scholarly journals The state of knowledge on the deglaciation of America in 2017

2017 ◽  
Vol 43 (2) ◽  
pp. 361
Author(s):  
D. Palacios
Keyword(s):  
Central America ◽  
North Atlantic ◽  
Mountain Range ◽  
Arid Areas ◽  
Special Issue ◽  
The North ◽  
The Andes ◽  
The North Atlantic ◽  
The Antarctic ◽  
The Impact

This work presents a summary of all contributions included in this Special Issue on the deglaciation of America. It analyses the differences and coincidences between the phases of glacial evolution and their chronology in each of the regions studied, and seeks a possible explanation for asynchronies, according to the opinions of the authors of the contributions. Most of the papers show significant diversity within each region due to local factors and different approaches to their study. Often, local differences are even more important than differences with other regions. In North and Central America glacial evolution appears quite uniform, in line with the evolution of the temperature in the North Atlantic. The differences found between some regions may be due to slight variations in the impact of the temperature of the Atlantic in each region, and to differences in approaching their study. The glacial evolution of the Andes presents a greater diversity, probably due to the existence of arid areas along most of the mountain range, which show a greater sensitivity to the reception of humidity than to temperature in their glacial balance. In general, researchers have detected an attenuation of the influence of the temperature of the North Atlantic towards the south, and of the Antarctic Cold Reversal towards the north.

Preaching and Sermons

2017 ◽  
Author(s):  
Robert H. Ellison
Keyword(s):  
Eighteenth Century ◽  
North Atlantic ◽  
Religious Revival ◽  
Early Nineteenth Century ◽  
Denominational Identity ◽  
The North ◽  
The North Atlantic ◽  
The One ◽  
The Impact

Prompted by the convulsions of the late eighteenth century and inspired by the expansion of evangelicalism across the North Atlantic world, Protestant Dissenters from the 1790s eagerly subscribed to a millennial vision of a world transformed through missionary activism and religious revival. Voluntary societies proliferated in the early nineteenth century to spread the gospel and transform society at home and overseas. In doing so, they engaged many thousands of converts who felt the call to share their experience of personal conversion with others. Though social respectability and business methods became a notable feature of Victorian Nonconformity, the religious populism of the earlier period did not disappear and religious revival remained a key component of Dissenting experience. The impact of this revitalization was mixed. On the one hand, growth was not sustained in the long term and, to some extent, involvement in interdenominational activity undermined denominational identity; on the other hand, Nonconformists gained a social and political prominence they had not enjoyed since the middle of the seventeenth century and their efforts laid the basis for the twentieth-century explosion of evangelicalism in Africa, Asia, and South America.

scholarly journals The Combined Effects of SST and the North Atlantic Subtropical High-Pressure System on the Atlantic Basin Tropical Cyclone Interannual Variability

Atmosphere ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 329
Author(s):  
Albenis Pérez-Alarcón ◽  
José C. Fernández-Alvarez ◽  
Rogert Sorí ◽  
Raquel Nieto ◽  
Luis Gimeno
Keyword(s):  
High Pressure ◽  
Interannual Variability ◽  
Central America ◽  
North Atlantic ◽  
The West ◽  
The Bahamas ◽  
Pressure System ◽  
North Atlantic Subtropical High ◽  
The North ◽  
The North Atlantic

The combined effect of the sea surface temperature (SST) and the North Atlantic subtropical high-pressure system (NASH) in the interannual variability of the genesis of tropical cyclones (TCs) and landfalling in the period 1980–2019 is explored in this study. The SST was extracted from the Centennial Time Scale dataset from the National Oceanic and Atmospheric Administration (NOAA), and TC records were obtained from the Atlantic Hurricane Database of the NOAA/National Hurricane Center. The genesis and landfalling regions were objectively clustered for this analysis. Seven regions of TC genesis and five for landfalling were identified. Intercluster differences were observed in the monthly frequency distribution and annual variability, both for genesis and landfalling. From the generalized least square multiple regression model, SST and NASH (intensity and position) covariates can explain 22.7% of the variance of the frequency of TC genesis, but it is only statistically significant (p < 0.1) for the NASH center latitude. The SST mostly modulates the frequency of TCs formed near the West African coast, and the NASH latitudinal variation affects those originated in the Lesser Antilles arc. For landfalling, both covariates explain 38.7% of the variance; however, significant differences are observed in the comparison between each region. With a statistical significance higher than 90%, SST and NASH explain 33.4% of the landfalling variability in the archipelago of the Bahamas and central–eastern region of Cuba. Besides, landfalls in the Gulf of Mexico and Central America seem to be modulated by SST. It was also found there was no statistically significant relationship between the frequency of genesis and landfalling with the NASH intensity. However, the NASH structure modulates the probability density of the TCs trajectory that make landfall once or several times in their lifetime. Thus, the NASH variability throughout a hurricane season affects the TCs trajectory in the North Atlantic basin. Moreover, we found that the landfalling frequency of TCs formed near the West Africa coast and the central North Atlantic is relatively low. Furthermore, the SST and NASH longitude center explains 31.6% (p < 0.05) of the variance of the landfalling intensity in the archipelago of the Bahamas, while the SST explains 26.4% (p < 0.05) in Central America. Furthermore, the 5-year moving average filter revealed decadal and multidecadal variability in both genesis and landfalling by region. Our findings confirm the complexity of the atmospheric processes involved in the TC genesis and landfalling.

The Role of Oscillating Southern Hemisphere Westerly Winds: Global Ocean Circulation

2020 ◽  
Vol 33 (6) ◽  
pp. 2111-2130
Author(s):  
Woo Geun Cheon ◽  
Jong-Seong Kug
Keyword(s):  
Ocean Circulation ◽  
North Atlantic ◽  
North Pacific ◽  
Global Ocean ◽  
The North ◽  
Westerly Winds ◽  
The North Atlantic ◽  
Global Ocean Circulation ◽  
The Antarctic ◽  
The North Pacific

AbstractIn the framework of a sea ice–ocean general circulation model coupled to an energy balance atmospheric model, an intensity oscillation of Southern Hemisphere (SH) westerly winds affects the global ocean circulation via not only the buoyancy-driven teleconnection (BDT) mode but also the Ekman-driven teleconnection (EDT) mode. The BDT mode is activated by the SH air–sea ice–ocean interactions such as polynyas and oceanic convection. The ensuing variation in the Antarctic meridional overturning circulation (MOC) that is indicative of the Antarctic Bottom Water (AABW) formation exerts a significant influence on the abyssal circulation of the globe, particularly the Pacific. This controls the bipolar seesaw balance between deep and bottom waters at the equator. The EDT mode controlled by northward Ekman transport under the oscillating SH westerly winds generates a signal that propagates northward along the upper ocean and passes through the equator. The variation in the western boundary current (WBC) is much stronger in the North Atlantic than in the North Pacific, which appears to be associated with the relatively strong and persistent Mindanao Current (i.e., the southward flowing WBC of the North Pacific tropical gyre). The North Atlantic Deep Water (NADW) formation is controlled by salt advected northward by the North Atlantic WBC.

REGIONAL SECURITY DYNAMICS IN NORTHERN EUROPE (ON THE EXAMPLE OF NORWAY) IN THE LIGHT OF RECENT CHANGES

2020 ◽  
Vol 73 (1) ◽  
pp. 103-111
Author(s):  
D. Kalibekuly ◽  
◽  
Y.S. Chukubayev ◽  
Keyword(s):  
North Atlantic ◽  
Member Country ◽  
Security Policy ◽  
Security System ◽  
Regional Security ◽  
Northern Europe ◽  
The North ◽  
The North Atlantic ◽  
The Impact

The paper examines the dynamics of regional security in Norway as a part of Northern Europe. Being a political and geographical part of the Euro-Atlantic security system. Northern Europe, in its turn, is experiencing the impact of the confrontation between Russia and NATO. Norway's security policy analyzed from the perspective of a regional leader, as a NATO member country participating in the operations of the North Atlantic Alliance and as NATO's northern wing.

scholarly journals External forcing mechanisms controlling the North Atlantic coastal upwelling regime during the mid-Holocene

Geology ◽  
2020 ◽  
Author(s):  
Armand Hernández ◽  
Mário Cachão ◽  
Pedro Sousa ◽  
Ricardo M. Trigo ◽  
Jürg Luterbacher ◽  
...  
Keyword(s):  
North Atlantic ◽  
Coastal Upwelling ◽  
Marine Ecosystem ◽  
External Forcing ◽  
The North ◽  
New Findings ◽  
The North Atlantic ◽  
Eastern North Atlantic ◽  
Forcing Mechanisms ◽  
The Impact

Nearshore upwelling along the eastern North Atlantic margin regulates regional marine ecosystem productivity and thus impacts blue economies. While most global circulation models show an increase in the intensity and duration of seasonal upwelling at high latitudes under future human-induced warmer conditions, projections for the North Atlantic are still ambiguous. Due to the low temporal resolution of coastal upwelling records, little is known about the impact of natural forcing mechanisms on upwelling variability. Here, we present a microfossil-based proxy record and modeling simulations for the warmest period of the Holocene (ca. 9–5 ka) to estimate the contribution of the natural variability in North Atlantic upwelling via atmospheric and oceanic dynamics. We found that more frequent high-pressure conditions in the eastern North Atlantic associated with solar activity and orbital parameters triggered upwelling variations at multidecadal and millennial time scales, respectively. Our new findings offer insights into the role of external forcing mechanisms in upwelling changes before the Anthropocene, which must be considered when producing future projections of midlatitude upwelling activity.

Climate Response to External Sources of Freshwater: North Atlantic versus the Southern Ocean

2007 ◽  
Vol 20 (3) ◽  
pp. 436-448 ◽  
Author(s):  
Ronald J. Stouffer ◽  
Dan Seidov ◽  
Bernd J. Haupt
Keyword(s):  
Southern Ocean ◽  
Southern Hemisphere ◽  
North Atlantic ◽  
Surface Waters ◽  
Real World ◽  
The Other ◽  
Sea Surface ◽  
The North ◽  
The North Atlantic ◽  
The Antarctic

Abstract The response of an atmosphere–ocean general circulation model (AOGCM) to perturbations of freshwater fluxes across the sea surface in the North Atlantic and Southern Ocean is investigated. The purpose of this study is to investigate aspects of the so-called bipolar seesaw where one hemisphere warms and the other cools and vice versa due to changes in the ocean meridional overturning. The experimental design is idealized where 1 Sv (1 Sv ≡ 106 m3 s−1) of freshwater is added to the ocean surface for 100 model years and then removed. In one case, the freshwater perturbation is located in the Atlantic Ocean from 50° to 70°N. In the second case, it is located south of 60°S in the Southern Ocean. In the case where the North Atlantic surface waters are freshened, the Atlantic thermohaline circulation (THC) and associated northward oceanic heat transport weaken. In the Antarctic surface freshening case, the Atlantic THC is mainly unchanged with a slight weakening toward the end of the integration. This weakening is associated with the spreading of the fresh sea surface anomaly from the Southern Ocean into the rest of the World Ocean. There are two mechanisms that may be responsible for such weakening of the Atlantic THC. First is that the sea surface salinity (SSS) contrast between the North Atlantic and North Pacific is reduced. And, second, when freshwater from the Southern Ocean reaches the high latitudes of the North Atlantic Ocean, it hinders the sinking of the surface waters, leading to the weakening of the THC. The spreading of the fresh SSS anomaly from the Southern Ocean into the surface waters worldwide was not seen in earlier experiments. Given the geography and climatology of the Southern Hemisphere where the climatological surface winds push the surface waters northward away from the Antarctic continent, it seems likely that the spreading of the fresh surface water anomaly could occur in the real world. A remarkable symmetry between the two freshwater perturbation experiments in the surface air temperature (SAT) response can be seen. In both cases, the hemisphere with the freshwater perturbation cools, while the opposite hemisphere warms slightly. In the zonally averaged SAT figures, both the magnitude and the pattern of the anomalies look similar between the two cases. The oceanic response, on the other hand, is very different for the two freshwater cases, as noted above for the spreading of the SSS anomaly and the associated THC response. If the differences between the atmospheric and oceanic responses apply to the real world, then the interpretation of paleodata may need to be revisited. To arrive at a correct interpretation, it matters whether or not the evidence is mainly of atmospheric or oceanic origin. Also, given the sensitivity of the results to the exact details of the freshwater perturbation locations, especially in the Southern Hemisphere, a more realistic scenario must be constructed to explore these questions.

scholarly journals Climatic impacts of fresh water hosing under Last Glacial Maximum conditions: a multi-model study

2013 ◽  
Vol 9 (2) ◽  
pp. 935-953 ◽  
Author(s):  
M. Kageyama ◽  
U. Merkel ◽  
B. Otto-Bliesner ◽  
M. Prange ◽  
A. Abe-Ouchi ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Fresh Water ◽  
North Atlantic ◽  
Greenland Ice Sheet ◽  
Meridional Overturning Circulation ◽  
Last Glacial ◽  
The North ◽  
Tropical North Atlantic ◽  
The North Atlantic ◽  
The Impact

Abstract. Fresh water hosing simulations, in which a fresh water flux is imposed in the North Atlantic to force fluctuations of the Atlantic Meridional Overturning Circulation, have been routinely performed, first to study the climatic signature of different states of this circulation, then, under present or future conditions, to investigate the potential impact of a partial melting of the Greenland ice sheet. The most compelling examples of climatic changes potentially related to AMOC abrupt variations, however, are found in high resolution palaeo-records from around the globe for the last glacial period. To study those more specifically, more and more fresh water hosing experiments have been performed under glacial conditions in the recent years. Here we compare an ensemble constituted by 11 such simulations run with 6 different climate models. All simulations follow a slightly different design, but are sufficiently close in their design to be compared. They all study the impact of a fresh water hosing imposed in the extra-tropical North Atlantic. Common features in the model responses to hosing are the cooling over the North Atlantic, extending along the sub-tropical gyre in the tropical North Atlantic, the southward shift of the Atlantic ITCZ and the weakening of the African and Indian monsoons. On the other hand, the expression of the bipolar see-saw, i.e., warming in the Southern Hemisphere, differs from model to model, with some restricting it to the South Atlantic and specific regions of the southern ocean while others simulate a widespread southern ocean warming. The relationships between the features common to most models, i.e., climate changes over the north and tropical Atlantic, African and Asian monsoon regions, are further quantified. These suggest a tight correlation between the temperature and precipitation changes over the extra-tropical North Atlantic, but different pathways for the teleconnections between the AMOC/North Atlantic region and the African and Indian monsoon regions.

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