scholarly journals Whither the Chukchi Slope Current?

2020 ◽  
Vol 50 (6) ◽  
pp. 1717-1732
Author(s):  
Samuel Boury ◽  
Robert S. Pickart ◽  
Philippe Odier ◽  
Peigen Lin ◽  
Min Li ◽  
...  
Keyword(s):  
Chukchi Sea ◽  
Volume Transport ◽  
Wind Stress Curl ◽  
The North ◽  
Beaufort Gyre ◽  
The Pacific ◽  
Combined Use ◽  
Vorticity Dynamics ◽  
Chukchi Borderland ◽  
Chukchi Shelf

AbstractRecent measurements and modeling indicate that roughly half of the Pacific-origin water exiting the Chukchi Sea shelf through Barrow Canyon forms a westward-flowing current known as the Chukchi Slope Current (CSC), yet the trajectory and fate of this current is presently unknown. In this study, through the combined use of shipboard velocity data and information from five profiling floats deployed as quasi-Lagrangian particles, we delve further into the trajectory and the fate of the CSC. During the period of observation, from early September to early October 2018, the CSC progressed far to the north into the Chukchi Borderland. The northward excursion is believed to result from the current negotiating Hanna Canyon on the Chukchi slope, consistent with potential vorticity dynamics. The volume transport of the CSC, calculated using a set of shipboard transects, decreased from approximately 2 Sv (1 Sv ≡ 106 m3 s−1) to near zero over a period of 4 days. This variation can be explained by a concomitant change in the wind stress curl over the Chukchi shelf from positive to negative. After turning northward, the CSC was disrupted and four of the five floats veered offshore, with one of the floats permanently leaving the current. It is hypothesized that the observed disruption was due to an anticyclonic eddy interacting with the CSC, which has been observed previously. These results demonstrate that, at times, the CSC can get entrained into the Beaufort Gyre.

scholarly journals Mean Three-Dimensional Circulation in the Northeast Tropical Pacific*

2002 ◽  
Vol 32 (9) ◽  
pp. 2457-2471 ◽  
Author(s):  
William S. Kessler
Keyword(s):  
Three Dimensional ◽  
Tropical Pacific ◽  
Wind Forcing ◽  
Central American ◽  
Wind Stress Curl ◽  
The North ◽  
The Pacific ◽  
Sverdrup Balance ◽  
Counter Current ◽  
Depth Water

Abstract Historical XBT data are used to construct a mean climatology of the three-dimensional geostrophic circulation in the northeast tropical Pacific (southwest of Mexico and Central America) and are diagnosed based on linear dynamics forced with satellite scatterometer winds. Unlike the familiar central tropical Pacific, where the zonal scales are very large and the wind forcing nearly a function of latitude alone, the North Pacific east of about 120°W is strongly influenced by wind jets blowing through gaps in the Central American cordillera. The curl imposed by these wind jets imprints on the ocean, producing a distinctive pattern of thermocline topography and geostrophic currents that are consistent with the Sverdrup balance. Notably, the weakening of the North Equatorial Countercurrent near 110°W is due to the wind forcing. Given the observed stratification and wind stress curl, planetary vorticity conservation also determines the distribution of vertical velocity in the region, with about 3.5 Sv (Sv ≡ 106 m3 s−1) of upwelling through the base of the thermocline under the Costa Rica Dome. This upwelling is associated with stretching of the water column under the dome, which thereby causes the northern “Subsurface Counter Current” (SSCC or Tsuchiya Jet) to turn away from the equator; about half the transport of the SSCC upwells through the thermocline via this mechanism. This may be part of the process by which intermediate-depth water, flowing into the Pacific from the south, is brought to the surface and into the Northern Hemisphere.

scholarly journals Export of Arctic freshwater components through the Fram Strait 1998–2010

2012 ◽  
Vol 9 (4) ◽  
pp. 2749-2792
Author(s):  
B. Rabe ◽  
P. Dodd ◽  
E. Hansen ◽  
E. Falck ◽  
U. Schauer ◽  
...  
Keyword(s):  
Arctic Ocean ◽  
The Arctic ◽  
Ice Formation ◽  
Fram Strait ◽  
Pacific Water ◽  
Ice Melt ◽  
The North ◽  
Beaufort Gyre ◽  
The Pacific ◽  
The Arctic Ocean

Abstract. The East Greenland Current in the Western Fram Strait is an important pathway for liquid freshwater export from the Arctic Ocean to the Nordic Seas and the North Atlantic subpolar gyre. We analysed five hydrographic surveys and data from moored current meters around 79° N in the Western Fram Strait between 1998 and 2010. To estimate the composition of southward liquid freshwater transports, inventories of liquid freshwater and components from Dodd et al. (2012) were combined with transport estimates from an inverse model between 10.6° W and 4° E. The southward liquid freshwater transports through the section averaged to 92 mSv (2900 km3 yr−1), relative to a salinity of 34.9. The transports consisted of 123 mSv water from rivers and precipitation (meteoric water), 28 mSv freshwater from the Pacific and 60 mSv freshwater deficit due to brine from ice formation. Variability in liquid freshwater and component transports appear to have been partly due to advection of these water masses to the Fram Strait and partly due to variations in the local volume transport; an exception are Pacific Water transports, which showed little co-variability with volume transports. An increase in Pacific Water transports from 2005 to 2010 suggests a release of Pacific Water from the Beaufort Gyre, in line with an observed expansion of Pacific Water towards the Eurasian Basin. The co-variability of meteoric water and brine from ice formation suggests joint processes in the main sea ice formation regions on the Arctic Ocean shelves. In addition, enhanced levels of sea ice melt observed in 2009 likely led to reduced transports of brine from ice formation. At least part of this additional ice melt appears to have been advected from the Beaufort Gyre and from north of the Bering Strait towards the Fram Strait. The observed changes in liquid freshwater component transports are much larger than known trends in the Arctic liquid freshwater inflow from rivers and the Pacific. Instead, recent observations of an increased storage of liquid freshwater in the Arctic Ocean suggest a decreased export of liquid freshwater. This raises the question how fast the accumulated liquid freshwater will be exported from the Arctic Ocean to the deep water formation regions in the North Atlantic and if an increased export will occur through the Fram Strait.

Numerical modeling of the consequences of "marine heatwaves" in the North Pacific for the Arctic Ocean

2021 ◽  
Author(s):  
Elena Golubeva ◽  
Gennady Platov ◽  
Marina Kraineva
Keyword(s):  
Pacific Ocean ◽  
Chukchi Sea ◽  
Heat Content ◽  
The Arctic ◽  
Bering Strait ◽  
The North ◽  
Pacific Waters ◽  
The Pacific ◽  
The Pacific Ocean ◽  
The North Pacific

<p>As a result of the analysis of the NOAA surface temperature observational data (Huang et al., 2020), the periods corresponding to "marine heatwaves" in the northeastern Pacific Ocean (2013-2019) were identified. Marine heatwaves were defined as exceeding the 90th percentile threshold. The same analysis of the temperature in the Bering Strait's immediate vicinity showed anomalously warm waters in the same years. Analysis of the pressure field, which forms the atmosphere's dynamic state and affects the water circulation system of the Bering Sea, allowed us to assume the inflow of anomalously warm Pacific waters into the Chukchi Sea. To analyze the North Pacific heatwaves' consequences for the Arctic Ocean, we carried out two numerical experiments using the regional ocean and sea ice model SibCIOM (Golubeva et al., 2018) and NCEP/NCAR atmospheric reanalysis data (Kalnay et al., 1996). The first numerical experiment was carried out to calculate hydrodynamic and ice fields from January 2000 to November 2020 (Experiment 1). On the Arctic and the Pacific Ocean boundary in the Bering Strait, we used the monthly average climatic values ​​of the transport, temperature, and salinity of waters coming from the Pacific Ocean. Experiment 2 was carried out from 2014 to November 2020. The calculated values ​​of hydrological and ice characteristics obtained in Experiment 1 were used as the initial state for this experiment. In contrast to Experiment 1,  a heat flux exceeding the average climatic values ​​was set at the Bering Strait in Experiment 2. Its assignment was provided by using temperature values ​​from observational data in the Bering Strait vicinity (Huang et al., 2020). Comparison of monthly average hydrological and ice fields obtained in two numerical experiments and analysis of numerical results showed that an increase in the temperature of the Pacific waters entering the Arctic shelf through the Bering Strait leads to an increase in the heat content of the Chukchi Sea waters, heat transfer by currents in the surface and subsurface layers, a gradual increase in the heat content of the Beaufort Sea, and the reduction of Arctic ice cover. The increase in heat content in Experiment 2 for the Beaufort Sea was obtained in both the upper 50-meter and 250-meter layers.</p><p>The research is supported by the Russian Science Foundation, grant №. 19-17-00154.</p>

scholarly journals Pathways, Volume Transport, and Mixing of Abyssal Water in the Samoan Passage

2015 ◽  
Vol 45 (2) ◽  
pp. 562-588 ◽  
Author(s):  
Gunnar Voet ◽  
James B. Girton ◽  
Matthew H. Alford ◽  
Glenn S. Carter ◽  
Jody M. Klymak ◽  
...  
Keyword(s):  
Volume Transport ◽  
Heat Fluxes ◽  
Meridional Overturning Circulation ◽  
Turbulent Heat ◽  
Turbulent Dissipation ◽  
The North ◽  
The Pacific ◽  
Turbulent Heat Fluxes ◽  
Transport And Mixing ◽  
Heat Budgets

AbstractThe flow of dense water through the Samoan Passage accounts for the major part of the bottom water renewal in the North Pacific and is thus an important element of the Pacific meridional overturning circulation. A recent set of highly resolved measurements used CTD/LADCP, a microstructure profiler, and moorings to constrain the complex pathways and variability of the abyssal flow. Volume transport estimates for the dense northward current at several sections across the passage, calculated using direct velocity measurements from LADCPs, range from 3.9 × 106 to 6.0 × 106 ± 1 × 106 m3 s−1. The deep channel to the east and shallower pathways to the west carried about equal amounts of this volume transport, with the densest water flowing along the main eastern channel. Turbulent dissipation rates estimated from Thorpe scales and direct microstructure agree to within a factor of 2 and provide a region-averaged value of O(10−8) W kg−1 for layers colder than 0.8°C. Associated diapycnal diffusivities and downward turbulent heat fluxes are about 5 × 10−3 m2 s−1 and O(10) W m−2, respectively. However, heat budgets suggest heat fluxes 2–6 times greater. In the vicinity of one of the major sills of the passage, highly resolved Thorpe-inferred diffusivity and heat flux were over 10 times larger than the region-averaged values, suggesting the mismatch is likely due to undersampled mixing hotspots.

scholarly journals Increased Eddy Activity in the Northeastern Pacific during 1993–2011

2017 ◽  
Vol 31 (1) ◽  
pp. 387-399 ◽  
Author(s):  
Mengrong Ding ◽  
Pengfei Lin ◽  
Hailong Liu ◽  
Fei Chai
Keyword(s):  
Surface Wind ◽  
Mesoscale Eddy ◽  
Wind Stress Curl ◽  
Eddy Activity ◽  
The North ◽  
The Pacific ◽  
Northeastern Pacific ◽  
North Pacific Gyre Oscillation ◽  
Decadal Climate ◽  
Anticyclonic Eddies

Abstract The authors study the long-term behaviors of eddy activity in the northeastern Pacific (NEP) and the dynamic mechanism behind them, using the third version of the mesoscale eddy trajectory dataset released by Chelton and Schlax as well as other observation and reanalysis datasets. Both the eddy kinetic energy (EKE) and eddy occurrence number (EON) present prominent increases, with interannual and decadal variabilities northeast of the Hawaiian–Emperor seamounts. The increasing EON is mainly due to the prolongation of eddy lifetimes associated with eddy intensification, particularly for anticyclonic eddies (AEs). The prolongation of eddy lifetimes results from weakened surface winds. The enhanced anticyclonic wind stress curl (WSC) injects more energy into the AEs in the study domain, providing a more suitable environment for their growth. The decadal climate modes, such as the Pacific decadal oscillation (PDO) and the North Pacific Gyre Oscillation (NPGO), may also modulate eddy activity in the NEP by exerting fluctuations in the surface wind system.

scholarly journals Sea Ice Reduction During Winter of 2017 Due to Oceanic Heat Supplied by Pacific Water in the Chukchi Sea, West Arctic Ocean

2021 ◽  
Vol 8 ◽  
Author(s):  
Yingjie Wang ◽  
Na Liu ◽  
Zhanhai Zhang
Keyword(s):  
Sea Ice ◽  
Chukchi Sea ◽  
Heat Content ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Pacific Water ◽  
Sea Ice Concentration ◽  
The Pacific ◽  
Arctic Sea ◽  
Chukchi Shelf

Over the past few decades, the areal extent of the Arctic sea ice cover has decreased. During the winter of 2017, negative sea ice concentration anomalies occurred mainly in the Chukchi Sea and adjacent seas. The properties of Pacific water through the Bering Strait have changed in recent years. To highlight the role of the Pacific inflow during the 2017 Arctic sea ice retreat, we used mooring measurements and conductivity–temperature–depth (CTD) data to quantify the effect of inflow on sea ice in the Chukchi shelf. In September 2017, the temperature of the Pacific inflow was relatively high compared with the multi-year average, especially in the shelf north of 69°N where the temperature anomaly was generally greater than 1°C. The average heat content of each CTD station in September 2017 ranged from 0.77 to 1.58 GJ m–2, where each station was 0.25 GJ m–2 higher than the multi-year average. In the central shelf of the Chukchi Sea, the temperature of the 25–40 m layer increased after late May, and decreased after mid-September. The Pacific inflow could have provided a large amount of heat to the Chukchi shelf, the accumulated convective heat transported to the surface from September to October was approximately 1.68 × 1018 J and it impacted the sea ice growth conditions.

scholarly journals Holocene dynamics in the Bering Strait inflow to the Arctic and the Beaufort Gyre circulation based on sedimentary records from the Chukchi Sea

2016 ◽  
Author(s):  
Masanobu Yamamoto ◽  
Seung Il Nam ◽  
Leonid Polyak ◽  
Daisuke Kobayashi ◽  
Kenta Suzuki ◽  
...  
Keyword(s):  
North Atlantic ◽  
Chukchi Sea ◽  
The Arctic ◽  
Bering Strait ◽  
The Holocene ◽  
The North ◽  
Beaufort Gyre ◽  
The North Atlantic ◽  
Gyre Circulation

Abstract. The Beaufort Gyre (BG) and the Bering Strait inflow (BSI) are important elements of the Arctic Ocean circulation system and major controls on the distribution of Arctic sea ice. We report records of the quartz/feldspar and chlorite/illite ratios in two sediment cores from the northern Chukchi Sea providing insights into the long-term dynamics of the BG circulation and the BSI during the Holocene. The quartz/feldspar ratio, a proxy of the BG strength, gradually decreased during the Holocene, suggesting a long-term decline in the BG strength, consistent with orbitally-controlled decrease in summer insolation. We suppose that the BG rotation weakened as a result of increasing stability of sea-ice cover at the margins of the Canada Basin, driven by decreasing insolation. Millennial to multi-centennial variability in the quartz/feldspar ratio (the BG circulation) is consistent with fluctuations in solar irradiance, suggesting that solar activity affected the BG strength on these timescales. The BSI, approximated by the chlorite/illite record, shows intensified flow from the Bering Sea to the Arctic during the middle Holocene, which is attributed primarily to the effect of an overall weaker Aleutian Low. This middle Holocene strengthening of the BSI was coeval with intense subpolar gyre circulation in the North Atlantic. We propose that the BSI is linked with the North Atlantic circulation via an atmospheric teleconnection between the Aleutian and Icelandic Lows. A correspondence between the Holocene variability of the BSI and North Atlantic Drift suggests that this connection is involved in a mechanism muting salinity changes in the North Atlantic, and thereby stabilizing the Atlantic Meridional Overturning Circulation.

WTO SUCCESSOR TO GATT

1997 ◽  
Vol 14 (2) ◽  
pp. 172-187
Author(s):  
Arif Sultan
Keyword(s):  
North Africa ◽  
European Economic Community ◽  
Developed Countries ◽  
Economic Community ◽  
Land Area ◽  
The North ◽  
Muslim Countries ◽  
The Pacific ◽  
The World ◽  
The Developed Countries

Within a short span of time a number of economic blocs have emergedon the world horizon. In this race, all countriedeveloped, developingand underdeveloped-are included. Members of the North America FreeTrade Agreement (NAITA) and the European Economic Community(EEC) are primarily of the developed countries, while the EconomicCooperation Organization (ECO) and the Association of South EastAsian Nations (ASEAN) are of the developing and underdevelopedAsian countries.The developed countries are scrambling to create hegemonies throughthe General Agreement on Tariff and Trade (GATT). In these circumstances,economic cooperation among Muslim countries should be onthe top of their agenda.Muslim countries today constitute about one-third of the membershipof the United Nations. There are around 56 independentMuslim states with a population of around 800 million coveringabout 20 percent of the land area of the world. Stretchingbetween Atlantic and the Pacific Oceans, the Muslim Worldstraddles from North Africa to Indonesia, in two major Islamicblocs, they are concentrated in the heart of Africa to Indonesia,in two major blocs, they are concentrated in the heart of Africaand Asia and a smaller group in South and Southeast Asia.'GATT is a multilateral agreement on tariffs and trade establishing thecode of rules, regulations, and modalities regulating and operating internationaltrade. It also serves as a forum for discussions and negotiations ...

scholarly journals The evolving response of mesopelagic fishes to declining midwater oxygen concentrations in the southern and central California Current

2018 ◽  
Vol 76 (3) ◽  
pp. 626-638 ◽  
Author(s):  
J Anthony Koslow ◽  
Pete Davison ◽  
Erica Ferrer ◽  
S Patricia A Jiménez Rosenberg ◽  
Gerardo Aceves-Medina ◽  
...  
Keyword(s):  
Baja California ◽  
Southern Oscillation ◽  
Global Climate ◽  
California Current ◽  
Deep Ocean ◽  
Near Surface ◽  
Oxygen Minimum Zones ◽  
The North ◽  
The Pacific ◽  
Oxygen Concentrations

Abstract Declining oxygen concentrations in the deep ocean, particularly in areas with pronounced oxygen minimum zones (OMZs), are a growing global concern related to global climate change. Its potential impacts on marine life remain poorly understood. A previous study suggested that the abundance of a diverse suite of mesopelagic fishes off southern California was closely linked to trends in midwater oxygen concentration. This study expands the spatial and temporal scale of that analysis to examine how mesopelagic fishes are responding to declining oxygen levels in the California Current (CC) off central, southern, and Baja California. Several warm-water mesopelagic species, apparently adapted to the shallower, more intense OMZ off Baja California, are shown to be increasing despite declining midwater oxygen concentrations and becoming increasingly dominant, initially off Baja California and subsequently in the CC region to the north. Their increased abundance is associated with warming near-surface ocean temperature, the warm phase of the Pacific Decadal oscillation and Multivariate El Niño-Southern Oscillation Index, and the increased flux of Pacific Equatorial Water into the southern CC.

The Relevance of Old World Archaeology to the First Entry of Man into New Worlds: Colonization Seen from the Antipodes

1977 ◽  
Vol 8 (1) ◽  
pp. 128-148 ◽  
Author(s):  
Sylvia J. Hallam
Keyword(s):  
Demographic Data ◽  
Ecological Zones ◽  
The North ◽  
Technological Potential ◽  
The Pacific ◽  
Peopling Of The Americas ◽  
Rapid Spread ◽  
History Of ◽  
Economic Innovation ◽  
Considerable Complexity

Following several discussions in recent numbers of Quaternary Research on the peopling of the Americas, this paper suggests that movements into the New World should be viewed in the wider context of subsistence, technology, and movement around the western littorals of the Pacific, resulting in the colonization not of one but of two new continents by men out of Asia. Specific points which have been raised by these recent papers are reviewed in the light of Australian, Wallacian, and East Asian data.(1) The earliness of watercraft is evidenced by chronology of the human diaspora through Wallacia and Greater Australia.(2) The simplistic nomenclature of chopper-flake traditions masks considerable complexity and technological potential, revealed in detailed Antipodean studies.(3) These traditions also have great potential for adapting to differing ecological zones, evidenced within Greater Australia; and for technological and economic innovation there, through Southeast Asia, and to Japan and the north Asian littoral.(4) The history of discovery and the nature of the evidence from Australia cannot validly be used to controvert early dates in the Americas.(5) Demographic data from Australia suggest that total commitment to a rapid-spread “bowwave” model for the peopling of new continents may be unwise.

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