scholarly journals Notes on the Foraminiferal Genera <i>Laterostomella</i> De Klasz and Rérat and <i>Streptochilus</i> Brönnimann and Resig

1989 ◽  
Vol 8 (2) ◽  
pp. 215-225 ◽  
Author(s):  
Ivan De Klasz ◽  
Dick Kroon ◽  
Jan E. Van Hinte
Keyword(s):  
North Atlantic ◽  
Morphological Variability ◽  
Isotopic Data ◽  
General Shape ◽  
The North ◽  
The Pacific ◽  
Upper Cenozoic ◽  
The Indian Ocean ◽  
The North Atlantic ◽  
First Time

Abstract. the biserial foraminiferal genera Laterostomella de Klasz &amp; Rérat (1962) and Streptochilus Brönnimann &amp; Resig (1971) have been described from the Miocene of Gabon and from Miocene to Recent levels of the Pacific and Indian Oceans, respectively. Both genera have since been found in the Upper Cenozoic of other regions: Laterostomella at Rockall Bank in the North Atlantic and in Papua-New-Guinea, and modern Streptochilus specimens were collected with plankton nets in the northern part of the Indian Ocean. The apertural characteristics of Laterostomella and Streptochilus show marked similarities as does the general shape of Laterostomella guembeliniformis with some Streptochilus species. However, other Laterostomella species have a very different form and isotopic data indicate that Laterostomella has a benthic and Streptochilus a planktic life habitat. We conclude that both genera are valid. For the first time SEM pictures of Laterostomella species are presented to show morphological variability, surface texture and aperture types.

Amblyopsoides ohlinii (W.M. Tattersall, 1951) (Peracarida, Mysida, Mysidae) in western Mexico

Zootaxa ◽  
2020 ◽  
Vol 4878 (1) ◽  
pp. 169-181
Author(s):  
JOSÉ CARLOS HERNÁNDEZ-PAYÁN ◽  
MICHEL E. HENDRICKX
Keyword(s):  
North Atlantic ◽  
First Record ◽  
Sem Images ◽  
Western Mexico ◽  
The North ◽  
The Pacific ◽  
The Pacific Ocean ◽  
The North Atlantic ◽  
First Time ◽  
The North Pacific

The rare pelagic mysid Amblyopsoides ohlinii (W.M. Tattersall, 1951) is reported for the first time off western Mexico and represents the first record in the Pacific Ocean south of Japan and the Kurile-Kamchatka Trench. So far, this species only has been recorded from seven localities in the North Atlantic and in the North Pacific. A complete description of the only specimen available (a male), including illustrations of all appendages and SEM images of the mandibles, is provided.

A biological consequence of reducing Arctic ice cover: arrival of the Pacific diatom Neodenticula seminae in the North Atlantic for the first time in 800 000 years

2007 ◽  
Vol 13 (9) ◽  
pp. 1910-1921 ◽  
Author(s):  
PHILIP C. REID ◽  
DAVID G. JOHNS ◽  
MARTIN EDWARDS ◽  
MICHEL STARR ◽  
MICHEL POULIN ◽  
...  
Keyword(s):  
North Atlantic ◽  
Ice Cover ◽  
Biological Consequence ◽  
The North ◽  
The Pacific ◽  
The North Atlantic ◽  
Arctic Ice ◽  
First Time

scholarly journals The Meridional Shift of the Midlatitude Westerlies over Arid Central Asia during the Past 21 000 Years Based on the TraCE-21ka Simulations

2020 ◽  
Vol 33 (17) ◽  
pp. 7455-7478
Author(s):  
Nanxuan Jiang ◽  
Qing Yan ◽  
Zhiqing Xu ◽  
Jian Shi ◽  
Ran Zhang
Keyword(s):  
Indian Ocean ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Last Deglaciation ◽  
The Past ◽  
The North ◽  
External Forcings ◽  
The Indian Ocean ◽  
The Last Deglaciation ◽  
The North Atlantic

AbstractTo advance our knowledge of the response of midlatitude westerlies to various external forcings, we investigate the meridional shift of midlatitude westerlies over arid central Asia (ACA) during the past 21 000 years, which experienced more varied forcings than the present day based on a set of transient simulations. Our results suggest that the evolution of midlatitude westerlies over ACA and driving factors vary with time and across seasons. In spring, the location of midlatitude westerlies over ACA oscillates largely during the last deglaciation, driven by meltwater fluxes and continental ice sheets, and then shows a long-term equatorward shift during the Holocene controlled by orbital insolation. In summer, orbital insolation dominates the meridional shift of midlatitude westerlies, with poleward and equatorward migration during the last deglaciation and the Holocene, respectively. From a thermodynamic perspective, variations in zonal winds are linked with the meridional temperature gradient based on the thermal wind relationship. From a dynamic perspective, variations in midlatitude westerlies are mainly induced by anomalous sea surface temperatures over the Indian Ocean through the Matsuno–Gill response and over the North Atlantic Ocean by the propagation of Rossby waves, or both, but their relative importance varies across forcings. Additionally, the modeled meridional shift of midlatitude westerlies is broadly consistent with geological evidence, although model–data discrepancies still exist. Overall, our study provides a possible scenario for a meridional shift of midlatitude westerlies over ACA in response to various external forcings during the past 21 000 years and highlights important roles of both the Indian Ocean and the North Atlantic Ocean in regulating Asian westerlies, which may shed light on the behavior of westerlies in the future.

The North Atlantic anchor: Canada and the Pacific Century

2018 ◽  
Vol 73 (3) ◽  
pp. 364-378 ◽  
Author(s):  
Kim Richard Nossal
Keyword(s):  
North Atlantic ◽  
Policy Making ◽  
International Order ◽  
Asia Pacific ◽  
The North ◽  
The Pacific ◽  
Defence Policy ◽  
Key Driver ◽  
The North Atlantic ◽  
Strategic Perspective

This paper surveys Canada’s ambivalence towards the Asia Pacific, and seeks to put that ambivalence into the broader context of the dominant strategic perspective in Canada that has privileged, and continues to privilege, a North Atlantic focus for Canadian foreign and defence policy. It argues that Canada’s laggardly approach to Asia Pacific diplomacy can be best explained by the widespread perception among Canadians—and their government—that the North Atlantic alliance should remain the key driver of Canadian foreign and defence policy. Indeed, this geostrategic outlook has actually intensified with the election of Donald J. Trump and his unorthodox approach to the transatlantic alliance and the liberal international order. I argue that this North Atlantic outlook, so dominant for so much of Canada’s history, will continue to anchor Canadian foreign and defence policy, making Canada’s engagement in the Asia Pacific more problematic.

scholarly journals The seasonal cycle of δ<sup>3</sup>C<sub>DIC</sub> in the North Atlantic subpolar gyre

2014 ◽  
Vol 11 (6) ◽  
pp. 1683-1692 ◽  
Author(s):  
V. Racapé ◽  
N. Metzl ◽  
C. Pierre ◽  
G. Reverdin ◽  
P. D. Quay ◽  
...  
Keyword(s):  
North Atlantic ◽  
Dissolved Inorganic Carbon ◽  
Ocean Dynamics ◽  
Subpolar Gyre ◽  
The North ◽  
Winter Convection ◽  
North Atlantic Subpolar Gyre ◽  
The North Atlantic ◽  
First Time ◽  
Negative Linear Relationship

Abstract. This study introduces for the first time the δ13CDIC seasonality in the North Atlantic subpolar gyre (NASPG) using δ13CDIC data obtained in 2005–2006 and 2010–2012 with dissolved inorganic carbon (DIC) and nutrient observations. On the seasonal scale, the NASPG is characterized by higher δ13CDIC values during summer than during winter, with a seasonal amplitude between 0.70 ± 0.10‰ (August 2010–March 2011) and 0.77 ± 0.07‰ (2005–2006). This is mainly attributed to photosynthetic activity in summer and to a deep remineralization process during winter convection, sometimes influenced by ocean dynamics and carbonate pumps. There is also a strong and negative linear relationship between δ13CDIC and DIC during all seasons. Winter data also showed a large decrease in δ13CDIC associated with an increase in DIC between 2006 and 2011–2012, but the observed time rates (−0.04‰ yr−1and +1.7 μmol kg−1 yr−1) are much larger than the expected anthropogenic signal.

scholarly journals The Linear Sensitivity of the North Atlantic Oscillation and Eddy-Driven Jet to SSTs

2019 ◽  
Vol 32 (19) ◽  
pp. 6491-6511 ◽  
Author(s):  
Hugh S. Baker ◽  
Tim Woollings ◽  
Chris E. Forest ◽  
Myles R. Allen
Keyword(s):  
Indian Ocean ◽  
North Atlantic Oscillation ◽  
North Atlantic ◽  
High Sensitivity ◽  
Internal Variability ◽  
The North ◽  
The Indian Ocean ◽  
The North Atlantic ◽  
The North Atlantic Oscillation ◽  
The Impact

Abstract The North Atlantic Oscillation (NAO) and eddy-driven jet contain a forced component arising from sea surface temperature (SST) variations. Due to large amounts of internal variability, it is not trivial to determine where and to what extent SSTs force the NAO and jet. A linear statistical–dynamic method is employed with a large climate ensemble to compute the sensitivities of the winter and summer NAO and jet speed and latitude to the SSTs. Key regions of sensitivity are identified in the Indian and Pacific basins, and the North Atlantic tripole. Using the sensitivity maps and a long observational SST dataset, skillful reconstructions of the NAO and jet time series are made. The ability to skillfully forecast both the winter and summer NAO using only SST anomalies is also demonstrated. The linear approach used here allows precise attribution of model forecast signals to SSTs in particular regions. Skill comes from the Atlantic and Pacific basins on short lead times, while the Indian Ocean SSTs may contribute to the longer-term NAO trend. However, despite the region of high sensitivity in the Indian Ocean, SSTs here do not provide significant skill on interannual time scales, which highlights the limitations of the imposed SST approach. Given the impact of the NAO and jet on Northern Hemisphere weather and climate, these results provide useful information that could be used for improved attribution and forecasting.

scholarly journals Biogeochemistry of the North Atlantic during oceanic anoxic event 2: role of changes in ocean circulation and phosphorus input

2014 ◽  
Vol 11 (4) ◽  
pp. 977-993 ◽  
Author(s):  
I. Ruvalcaba Baroni ◽  
R. P. M. Topper ◽  
N. A. G. M. van Helmond ◽  
H. Brinkhuis ◽  
C. P. Slomp
Keyword(s):  
Pacific Ocean ◽  
Ocean Circulation ◽  
North Atlantic ◽  
Primary Productivity ◽  
Low Oxygen ◽  
Deep Basin ◽  
The North ◽  
The Pacific ◽  
The Pacific Ocean ◽  
The North Atlantic

Abstract. The geological record provides evidence for the periodic occurrence of water column anoxia and formation of organic-rich deposits in the North Atlantic Ocean during the mid-Cretaceous (hereafter called the proto-North Atlantic). Both changes in primary productivity and oceanic circulation likely played a role in the development of the low-oxygen conditions. Several studies suggest that an increased input of phosphorus from land initiated oceanic anoxic events (OAEs). Other proposed mechanisms invoke a vigorous upwelling system and an ocean circulation pattern that acted as a trap for nutrients from the Pacific Ocean. Here, we use a detailed biogeochemical box model for the proto-North Atlantic to analyse under what conditions anoxia could have developed during OAE2 (94 Ma). The model explicitly describes the coupled water, carbon, oxygen and phosphorus cycles for the deep basin and continental shelves. In our simulations, we assume the vigorous water circulation from a recent regional ocean model study. Our model results for pre-OAE2 and OAE2 conditions are compared to sediment records of organic carbon and proxies for photic zone euxinia and bottom water redox conditions (e.g. isorenieratane, carbon/phosphorus ratios). Our results show that a strongly elevated input of phosphorus from rivers and the Pacific Ocean relative to pre-OAE2 conditions is a requirement for the widespread development of low oxygen in the proto-North Atlantic during OAE2. Moreover, anoxia in the proto-North Atlantic is shown to be greatly influenced by the oxygen concentration of Pacific bottom waters. In our model, primary productivity increased significantly upon the transition from pre-OAE2 to OAE2 conditions. Our model captures the regional trends in anoxia as deduced from observations, with euxinia spreading to the northern and eastern shelves but with the most intense euxinia occurring along the southern coast. However, anoxia in the central deep basin is difficult to achieve in the model. This suggests that the ocean circulation used in the model may be too vigorous and/or that anoxia in the proto-North Atlantic was less widespread than previously thought.

On the Role of Atmospheric Teleconnections in Climate

2008 ◽  
Vol 21 (12) ◽  
pp. 2990-3001 ◽  
Author(s):  
Anastasios A. Tsonis ◽  
Kyle L. Swanson ◽  
Geli Wang
Keyword(s):  
Northern Hemisphere ◽  
North Atlantic ◽  
Recent Application ◽  
The North ◽  
The Pacific ◽  
Atmospheric Teleconnections ◽  
The North Atlantic ◽  
The North Atlantic Oscillation ◽  
The Tropics

Abstract In a recent application of networks to 500-hPa data, it was found that supernodes in the network correspond to major teleconnection. More specifically, in the Northern Hemisphere a set of supernodes coincides with the North Atlantic Oscillation (NAO) and another set is located in the area where the Pacific–North American (PNA) and the tropical Northern Hemisphere (TNH) patterns are found. It was subsequently suggested that the presence of atmospheric teleconnections make climate more stable and more efficient in transferring information. Here this hypothesis is tested by examining the topology of the complete network as well as of the networks without teleconnections. It is found that indeed without teleconnections the network becomes less stable and less efficient in transferring information. It was also found that the pattern chiefly responsible for this mechanism in the extratropics is the NAO. The other patterns are simply a linear response of the activity in the tropics and their role in this mechanism is inconsequential.

On a new species of Siboglinum (Pogonophora), found on both sides of the North Atlantic

1963 ◽  
Vol 43 (2) ◽  
pp. 513-517 ◽  
Author(s):  
Eve C. Southward
Keyword(s):  
New Species ◽  
Shallow Water ◽  
North Atlantic ◽  
Related Species ◽  
The North ◽  
The Pacific ◽  
The North Atlantic ◽  
A New Species

A description is given of Siboglinum holmei sp.nov., a shallow-water Atlantic species. It is compared with S. caulleryi, a related species from the Pacific.

Second reply to the comment by Romero and Kannada on “Genetic analysis of 16th-century whale bones prompts a revision of the impact of Basque whaling on right and bowhead whales in the western North Atlantic”Appears in Can. J. Zool. 84(7): 1059–1065.

2008 ◽  
Vol 86 (1) ◽  
pp. 76-79 ◽  
Author(s):  
Jeff W. Higdon
Keyword(s):  
Genetic Analysis ◽  
North Atlantic ◽  
16Th Century ◽  
Bowhead Whales ◽  
Potential Value ◽  
The North ◽  
The Pacific ◽  
History Of ◽  
The North Atlantic ◽  
The Impact

The comments by A. Romero and S. Kannada (2006. Can. J. Zool. 84: 1059–1065) provide a brief summary of North Atlantic whaling history as a critique of T. Rastogi et al. (2004. Can. J. Zool. 82: 1647–1654) . However, they fall far short of providing an accurate review of whaling history in this region. The authors present a number of factual errors, misuse several key sources, and make significant omissions, ultimately defeating the purpose of providing information to biologists, managers, and historians. In this comment I highlight the mistakes in their representation of the history of North Atlantic whaling for bowhead whales ( Balaena mysticetus L., 1758). There are unacceptable errors for most nations covered, and for American whaling in particular. The authors assert that over 30 000 bowhead whales were landed by Yankee whalers in the North Atlantic when the vast majority were in fact taken on the Pacific grounds. Although a summary of whaling history is an admirable goal and of potential value, it is unfortunate that the authors missed such an opportunity by failing to adequately research this topic, failing to include important citations, and by including sources that do not provide the information indicated. Providing a whaling summary with such errors and omissions only adds further confusion to an already confusing theme.

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