scholarly journals Rapid Red Sea Deep Water renewals caused by volcanic eruptions and the North Atlantic Oscillation

2018 ◽  
Vol 4 (6) ◽  
pp. eaar5637 ◽  
Author(s):  
Fengchao Yao ◽  
Ibrahim Hoteit
Keyword(s):  
North Atlantic Oscillation ◽  
Red Sea ◽  
North Atlantic ◽  
Deep Water ◽  
Volcanic Eruptions ◽  
The North ◽  
The North Atlantic ◽  
The North Atlantic Oscillation

scholarly journals Robust winter warming over Eurasia under stratospheric sulfate geoengineering – the role of stratospheric dynamics

2020 ◽  
Author(s):  
Antara Banerjee ◽  
Amy H. Butler ◽  
Lorenzo M. Polvani ◽  
Alan Robock ◽  
Isla R. Simpson ◽  
...  
Keyword(s):  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Volcanic Eruptions ◽  
Forced Response ◽  
Positive Phase ◽  
Dynamical Response ◽  
The North ◽  
The North Atlantic ◽  
The North Atlantic Oscillation

Abstract. It has been suggested that increased stratospheric sulfate aerosol loadings following large, low latitude volcanic eruptions can lead to wintertime warming over Eurasia through dynamical stratosphere-troposphere coupling. We here investigate the proposed connection in the context of hypothetical future stratospheric sulfate geoengineering in the Geoengineering Large Ensemble simulations. In those geoengineering simulations, we find that stratospheric circulation anomalies that resemble the positive phase of the Northern Annular Mode in winter is a distinguishing climate response which is absent when increasing greenhouse gases alone are prescribed. This stratospheric dynamical response projects onto the positive phase of the North Atlantic Oscillation, leading to associated side-effects of this climate intervention strategy, such as continental Eurasian warming and precipitation changes. Seasonality is a key signature of the dynamically-driven surface response. We find an opposite response of the North Atlantic Oscillation in summer, when no dynamical role of the stratosphere is expected. The robustness of the wintertime forced response stands in contrast to previously proposed volcanic responses.

scholarly journals On the effect of the North Atlantic Oscillation on temperature and salinity of the subpolar North Atlantic intermediate and deep waters

2009 ◽  
Vol 66 (7) ◽  
pp. 1448-1454 ◽  
Author(s):  
Artem Sarafanov
Keyword(s):  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Deep Water ◽  
Water Mass ◽  
General Mechanism ◽  
The North ◽  
Deep Waters ◽  
Mass Properties ◽  
The North Atlantic ◽  
The North Atlantic Oscillation

Abstract Sarafanov, A. 2009. On the effect of the North Atlantic Oscillation on temperature and salinity of the subpolar North Atlantic intermediate and deep waters. – ICES Journal of Marine Science, 66: 1448–1454. The close relationship between the observed water mass properties and the winter North Atlantic Oscillation (NAO) index (1950–2000s; r2 ≈ 0.65) implies that changes in the NAO-related atmospheric forcing may account for up to two-thirds of thermohaline changes at the intermediate and deep levels in the subpolar North Atlantic on a decadal time-scale. Persistent NAO decline (amplification) results in increase (decrease) in temperature and salinity in the intermediate–deep water column. A general mechanism explaining the close link between the NAO and coherent decadal changes in the intermediate and deep-water temperature and salinity in the region is inferred from the observed changes in the regional circulation and water mass properties. Two factors dominate this link: (i) intensity of convection in the Labrador Sea controlling injection of relatively cold freshwater into the intermediate layer, and (ii) zonal extension of the Subpolar Gyre that regulates the relative contribution of cold fresh subpolar water and warm saline subtropical water to the deep-water formation.

Volcanic imprint in the North Atlantic climate variability as recorded by stable water isotopes of Greenland ice cores

2020 ◽  
Author(s):  
Hera Guðlaugsdóttir ◽  
Jesper Sjolte ◽  
Árný Erla Sveinbjörnsdóttir ◽  
Hans Christian Steen-Larsen
Keyword(s):  
Climate Variability ◽  
North Atlantic Oscillation ◽  
Atmospheric Circulation ◽  
North Atlantic ◽  
High Latitude ◽  
Ice Cores ◽  
Volcanic Eruptions ◽  
The North ◽  
The North Atlantic ◽  
The North Atlantic Oscillation

Abstract Volcanic eruptions are important drivers of climate variability on both seasonal and multi-decadal time scales as a result of atmosphere-ocean coupling. While the direct response after equatorial eruptions emerges as the positive phase of the North Atlantic Oscillation in the first two years after an eruption, less is known about high latitude northern hemisphere eruptions. In this study we assess the difference between equatorial and high latitude volcanic eruptions through the reconstructed atmospheric circulation and stable water isotope records of Greenland ice cores for the last millennia (1241-1979 CE), where the coupling mechanism behind the long-term response is addressed. The atmospheric circulation is studied through the four main modes of climate variability in the North Atlantic, the Atlantic Ridge, Scandinavian Blocking and the positive and negative phase of the North Atlantic Oscillation. We report a difference in the atmospheric circulation response after high latitude eruptions compared to the response after equatorial eruptions, where the positive phase of the North Atlantic Oscillation and the Atlantic Ridge seem to be more associated with equatorial eruptions while the negative phase of the North Atlantic Oscillation seems to follow high latitude eruptions. This response is present during the first five years and then again in years 8-12 after both equatorial and high latitude eruptions. Such a prolonged response is evidence of an ocean-atmosphere coupling that is initiated through different mechanisms, where we suspect sea ice to play a key role.

scholarly journals Robust winter warming over Eurasia under stratospheric sulfate geoengineering – the role of stratospheric dynamics

2021 ◽  
Vol 21 (9) ◽  
pp. 6985-6997
Author(s):  
Antara Banerjee ◽  
Amy H. Butler ◽  
Lorenzo M. Polvani ◽  
Alan Robock ◽  
Isla R. Simpson ◽  
...  
Keyword(s):  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Volcanic Eruptions ◽  
Forced Response ◽  
Positive Phase ◽  
Dynamical Response ◽  
The North ◽  
The North Atlantic ◽  
The North Atlantic Oscillation

Abstract. It has been suggested that increased stratospheric sulfate aerosol loadings following large, low latitude volcanic eruptions can lead to wintertime warming over Eurasia through dynamical stratosphere–troposphere coupling. We here investigate the proposed connection in the context of hypothetical future stratospheric sulfate geoengineering in the Geoengineering Large Ensemble simulations. In those geoengineering simulations, we find that stratospheric circulation anomalies that resemble the positive phase of the Northern Annular Mode in winter are a distinguishing climate response which is absent when increasing greenhouse gases alone are prescribed. This stratospheric dynamical response projects onto the positive phase of the North Atlantic Oscillation, leading to associated side effects of this climate intervention strategy, such as continental Eurasian warming and precipitation changes. Seasonality is a key signature of the dynamically driven surface response. We find an opposite response of the North Atlantic Oscillation in summer, when no dynamical role of the stratosphere is expected. The robustness of the wintertime forced response stands in contrast to previously proposed volcanic responses.

scholarly journals Volcanic imprint in the North Atlantic climate variability as recorded by stable water isotopes of Greenland ice cores

2019 ◽  
Author(s):  
Hera Guðlaugsdóttir ◽  
Jesper Sjolte ◽  
Árný Erla Sveinbjörnsdóttir ◽  
Hans Christian Steen-Larsen
Keyword(s):  
Climate Variability ◽  
North Atlantic Oscillation ◽  
Atmospheric Circulation ◽  
North Atlantic ◽  
High Latitude ◽  
Ice Cores ◽  
Volcanic Eruptions ◽  
The North ◽  
The North Atlantic ◽  
The North Atlantic Oscillation

Abstract. Volcanic eruptions are important drivers of climate variability on both seasonal and multi-decadal time scales as a result of atmosphere-ocean coupling. While the direct response after equatorial eruptions emerges as the positive phase of the North Atlantic Oscillation in the first two years after an eruption, less is known about high latitude northern hemisphere eruptions. In this study we assess the difference between equatorial and high latitude volcanic eruptions through the reconstructed atmospheric circulation and stable water isotope records of Greenland ice cores for the last millennia (1241–1979 CE), where the coupling mechanism behind the long-term response is addressed. The atmospheric circulation is studied through the four main modes of climate variability in the North Atlantic, the Atlanti Ridge (AtR), Scandinavian Blocking (ScB) and the positive and negative phase of the North Atlantic Oscillation (NAO+/NAO−). We report a difference in the atmospheric circulation response after equatorial eruptions compared to the response after high latitude eruptions, where NAO+ and AtR seem to be more associated with equatorial eruptions while NAO- and ScB seems to follow high latitude eruptions. This response is present during the first five years and then again in years 8–12 after both equatorial and high latitude eruptions. Such a prolonged response is evidence of an ocean-atmosphere coupling that is initiated through different mechanisms, where we suspect sea ice to play a key role.

scholarly journals Influence of the North Atlantic oscillation on the atmospheric levels of benzo[a]pyrene over Europe

2021 ◽  
Author(s):  
Pedro Jiménez-Guerrero ◽  
Nuno Ratola
Keyword(s):  
Spatial Pattern ◽  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Transport Model ◽  
Regional Scale ◽  
The South ◽  
Climatic Fluctuations ◽  
The North ◽  
The North Atlantic ◽  
The North Atlantic Oscillation

AbstractThe atmospheric concentration of persistent organic pollutants (and of polycyclic aromatic hydrocarbons, PAHs, in particular) is closely related to climate change and climatic fluctuations, which are likely to influence contaminant’s transport pathways and transfer processes. Predicting how climate variability alters PAHs concentrations in the atmosphere still poses an exceptional challenge. In this sense, the main objective of this contribution is to assess the relationship between the North Atlantic Oscillation (NAO) index and the mean concentration of benzo[a]pyrene (BaP, the most studied PAH congener) in a domain covering Europe, with an emphasis on the effect of regional-scale processes. A numerical simulation for a present climate period of 30 years was performed using a regional chemistry transport model with a 25 km spatial resolution (horizontal), higher than those commonly applied. The results show an important seasonal behaviour, with a remarkable spatial pattern of difference between the north and the south of the domain. In winter, higher BaP ground levels are found during the NAO+ phase for the Mediterranean basin, while the spatial pattern of this feature (higher BaP levels during NAO+ phases) moves northwards in summer. These results show deviations up to and sometimes over 100% in the BaP mean concentrations, but statistically significant signals (p<0.1) of lower changes (20–40% variations in the signal) are found for the north of the domain in winter and for the south in summer.

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