scholarly journals North Atlantic Oscillation seesaw effect in leaf morphological records from dwarf birch shrubs in Greenland and Finland

2021 ◽  
Vol 40 ◽  
Author(s):  
Fabian E.Z. Ercan ◽  
Daan Blok ◽  
Stef Weijers ◽  
Astrid Odé ◽  
Friederike Wagner-Cremer
Keyword(s):  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Early Summer ◽  
The Arctic ◽  
Late Winter ◽  
The North ◽  
Dwarf Birch ◽  
Spring Temperatures ◽  
Seasonal Heat ◽  
The North Atlantic Oscillation

The North Atlantic Oscillation (NAO) determines wind speed and direction, seasonal heat, moisture transport, storm tracks, cloudiness and sea-ice cover through atmospheric mass balance shifts between the Arctic and the subtropical Atlantic. The NAO is characterized by the typical, yet insufficiently understood, seesaw pattern of warmer winter and spring temperatures over Scandinavia and cooler temperatures over Greenland during the positive phase of the NAO, and vice versa during the negative phase. We tested the potential to reconstruct NAO variation beyond the meteorological record through the application of a microphenological proxy. We measured the Undulation Index (UI) in Betula nana epidermal cells from herbarium leaf samples and fossil peat fragments dating back to 1865—exceeding most meteorological records in the Arctic—to estimate imprints of spring thermal properties and NAO in Greenland and Finland. We found negative relations between Greenland UI and late winter, spring and early summer NAO, and mostly positive, but not significant, relations between Finland UI and NAO in years with pronounced NAO expression. The direction of the UI response in this common circumpolar species is, therefore, likely in line with the NAO seesaw effect, with leaf development response to NAO fluctuations in northern Europe opposing the response in Greenland and vice versa. Increased knowledge of the UI response to climate may contribute to understanding ecological properties of key Arctic species, whilst additionally providing a proxy for NAO dynamics.

The North Atlantic Oscillation and the Arctic Oscillation favour harmful algal blooms in SW Europe

Harmful Algae ◽  
2014 ◽  
Vol 39 ◽  
pp. 121-126 ◽  
Author(s):  
José C. Báez ◽  
Raimundo Real ◽  
Victoria López-Rodas ◽  
Eduardo Costas ◽  
A. Enrique Salvo ◽  
...  
Keyword(s):  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Arctic Oscillation ◽  
The Arctic ◽  
The North ◽  
The North Atlantic ◽  
The Arctic Oscillation ◽  
The North Atlantic Oscillation

scholarly journals The Occurrence and Properties of Long-Lived Liquid-Bearing Clouds over the Greenland Ice Sheet and Their Relationship to the North Atlantic Oscillation

2018 ◽  
Vol 57 (4) ◽  
pp. 921-935 ◽  
Author(s):  
Jonathan Edwards-Opperman ◽  
Steven Cavallo ◽  
David Turner
Keyword(s):  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
The Arctic ◽  
Positive Phase ◽  
Cloud Base ◽  
The North ◽  
The North Atlantic ◽  
The North Atlantic Oscillation

AbstractStratiform liquid-bearing clouds (LBCs), defined herein as either pure liquid or mixed-phase clouds, have a large impact on the surface radiation budget across the Arctic. LBCs lasting at least 6 h are observed at Summit, Greenland, year-round with a maximum in occurrence during summer. Mean cloud-base height is below 1 km for 85% of LBC cases identified, 59% have mean liquid water path (LWP) values between 10 and 40 g m−2, and most produce sporadic light ice-phase precipitation. During their occurrence, the atmosphere above the ice sheet is anomalously warm and moist, with southerly winds observed over much of the ice sheet, including at Summit. LBCs that occur when the North Atlantic Oscillation (NAO) is in the negative phase correspond to strong ridging centered over the Greenland Ice Sheet (GIS), allowing for southwesterly flow over the GIS toward Summit. During the positive phase of the NAO, the occurrence of LBCs corresponds to a cyclone located off the southeastern coast of the ice sheet, which leads to easterly-to-southeasterly flow toward Summit. Furthermore, air parcels at Summit frequently originate from below the elevation of Summit, indicating that orographic lift along the ice sheet is a factor in the occurrence of LBCs at Summit. LBCs are more frequently observed during the negative NAO, and both the LWP and precipitation rate are larger in LBCs occurring during this phase. Mean LWP in LBCs occurring during the negative NAO is 15 g m−2 larger than in LBCs occurring during the positive phase.

scholarly journals Influence of the North Atlantic Oscillation on air pollution transport

2012 ◽  
Vol 12 (2) ◽  
pp. 869-877 ◽  
Author(s):  
T. Christoudias ◽  
A. Pozzer ◽  
J. Lelieveld
Keyword(s):  
North Atlantic Oscillation ◽  
North Atlantic ◽  
North American ◽  
Trace Gases ◽  
Water Soluble ◽  
The Arctic ◽  
Pollution Transport ◽  
The North ◽  
The North Atlantic ◽  
The North Atlantic Oscillation

Abstract. We examined the influence of the North Atlantic Oscillation (NAO) on the atmospheric dispersion of pollution by computing the emission, transport and removal of idealized insoluble gaseous and water-soluble aerosol tracers, tagged by the continent of origin. We simulated a period of 50 yr (1960–2010), using the ECHAM5/MESSy1 atmospheric chemistry (EMAC) general circulation model. The model accounts for anthropogenic, biogenic and biomass burning sources, removal of trace gases through OH oxidation, and precipitation, sedimentation and deposition of aerosols. The model is shown to reproduce the observed spatial features of the NAO, moisture transports and precipitation. During high NAO phase seasons the axis of maximum westerly North American trace gas transports extends relatively far to the north and east over Europe. The NAO phase is significantly correlated with North American insoluble gas and soluble aerosol tracer concentrations over the northwestern Atlantic Ocean and across northern Europe, and with European trace gases and aerosols over Africa and north of the Arctic circle. We find a strong anti-correlation between the phase of the NAO and European pollutant gas concentration over western and central Europe.

scholarly journals Influence of the North Atlantic Oscillation on air pollution transport

2011 ◽  
Vol 11 (9) ◽  
pp. 25967-25989
Author(s):  
T. Christoudias ◽  
A. Pozzer ◽  
J. Lelieveld
Keyword(s):  
North Atlantic Oscillation ◽  
North Atlantic ◽  
North American ◽  
Trace Gases ◽  
Water Soluble ◽  
The Arctic ◽  
Pollution Transport ◽  
The North ◽  
The North Atlantic ◽  
The North Atlantic Oscillation

Abstract. We examined the influence of the North Atlantic Oscillation (NAO) on the atmospheric dispersion of pollution by computing the emission, transport and removal of insoluble gaseous and water-soluble aerosol tracers, tagged by the continent of origin. We simulated a period of 50 yr (1960–2010), using the ECHAM/MESSy atmospheric chemistry (EMAC) general circulation model. The model accounts for anthropogenic, biogenic and biomass burning sources, removal of trace gases through OH oxidation, and precipitation, sedimentation and deposition of aerosols. The model is shown to reproduce the observed spatial features of the NAO, moisture transports and precipitation. During high NAO phase seasons the axis of maximum westerly North American trace gas transports extends relatively far to the north and east over Europe. The NAO phase is significantly correlated with North American tracer concentrations over the northwestern Atlantic Ocean and across northern Europe, and with European trace gases and aerosols beyond the arctic circle. Our results indicate marked differences and partly reversed correlations for the insoluble gas and the soluble aerosol tracers. We find a strong anti-correlation over western and central Europe between European pollutant gas and aerosol concentrations and the phase of the NAO.

scholarly journals The North Atlantic Oscillation controls air pollution transport to the Arctic

2003 ◽  
Vol 3 (5) ◽  
pp. 1769-1778 ◽  
Author(s):  
S. Eckhardt ◽  
A. Stohl ◽  
S. Beirle ◽  
N. Spichtinger ◽  
P. James ◽  
...  
Keyword(s):  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Model Simulation ◽  
The Arctic ◽  
Pollution Transport ◽  
Pollution Levels ◽  
The North ◽  
The North Atlantic ◽  
The North Atlantic Oscillation ◽  
Strong Control

Abstract. This paper studies the interannual variability of pollution pathways from northern hemisphere (NH) continents into the Arctic. Using a 15-year model simulation of the dispersion of passive tracers representative of anthropogenic emissions from NH continents, we show that the North Atlantic Oscillation (NAO) exerts a strong control on the pollution transport into the Arctic, particularly in winter and spring. For tracer lifetimes of 5 (30) days, surface concentrations in the Arctic winter are enhanced by about 70% (30%) during high phases of the NAO (in the following referred to as NAO+) compared to its low phases (NAO-). This is mainly due to great differences in the pathways of European pollution during NAO+ and NAO- phases, respectively, but reinforced by North American pollution, which is also enhanced in the Arctic during NAO+ phases. In contrast, Asian pollution in the Arctic does not significantly depend on the NAO phase. The model results are confirmed using remotely-sensed NO2 vertical atmospheric columns obtained from seven years of satellite measurements, which show enhanced northward NO2 transport and reduced NO2 outflow into the North Atlantic from Central Europe during NAO+ phases. Surface measurements of carbon monoxide (CO) and black carbon at high-latitude stations further corroborate the overall picture of enhanced Arctic pollution levels during NAO+ phases

scholarly journals The North Atlantic Oscillation controls air pollution transport to the Arctic

2003 ◽  
Vol 3 (3) ◽  
pp. 3222-3240 ◽  
Author(s):  
S. Eckhardt ◽  
A. Stohl ◽  
S. Beirle ◽  
N. Spichtinger ◽  
P. James ◽  
...  
Keyword(s):  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Model Simulation ◽  
The Arctic ◽  
Pollution Transport ◽  
Pollution Levels ◽  
The North ◽  
The North Atlantic ◽  
The North Atlantic Oscillation ◽  
Strong Control

Abstract. This paper studies the interannual variability of pollution pathways from northern hemisphere (NH) continents into the Arctic. Using a 1-year model simulation of the dispersion of passive tracers representative of anthropogenic emissions from NH continents, we show that the North Atlantic Oscillation (NAO) exerts a strong control on the pollution transport into the Arctic, particularly in winter and spring. For tracer lifetimes of 5 (30) days, surface concentrations in the Arctic winter are enhanced by about 70% (30%) during high phases of the NAO (in the following referred to as NAO+) compared to its low phases (NAO−). This is mainly due to great differences in the pathways of European pollution during NAO+ and NAO− phases, respectively, but reinforced by North American pollution, which is also enhanced in the Arctic during NAO+  phases. In contrast, Asian pollution in the Arctic does not significantly depend on the NAO phase. The model results are confirmed using remotely-sensed NO2 vertical atmospheric columns obtained from seven years of satellite measurements, which show enhanced northward NO2 transport and reduced NO2 outflow into the North Atlantic from Central Europe during NAO+ phases. Surface measurements of carbon monoxide (CO) and black carbon at high-latitude stations further corroborate the overall picture of enhanced Arctic pollution levels during NAO+ phases.

scholarly journals The Arctic Winter Sea Ice Quadrupole Revisited

2017 ◽  
Vol 30 (9) ◽  
pp. 3157-3167 ◽  
Author(s):  
S. Close ◽  
M.-N. Houssais ◽  
C. Herbaut
Keyword(s):  
Sea Ice ◽  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Large Scale ◽  
Dominant Mode ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
The North ◽  
The North Atlantic ◽  
The North Atlantic Oscillation

The dominant mode of Arctic sea ice variability in winter is often maintained to be represented by a quadrupole structure, comprising poles of one sign in the Okhotsk, Greenland, and Barents Seas and of opposing sign in the Labrador and Bering Seas, forced by the North Atlantic Oscillation. This study revisits this large-scale winter mode of sea ice variability using microwave satellite and reanalysis data. It is found that the quadrupole structure does not describe a significant covariance relationship among all four component poles. The first empirical orthogonal mode, explaining covariability in the sea ice of the Barents, Greenland, and Okhotsk Seas, is linked to the Siberian high, while the North Atlantic Oscillation only exhibits a significant relationship with the Labrador Sea ice, which varies independently as the second mode. The principal components are characterized by a strong low-frequency signal; because the satellite record is still short, these results suggest that statistical analyses should be applied cautiously.

Regime behaviour in the Atlantic-Eurasian Arctic related to sea ice and sea surface temperature changes

2020 ◽  
Author(s):  
Ralf Jaiser ◽  
Mirseid Akperov ◽  
Alexander Timazhev ◽  
Erik Romanowsky ◽  
Dörthe Handorf ◽  
...  
Keyword(s):  
Sea Ice ◽  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Sea Surface ◽  
The Arctic ◽  
Frequency Of Occurrence ◽  
Temporal Behaviour ◽  
The North ◽  
The North Atlantic ◽  
The North Atlantic Oscillation

<p>Climate change in the Arctic is embedded in the global climate system leading to phenomenon like Arctic Amplification and linkages to the mid-latitudes. A major forcing emerges from changed surface conditions like declining sea ice cover (SIC) and rising sea surface temperatures (SST). We performed time-slice model experiments with the global atmosphere-only model ECHAM6 and changed SIC and SST to either high or low states, respectively. These experiments are compared to reanalysis data and analysed aiming at a separation between the influences of SIC and SST, while focusing on linkages between the Arctic and mid-latitudes in winter.</p><p>We identify five significant regimes in the Atlantic-Eurasian sector with the k-means clustering method. The regimes include different blocking patterns, situation with strong low pressure influence and the North Atlantic Oscillation in its two phases. Their frequency of occurrence is discussed for winter months. In the reanalysis we observe an increase of blocking patterns in early winter of the most recent decades. This is reproduced by our experiments with increased SST, where blocking becomes more dominant overall. In late winter, an increased frequency of occurrence of the North Atlantic Oscillation in its negative phase is observed. This and the overall temporal behaviour of regimes in recent years is best represented if SST and SIC are changed to their more recent state simultaneously. Therefore, our results suggest that increased SSTs and reduced SIC together act on observed linkages between polar regions and mid-latitudes.</p>

On monsoon character of circulation over the Barents and Kara Seas

2020 ◽  
Author(s):  
Alexander Kislov ◽  
Tatiana Matveeva
Keyword(s):  
North Atlantic Oscillation ◽  
Atmospheric Circulation ◽  
North Atlantic ◽  
Winter Season ◽  
The Arctic ◽  
Modes Of Variability ◽  
The North ◽  
The North Atlantic ◽  
Barents And Kara Seas ◽  
The North Atlantic Oscillation

<p>This study analysed the monsoon features of atmospheric circulation in the Barents and Kara Seas, the variability of atmospheric circulation, and anomalies in temperature, precipitation, and wind speed. In a cold period, the extreme winds are southerly winds that develop in the eastern parts of cyclones. In the warm season, the extreme speeds correspond to a northerly wind in the western periphery of cyclones. The regional circulation systems were divided into ten circulation weather types, separately for each sea. Their frequencies were compared with different indexes, describing the main modes of variability for the arctic region (the North Atlantic Oscillation, the summer North Atlantic Oscillation, the Scandinavia teleconnection pattern, the Siberian High). In the winter season, the monsoon currents from land to sea occur only when the North Atlantic Oscillation index is positive. With the prevalence of other modes of variability, the direction of the winds can be different, and this causes the monsoon regularity to be stochastic. In summer, the northern streams move on the western periphery of cyclones, regenerating and stabilizing over the Kara Sea.</p><p>The work was supported by the grant of the Russian Foundation for Basic Research (RFBR) [project number 18-05-60147] and this work was carried out as part of governmental assignment АААА-А16-116032810086-4.</p>

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