the Arctic / Elizabeth L. Miller, Kristian E. Meisling, Vyacheslav V. Akinin, Kelley Brumley, Bernard J. Coakley, Eric S. Gottlieb, Carl W. Hoiland, Timothy M. O'Brien, Anna Soboleva and Jaime Toro / Geological Society, London, Special Publications, 460, 57-120, 21 July 2017, https://doi.org/10.1144/SP460.9 --- Detrital zircon U–Pb geochronology and Hf isotope geochemistry of metasedimentary strata in the southern Brooks Range: constraints on Neoproterozoic–Cretaceous evolution of Arctic Alaska / Carl W. Hoiland, Elizabeth L. Miller, Victoria Pease and Jeremy K. Hourigan / Geological Society, London, Special Publications, 460, 121-158, 22 June 2017, https://doi.org/10.1144/SP460.16 --- U–Pb zircon geochronology of Cretaceous arc magmatism in eastern Chukotka, NE Russia, with implications for Pacific plate subduction and the opening of the Amerasia Basin / Victoria Pease, Elizabeth Miller, Sandra J. Wyld, Sergey Sokolov, Viacheslav Akinin and James E. Wright / Geological Society, London, Special Publications, 460, 159-182, 21 June 2017, https://doi.org/10.1144/SP460.14 --- Neoproterozoic basement history of Wrangel Island and Arctic Chukotka: integrated insights from zircon U–Pb, O and Hf isotopic studies / Eric S. Gottlieb, Victoria Pease, Elizabeth L. Miller and Vyacheslav V. Akinin / Geological Society, London, Special Publications, 460, 183-206, 3 May 2017, https://doi.org/10.1144/SP460.11 --- Deformational history and thermochronology of Wrangel Island, East Siberian Shelf and coastal Chukotka, Arctic Russia / Elizabeth L. Miller, V. V. Akinin, T. A. Dumitru, E. S. Gottlieb, M. Grove, K. Meisling and G. Seward / Geological Society, London, Special Publications, 460, 207-238, 3 May 2017, https://doi.org/10.1144/SP460.7 --- Laptev Sea region --- Mesozoic structural evolution of the New Siberian Islands / Karsten Piepjohn, Henning Lorenz, Dieter Franke, Christian Brandes, Werner von Gosen, Christoph Gaedicke, Loic Labrousse, Nikolay N. Sobolev, Piotr Solobev, Guillaume Suan, Sabine Mrugalla, Franco Talarico and Tatiana Tolmacheva / Geological Society, London, Special Publications, 460, 239-262, 11 August 2017, https://doi.org/10.1144/SP460.1 --- Tectonics of the Laptev Shelf, Siberian Arctic / Sergey S. Drachev and Sergey I. Shkarubo / Geological Society, London, Special Publications, 460, 263-283, 13 June 2017, https://doi.org/10.1144/SP460.15 --- Barents/Kara shelf region --- Tectonic implications of the lithospheric structure across the Barents and Kara shelves / Jan Inge Faleide, Victoria Pease, Mike Curtis, Peter Klitzke, Alexander Minakov, Magdalena Scheck-Wenderoth, Sergei Kostyuchenko and Andrei Zayonchek / Geological Society, London, Special Publications, 460, 285-314, 23 August 2017, https://doi.org/10.1144/SP460.18 --- Timing of exhumation and deformation across the Taimyr fold–thrust belt: insights from apatite fission track dating and balanced cross-sections / Xiaojing Zhang, Victoria Pease, Andrew Carter, Sergey Kostuychenko, Arsen Suleymanov and Robert Scott / Geological Society, London, Special Publications, 460, 315-333, 15 June 2017, https://doi.org/10.1144/SP460.3 --- Reconstructing Palaeozoic and Mesozoic tectonic evolution of Novaya Zemlya: combing geochronology and thermochronology / Xiaojing Zhang, Victoria Pease, Andrew Carter and Robert Scott / Geological Society, London, Special Publications, 460, 335-353, 26 May 2017, https://doi.org/10.1144/SP460.13 --- Early Mesozoic sinistral transpression along the Pai-Khoi–Novaya Zemlya fold–thrust belt, Russia / Michael L. Curtis, Berta Lopez-Mir, Robert A. Scott and James P. Howard / Geological Society, London, Special Publications, 460, 355-370, 14 August 2017, https://doi.org/10.1144/SP460.2 --- Dyke emplacement and crustal structure within a continental large igneous province, northern Barents Sea / Alexander Minakov, Viktoriya Yarushina, Jan Inge Faleide, Nataliya Krupnova, Tamara Sakoulina, Nikolay Dergunov and Vladimir Glebovsky / Geological Society, London, Special Publications, 460, 371-395, 24 May 2017, https://doi.org/10.1144/SP460.4 --- Samples from the Lomonosov Ridge place new constraints on the geological evolution of the Arctic Ocean / C. Knudsen, J. R. Hopper, P. R. Bierman, M. Bjerager, T. Funck, P. F. Green, J. R. Ineson, P. Japsen, C. Marcussen, S. C. Sherlock and T. B. Thomsen / Geological Society, London, Special Publications, 460, 397-418, 18 August 2017, https://doi.org/10.1144/SP460.17 --- Circum-Arctic themes --- Seismic tomography of the Arctic region: inferences for the thermal structure and evolution of the lithosphere / Sergei Lebedev, Andrew J. Schaeffer, Javier Fullea and Victoria Pease / Geological Society, London, Special Publications, 460, 419-440, 6 July 2017, https://doi.org/10.1144/SP460.10 --- High Arctic geopotential stress field and implications for geodynamic evolution / Christian Schiffer, Christian Tegner, Andrew J. Schaeffer, Victoria Pease and Søren B. Nielsen / Geological Society, London, Special Publications, 460, 441-465, 13 April 2017, https://doi.org/10.1144/SP460.6
    Pages: Online-Ressource (VIII, 475 Seiten) , Diagramme, Karten
    ISBN: 9781786203236
    Language: English
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  • 2
    Unknown
    Anchorage, AK : Audubon Alaska
    Keywords: Arctic Ocean ; Alaska ; ecology
    Description / Table of Contents: Introduction 2 --- Physical Setting 6 --- Topography 8 --- Geologic Setting: Glaciers & Karst 11 --- Air Temperature 14 --- Precipitation 18 --- Snow 22 --- Watersheds & Value Comparison Units (VCUs) 27 --- Biological Setting 32 --- Biogeographic Provinces 34 --- Wetlands 39 --- Estuaries 41 --- Land Cover & Forest Vegetation 44 --- Old-growth & Second-growth Forest 51 --- Core Areas of High Biological Value 57 --- Index of Cumulative Ecological Risk 60 --- Anadromous Fish 66 --- Anadromous Fish Habitat 68 --- King (Chinook) Salmon 73 --- Red (Sockeye) Salmon 76 --- Silver (Coho) Salmon 79 --- Pink (Humpy) Salmon 82 --- Chum (Dog) Salmon 85 --- Steelhead Trout 88 --- Dolly Varden 91 --- Coastal Cutthroat Trout 95 --- Eulachon 99 --- Birds 108 --- Bird Species Richness 110 --- Important Bird Areas (IBAs) 114 --- Marine Bird Colonies 117 --- Marbled Murrelet 120 --- Kittlitz’s Murrelet 123 --- Shorebirds 126 --- Prince of Wales Spruce Grouse 129 --- Queen Charlotte Goshawk 132 --- Bald Eagle 135 --- Mammals 142 --- Mammal Species Richness 144 --- Northern Flying Squirrel 147 --- Sitka Black-tailed Deer 150 --- Alexander Archipelago Wolf 155 --- Brown Bear 160 --- Black Bear 164 --- Human Uses 174 --- Land Ownership 176 --- Transportation and Energy Infrastructure 180 --- Community Subsistence Use 187 --- Timber 191 --- Metals Mining 195 --- Sport and Commercial Fishing 201 --- Land Use Designations 206 --- Conservation Area Design for Southeast Alaska 211 --- Tongass 77 Watersheds 214 --- Conservation Summary 222
    Pages: Online-Ressource (223 Seiten) , Illustrationen, Diagramme, Karten
    Language: English
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  • 3
    Unknown
    Anchorage, AK : Audubon Alaska
    Keywords: Arctic Ocean ; Alaska ; ecology
    Description / Table of Contents: In July 2016, Audubon Alaska completed a long-term effort to integrate the best available science into a series of maps highlighting key resources within Alaska's Western Arctic. The resulting publication, the Ecological Atlas of Alaska's Western Arctic, helps the reader explore the land­scape and better understand the overlap of wildlife, people, and development to inform conservation and management.
    Pages: Online-Ressource (71 Seiten) , Illustrationen, Diagramme, Karten
    Edition: 3rd edition
    Language: English
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  • 4
    Keywords: Arctic Ocean ; Alaska ; ecology
    Description / Table of Contents: Chapter 1: Introduction 2 --- 1.1 Introduction 2 --- 1.2 A Closer Look: Kawerak’s Contribution of Traditional Knowledge 7 --- Map 1.1 Regional Overview 12 --- Chapter 2: Physical Setting 14 --- 2.1 Ocean Currents 16 --- Map 2.1 Ocean Currents 20 --- 2.2 Sea Ice 22 --- Map 2.2a Sea Ice Advance 26 --- Map 2.2b Sea Ice Retreat 28 --- 2.3 Climate 30 --- Maps 2.3a–p Climate 36 --- 2.4 A Closer Look: Bering Sea Weather 38 --- Chapter 3: Biological Setting 42 --- 3.1 Primary Productivity 44 --- Map 3.1 Primary Productivity 46 --- 3.2 Zooplankton 48 --- Map 3.2 Zooplankton 50 --- 3.3 Benthic Biomass 52 --- Map 3.3 Benthic Biomass 56 --- 3.4 Snow and Tanner Crabs 58 --- Map 3.4 Snow Crab 62 --- 3.5 Red King Crab 64 --- Map 3.5 Red King Crab 67 --- Chapter 4: Fishes 72 --- 4.1 Forage Fish Assemblages 74 --- Map 4.1.1 Osmerids 78 --- Map 4.1.2 Pacific Herring 80 --- 4.2 Walleye Pollock 82 --- Map 4.2 Walleye Pollock 84 --- 4.3 North Pacific Cods 85 --- Map 4.3 North Pacific Cods 88 --- 4.4 Atka Mackerel 90 --- Map 4.4 Atka Mackerel 92 --- 4.5 Yellowfin Sole 94 --- Map 4.5 Yellowfin Sole 96 --- 4.6 Pacific Halibut 98 --- Map 4.6 Pacific Halibut 100 --- 4.7 Pacific Salmon 101 --- Map 4.7 Pacific Salmon 104 --- Chapter 5: Birds 110 --- 5.1 Marine Bird Colonies 112 --- Map 5.1.1 Marine Bird Colonies 116 --- Maps 5.1.2a–d Foraging Guilds 118 --- 5.2 Important Bird Areas 120 --- Map 5.2 Important Bird Areas 122 --- 5.3 A Closer Look: Bird Density and Survey Effort 124 --- Map 5.3.1 Annual Bird Density 124 --- Map 5.3.2 Bird Survey Effort 124 --- Maps 5.3.3a–d Seasonal Bird Density 125 --- Marine Waterbirds --- 5.4 Eiders 126 --- Map 5.4.1 King Eider 132 --- Map 5.4.2 Spectacled Eider 134 --- Map 5.4.3 Steller’s Eider 136 --- Map 5.4.4 Common Eider 138 --- 5.5 Long-tailed Duck 140 --- Map 5.5 Long-tailed Duck 144 --- 5.6 Loons 146 --- Map 5.6.1 Yellow-billed Loon 150 --- Map 5.6.2 Red-throated Loon 152 --- 5.7 Red-faced Cormorant 154 --- Map 5.7 Red-faced Cormorant 156 --- 5.8 Phalaropes 157 --- Map 5.8.1 Red-necked Phalarope 160 --- Map 5.8.2 Red Phalarope 160 --- 5.9 Aleutian Tern 161 --- Map 5.9 Aleutian Tern 163 --- 5.10 Kittiwakes 164 --- Map 5.10.1 Red-legged Kittwake 167 --- Map 5.10.2 Black-legged Kittwake 167 --- 5.11 Ivory Gull 168 --- Map 5.11 Ivory Gull 170 --- Seabirds --- 5.12 Murres 171 --- Map 5.12.1 Common Murre 174 --- Map 5.12.2 Thick-billed Murre 174 --- Map 5.12.3 Total Murres 175 --- 5.13 Puffins 176 --- Map 5.13.1 Horned Puffin 179 --- Map 5.13.2 Tufted Puffin 179 --- 5.14 Auklets 180 --- Map 5.14.1 Parakeet Auklet 186 --- Map 5.14.2 Crested Auklet 186 --- Map 5.14.3 Whiskered Auklet 187 --- Map 5.14.4 Least Auklet 187 --- 5.15 Short-tailed Albatross 188 --- Map 5.15 Short-tailed Albatross 190 --- 5.16 Shearwaters 191 --- Map 5.16 Short-tailed / Sooty Shearwater 194 --- Chapter 6: Mammals 204 --- 6.1 Polar Bear 206 --- Maps 6.1a–d Polar Bear Seasonal Distribution 212 --- Pinnipeds --- 6.2 Pacific Walrus 214 --- Map 6.2a Pacific Walrus Summer / Fall 220 --- Map 6.2b Pacific Walrus Winter / Spring 222 --- 6.3 Ice Seals 224 --- Map 6.3.1 Bearded Seal 230 --- Map 6.3.2 Ribbon Seal 230 --- Map 6.3.3 Ringed Seal 231 --- Map 6.3.4 Spotted Seal 231 --- 6.4 Steller Sea Lion 232 --- Map 6.4 Steller Sea Lion 234 --- 6.5 Northern Fur Seal 236 --- Map 6.5 Northern Fur Seal 238 --- Cetaceans --- 6.6 Beluga Whale 240 --- Map 6.6.1 Beluga Whale Stocks 243 --- Map 6.6.2 Beluga Whale 244 --- 6.7 Bowhead Whale 246 --- Maps 6.7a–d Bowhead Whale Seasonal Distribution 250 --- 6.8 Gray Whale 252 --- Map 6.8 Gray Whale 254 --- 6.9 Humpback Whale 255 --- Map 6.9 Humpback Whale 257 --- Chapter 7: Human Uses 266 --- 7.1 A Closer Look: Historical Perspective 268 --- 7.2 Transportation and Energy Infrastructure 270 --- Map 7.2 Transportation and Energy Infrastructure 274 --- 7.3 Petroleum Exploration and Development 276 --- Map 7.3 Petroleum Exploration and Development 282 --- 7.4 A Closer Look: Artificial Islands 284 --- 7.5 Vessel Traffic 285 --- Map 7.5.1 Vessel Density 288 --- Map 7.5.2 Vessel Traffic Patterns 290 --- Maps 7.5.3a–m Vessel Traffic by Month 292 --- 7.6 A Closer Look: Unimak Pass and Bering Strait Vessel Traffic 294 --- 7.7 Fisheries Management Conservation Areas 296 --- Map 7.7 Fisheries Management Conservation Areas 298 --- 7.8 Subsistence 300 --- Maps 7.8.1a–g Subsistence Harvest Areas by Species 306 --- Map 7.8.2 Reported Subsistence Harvest 310 --- 7.9 A Closer Look: The Legal Framework for US Arctic Marine Resource Protection 312 --- 7.10 Conservation Areas 314 --- Map 7.10 Conservation Areas 318 --- Chapter 8: Conservation Summary 326
    Pages: Online-Ressource (332 Seiten) , Illustrationen, Diagramme, Karten
    Edition: 2nd edition
    Language: English
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  • 5
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2015. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 120 (2015): 3542-3566, doi:10.1002/2014JC010620.
    Description: We present the results of a 6 week time series of carbonate system and stable isotope measurements investigating the effects of sea ice on air-sea CO2 exchange during the early melt period in the Canadian Arctic Archipelago. Our observations revealed significant changes in sea ice and sackhole brine carbonate system parameters that were associated with increasing temperatures and the buildup of chlorophyll a in bottom ice. The warming sea-ice column could be separated into distinct geochemical zones where biotic and abiotic processes exerted different influences on inorganic carbon and pCO2 distributions. In the bottom ice, biological carbon uptake maintained undersaturated pCO2 conditions throughout the time series, while pCO2 was supersaturated in the upper ice. Low CO2 permeability of the sea ice matrix and snow cover effectively impeded CO2 efflux to the atmosphere, despite a strong pCO2 gradient. Throughout the middle of the ice column, brine pCO2 decreased significantly with time and was tightly controlled by solubility, as sea ice temperature and in situ melt dilution increased. Once the influence of melt dilution was accounted for, both CaCO3 dissolution and seawater mixing were found to contribute alkalinity and dissolved inorganic carbon to brines, with the CaCO3 contribution driving brine pCO2 to values lower than predicted from melt-water dilution alone. This field study reveals a dynamic carbon system within the rapidly warming sea ice, prior to snow melt. We suggest that the early spring period drives the ice column toward pCO2 undersaturation, contributing to a weak atmospheric CO2 sink as the melt period advances.
    Description: We acknowledge support from the Polar Continental Shelf Program (PCSP) of Natural Resources Canada, the Natural Sciences and Engineering Research Council of Canada, the Northern Scientific Training Program, Canada Economic Development, and Fisheries and Oceans Canada.
    Description: 2015-11-19
    Keywords: Sea ice ; Carbon cycling ; CO2 ; Brines ; Stable isotopes ; Arctic Ocean
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/pdf
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  • 6
    Publication Date: 2022-05-25
    Description: © The Author(s), 2015. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Deep Sea Research Part II: Topical Studies in Oceanography 118 (2015): 122-135, doi:10.1016/j.dsr2.2015.02.008.
    Description: A coupled biophysical model is used to examine the impact of changes in sea ice and snow cover and nutrient availability on the formation of massive under-ice phytoplankton blooms (MUPBs) in the Chukchi Sea of the Arctic Ocean over the period 1988–2013. The model is able to reproduce the basic features of the ICESCAPE (Impacts of Climate on EcoSystems and Chemistry of the Arctic Pacific Environment) observed MUPB during July 2011. The simulated MUPBs occur every year during 1988–2013, mainly in between mid-June and mid-July. While the simulated under-ice blooms of moderate magnitude are widespread in the Chukchi Sea, MUPBs are less so. On average, the area fraction of MUPBs in the ice-covered areas of the Chukchi Sea during June and July is about 8%, which has been increasing at a rate of 2% yr–1 over 1988–2013. The simulated increase in the area fraction as well as primary productivity and chlorophyll a biomass is linked to an increase in light availability, in response to a decrease in sea ice and snow cover, and an increase in nutrient availability in the upper 100 m of the ocean, in conjunction with an intensification of ocean circulation. Simulated MUPBs are temporally sporadic and spatially patchy because of strong spatiotemporal variations of light and nutrient availability. However, as observed during ICESCAPE, there is a high likelihood that MUPBs may form at the shelf break, where the model simulates enhanced nutrient concentration that is seldom depleted between mid-June and mid-July because of generally robust shelf-break upwelling and other dynamic ocean processes. The occurrence of MUPBs at the shelf break is more frequent in the past decade than in the earlier period because of elevated light availability there. It may be even more frequent in the future if the sea ice and snow cover continues to decline such that light is more available at the shelf break to further boost the formation of MUPBs there.
    Description: This work is supported by the NASA Cryosphere Program and Climate and Biological Response Program and the NSF Office of Polar Programs (Grant Nos. NNX12AB31G; NNX11AO91G; ARC-0901987).
    Keywords: Arctic Ocean ; Chukchi Sea ; Phytoplankton ; Blooms ; Sea ice ; Snow depth ; Light availability ; Nutrient availability
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 7
    Publication Date: 2022-05-25
    Description: © The Author(s), 2017. This is the author's version of the work. It is posted here under a nonexclusive, irrevocable, paid-up, worldwide license granted to WHOI. It is made available for personal use, not for redistribution. The definitive version was published in Progress in Oceanography 153 (2017): 50-65, doi:10.1016/j.pocean.2017.04.005.
    Description: Using a collection of 46 shipboard hydrographic/velocity transects occupied across the shelfbreak and slope of the Chukchi Sea between 2002 and 2014, we have quantified the existence of a current transporting Pacific-origin water westward over the upper continental slope. It has been named the Chukchi slope current, which is believed to emanate from Barrow Canyon. The current is surface-intensified, order 50 km wide, and advects both summer and winter waters. It is not trapped to a particular isobath, but instead is reminiscent of a free jet. There is no significant variation in Pacific water transport with distance from Barrow Canyon. A potential vorticity analysis suggests that the flow is baroclinically unstable, consistent with the notion that it meanders. The current is present during all synoptic wind conditions, but increases in strength from summer to fall presumably due to the seasonal enhancement of the easterly winds in the region. Its transport increased over the 12-year period of data coverage, also likely in response to wind forcing. In the mean, the slope current transports 0.50±0.070.50±0.07 Sv of Pacific water. This estimate allows us to construct a balanced mass budget of the Chukchi shelf inflows and outflows. Our study also confirms the existence of an eastward-flowing Chukchi shelfbreak jet transporting 0.10±0.030.10±0.03 Sv of Pacific water towards Barrow Canyon.
    Description: This work was funded under contract M12AC00008 from the Bureau of Ocean and Energy Management.
    Keywords: Arctic Ocean ; Chukchi Sea ; Shelfbreak ; Mass budget
    Repository Name: Woods Hole Open Access Server
    Type: Preprint
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  • 8
    Publication Date: 2022-05-25
    Description: Author Posting. © The Author(s), 2017. This is the author's version of the work. It is posted here under a nonexclusive, irrevocable, paid-up, worldwide license granted to WHOI. It is made available for personal use, not for redistribution. The definitive version was published in Global Change Biology 24 (2018): e159-e170, doi:10.1111/gcb.13890.
    Description: Dramatic changes have occurred in the Arctic Ocean over the past few decades, especially in terms of sea ice loss and ocean warming. Those environmental changes may modify the planktonic ecosystem with changes from lower to upper trophic levels. This study aimed to understand how the biogeographic distribution of a crucial endemic copepod species, Calanus glacialis, may respond to both abiotic (ocean temperature) and biotic (phytoplankton prey) drivers. A copepod individual-based model coupled to an ice-ocean-biogeochemical model was utilized to simulate temperature- and food-dependent life cycle development of C. glacialis annually from 1980 to 2014. Over the 35-year study period, the northern boundaries of modeled diapausing C. glacialis expanded poleward and the annual success rates of C. glacialis individuals attaining diapause in a circumpolar transition zone increased substantially. Those patterns could be explained by a lengthening growth season (during which time food is ample) and shortening critical development time (the period from the first feeding stage N3 to the diapausing stage C4). The biogeographic changes were further linked to large scale oceanic processes, particularly diminishing sea ice cover, upper ocean warming, and increasing and prolonging food availability, which could have potential consequences to the entire Arctic shelf/slope marine ecosystems.
    Description: This study was funded by National Science Foundation Arctic System Science (ARCSS) Program (PLR-1417677, PLR-1417339, and PLR-1416920).
    Keywords: Arctic Ocean ; Marine ecosystem ; Climate change ; Copepod ; Biogeography ; Ocean warming ; Poleward range shift ; Individual-based model
    Repository Name: Woods Hole Open Access Server
    Type: Preprint
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  • 9
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2017. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 122 (2017): 1425–1438, doi:10.1002/2016JC012162.
    Description: Understanding the physical and biogeochemical processes that control CO2 and dissolved oxygen (DO) dynamics in the Arctic Ocean (AO) is crucial for predicting future air-sea CO2 fluxes and ocean acidification. Past studies have primarily been conducted on the AO continental shelves during low-ice periods and we lack information on gas dynamics in the deep AO basins where ice typically inhibits contact with the atmosphere. To study these gas dynamics, in situ time-series data have been collected in the Canada Basin during late summer to autumn of 2012. Partial pressure of CO2 (pCO2), DO concentration, temperature, salinity, and chlorophyll-a fluorescence (Chl-a) were measured in the upper ocean in a range of sea ice states by two drifting instrument systems. Although the two systems were on average only 222 km apart, they experienced considerably different ice cover and external forcings during the 40–50 day periods when data were collected. The pCO2 levels at both locations were well below atmospheric saturation whereas DO was almost always slightly supersaturated. Modeling results suggest that air-sea gas exchange, net community production (NCP), and horizontal gradients were the main sources of pCO2 and DO variability in the sparsely ice-covered AO. In areas more densely covered by sea ice, horizontal gradients were the dominant source of variability, with no significant NCP in the surface mixed layer. If the AO reaches equilibrium with atmospheric CO2 as ice cover continues to decrease, aragonite saturation will drop from a present mean of 1.00 ± 0.02 to 0.86 ± 0.01.
    Description: U.S. National Science Foundation Arctic Observing Network Grant Number: ARC-1107346 and ARC-0856479
    Description: 2017-08-25
    Keywords: Arctic Ocean ; CO2 ; O2 ; Biogeochemistry ; Dynamics ; Carbon cycle
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 10
    Publication Date: 2022-05-25
    Description: © The Author(s), 2018. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Journal of Geophysical Research: Oceans 123 (2018): 4853-4873, doi:10.1029/2018JC013888.
    Description: The first full transarctic section of 228Ra in surface waters measured during GEOTRACES cruises PS94 and HLY1502 (2015) shows a consistent distribution with maximum activities in the transpolar drift. Activities in the central Arctic have increased from 2007 through 2011 to 2015. The increased 228Ra input is attributed to stronger wave action on shelves resulting from a longer ice‐free season. A concomitant decrease in the 228Th/228Ra ratio likely results from more rapid transit of surface waters depleted in 228Th by scavenging over the shelf. The 228Ra activities observed in intermediate waters (〈1,500 m) in the Amundsen Basin are explained by ventilation with shelf water on a time scale of about 15–18 years, in good agreement with estimates based on SF6 and 129I/236U. The 228Th excess below the mixed layer up to 1,500 m depth can complement 234Th and 210Po as tracers of export production, after correction for the inherent excess resulting from the similarity of 228Ra and 228Th decay times. We show with a Th/Ra profile model that the 228Th/228Ra ratio below 1,500 m is inappropriate for this purpose because it is a delicate balance between horizontal supply of 228Ra and vertical flux of particulate 228Th. The accumulation of 226Ra in the deep Makarov Basin is not associated with an accumulation of Ba and can therefore be attributed to supply from decay of 230Th in the bottom sediment. We estimate a ventilation time of 480 years for the deep Makarov‐Canada Basin, in good agreement with previous estimates using other tracers.
    Description: U.S. National Science Foundation Grant Numbers: OCE‐1458305, OCE‐1458424; US NSF Grant Number: OCE‐1433922
    Keywords: Radium‐228 ; Thorium‐228 ; Arctic Ocean ; Transpolar drift ; GEOTRACES
    Repository Name: Woods Hole Open Access Server
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  • 11
    Publication Date: 2022-05-25
    Description: © The Author(s), 2018. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Journal of Geophysical Research: Oceans 123 (2018): 6373-6391, doi:10.1029/2018JC013814.
    Description: We quantify Atlantic Water heat loss north of Svalbard using year‐long hydrographic and current records from three moorings deployed across the Svalbard Branch of the Atlantic Water boundary current in 2012–2013. The boundary current loses annually on average 16 W m−2 during the eastward propagation along the upper continental slope. The largest vertical fluxes of 〉100 W m−2 occur episodically in autumn and early winter. Episodes of sea ice imported from the north in November 2012 and February 2013 coincided with large ocean‐to‐ice heat fluxes, which effectively melted the ice and sustained open water conditions in the middle of the Arctic winter. Between March and early July 2013, a persistent ice cover‐modulated air‐sea fluxes. Melting sea ice at the start of the winter initiates a cold, up to 100‐m‐deep halocline separating the ice cover from the warm Atlantic Water. Semidiurnal tides dominate the energy over the upper part of the slope. The vertical tidal structure depends on stratification and varies seasonally, with the potential to contribute to vertical fluxes with shear‐driven mixing. Further processes impacting the heat budget include lateral heat loss due to mesoscale eddies, and modest and negligible contributions of Ekman pumping and shelf break upwelling, respectively. The continental slope north of Svalbard is a key example regarding the role of ocean heat for the sea ice cover. Our study underlines the complexity of the ocean's heat budget that is sensitive to the balance between oceanic heat advection, vertical fluxes, air‐sea interaction, and the sea ice cover.
    Description: Arctic Ocean program at the FRAM-High North Research Centre for Climate and the environment; National Science Foundation (NSF) Grant Number: ARC-1264098; Polish-Norwegian Research Programme Grant Number: POL-NOR/202006/10/2013; Research Council of Norway Grant Number: 276730; Steven Grossman Family Foundation
    Keywords: Atlantic Water ; Arctic Ocean ; Heat flux ; Nansen Basin ; Boundary current ; A‐TWAIN
    Repository Name: Woods Hole Open Access Server
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  • 12
    Publication Date: 2022-05-25
    Description: © The Author(s), 2015. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Deep Sea Research Part I: Oceanographic Research Papers 102 (2015): 43-54, doi:10.1016/j.dsr.2015.04.004.
    Description: Over the past few decades, sea ice retreat during summer has been enhanced in the Pacific sector of the Arctic basin, likely due in part to increasing summertime heat flux of Pacific-origin water from the Bering Strait. Barrow Canyon, in the northeast Chukchi Sea, is a major conduit through which the Pacific-origin water enters the Arctic basin. This paper presents results from 6 repeat high-resolution shipboard hydrographic/velocity sections occupied across Barrow Canyon in summer 2010. The different Pacific water masses feeding the canyon – Alaskan coastal water (ACW), summer Bering Sea water (BSW), and Pacific winter water (PWW) – all displayed significant intra-seasonal variability. Net volume transports through the canyon were between 0.96 and 1.70 Sv poleward, consisting of 0.41–0.98 Sv of warm Pacific water (ACW and BSW) and 0.28–0.65 Sv of PWW. The poleward heat flux also varied strongly, ranging from 8.56 TW to 24.56 TW, mainly due to the change in temperature of the warm Pacific water. Using supplemental mooring data from the core of the warm water, along with wind data from the Pt. Barrow weather station, we derive and assess a proxy for estimating heat flux in the canyon for the summer time period, which is when most of the heat passes northward towards the basin. The average heat flux for 2010 was estimated to be 3.34 TW, which is as large as the previous record maximum in 2007. This amount of heat could melt 315,000 km2 of 1-meter thick ice, which likely contributed to significant summer sea ice retreat in the Pacific sector of the Arctic Ocean.
    Description: MI, TK, YF, KO and DS were supported by Green Network of Excellence Program (GRENE Program), Arctic Climate Change Research Project ‘Rapid Change of the Arctic Climate System and its Global Influences’ by Ministry of Education, Culture, Sports, Science and Technology Japan. RP was supported by grant ARC-1203906 from the US National Science Foundation. CA was supported by grant ARC-1023331 from the US National Science Foundation and by the Cooperative Institute for the North Atlantic Region (NOAA Cooperative AgreementNA09OAR4320129) with funds provided by the US National Oceanographic and Atmospheric Administration through an Interagency Agreement between the US Bureau of Ocean and Energy Management and the National Marine Mammal Laboratory. SV was supported by the Department of Fisheries and Oceans Canada. MI and TK were supported by the Japan Agency for Marine-Earth Science and Technology. MI, TK, YF and KO were supported by Grant no. 2014-23 from Joint Research Program of the Institute of Low Temperature Science, Hokkaido University. YF and KO were supported by grants-in-aid 20221001 for scientific research from the Ministry of Education, Culture, Sports, Science and Technology of Japan. JTM was supported by grant PLR-1041102 from the US National Science Foundation.
    Keywords: Polar oceanography ; Arctic Ocean ; Chukchi Sea ; Heat fluxes ; Volume transports ; Water properties
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  • 13
    Publication Date: 2022-05-25
    Description: © The Author(s), 2014. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Journal of Marine Systems 147 (2015): 29-44, doi:10.1016/j.jmarsys.2014.04.006.
    Description: The Arctic Ocean is changing rapidly as the global climate warms but it is not well known how these changes are affecting biological productivity and the carbon cycle. Here we study the Beaufort Gyre region of the Canada Basin in August and use the large reduction in summertime sea ice extent from 2011 to 2012 to investigate potential impacts of climate warming on biological productivity. We use the gas tracers O2/Ar and triple oxygen isotopes to quantify rates of net community production (NCP) and gross oxygen production (GOP) in the gyre. Comparison of the summer of 2011 with the summer of 2012, the latter of which had record low sea ice coverage, is relevant to how biological productivity might change in a seasonally ice-free Arctic Ocean. We find that, in the surface waters measured here, GOP in 2012 is significantly greater than in 2011, with the mean basin-wide 2012 GOP = 38 ± 3 mmol O2 m− 2 d− 1 whereas in 2011, mean basin GOP = 16 ± 5 mmol O2 m− 2 d− 1. We hypothesize that this is because the lack of sea ice and consequent increase in light penetration allows photosynthesis to increase in 2012. However, despite the increase in GOP, NCP is the same in the two years; mean NCP in 2012 is 3.0 ± 0.2 mmol O2 m− 2 y− 1 and in 2011 is 3.1 ± 0.2 mmol O2 m− 2 y− 1. This suggests that the heterotrophic community (zooplankton and/or bacteria) increased its activity as well and thus respired the additional carbon produced by the increased photosynthetic production. In both years, stations on the shelf had GOP 3 to 5 times and NCP 2 to 10 times larger than the basin stations. Additionally, we show that in 2011, the NCP/GOP ratio is smallest in regions with highest ice cover, suggesting that the microbial loop was more efficient at recycling carbon in regions where the ice was just starting to melt. These results highlight that although satellite chlorophyll records show, and many models predict, an increase in summertime primary production in the Arctic Basin as it warms, the net amount of carbon processed by the biological pump during summer may not change as a function of ice cover. Thus, a rapid reduction in summertime ice extent may not change the net community productivity or carbon balance in the Beaufort Gyre.
    Description: We thank our funding sources: the National Science Foundation (PLR 1304406, PLR-0856531) and the support of Fisheries and Oceans Canada.
    Keywords: Arctic Ocean ; Canada Basin ; Beaufort Gyre ; Gross production ; Net community production
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  • 14
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2016. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry, Geophysics, Geosystems 17 (2016): 4333–4353, doi:10.1002/2016GC006582.
    Description: Borehole logging data from legacy wells directly constrain the contemporary distribution of subsea permafrost in the sedimentary section at discrete locations on the U.S. Beaufort Margin and complement recent regional analyses of exploration seismic data to delineate the permafrost's offshore extent. Most usable borehole data were acquired on a ∼500 km stretch of the margin and within 30 km of the contemporary coastline from north of Lake Teshekpuk to nearly the U.S.-Canada border. Relying primarily on deep resistivity logs that should be largely unaffected by drilling fluids and hole conditions, the analysis reveals the persistence of several hundred vertical meters of ice-bonded permafrost in nearshore wells near Prudhoe Bay and Foggy Island Bay, with less permafrost detected to the east and west. Permafrost is inferred beneath many barrier islands and in some nearshore and lagoonal (back-barrier) wells. The analysis of borehole logs confirms the offshore pattern of ice-bearing subsea permafrost distribution determined based on regional seismic analyses and reveals that ice content generally diminishes with distance from the coastline. Lacking better well distribution, it is not possible to determine the absolute seaward extent of ice-bearing permafrost, nor the distribution of permafrost beneath the present-day continental shelf at the end of the Pleistocene. However, the recovery of gas hydrate from an outer shelf well (Belcher) and previous delineation of a log signature possibly indicating gas hydrate in an inner shelf well (Hammerhead 2) imply that permafrost may once have extended across much of the shelf offshore Camden Bay.
    Description: 2017-05-04
    Keywords: Permafrost ; Arctic Ocean ; Climate change ; Borehole logging ; Gas hydrates
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  • 15
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2017. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 122 (2017): 980–994, doi:10.1002/2016JC012419.
    Description: The Arctic Ocean thermohaline stratification frequently exhibits a staircase structure overlying the Atlantic Water Layer that can be attributed to the diffusive form of double-diffusive convection. The staircase consists of multiple layers of O(1) m in thickness separated by sharp interfaces, across which temperature and salinity change abruptly. Through a detailed analysis of Ice-Tethered Profiler measurements from 2004 to 2013, the double-diffusive staircase structure is characterized across the entire Arctic Ocean. We demonstrate how the large-scale Arctic Ocean circulation influences the small-scale staircase properties. These staircase properties (layer thicknesses and temperature and salinity jumps across interfaces) are examined in relation to a bulk vertical density ratio spanning the staircase stratification. We show that the Lomonosov Ridge serves as an approximate boundary between regions of low density ratio (approximately 3–4) on the Eurasian side and higher density ratio (approximately 6–7) on the Canadian side. We find that the Eurasian Basin staircase is characterized by fewer, thinner layers than that in the Canadian Basin, although the margins of all basins are characterized by relatively thin layers and the absence of a well-defined staircase. A double-diffusive 4/3 flux law parametrization is used to estimate vertical heat fluxes in the Canadian Basin to be O(0.1) W m−2. It is shown that the 4/3 flux law may not be an appropriate representation of heat fluxes through the Eurasian Basin staircase. Here molecular heat fluxes are estimated to be between O(0.01) and O(0.1) W m−2. However, many uncertainties remain about the exact nature of these fluxes.
    Description: National Science Foundation Division of Polar Programs
    Description: 2017-08-08
    Keywords: Arctic Ocean ; Double-diffusion ; Atlantic Water
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  • 16
    Publication Date: 2022-05-25
    Description: This paper is not subject to U.S. copyright. The definitive version was published in Deep Sea Research Part II: Topical Studies in Oceanography 152 (2018): 67-81, doi:10.1016/j.dsr2.2018.05.020.
    Description: Ocean acidification (OA), driven by rising anthropogenic carbon dioxide (CO2), is rapidly advancing in the Pacific Arctic Region (PAR), producing conditions newly corrosive to biologically important carbonate minerals like aragonite. Naturally short linkages across the PAR food web mean that species-specific acidification stress can be rapidly transmitted across multiple trophic levels, resulting in widespread impacts. Therefore, it is critical to understand the formation, transport, and persistence of acidified conditions in the PAR in order to better understand and project potential impacts to this delicately balanced ecosystem. Here, we synthesize data from process studies across the PAR to show the formation of corrosive conditions in colder, denser winter-modified Pacific waters over shallow shelves, resulting from the combination of seasonal terrestrial and marine organic matter respiration with anthropogenic CO2. When these waters are subsequently transported off the shelf, they acidify the Pacific halocline. We estimate that Barrow Canyon outflow delivers ~2.24 Tg C yr-1 to the Arctic Ocean through corrosive winter water transport. This synthesis also allows the combination of spatial data with temporal data to show the persistence of these conditions in halocline waters. For example, one study in this synthesis indicated that 0.5–1.7 Tg C yr-1 may be returned to the atmosphere via air-sea gas exchange of CO2 during upwelling events along the Beaufort Sea shelf that bring Pacific halocline waters to the ocean surface. The loss of CO2 during these events is more than sufficient to eliminate corrosive conditions in the upwelled Pacific halocline waters. However, corresponding moored and discrete data records indicate that potentially corrosive Pacific waters are present in the Beaufort shelfbreak jet during 80% of the year, indicating that the persistence of acidified waters in the Pacific halocline far outweighs any seasonal mitigation from upwelling. Across the datasets in this large-scale synthesis, we estimate that the persistent corrosivity of the Pacific halocline is a recent phenomenon that appeared between 1975 and 1985. Over that short time, these potentially corrosive waters originating over the continental shelves have been observed as far as the entrances to Amundsen Gulf and M’Clure Strait in the Canadian Arctic Archipelago. The formation and transport of corrosive waters on the Pacific Arctic shelves may have widespread impact on the Arctic biogeochemical system and food web reaching all the way to the North Atlantic.
    Description: National Science Foundation Grant PLR-1303617.
    Keywords: Ocean acidification ; Pacific Arctic ; Arctic Ocean ; East Siberian Sea ; Chukchi Sea ; Beaufort Sea ; Transport ; Arctic Rivers ; Sea Ice ; Respiration ; Upwelling ; Biological vulnerability ; Community resilience
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  • 17
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2016. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 121 (2016): 1249–1261, doi:10.1002/2015JC011296.
    Description: The Beaufort Gyre in the Arctic Ocean differs from a typical moderate-latitude gyre in some major aspects of its dynamics. First, it is located in a basin without a western boundary, which is essential for closing midlatitude circulations. Second, the gradient in Coriolis parameter, β, is small and so the validity of the Sverdrup balance is uncertain. In this paper, we use an idealized two-layer model to examine several processes that are related to these two issues. In a circular basin with closed geostrophic contours in interior, the variability of vorticity in the upper layer is dominated by eddies. But in the time-mean circulation, the main dynamical balance in the basin's interior is between the curl of wind stress and the eddy vorticity fluxes. The torque of friction becomes important along the boundary where the rim current is strong. It is found that the smallness of β has only a relatively small impact in a circular basin without a meridional boundary. The gyre is considerably more sensitive to the existence of a meridional boundary. The time-mean circulation weakens considerably when a peninsula is inserted between the model's center and the rim. (One side of the peninsula is dynamically equivalent to a midlatitude western boundary.) The gyre's sensitivity to β has also increased significantly when a meridional boundary is present. Subsurface ridges have similar effects on the gyre as a boundary, indicating that such topographic features may substitute, to some extents, the dynamical role of a western boundary.
    Description: This study has been supported by the National Science Foundation's Arctic Natural Science Program for J.Y. and A.P. via grant PRL-1107412, and for AP via grants PRL-1313614, PRL-1302884, and PRL-1107277.
    Description: 2016-08-12
    Keywords: Arctic Ocean ; Beaufort Gyre ; Freshwater content ; Beta effect ; Western boundary
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  • 18
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2016. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 121 (2016): 2918–2936, doi:10.1002/2015JC011535.
    Description: We examine the dissolved inorganic carbon maximum in the Canada Basin halocline using a suite of geochemical tracers to gain insight into the factors that contribute to the persistence of this feature. Hydrographic and geochemical samples were collected in the upper 500 m of the southwestern Canada Basin water column in the summer of 2008 and fall of 2009. These observations were used to identify conservative and nonconservative processes that contribute dissolved inorganic carbon to halocline source waters, including shelf sediment organic matter remineralization, air-sea gas exchange, and sea-ice brine export. Our results indicate that the remineralization of organic matter that occurs along the Bering and Chukchi Sea shelves is the overwhelming contributor of dissolved inorganic carbon to Pacific Winter Water that occupies the middle halocline in the southwestern Canada Basin. Nonconservative contributions from air-sea exchange and sea-ice brine are not significant. The broad salinity range associated with the DIC maximum, compared to the narrow salinity range of the nutrient maximum, is due to mixing between Pacific and Atlantic water and not abiotic addition of DIC.
    Description: NSERC; Fisheries and Oceans Canada; US National Science Foundation Office of Polar Programs Grant Number: OPP-0424864; Canadian International Polar Year Office
    Description: 2016-11-04
    Keywords: Arctic Ocean ; Dissolved inorganic carbon ; Nutrients ; Stable isotopes ; Shelf-basin CO2 pump
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  • 19
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2016. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 43 (2016): 8106–8114, doi:10.1002/2016GL069671.
    Description: The eddy field across the Arctic Ocean's Canada Basin is analyzed using Ice-Tethered Profiler (ITP) and moored measurements of temperature, salinity, and velocity spanning 2005 to 2015. ITPs encountered 243 eddies, 98% of which were anticyclones, with approximately 70% of these having anomalously cold cores. The spatially and temporally varying eddy field is analyzed accounting for sampling biases in the unevenly distributed ITP data and caveats in detection methods. The highest concentration of eddies was found in the western and southern portions of the basin, close to topographic margins and boundaries of the Beaufort Gyre. The number of lower halocline eddies approximately doubled from 2005–2012 to 2013–2014. The increased eddy density suggests more active baroclinic instability of the Beaufort Gyre that releases available potential energy to balance the wind energy input; this may stabilize the Gyre spin-up and associated freshwater increase.
    Description: National Science Foundation Division of Polar Programs Grant Number: 1350046
    Description: 2017-02-03
    Keywords: Arctic Ocean ; Eddies ; Beaufort Gyre
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  • 20
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2017. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 44 (2017): 5008–5015, doi:10.1002/2017GL073042.
    Description: The Arctic halocline stratification is an important barrier to the transport of deep ocean heat to the underside of sea ice. Surface water in the Chukchi Sea, warmed in summer by solar radiation, ventilates the Canada Basin halocline to create a warm layer below the mixed-layer base. The year-round persistence of this layer is shown to be consistent with the seasonal cycle of halocline ventilation. We present hydrographic observations and model results to show how Chukchi Sea density outcrops migrate seasonally as surface fluxes modify salinity and temperature. This migration is such that in winter, isopycnals bounding the warm halocline are blocked from ventilation, while the cool, relatively salty and deeper halocline layers are ventilated. In this way, the warm halocline is isolated by stratification (both vertically and laterally) each winter. Results shed light on the fate and impact to sea ice of the warm halocline under future freshening and warming of the surface Arctic Ocean.
    Description: National Science Foundation Division of Polar Programs Grant Number: 1107623
    Description: 2017-11-26
    Keywords: Arctic Ocean ; Halocline ; Ventilation
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  • 21
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2018. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research-Oceans, 123(11), (2018): 7983-8003. doi:10.1029/2018JC014298.
    Description: A melt pond (MP) distribution equation has been developed and incorporated into the Marginal Ice‐Zone Modeling and Assimilation System to simulate Arctic MPs and sea ice over 1979–2016. The equation differs from previous MP models and yet benefits from previous studies for MP parameterizations as well as a range of observations for model calibration. Model results show higher magnitude of MP volume per unit ice area and area fraction in most of the Canada Basin and the East Siberian Sea and lower magnitude in the central Arctic. This is consistent with Moderate Resolution Imaging Spectroradiometer observations, evaluated with Measurements of Earth Data for Environmental Analysis (MEDEA) data, and closely related to top ice melt per unit ice area. The model simulates a decrease in the total Arctic sea ice volume and area, owing to a strong increase in bottom and lateral ice melt. The sea ice decline leads to a strong decrease in the total MP volume and area. However, the Arctic‐averaged MP volume per unit ice area and area fraction show weak, statistically insignificant downward trends, which is linked to the fact that MP water drainage per unit ice area is increasing. It is also linked to the fact that MP volume and area decrease relatively faster than ice area. This suggests that overall the actual MP conditions on ice have changed little in the past decades as the ice cover is retreating in response to Arctic warming, thus consistent with the Moderate Resolution Imaging Spectroradiometer observations that show no clear trend in MP area fraction over 2000–2011.
    Description: We gratefully acknowledge the support of the NASA Cryosphere Program (grants NNX15AG68G, NNX17AD27G, and NNX14AH61G), the Office of Naval Research (N00014‐12‐1‐0112), the NSF Office of Polar Programs (PLR‐1416920, PLR‐1603259, PLR‐1602521, and ARC‐1203425), and the Department of Homeland Security (DHS, 2014‐ST‐061‐ML‐0002). The DHS grant is coordinated through the Arctic Domain Awareness Center (ADAC), a DHS Center of Excellence, which conducts maritime research and development for the Arctic region. The views and conclusions in this document are those of the authors and should not be interpreted as representing the official policies, either expressed or implied, of the DHS. MODIS‐derived MP area data are available at https://icdc.cen.uni‐hamburg.de/1/daten/cryosphere/arctic‐meltponds.html. MP area fraction statistics derived from MEDEA images are available from http://psc.apl.uw.edu/melt‐pond‐data/. Sea ice thickness and snow observations are available at http://psc.apl.washington.edu/sea_ice_cdr. CFS forcing data used to drive MIZMAS are available at https://www.ncdc.noaa.gov/data‐access/model‐data/model‐datasets/climate‐forecast‐system‐version2‐cfsv2.
    Description: 2019-04-18
    Keywords: Arctic Ocean ; sea ice ; melt ponds ; numerical modeling ; climate variability
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  • 22
    Publication Date: 2022-05-26
    Description: © The Author(s), 2014. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Journal of Geophysical Research: Oceans 119 (2014): 7523–7548, doi:10.1002/2014JC010273.
    Description: Pacific Water flows northward through Bering Strait and penetrates the Arctic Ocean halocline throughout the Canadian Basin sector of the Arctic. In summer, Pacific Summer Water (PSW) is modified by surface buoyancy fluxes and mixing as it crosses the shallow Chukchi Sea before entering the deep ocean. Measurements from Ice-Tethered Profilers, moorings, and hydrographic surveys between 2003 and 2013 reveal spatial and temporal variability in the PSW component of the halocline in the Central Canada Basin with increasing trends in integrated heat and freshwater content, a consequence of PSW layer thickening as well as layer freshening and warming. It is shown here how properties in the Chukchi Sea in summer control the temperature-salinity properties of PSW in the interior by subduction at isopycnals that outcrop in the Chukchi Sea. Results of an ocean model, forced by idealized winds, provide support to the mechanism of surface ocean Ekman transport convergence maintaining PSW ventilation of the halocline.
    Description: Funding was provided by the National Science Foundation Division of Polar Programs under award 1107623, 1313614, 1107412, 1107277, 1303644, and 0938137 and by Yale University. ICMMG model development was supported by the Russian Fund for Basic Research (14-05-00730A).
    Keywords: Arctic Ocean ; Halocline ventilation ; Pacific Water
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  • 23
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    Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu
    Publication Date: 2022-10-31
    Description: Dataset: Arctic Nitrogen Fixation Rates
    Description: This dataset provides rates of nitrogen fixation for the coastal Chukchi Sea near Barrow, Alaska. Nitrogen fixation supplies ‘new’ nitrogen to the global ocean and supports primary production and impacts global biogeochemical cycles. Historically, nitrogen fixation in marine waters was considered a predominantly warm water process but this and other recent studies have shown that nitrogen fixation is occurring at low rates in polar waters. This dataset reports rates of 3.5 – 17.2 nmol N L-1 d-1 in the ice-free coastal Alaskan Arctic. Additional investigations of high-latitude marine diazotrophic physiology are required to refine these N2 fixation estimates. For a complete list of measurements, refer to the supplemental document 'Field_names.pdf', and a full dataset description is included in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: http://www.bco-dmo.org/dataset/701789
    Description: NSF Arctic Sciences (NSF ARC) PLR-0909839
    Keywords: Nitrogen fixation ; Temperature ; Arctic Ocean ; Nitrogen ; Nutrients ; Chukchi Sea
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  • 24
    Publication Date: 2022-10-26
    Description: Author Posting. © American Geophysical Union, 2019. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research-Oceans 124(7), (2019): 4618-4630, doi: 10.1029/2019JC014940.
    Description: The Arctic Ocean mixed layer interacts with the ice cover above and warmer, nutrient‐rich waters below. Ice‐Tethered Profiler observations in the Canada Basin of the Arctic Ocean over 2006–2017 are used to investigate changes in mixed layer properties. In contrast to decades of shoaling since at least the 1980s, the mixed layer deepened by 9 m from 2006–2012 to 2013–2017. Deepening resulted from an increase in mixed layer salinity that also weakened stratification at the base of the mixed layer. Vertical mixing alone can explain less than half of the observed change in mixed layer salinity, and so the observed increase in salinity is inferred to result from changes in freshwater accumulation via changes to ice‐ocean circulation or ice melt/growth and river runoff. Even though salinity increased, the shallowest density surfaces deepened by 5 m on average suggesting that Ekman pumping over this time period remained downward. A deeper mixed layer with weaker stratification has implications for the accessibility of heat and nutrients stored in the upper halocline. The extent to which the mixed layer will continue to deepen appears to depend primarily on the complex set of processes influencing freshwater accumulation.
    Description: We gratefully acknowledge J. Toole for helpful conversations. S. Cole was supported by the National Science Foundation under grant PLR‐1602926 and J. Stadler by the Woods Hole Oceanographic Institution Summer Student Fellowship program. Profile data are available via the Ice‐Tethered Profiler program website: http://whoi.edu/itp. SSM/I ice concentration data were downloaded from the National Snow and Ice Data Center.
    Description: 2019-12-22
    Keywords: Arctic Ocean ; Mixed layer ; Freshwater
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  • 25
    Publication Date: 2022-10-26
    Description: Author Posting. © American Geophysical Union, 2019. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research-Oceans 124(5), (2019): 3279-3297, doi: 10.1029/2019JC014988.
    Description: Radium isotopes are produced through the decay of thorium in sediments and are soluble in seawater; thus, they are useful for tracing ocean boundary‐derived inputs to the ocean. Here we apply radium isotopes to study continental inputs and water residence times in the Arctic Ocean, where land‐ocean interactions are currently changing in response to rising air and sea temperatures. We present the distributions of radium isotopes measured on the 2015 U.S. GEOTRACES transect in the Western Arctic Ocean and combine this data set with historical radium observations in the Chukchi Sea and Canada Basin. The highest activities of radium‐228 were observed in the Transpolar Drift and the Chukchi shelfbreak jet, signaling that these currents are heavily influenced by interactions with shelf sediments. The ventilation of the halocline with respect to inputs from the Chukchi shelf occurs on time scales of ≤19–23 years. Intermediate water ventilation time scales for the Makarov and Canada Basins were determined to be ~20 and 〉30 years, respectively, while deep water residence times in these basins were on the order of centuries. The radium distributions and residence times described in this study serve as a baseline for future studies investigating the impacts of climate change on the Arctic Ocean.
    Description: We thank the captain and crew of the USCGC Healy (HLY1502) and the chief scientists D. Kadko and W. Landing for coordinating a safe and successful expedition. We thank the members of the pump team, P. Lam, E. Black, S. Pike, X. Yang, and M. Heller for their assistance with sample collection and for their unfailingly positive attitudes during this 65‐day expedition. We also appreciate sampling assistance from P. Aguilar and M. Stephens, and MATLAB assistance from B. Corlett, A. Pacini, P. Lin, and M. Li. The radium data from the HLY1502 expedition are available through the Biological & Chemical Oceanography Data Management Office (https://www.bco‐dmo.org/dataset/718440) and the radium measurements from the SHEBA, AWS‐2000, and SBI expeditions can be found in the supporting information. This work was funded by NSF awards OCE‐1458305 to M.A.C., OCE‐1458424 to W.S.M., and PLR‐1504333 to R.S.P. This research was conducted with Government support under and awarded by a DoD, Air Force Office of Scientific Research, National Defense Science and Engineering Graduate (NDSEG) Fellowship awarded to L.E.K., 32 CFR 168a.
    Description: 2019-10-26
    Keywords: Radium ; Arctic Ocean ; GEOTRACES ; Chukchi shelf
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  • 26
    Publication Date: 2022-05-26
    Description: Author Posting. © The Authors, 2018. This is the author's version of the work. It is posted here under a nonexclusive, irrevocable, paid-up, worldwide license granted to WHOI. It is made available for personal use, not for redistribution. The definitive version was published in Roca-Marti, M., Puigcorbe, V., Friedrich, J., van der Loeff, M. R., Rabe, B., Korhonen, M., Camara-Mor, P., Garcia-Orellana, J., & Masque, P. (2018). Distribution of pb-210 and po-210 in the arctic water column during the 2007 sea-ice minimum: Particle export in the ice-covered basins. Deep-Sea Research Part I-Oceanographic Research Papers, 142, 94-106, doi:10.1016/j.dsr.2018.09.011.
    Description: 210Pb and 210Po are naturally occurring radionuclides that are commonly used as a proxy for particle and carbon export. In this study, the distribution of the 210Po/210Pb pair was investigated in the water column of the Barents, Kara and Laptev Seas and the Nansen, Amundsen and Makarov Basins in order to understand the particle dynamics in the Arctic Ocean during the 2007 sea-ice minimum (August-September). Minimum activities of total 210Pb and 210Po were found in the upper and lower haloclines (approx. 60-130 m), which are partly attributed to particle scavenging over the shelves, boundary current transport and subsequent advection of the water with low 210Pb and 210Po activities into the central Arctic. Widespread and substantial (〉50%) deficits of 210Po with respect to 210Pb were detected from surface waters to 200 m on the shelves, but also in the basins. This was particularly important in the Makarov Basin where, despite very low chlorophyll-a levels, estimates of annual new primary production were three times higher than in the Eurasian Basin. In the Nansen, Amundsen and Makarov 32 Basins, estimates of annual new primary production correlated with the deficits of 210Po in the upper 200 m of the water column, suggesting that in situ production and subsequent export of biogenic material were the mechanisms that controlled the removal of 210Po in the central Arctic. Unlike 210Po, 234Th deficits measured during the same expedition were found to be very small and not significant below 25 m in the basins (Cai et al., 2010), which indicates, given the shorter half-life of 234Th, that particle export fluxes in the central Arctic would have been higher before July-August in 2007 than later in the season.
    Description: We would like to thank the crew of the R/V Polarstern and the scientists on board for their cooperation during the ARK-XXII/2 expedition. We greatly appreciate the hard work of Oliver Lechtenfeld who collected and processed the samples on board. Thanks to Dorothea Bauch for sharing her results on freshwater origin and Adam Ulfsbo for providing insightful comments on the estimates of primary production. This project was partly supported by the Ministerio de Ciencia e Innovación (CTM2011-28452, Spain). We wish to acknowledge the support of the Generalitat de Catalunya to the research group MERS (2017 SGR-1588). This work is contributing to the ICTA ‘Unit of Excellence’ (MinECo, MDM2015-0552). M.R.-M. was supported by a Spanish PhD fellowship (AP2010-2510) and an Australian postdoctoral fellowship (2017 Endeavour Research Fellowship).
    Description: 2019-10-22
    Keywords: Particle export ; Annual new primary production ; Scavenging ; 210Po/210Pb ; Arctic Ocean ; 2007 sea-ice minimum
    Repository Name: Woods Hole Open Access Server
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  • 27
    Publication Date: 2022-05-26
    Description: © The Author(s), 2016. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Journal of Geophysical Research: Oceans 121 (2016): 27–59, doi:10.1002/2015JC011299.
    Description: Pacific Water (PW) enters the Arctic Ocean through Bering Strait and brings in heat, fresh water, and nutrients from the northern Bering Sea. The circulation of PW in the central Arctic Ocean is only partially understood due to the lack of observations. In this paper, pathways of PW are investigated using simulations with six state-of-the art regional and global Ocean General Circulation Models (OGCMs). In the simulations, PW is tracked by a passive tracer, released in Bering Strait. Simulated PW spreads from the Bering Strait region in three major branches. One of them starts in the Barrow Canyon, bringing PW along the continental slope of Alaska into the Canadian Straits and then into Baffin Bay. The second begins in the vicinity of the Herald Canyon and transports PW along the continental slope of the East Siberian Sea into the Transpolar Drift, and then through Fram Strait and the Greenland Sea. The third branch begins near the Herald Shoal and the central Chukchi shelf and brings PW into the Beaufort Gyre. In the models, the wind, acting via Ekman pumping, drives the seasonal and interannual variability of PW in the Canadian Basin of the Arctic Ocean. The wind affects the simulated PW pathways by changing the vertical shear of the relative vorticity of the ocean flow in the Canada Basin.
    Description: National Science Foundation (NSF). Grant Numbers: PLR-0806306 , PLR-85653100 , PLR-82486400 , PLR-1313614; NASA Advanced Supercomputing (NAS) Division; JPL Supercomputing and Visualization Facility (SVF) Grant Numbers: ARC-0806306 , ARC-85653100 , ARC-82486400; Russian Foundation of Basic Research; Ministry of the Education and Science of the Russian Federation; UK Natural Environment Research Council Grant Number: NE/I028947/
    Keywords: Arctic Ocean ; Beaufort Gyre ; Pacific Water ; Ocean dynamics ; Wind forcing
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  • 28
    Publication Date: 2022-05-26
    Description: Author Posting. © American Geophysical Union, 2016. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 121 (2016); 934–948, doi:10.1002/2015JC011183.
    Description: Previous observational studies have found increasing primary production (PP) in response to declining sea ice cover in the Arctic Ocean. In this study, under-ice PP was assessed based on three coupled ice-ocean-ecosystem models participating in the Forum for Arctic Modeling and Observational Synthesis (FAMOS) project. All models showed good agreement with under-ice measurements of surface chlorophyll-a concentration and vertically integrated PP rates during the main under-ice production period, from mid-May to September. Further, modeled 30-year (1980–2009) mean values and spatial patterns of sea ice concentration compared well with remote sensing data. Under-ice PP was higher in the Arctic shelf seas than in the Arctic Basin, but ratios of under-ice PP over total PP were spatially correlated with annual mean sea ice concentration, with higher ratios in higher ice concentration regions. Decreases in sea ice from 1980 to 2009 were correlated significantly with increases in total PP and decreases in the under-ice PP/total PP ratio for most of the Arctic, but nonsignificantly related to under-ice PP, especially in marginal ice zones. Total PP within the Arctic Circle increased at an annual rate of between 3.2 and 8.0 Tg C/yr from 1980 to 2009. This increase in total PP was due mainly to a PP increase in open water, including increases in both open water area and PP rate per unit area, and therefore much stronger than the changes in under-ice PP. All models suggested that, on a pan-Arctic scale, the fraction of under-ice PP declined with declining sea ice cover over the last three decades.
    Description: NASA Grant Number: NNX13AE81G; the NSF Office of Polar Programs Grant Number: (ARC-0968676, PLR-1417925, PLR-1417677 and PLR-1416920); the NASA Cryosphere Grant Number: (NNX12AB31G); Climate and Biological Response Grant Number: (NNX11AO91G)
    Description: 2016-07-27
    Keywords: Ecosystem modeling ; Sea ice ; Under-ice production ; Phenology ; Primary production ; Arctic Ocean
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  • 29
    Publication Date: 2022-05-26
    Description: This data was compiled from June-Aug. 2014, and covers all historical hydrography in the north-east Chukchi shelfbreak region with in-situ velocity measurements available at the time of compilation. All data is provided as collected, and the velocity data has been detided by the Oregon State University tidal inversion software (see Padman and Erofeeva, 2004). Nine of the total 46 sections required detiding (see ‘chukchi_data_sources.pdf’), and seven of these nine required additional quality control to remove ship velocities from the record. Overall, the record extends from May 2002 through July 2014. Seasonally, the data is limited to May through October, with data from May through June only available from 2002-4. In addition, there is an absence of data between 2004 and 2009, restricting interannual analyses to be comparisons between the early (2002-4) and late (2009-14) regimes.
    Description: 2018-12-31
    Keywords: Arctic Ocean ; Chukchi Sea ; Temperature ; Salinity ; Velocity ; Hydrographic sections
    Repository Name: Woods Hole Open Access Server
    Type: Dataset
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  • 30
    Publication Date: 2022-05-26
    Description: Author Posting. © American Geophysical Union, 2016. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 121 (2016): 6137-6158, doi:10.1002/2016JC011784.
    Description: Early ice retreat and ocean warming are changing various facets of the Arctic marine ecosystem, including the biogeographic distribution of marine organisms. Here an endemic copepod species, Calanus glacialis, was used as a model organism, to understand how and why Arctic marine environmental changes may induce biogeographic boundary shifts. A copepod individual-based model was coupled to an ice-ocean-ecosystem model to simulate temperature- and food-dependent copepod life history development. Numerical experiments were conducted for two contrasting years: a relatively cold and normal sea ice year (2001) and a well-known warm year with early ice retreat (2007). Model results agreed with commonly known biogeographic distributions of C. glacialis, which is a shelf/slope species and cannot colonize the vast majority of the central Arctic basins. Individuals along the northern boundaries of this species' distribution were most susceptible to reproduction timing and early food availability (released sea ice algae). In the Beaufort, Chukchi, East Siberian, and Laptev Seas where severe ocean warming and loss of sea ice occurred in summer 2007, relatively early ice retreat, elevated ocean temperature (about 1–2°C higher than 2001), increased phytoplankton food, and prolonged growth season created favorable conditions for C. glacialis development and caused a remarkable poleward expansion of its distribution. From a pan-Arctic perspective, despite the great heterogeneity in the temperature and food regimes, common biogeographic zones were identified from model simulations, thus allowing a better characterization of habitats and prediction of potential future biogeographic boundary shifts.
    Description: National Science Foundation Polar Programs Grant Number: (PLR-1417677, PLR-1417339, and PLR-1416920)
    Description: 2017-02-20
    Keywords: Arctic Ocean ; Marine ecosystem ; Climate change ; Biogeography ; Individual-based model ; C. glacialis
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  • 31
    Publication Date: 2022-05-26
    Description: Author Posting. © American Geophysical Union, 2016. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry, Geophysics, Geosystems 17 (2016): 4354–4365, doi:10.1002/2016GC006584.
    Description: Subsea ice-bearing permafrost (IBPF) and associated gas hydrate in the Arctic have been subject to a warming climate and saline intrusion since the last transgression at the end of the Pleistocene. The consequent degradation of IBPF is potentially associated with significant degassing of dissociating gas hydrate deposits. Previous studies interpreted the distribution of subsea permafrost on the U.S. Beaufort continental shelf based on geographically sparse data sets and modeling of expected thermal history. The most cited work projects subsea permafrost to the shelf edge (∼100 m isobath). This study uses a compilation of stacking velocity analyses from ∼100,000 line-km of industry-collected multichannel seismic reflection data acquired over 57,000 km2 of the U.S. Beaufort shelf to delineate continuous subsea IBPF. Gridded average velocities of the uppermost 750 ms two-way travel time range from 1475 to 3110 m s−1. The monotonic, cross-shore pattern in velocity distribution suggests that the seaward extent of continuous IBPF is within 37 km of the modern shoreline at water depths 〈 25 m. These interpretations corroborate recent Beaufort seismic refraction studies and provide the best, margin-scale evidence that continuous subsea IBPF does not currently extend to the northern limits of the continental shelf.
    Description: DOE NETL/NRC Methane Hydrate Fellowship Grant Number: DE-FC26-05NT42248; USGS–DOE Interagency Agreements Grant Number: DE-FE000291 and 0023495
    Description: 2017-05-04
    Keywords: Subsea permafrost ; Gas hydrates ; Multichannel seismic data ; Arctic Ocean
    Repository Name: Woods Hole Open Access Server
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  • 32
    Publication Date: 2022-05-26
    Description: Author Posting. © American Geophysical Union, 2017. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 122 (2017): 2269–2290, doi:10.1002/2016JC012486.
    Description: Data from a shipboard hydrographic/velocity survey carried out in September 2013 of the region north of Svalbard in the Nansen Basin are analyzed to characterize the Atlantic Water (AW) boundary current as it flows eastward along the continental slope. Eight meridional transects across the current, spanning an alongstream distance of 180 km, allow for a detailed description of the current and the regional water masses. During the survey the winds were light and there was no pack-ice. The mean section reveals that the boundary current was O(40 km) wide, surface-intensified, with a maximum velocity of 20 cm/s. Its mean transport during the survey was 3.11 ± 0.33 Sv, of which 2.31 ± 0.29 Sv was AW. This suggests that the two branches of AW entering the Arctic Ocean via Fram Strait—the Yermak Plateau branch and the Svalbard branch—have largely combined into a single current by 30°E. At this location the boundary current meanders with a systematic change in its kinematic structure during offshore excursions. A potential vorticity analysis indicates that the flow is baroclinically unstable, consistent with previous observations of AW anticyclones offshore of the current as well as the presence of a near-field cyclone in this data set. Our survey indicates that only a small portion of the boundary current is diverted into the Kvitøya Trough (0.17 ± 0.08 Sv) and that the AW temperature/salinity signal is quickly eroded within the trough.
    Description: National Science Foundation Grant Number: ARC-1264098
    Description: 2017-09-21
    Keywords: Atlantic Water ; Arctic Ocean ; Kvitøya Trough ; Nansen Basin ; Svalbard Branch ; A-TWAIN
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  • 33
    Publication Date: 2022-05-26
    Description: © The Author(s), 2017. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Frontiers in Marine Science 4 (2017): 332, doi:10.3389/fmars.2017.00332.
    Description: While sound scattering layers (SSLs) have been described previously from ice-covered waters in the Arctic, the existence of a viable mesopelagic community that also includes mesopelagic fishes in the Arctic has been questioned. In addition, it has been hypothesized that vertical migration would hardly exist in these areas. We wanted to check if deep scattering layers (DSLs) was found to the west and north of Svalbard (79°30′N−82°10′N) during autumn 2015, and if present; whether organisms in such DSLs undertook vertical migrations. Our null hypothesis was that there would be no evidence of diel vertical migration. Multi-frequency acoustic observations by hull mounted echo sounder (18, 38, and 120 kHz) revealed a DSL at depths ~210–510 m in areas with bottom depths exceeding ~600 m. Investigating eight geographical locations that differed with respect to time periods, light cycle and sea ice conditions, we show that the deeper layer of DSL displayed a clear ascending movement during night time and a descending movement during daytime. The high-light weighted mean depth (WMD) (343–514 m) with respect to backscattered energy was statistically deeper than the low-light WMD (179–437 m) for the locations studied. This behavior of the DSL was found to be consistent both when the sun was continuously above the horizon and after it started to set on 1 September, and both in open water and sea ice covered waters. The WMD showed an increasing trend, while the nautical area backscattering strength from the DSL showed a decreasing trend from south to north among the studied locations. Hydrographic observations revealed that the diel migration was found in the lower part of the north-flowing Atlantic Water, and was disconnected from the surface water masses above the Atlantic Water during day and night. The organisms conducting vertical migrations were studied by vertical and oblique hauls with zooplankton nets and pelagic trawls. These data suggest that these organisms were mainly various mesopelagic fishes, some few larger fishes, large zooplankton like krill and amphipods, and various gelatinous forms.
    Description: The Research Council of Norway is thanked for the financial support through the projects “The Arctic Ocean Ecosystem” — (SI_ARCTIC, RCN 228896), the “Effects of climate change on the Calanus complex”—(ECCO, RCN 200508), “Harvesting marine cold water plankton species—abundance estimation and stock assessment”—(Harvest II, RCN 203871).
    Keywords: Arctic Ocean ; Deep scattering layer ; Diel vertical migration ; Mesopelagic organisms ; Acoustics
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  • 34
    Publication Date: 2022-05-26
    Description: © The Author(s), 2017. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Geochemistry, Geophysics, Geosystems 18 (2017): 4156–4178, doi:10.1002/2017GC007099.
    Description: Synthesis of seismic velocity, potential field, and geological data from Canada Basin and its surrounding continental margins suggests that a northeast-trending structural fabric has influenced the origin, evolution, and current tectonics of the basin. This structural fabric has a crustal origin, based on the persistence of these trends in upward continuation of total magnetic intensity data and vertical derivative analysis of free-air gravity data. Three subparallel northeast-trending features are described. Northwind Escarpment, bounding the east side of the Chukchi Borderland, extends ∼600 km and separates continental crust of Northwind Ridge from high-velocity transitional crust in Canada Basin. A second, shorter northeast-trending zone extends ∼300 km in northern Canada Basin and separates inferred continental crust of Sever Spur from magmatically intruded crust of the High Arctic Large Igneous Province. A third northeast-trending feature, here called the Alaska-Prince Patrick magnetic lineament (APPL) is inferred from magnetic data and its larger regional geologic setting. Analysis of these three features suggests strike slip or transtensional deformation played a role in the opening of Canada Basin. These features can be explained by initial Jurassic-Early Cretaceous strike slip deformation (phase 1) followed in the Early Cretaceous (∼134 to ∼124 Ma) by rotation of Arctic Alaska with seafloor spreading orthogonal to the fossil spreading axis preserved in the central Canada Basin (phase 2). In this model, the Chukchi Borderland is part of Arctic Alaska.
    Description: Funding for this work was provided in part through the Geological Survey of Canada as part of Canada’s UNCLOS Project and through the U.S. Geological Survey as part of the U.S. Extended Continental Shelf project.
    Keywords: Canada Basin ; Tectonics ; Arctic Ocean ; Strike slip ; Seafloor spreading
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  • 35
    Publication Date: 2022-05-26
    Description: © The Author(s), 2016. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Ocean Modelling 105 (2016): 1-12, doi:10.1016/j.ocemod.2016.02.009
    Description: The sea state of the Beaufort and Chukchi seas is controlled by the wind forcing and the amount of ice-free water available to generate surface waves. Clear trends in the annual duration of the open water season and in the extent of the seasonal sea ice minimum suggest that the sea state should be increasing, independent of changes in the wind forcing. Wave model hindcasts from four selected years spanning recent conditions are consistent with this expectation. In particular, larger waves are more common in years with less summer sea ice and/or a longer open water season, and peak wave periods are generally longer. The increase in wave energy may affect both the coastal zones and the remaining summer ice pack, as well as delay the autumn ice-edge advance. However, trends in the amount of wave energy impinging on the ice-edge are inconclusive, and the associated processes, especially in the autumn period of new ice formation, have yet to be well-described by in situ observations. There is an implicit trend and evidence for increasing wave energy along the coast of northern Alaska, and this coastal signal is corroborated by satellite altimeter estimates of wave energy.
    Description: This work was supported by the Office of Naval Research, Code 322, “Arctic and Global Prediction”, directed by Drs. Martin Jeffries and Scott Harper. (Grant numbers and Principal Investigators are: Ackley, N000141310435; Babanin, N000141310278; Doble, N000141310290; Fairall, N0001413IP20046; Gemmrich, N000141310280; Girard-Ardhuin and Ardhuin, N000141612376; Graber, N000141310288; Guest, N0001413WX20830; Holt, N0001413IP20050; Lehner, N000141310303; Maksym, N000141310446; Perrie, N00014-15-1-2611; Rogers, N0001413WX20825; Shen, N000141310294; Squire, N000141310279; Stammerjohn, N000141310434; Thomson, N000141310284; Wadhams, N000141310289.)
    Keywords: Sea ice ; Arctic Ocean ; Ocean surface waves
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  • 36
    Publication Date: 2022-05-26
    Description: Author Posting. © American Geophysical Union, 2017. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry, Geophysics, Geosystems 18 (2017): 3771–3800, doi:10.1002/2017GC007186.
    Description: Little is known about marine mineral deposits in the Arctic Ocean, an ocean dominated by continental shelf and basins semi-closed to deep-water circulation. Here, we present data for ferromanganese crusts and nodules collected from the Amerasia Arctic Ocean in 2008, 2009, and 2012 (HLY0805, HLY0905, and HLY1202). We determined mineral and chemical compositions of the crusts and nodules and the onset of their formation. Water column samples from the GEOTRACES program were analyzed for dissolved and particulate scandium concentrations, an element uniquely enriched in these deposits. The Arctic crusts and nodules are characterized by unique mineral and chemical compositions with atypically high growth rates, detrital contents, Fe/Mn ratios, and low Si/Al ratios, compared to deposits found elsewhere. High detritus reflects erosion of submarine outcrops and North America and Siberia cratons, transport by rivers and glaciers to the sea, and distribution by sea ice, brines, and currents. Uniquely high Fe/Mn ratios are attributed to expansive continental shelves, where diagenetic cycling releases Fe to bottom waters, and density flows transport shelf bottom water to the open Arctic Ocean. Low Mn contents reflect the lack of a mid-water oxygen minimum zone that would act as a reservoir for dissolved Mn. The potential host phases and sources for elements with uniquely high contents are discussed with an emphasis on scandium. Scandium sorption onto Fe oxyhydroxides and Sc-rich detritus account for atypically high scandium contents. The opening of Fram Strait in the Miocene and ventilation of the deep basins initiated Fe-Mn crust growth ∼15 Myr ago.
    Description: National Science Foundation Grant Numbers: 1434493, 1713677; NSF-OCE Grant Number: 1535854
    Description: 2018-05-08
    Keywords: Arctic Ocean ; Ferromanganese deposits ; Rare metals ; Scandium ; Paleoceanography ; Genetic model
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  • 37
    Publication Date: 2022-05-26
    Description: Author Posting. © American Geophysical Union, 2019. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research-Oceans 124(3), (2019): 1679-1698, doi:10.1029/2018JC014759.
    Description: The characteristics and seasonality of the Svalbard branch of the Atlantic Water (AW) boundary current in the Eurasian Basin are investigated using data from a six‐mooring array deployed near 30°E between September 2012 and September 2013. The instrument coverage extended to 1,200‐m depth and approximately 50 km offshore of the shelf break, which laterally bracketed the flow. Averaged over the year, the transport of the current over this depth range was 3.96 ± 0.32 Sv (1 Sv = 106 m3/s). The transport within the AW layer was 2.08 ± 0.24 Sv. The current was typically subsurface intensified, and its dominant variability was associated with pulsing rather than meandering. From late summer to early winter the AW was warmest and saltiest, and its eastward transport was strongest (2.44 ± 0.12 Sv), while from midspring to midsummer the AW was coldest and freshest and its transport was weakest (1.10 ± 0.06 Sv). Deep mixed layers developed through the winter, extending to 400‐ to 500‐m depth in early spring until the pack ice encroached the area from the north shutting off the air‐sea buoyancy forcing. This vertical mixing modified a significant portion of the AW layer, suggesting that, as the ice cover continues to decrease in the southern Eurasian Basin, the AW will be more extensively transformed via local ventilation.
    Description: We are grateful to the crew of the R/V Lance for the collection of the data. The U.S. component of A‐TWAIN was funded by the National Science Foundation under grant ARC‐1264098 as well as a grant from the Steven Grossman Family Foundation. The Norwegian component of A‐TWAIN was funded by the “Arctic Ocean” flagship program at the Fram Centre. The data used in this study are available at http://atwain.whoi.edu and data.npolar.no (Sundfjord et al., 2017). The data from Fram Strait are available at https://doi.pangaea.de/10.1594/PANGAEA.853902
    Description: 2019-08-15
    Keywords: Atlantic Water ; Svalbard branch ; A‐TWAIN ; seasonality ; Arctic Ocean ; Fram Strait branch
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  • 38
    Publication Date: 2022-10-26
    Description: © The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in DeGrandpre, M. D., Lai, C., Timmermans, M., Krishfield, R. A., Proshutinsky, A., & Torres, D. Inorganic carbon and pCO(2) variability during ice formation in the Beaufort Gyre of the Canada Basin. Journal of Geophysical Research-Oceans, 124(6), (2019): 4017-4028, doi:10.1029/2019JC015109.
    Description: Solute exclusion during sea ice formation is a potentially important contributor to the Arctic Ocean inorganic carbon cycle that could increase as ice cover diminishes. When ice forms, solutes are excluded from the ice matrix, creating a brine that includes dissolved inorganic carbon (DIC) and total alkalinity (AT). The brine sinks, potentially exporting DIC and AT to deeper water. This phenomenon has rarely been observed, however. In this manuscript, we examine a ~1 year pCO2 mooring time series where a ~35‐μatm increase in pCO2 was observed in the mixed layer during the ice formation period, corresponding to a simultaneous increase in salinity from 27.2 to 28.5. Using salinity and ice based mass balances, we show that most of the observed increases can be attributed to solute exclusion during ice formation. The resulting pCO2 is sensitive to the ratio of AT and DIC retained in the ice and the mixed layer depth, which controls dilution of the ice‐derived AT and DIC. In the Canada Basin, of the ~92 μmol/kg increase in DIC, 17 μmol/kg was taken up by biological production and the remainder was trapped between the halocline and the summer stratified surface layer. Although not observed before the mooring was recovered, this inorganic carbon was likely later entrained with surface water, increasing the pCO2 at the surface. It is probable that inorganic carbon exclusion during ice formation will have an increasingly important influence on DIC and pCO2 in the surface of the Arctic Ocean as seasonal ice production and wind‐driven mixing increase with diminishing ice cover.
    Description: Research Associate Cory Beatty (University of Montana) prepared the CO2 instruments and helped with the mooring deployments and data processing. Pierce Fix (undergraduate intern, University of Montana) helped with the mass balance modeling. The moorings were designed and deployed by personnel at Woods Hole Oceanographic Institution. Michiyo Yamamoto‐Kawai (University of Tokyo) and Marty Davelaar (Institute of Ocean Sciences; IOS) provided the alkalinity and dissolved inorganic carbon data. We thank the captain, officers, crew, and chief scientists (Bill Williams and Sarah Zimmerman, IOS) of the CCGS Louis S. St. Laurent. The data used in this study are available through the U.S. National Science Foundation (NSF) Arctic Data Center (https://arcticdata.io). This research was made possible by grants from the NSF Arctic Observing Network program (ARC‐1107346, PLR‐1302884, PLR‐1504410, and PLR‐1723308).
    Keywords: Sea ice ; Dissolved inorganic carbon ; Carbon cycle ; Solute exclusion ; Partial pressure of CO2 ; Arctic Ocean
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