scholarly journals Sources of Eddy Energy Simulated by a Model of the Northeast Pacific Ocean

2008 ◽  
Vol 38 (10) ◽  
pp. 2283-2293 ◽  
Author(s):  
Jennifer Shore ◽  
Michael W. Stacey ◽  
Daniel G. Wright
Keyword(s):  
Pacific Ocean ◽  
Spatial Scales ◽  
Gulf Of Alaska ◽  
North Coast ◽  
Mean Flow ◽  
Spectral Nudging ◽  
The North ◽  
The Mean ◽  
Eddy Field ◽  
Mean State

Abstract This paper examines the energy sources for eddy variability in the Gulf of Alaska using a numerical model and a novel form of data assimilation referred to as spectral nudging. Spectral nudging is distinguished from conventional nudging by its ability to operate only on specified frequency and wavenumber bands; in the present case, only the subannual variability is nudged, and only on spatial scales of 100 km or more. By using this approach, the broad-brush aspects of the model’s mean state are constrained to remain near the mean climatological conditions, while the simulated eddy field is determined by the model dynamics. Simulations of the North Pacific Ocean with a 0.25° horizontal resolution and spectral nudging have been previously shown to produce eddy fields that are significantly more energetic and more realistic than those produced by prognostic (i.e., not nudged) simulations. The analysis of the spectrally nudged model results undertaken here reveals the tendency of the circulation to be both baroclinically and barotropically unstable in different regions and to differing degrees. Along the north coast of the Gulf of Alaska, the simulation suggests that barotropic instability is more important overall as an energy source for eddies than is baroclinic instability. Along the east coast of the Gulf of Alaska, the simulation suggests that both baroclinic and barotropic instabilities are important. Although the overall energy transfer is from the mean state to the eddy field, there are regions of the model, particularly along the north coast of the Gulf of Alaska, where the transfer of energy is from the eddy field to the mean flow.

Biology and Management of Dogfish Sharks

2009 ◽  
Keyword(s):  
Stable Isotope ◽  
Pacific Ocean ◽  
Food Webs ◽  
Trophic Position ◽  
Nitrogen Isotope ◽  
Isotope Ratios ◽  
Gulf Of Alaska ◽  
The North ◽  
Northeastern Pacific ◽  
The Mean

Abstract.—Spiny dogfish <em>Squalus acanthias </em>biomass has increased in the Gulf of Alaska, yet little is known about the ecological niche that dogfish fill in this ecosystem. Trophic position is an important indicator of the ecological role of an organism. To explore the trophic position of dogfish we analyzed the nitrogen and carbon stable isotope ratios of 60 dogfish from five locations between Washington and the Gulf of Alaska. The mean δ<sup>15</sup>N values for dogfish ranged from 12.0‰ (central Gulf of Alaska) to 13.4‰ (Howe Sound, British Columbia) and the mean δ<sup>13</sup>C values ranged from –21.3‰ (Yakutat Bay, Alaska) to –17.9‰ (Puget Sound, Washington). Sites to the north tended to be significantly depleted in the heavy isotopes of both nitrogen and carbon. The differences in nitrogen isotope ratios among sites were attributed to potential changes in dogfish feeding behavior and trophic position. Differences in carbon isotope ratios suggested that dogfish utilize different food webs along the northeastern Pacific Ocean shelf. Additionally it was hypothesized that feeding differentially in offshore versus inshore food webs or targeting pelagic versus benthic prey species may explain the isotopic variability. These results are preliminary and require additional tests before conclusions can be made about the trophic position of dogfish in this region. Future work will explore stable isotope variability at lower trophic levels to test the hypothesis that entire food webs are isotopically shifted owing to differences in isotopic fractionation at the base of the food web. Also, trophic level differences among dogfish size classes and between sexes will be explored among a greater diversity of locations to better describe the ecological consequences of increased biomass of dogfish in the northeastern Pacific Ocean.

scholarly journals Energetics of Eddy–Mean Flow Interactions along the Western Boundary Currents in the North Pacific

2019 ◽  
Vol 49 (3) ◽  
pp. 789-810 ◽  
Author(s):  
Xiaomei Yan ◽  
Dujuan Kang ◽  
Enrique N. Curchitser ◽  
Chongguang Pang
Keyword(s):  
Kinetic Energy ◽  
Western Boundary ◽  
Mean Flow ◽  
Boundary Currents ◽  
The North ◽  
Flow Interactions ◽  
The Mean ◽  
Eddy Field ◽  
The Kuroshio ◽  
The North Pacific

AbstractThe energetics of eddy–mean flow interactions along two western boundary currents of the North Pacific, the Kuroshio and Ryukyu Currents, are systematically investigated using 22 years of numerical data from the Ocean General Circulation Model for the Earth Simulator (OFES). For the time-mean and time-varying flow fields, all the energy components and conversions exhibit inhomogeneous spatial distributions. In the two currents, complex cross-stream and along-stream variations are seen in the eddy–mean flow energy conversions. East of Taiwan, the kinetic energy is mainly transferred from the mean flow to the eddy field through barotropic instability, whereas the baroclinic energy conversions form a meridional dipole structure caused by the topographic constraint. In the northern area, particularly, the eddy field drains 2.25 × 108 W of kinetic energy and releases 2.82 × 108 W of available potential energy when interacting with the mean flow, indicating that mesoscale eddies impinging on the Kuroshio decay with baroclinic inverse energy cascades. In the Ryukyu Current, inverse energy conversions from the eddy field to the mean flow also dominate the power transfer in the subsurface layer. The eddy field transfers 0.16 × 108 W of kinetic energy and 1.89 × 108 W of available potential energy to the mean flow, suggesting that meososcale eddies play an important role in maintaining the velocity and hydrographic structure of the current. In other areas, both barotropic and baroclinic instabilities contribute to the generation of eddy kinetic energy with the latter one providing more than 3 times as much power as the former one.

Bankarization in the first European cities with an equal number of Muslim and Christian inhabitants

2017 ◽  
Vol 10 (4) ◽  
pp. 554-580
Author(s):  
Miguel Ángel Pérez-Castro ◽  
Miguel Ángel Montero-Alonso ◽  
Akram Abderrahman-Azaar
Keyword(s):  
North Coast ◽  
Content Type ◽  
European Cities ◽  
The North ◽  
Financial Depth ◽  
Financial Framework ◽  
European Banks ◽  
The Mean ◽  
Different Cultures ◽  
Near Future

Purpose This paper aims to analyze the situation of the financial system in the Spanish-governed cities of Melilla and Ceuta, Christian and Muslim cities located on the north coast of Africa, and compared it with the mean bankarization level in the rest of Spain in 2000-2015. Design/methodology/approach Although different calculation methods have been proposed, most authors agree that the bankarization level of a country or a territory reflects the development of the society as a whole and has a positive correlation with economic growth. The indicators of financial depth proposed by these researchers are not only the ratio between variables such as loans, deposits, etc., but also the ratios of these variables to the population and the gross domestic product (GDP) of the country or territory. Findings The results obtained revealed that there are differences between these two North African Spanish cities. Furthermore, the financing gap between the mean bankarization levels of these cities and those of mainland Spain was found to be even larger than most of the other economic indicators (GDP per capita and the unemployment rate). Practical implications The authors are convinced that the manuscript is a contribution of great interest for serving pilot experience in cities wishing to offer a development of traditional banking and Islamic banking. The paper should be of interest to readers in the areas of finance systems and commercial banks where two different cultures coexist. Originality/value This is the first research study on the financial framework of European cities whose populations have an approximately equal percentage of Christians and Muslims. The data reflected the existence of savings and loan methods parallel to conventional banking. The conclusion was that in the near future, it would be advisable for European banks to take into account the cultural customs and religious practices of potential Muslim clients.

scholarly journals The Mean State and Variability of the North Atlantic Circulation: A Perspective From Ocean Reanalyses

2019 ◽  
Vol 124 (12) ◽  
pp. 9141-9170 ◽  
Author(s):  
L. C. Jackson ◽  
C. Dubois ◽  
G. Forget ◽  
K. Haines ◽  
M. Harrison ◽  
...  
Keyword(s):  
North Atlantic ◽  
The North ◽  
Ocean Reanalyses ◽  
The Mean ◽  
The North Atlantic ◽  
Mean State

Sheep production on the north coast of New South Wales. 2. A feasibility study of prime lamb production

1980 ◽  
Vol 20 (102) ◽  
pp. 25
Author(s):  
RDH Cohen
Keyword(s):  
New South ◽  
New South Wales ◽  
Live Weight ◽  
Climatic Conditions ◽  
North Coast ◽  
The North ◽  
South Wales ◽  
Short Period ◽  
The Mean ◽  
Sheep Production

Lamb production was studied in an experiment that ran for four years, 1968 to 1972, at Grafton, New South Wales, in a region where no commercial sheep are grown. Merino and Dorset Horn x Merino ewes stocked at 15 ewes ha-1 were mated in spring to Border Leicester rams and the lambs sold for slaughter in October. The mean number of lambs born per 100 ewes mated was 81.7 for crossbred ewes and 48.4 for Merino ewes (P< 0.05) and the mean carcase weights of the lambs were 14.8 kg and 12.7 kg, respectively (P< 0.01). The mean weight of fleeces cut from Merino ewes (3.24 kg) was greater (P< 0.01) than that from crossbred ewes (2.58 kg). The ewes were treated with anthelmintics either every four weeks or according to climatic conditions. There were no significant differences between the anthelmintic treatments for lamb liveweights at birth, weaning or slaughter; carcase weight; ewe fleece weight; or mortality rate. Treatment every four weeks increased ewe live weight during only one short period from August 1971 to February 1972 (P< 0.05). Data from this experiment compared favourably with survey data for the high rainfall zone in Australia and it was concluded that prime lamb production on the north coast of New South Wales is biologically feasible.

Does ocean resolution affect the rate of AMOC weakening?

2020 ◽  
Author(s):  
Helene Hewitt ◽  
Laura Jackson ◽  
Malcolm Roberts ◽  
Dorotea Iovino ◽  
Torben Koenigk ◽  
...  
Keyword(s):  
Deep Water ◽  
Horizontal Resolution ◽  
Meridional Overturning Circulation ◽  
Subpolar Gyre ◽  
Deep Water Formation ◽  
North Atlantic Current ◽  
The North ◽  
Water Formation ◽  
The Mean ◽  
Mean State

&lt;p&gt;We examine the weakening of the Atlantic Meridional Overturning Circulation (AMOC) in response to increasing CO&lt;sub&gt;2&lt;/sub&gt;&amp;#160;at different horizontal resolutions in HadGEM3-GC3.1 and in a small ensemble of models with differing resolutions. There is a strong influence of the ocean mean state on the AMOC weakening: models with a more saline western subpolar gyre have a greater formation of deep water there. This makes the AMOC more susceptible to weakening from an increase in CO&lt;sub&gt;2&lt;/sub&gt;&amp;#160;since weakening ocean heat transports weaken the contrast between ocean and atmospheric temperatures and hence weaken the buoyancy loss. In models with a greater proportion of deep water formation further north (in the Greenland-Iceland-Norwegian basin), deep-water formation can be maintained by shifting further north to where there is a greater ocean-atmosphere temperature contrast.&lt;/p&gt;&lt;p&gt;We show that ocean horizontal resolution can have an impact on the mean state, and hence AMOC weakening. In the models examined, those with higher resolutions tend to have a more westerly path of the North Atlantic Current and hence greater impact of the warm, saline subtropical Atlantic waters on the western subpolar gyre. This results in greater dense water formation in the western subpolar gyre. Although there is some improvement of the higher resolution models over the lower resolution models in terms of the mean state, both still have biases and it is not clear which biases are the most important for influencing the AMOC strength and response to increasing CO&lt;sub&gt;2&lt;/sub&gt;.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

Biology of the Pacific Pomfret (Brama japonica) in the North Pacific Ocean

1993 ◽  
Vol 50 (12) ◽  
pp. 2608-2625 ◽  
Author(s):  
William G. Pearcy ◽  
Joseph P. Fisher ◽  
Mary M. Yoklavich
Keyword(s):  
Pacific Ocean ◽  
North Pacific ◽  
North Pacific Ocean ◽  
Gulf Of Alaska ◽  
Small Fish ◽  
Large Fish ◽  
The North ◽  
The Pacific ◽  
Subarctic Current ◽  
The North Pacific

Abundances of Pacific pomfret (Brama japonica), an epipelagic fish of the North Pacific Ocean, were estimated from gillnet catches during the summers of 1978–1989. Two size modes were common: small pomfret <1 yr old, and large fish ages 1–6. Large and small fish moved northward as temperatures increased, but large fish migrated farther north, often into the cool, low-salinity waters of the Central Subarctic Pacific. Lengths of small fish were positively correlated with latitude and negatively correlated with summer surface temperature. Interannual variations in the latitude of catches correlated with surface temperatures. Large catches were made in the eastern Gulf of Alaska (51–55°N) but modes of small pomfret were absent here, and large fish were rare at these latitudes farther to the west. Pomfret grow rapidly during their first two years of life. They are pectoral fin swimmers that swim continuously. They prey largely on gonatid squids in the region of the Subarctic Current in the Gulf of Alaska during summer. No evidence was found for aggregations on a scale ≤1 km. Differences in the incidence of tapeworm, spawning seasons, and size distributions suggest the possibility of discrete populations in the North Pacific Ocean.

scholarly journals The Rapid Warming of the North Atlantic Ocean in the Mid-1990s in an Eddy-Permitting Ocean Reanalysis (1982–2013)

2016 ◽  
Vol 29 (15) ◽  
pp. 5417-5430 ◽  
Author(s):  
Chunxue Yang ◽  
Simona Masina ◽  
Alessio Bellucci ◽  
Andrea Storto
Keyword(s):  
Atlantic Ocean ◽  
Heat Transport ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Ocean Reanalysis ◽  
The North ◽  
Mean Temperature ◽  
The Mean ◽  
The North Atlantic ◽  
Mean State

Abstract The rapid warming in the mid-1990s in the North Atlantic Ocean is investigated by means of an eddy-permitting ocean reanalysis. Both the mean state and variability, including the mid-1990s warming event, are well captured by the reanalysis. An ocean heat budget applied to the subpolar gyre (SPG) region (50°–66°N, 60°–10°W) shows that the 1995–99 rapid warming is primarily dictated by changes in the heat transport convergence term while the surface heat fluxes appear to play a minor role. The mean negative temperature increment suggests a warm bias in the model and data assimilation corrects the mean state of the model, but it is not crucial to reconstruct the time variability of the upper-ocean temperature. The decomposition of the heat transport across the southern edge of the SPG into time-mean and time-varying components shows that the SPG warming is mainly associated with both the anomalous advection of mean temperature and the mean advection of temperature anomalies across the 50°N zonal section. The relative contributions of the Atlantic meridional overturning circulation (AMOC) and gyre circulation to the heat transport are also analyzed. It is shown that both the overturning and gyre components are relevant to the mid-1990s warming. In particular, the fast adjustment of the barotropic circulation response to the NAO drives the anomalous transport of mean temperature at the subtropical/subpolar boundary, while the slowly evolving AMOC feeds the large-scale advection of thermal anomalies across 50°N. The persistently positive phase of the NAO during the years prior to the rapid warming likely favored the cross-gyre heat transfer and the following SPG warming.

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