Palynological evidence of Holocene climate change in the eastern Arctic: a possible shift in the Arctic oscillation at the millennial time scaleThis article is one of a series of papers published in this Special Issue on the theme Polar Climate Stability Network.

2008 ◽  
Vol 45 (11) ◽  
pp. 1363-1375 ◽  
Author(s):  
David Ledu ◽  
André Rochon ◽  
Anne de Vernal ◽  
Guillaume St-Onge
Keyword(s):  
Arctic Ocean ◽  
Arctic Oscillation ◽  
North Atlantic Ocean ◽  
Sediment Cores ◽  
Sea Surface ◽  
The Arctic ◽  
Last Deglaciation ◽  
Holocene Climate ◽  
The North ◽  
The Arctic Oscillation

Dinocyst assemblages and the physical properties of two sediment cores collected in the easternmost part of the main axis of the Northwest Passage, Canadian Arctic Ocean (cores 2004-804-009 BC and 2004-804-009 PC, 74°11.2′N, 81°11.7′W) were used to reconstruct changes in sea-surface conditions and to characterize changes in the depositional environment. Core 2004-804-009 PC spans the last 12 180 calibrated (cal) years BP, with sedimentation rates ranging from 45 to 122 cm/ka. Quantitative estimates of sea-surface parameters reveal relatively large hydrographic variability at millennial time scale. Before 11 000 cal years BP, our records suggest terrigenous inputs related to the last deglaciation. Between 11 000 and 9600 cal years BP, harsh conditions prevailed with August sea-surface temperatures <2 °C and the dominance of heterotrophic taxa. This episode was followed by a gradual increase in the relative abundance of phototrophic taxa and the establishment of milder condition with sea-surface temperature (SST) reaching ∼2 °C ∼8300 cal years BP, possibly related to increased exchange between the Arctic Ocean and the North Atlantic Ocean. From 6000 cal years BP to the late Holocene, climate variability could be the results of changes in the synoptic-scale atmospheric pattern such as the Arctic oscillation.

scholarly journals Combined Effects of the North Atlantic Oscillation and the Arctic Oscillation on Sea Surface Temperature in the Alborán Sea

PLoS ONE ◽  
2013 ◽  
Vol 8 (4) ◽  
pp. e62201 ◽  
Author(s):  
José C. Báez ◽  
Luis Gimeno ◽  
Moncho Gómez-Gesteira ◽  
Francisco Ferri-Yáñez ◽  
Raimundo Real
Keyword(s):  
Surface Temperature ◽  
North Atlantic ◽  
Arctic Oscillation ◽  
Sea Surface ◽  
The Arctic ◽  
Combined Effects ◽  
The North ◽  
The North Atlantic ◽  
The Arctic Oscillation ◽  
The North Atlantic Oscillation

scholarly journals The role of Northeast Pacific meltwater events in deglacial climate change

2020 ◽  
Vol 6 (9) ◽  
pp. eaay2915 ◽  
Author(s):  
Summer K. Praetorius ◽  
Alan Condron ◽  
Alan C. Mix ◽  
Maureen H. Walczak ◽  
Jennifer L. McKay ◽  
...  
Keyword(s):  
Ocean Circulation ◽  
North Pacific ◽  
Sediment Cores ◽  
Younger Dryas ◽  
Columbia River ◽  
Sea Surface ◽  
Subsurface Water ◽  
Last Deglaciation ◽  
Northeast Pacific ◽  
The North

Columbia River megafloods occurred repeatedly during the last deglaciation, but the impacts of this fresh water on Pacific hydrography are largely unknown. To reconstruct changes in ocean circulation during this period, we used a numerical model to simulate the flow trajectory of Columbia River megafloods and compiled records of sea surface temperature, paleo-salinity, and deep-water radiocarbon from marine sediment cores in the Northeast Pacific. The North Pacific sea surface cooled and freshened during the early deglacial (19.0-16.5 ka) and Younger Dryas (12.9-11.7 ka) intervals, coincident with the appearance of subsurface water masses depleted in radiocarbon relative to the sea surface. We infer that Pacific meltwater fluxes contributed to net Northern Hemisphere cooling prior to North Atlantic Heinrich Events, and again during the Younger Dryas stadial. Abrupt warming in the Northeast Pacific similarly contributed to hemispheric warming during the Bølling and Holocene transitions. These findings underscore the importance of changes in North Pacific freshwater fluxes and circulation in deglacial climate events.

scholarly journals Cooling down the world oceans and the earth by enhancing the North Atlantic Ocean current

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Julian David Hunt ◽  
Andreas Nascimento ◽  
Fabio A. Diuana ◽  
Natália de Assis Brasil Weber ◽  
Gabriel Malta Castro ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
Arctic Ocean ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
The Arctic ◽  
Ocean Current ◽  
The North ◽  
The Arctic Ocean ◽  
Albedo Effect ◽  
Arctic Atmosphere

AbstractThe world is going through intensive changes due to global warming. It is well known that the reduction in ice cover in the Arctic Ocean further contributes to increasing the atmospheric Arctic temperature due to the reduction of the albedo effect and increase in heat absorbed by the ocean’s surface. The Arctic ice cover also works like an insulation sheet, keeping the heat in the ocean from dissipating into the cold Arctic atmosphere. Increasing the salinity of the Arctic Ocean surface would allow the warmer and less salty North Atlantic Ocean current to flow on the surface of the Arctic Ocean considerably increasing the temperature of the Arctic atmosphere and release the ocean heat trapped under the ice. This paper argues that if the North Atlantic Ocean current could maintain the Arctic Ocean ice-free during the winter, the longwave radiation heat loss into space would be larger than the increase in heat absorption due to the albedo effect. This paper presents details of the fundamentals of the Arctic Ocean circulation and presents three possible approaches for increasing the salinity of the surface water of the Arctic Ocean. It then discusses that increasing the salinity of the Arctic Ocean would warm the atmosphere of the Arctic region, but cool down the oceans and possibly the Earth. However, it might take thousands of years for the effects of cooling the oceans to cool the global average atmospheric temperature.

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

Improvement in Prediction of the Arctic Oscillation with a Realistic Ocean Initial Condition in a CGCM

2015 ◽  
Vol 28 (22) ◽  
pp. 8951-8967 ◽  
Author(s):  
Hae-Jeong Kim ◽  
Joong-Bae Ahn
Keyword(s):  
Arctic Oscillation ◽  
Polar Vortex ◽  
Polar Front ◽  
Forecast Skill ◽  
Sea Surface ◽  
The Arctic ◽  
Initial Condition ◽  
Stratospheric Polar Vortex ◽  
The Arctic Oscillation ◽  
Polar Front Jet

Abstract This study verifies the impact of improved ocean initial conditions on the Arctic Oscillation (AO) forecast skill by assessing the one-month lead predictability of boreal winter AO using the Pusan National University (PNU) coupled general circulation model (CGCM). Hindcast experiments were performed on two versions of the model, one does not use assimilated ocean initial data (V1.0) and one does (V1.1), and the results were comparatively analyzed. The forecast skill of V1.1 was superior to that of V1.0 in terms of the correlation coefficient between the predicted and observed AO indices. In the regression analysis, V1.1 showed more realistic spatial similarities than V1.0 did in predicted sea surface temperature and atmospheric circulation fields. The authors suggest the relative importance of the contribution of the ocean initial condition to the AO forecast skill was because the ocean data assimilation increased the predictability of the AO, to some extent, through the improved interaction between tropical forcing induced by realistic sea surface temperature (SST) and atmospheric circulation. In V1.1, as in the observation, the cold equatorial Pacific SST anomalies generated the weakened tropical convection and Hadley circulation over the Pacific, resulting in a decelerated subtropical jet and accelerated polar front jet in the extratropics. The intensified polar front jet implies a stronger stratospheric polar vortex relevant to the positive AO phase; hence, surface manifestations of the reflected positive AO phase were then induced through the downward propagation of the stratospheric polar vortex. The results suggest that properly assimilated initial ocean conditions might contribute to improve the predictability of global oscillations, such as the AO, through large-scale tropical ocean–atmosphere interaction.

scholarly journals The influence of Arctic air masses on climatic conditions of the snow accumulation period in the center of the European territory of Russia

2021 ◽  
pp. 16-25
Author(s):  
Julia Nikolaevna Chizhova
Keyword(s):  
North Atlantic ◽  
Arctic Oscillation ◽  
Winter Precipitation ◽  
Climatic Conditions ◽  
The Arctic ◽  
Air Masses ◽  
The North ◽  
The Arctic Oscillation ◽  
The North Atlantic Oscillation ◽  
The Relationship

The subject of this article is exmination of the influence of the Arctic air flow on the climatic conditions of the winter period in the center of the European territory of Russia (Moscow). In recent years, the question of the relationship between regional climatic conditions and such global circulation patterns as the North Atlantic Oscillation (NAO) and the Arctic Oscillation (AK) has become increasingly important. Based on the data of long-term observations of temperature and precipitation, the relationship with the AK and NAO was considered. For the winter months of the period 2014-2018, the back trajectories of the movement of air masses were computed for each date of precipitation to identify the sources of precipitation. The amount of winter precipitation that forms the snow cover of Moscow has no connection with either the North Atlantic Oscillation or the Arctic Oscillation. The Moscow region is located at the intersection of the zones of influence of positive and negative phases of both cyclonic patterns (AK and NAO), which determine the weather in the Northern Hemisphere. For the winter months, a correlation between the surface air temperature and NAO (r = 0.72) and AK (r = 0.66) was established. Winter precipitation in the center of the European territory of Russiais mainly associated with the unloading of Atlantic air masses. Arctic air masses relatively rarely invade Moscow region and bring little precipitation (their contribution does not exceed 12% of the total winter precipitation).

scholarly journals Response of Arctic Freshwater to the Arctic Oscillation in Coupled Climate Models

2020 ◽  
Vol 33 (7) ◽  
pp. 2533-2555 ◽  
Author(s):  
Sam B. Cornish ◽  
Yavor Kostov ◽  
Helen L. Johnson ◽  
Camille Lique
Keyword(s):  
Arctic Ocean ◽  
Linear Response ◽  
Arctic Oscillation ◽  
Climate Models ◽  
Coupled Model ◽  
Step Change ◽  
The Arctic ◽  
Response Functions ◽  
The Arctic Ocean ◽  
The Arctic Oscillation

AbstractThe freshwater content (FWC) of the Arctic Ocean is intimately linked to the stratification—a physical characteristic of the Arctic Ocean with wide relevance for climate and biology. Here, we explore the relationship between atmospheric circulation and Arctic FWC across 12 different control-run simulations from phase 5 of the Coupled Model Intercomparison Project. Using multiple lagged regression, we seek to isolate the linear response of Arctic FWC to a step change in the strength of the Arctic Oscillation (AO) as well as the second and third orthogonal modes of SLP variability over the Arctic domain. There is broad agreement among models that a step change to a more anticyclonic AO leads to an increase in Arctic FWC, with an e-folding time scale of 5–10 yr. However, models differ widely in the degree to which a linear response to SLP variability can explain FWC changes. Although the mean states, time scales, and magnitudes of FWC variability may be broadly similar, the physical origins of variability are highly inconsistent among models. We perform a robustness test that incorporates a Monte Carlo approach to determine which response functions are most likely to represent causal, physical relationships within the models and which are artifacts of regression. Convolution with SLP reanalysis data shows that the four most robust response functions have some skill at reproducing observed accumulation of FWC during the late 1990s and 2000s, consistent with the idea that this change was largely wind driven.

Sediment archives from the Arctic Ocean provide evidence for massive remobilization of permafrost carbon in Siberia during the last glacial termination

2020 ◽  
Author(s):  
Jannik Martens ◽  
Birgit Wild ◽  
Tommaso Tesi ◽  
Francesco Muschitiello ◽  
Matt O’Regan ◽  
...  
Keyword(s):  
Arctic Ocean ◽  
Large Scale ◽  
Sediment Cores ◽  
The Arctic ◽  
Last Deglaciation ◽  
Central Arctic Ocean ◽  
Last Glacial ◽  
The Arctic Ocean ◽  
Siberian Shelf ◽  
The Last Glacial

&lt;p&gt;Environmental archives and carbon cycle models suggest that climate warming during the last deglaciation (the transition from the last glacial to the Holocene) caused large-scale thaw of Arctic permafrost, followed by the release of previously freeze-locked carbon. In addition to changing oceanic circulation and outgassing of CO&lt;sub&gt;2 &lt;/sub&gt;trapped in the deep glacial ocean, organic carbon (OC) release from thawing permafrost might have contributed to the rise in atmospheric CO&lt;sub&gt;2&lt;/sub&gt; by 80 ppmv or ~200 Pg C between 17.5 and 11.7 kyr before present (BP). The few Arctic sediment cores to date, however, lack either temporal resolution or reflect only regional catchments, leaving most of the permafrost OC remobilization of the deglaciation unconstrained.&lt;/p&gt;&lt;p&gt;Our study explores the flux and fate of OC released from permafrost to the Siberian Arctic Seas during the last deglaciation. The Arctic Ocean is the main recipient of permafrost material delivered by river transport or collapse of coastal permafrost, providing an archive for current and past release of OC from thawing permafrost. We studied isotopes (&amp;#916;&lt;sup&gt;14&lt;/sup&gt;C-OC, &amp;#948;&lt;sup&gt;13&lt;/sup&gt;C-OC) and terrestrial biomarkers (CuO-derived lignin phenols, &lt;em&gt;n&lt;/em&gt;-alkanes, &lt;em&gt;n&lt;/em&gt;-alkanoic acids) in a number of sediment cores from the Siberian Shelf and Central Arctic Ocean to reconstruct source and fate of OC previously locked in permafrost.&lt;/p&gt;&lt;p&gt;The composite record of three cores from the Laptev, East Siberian and Chukchi Seas suggest a combination of OC released by deepening of permafrost active layer in inland Siberia and by thermal collapse of coastal permafrost during the deglaciation. Coastal erosion of permafrost during the deglaciation suggests that sea-level rise and flooding of the Siberian shelf remobilized OC from permafrost deposits that covered the dry shelf areas during the last glacial. A sediment core from the Central Arctic Ocean demonstrates that this occurred in two major pulses; i) during the B&amp;#248;lling-Aller&amp;#248;d (14.7-12.9 kyr BP), but most strongly ii) during the early Holocene (11-7.6 kyr BP). In the early Holocene, flooding of 80% of the Siberian shelf amplified permafrost OC release to the Arctic Ocean, with peak fluxes 10-9 kyr BP one order of magnitude higher than at other times in the Holocene.&lt;/p&gt;&lt;p&gt;It is likely that the remobilization of permafrost OC by flooding of the Siberian shelf released climate-significant amounts of dormant OC into active biogeochemical cycling and the atmosphere. Previous studies estimated that a pool of 300-600 Pg OC was held in permafrost covering Arctic Ocean shelves during the last glacial maximum; one can only speculate about its whereabouts after the deglaciation. Present und future reconstructions of historical remobilization of permafrost OC will help to understand how important permafrost thawing is to large-scale carbon cycling.&lt;/p&gt;

scholarly journals Reconsideration of the True versus Apparent Arctic Oscillation

2008 ◽  
Vol 21 (10) ◽  
pp. 2047-2062 ◽  
Author(s):  
Hisanori Itoh
Keyword(s):  
Spatial Correlation ◽  
Arctic Oscillation ◽  
Physical Reality ◽  
The Arctic ◽  
Sea Level Pressure ◽  
The North ◽  
The Pacific ◽  
The Arctic Oscillation ◽  
The North Atlantic Oscillation ◽  
Almost All

Abstract The physical reality of the Arctic Oscillation (AO; or northern annular mode) is considered. The data used are mainly the monthly mean sea level pressure (SLP). A schematic figure is first presented to illustrate the relationship between the North Atlantic Oscillation (NAO)–Pacific–North American Oscillation (PNA) system and the AO–negative correlation mode between the Atlantic and the Pacific (AO–NCM) system. Although the NAO–PNA (apparent AO–NCM) and true AO–NCM systems give rise to the same EOFs, the probability density functions for the time coefficients of the two leading modes are different. Therefore, the discrimination of the two systems is possible. Several pieces of evidence indicate that, in the real world, the NAO–PNA and the AO–NCM are located on almost the same plane in phase space. This means that the NAO–PNA and AO–NCM systems have the same variations on the plane in common, implying that when the NAO–PNA system is real, the AO–NCM is unlikely to be real. Simple independent component analysis is carried out to distinguish between the true and apparent AO–NCM systems, indicating that the NAO and PNA are independent oscillations, that is, true ones. The analysis is extended to the winter mean SLP field, for which the EOF shows the NAO–PNA but not the AO–NCM. This may be due to the fact that the winter mean NAO and PNA patterns have little spatial correlation. Calculations using randomly selected samples also indicate that when the NAO and PNA patterns have little spatial correlation, the AO never appears as EOF1. All the preceding results show that almost all characteristics of the AO–NCM can be explained from those of the NAO–PNA. Hence it is concluded that the AO, which is extracted by EOF analysis from the temporarily independent but spatially overlapping variations of the NAO and PNA, is almost apparent.

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