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Tracking the Atlantic Multidecadal Oscillation through the last 8,000 years.

Knudsen MF, Seidenkrantz MS, Jacobsen BH, Kuijpers A - Nat Commun (2011)

Bottom Line: Understanding the internal ocean variability and its influence on climate is imperative for society.The nature and origin of the AMO is uncertain, and it remains unknown whether it represents a persistent periodic driver in the climate system, or merely a transient feature.We therefore conjecture that a quasi-persistent ∼55- to 70-year AMO, linked to internal ocean-atmosphere variability, existed during large parts of the Holocene.

View Article: PubMed Central - PubMed

Affiliation: Centre for Past Climate Studies, Department of Earth Sciences, Aarhus University, HÃøegh-Guldbergs Gade 2, Aarhus DK-8000, Denmark. mfk@geo.au.dk

ABSTRACT
Understanding the internal ocean variability and its influence on climate is imperative for society. A key aspect concerns the enigmatic Atlantic Multidecadal Oscillation (AMO), a feature defined by a 60- to 90-year variability in North Atlantic sea-surface temperatures. The nature and origin of the AMO is uncertain, and it remains unknown whether it represents a persistent periodic driver in the climate system, or merely a transient feature. Here, we show that distinct, ∼55- to 70-year oscillations characterized the North Atlantic ocean-atmosphere variability over the past 8,000 years. We test and reject the hypothesis that this climate oscillation was directly forced by periodic changes in solar activity. We therefore conjecture that a quasi-persistent ∼55- to 70-year AMO, linked to internal ocean-atmosphere variability, existed during large parts of the Holocene. Our analyses further suggest that the coupling from the AMO to regional climate conditions was modulated by orbitally induced shifts in large-scale ocean-atmosphere circulation.

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Global and North Atlantic climate trends over the past ∼150 years.(a) Global annual mean sea-surface temperature (SST) anomalies from HadISST for the period 1870–2008 (Ref. 58)(thin black line). (b) Annual mean North Atlantic SST anomalies for the period 1870–2008 (ref. 58; thin black line). (c) The Atlantic multidecadal oscillation (AMO) index for the period 1870–2008. The modern AMO index4 is defined by subtracting the global mean SST anomalies (a) from the North Atlantic SST anomalies (b). Five-year running means are shown by heavy black lines with fill in all panels.
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f1: Global and North Atlantic climate trends over the past ∼150 years.(a) Global annual mean sea-surface temperature (SST) anomalies from HadISST for the period 1870–2008 (Ref. 58)(thin black line). (b) Annual mean North Atlantic SST anomalies for the period 1870–2008 (ref. 58; thin black line). (c) The Atlantic multidecadal oscillation (AMO) index for the period 1870–2008. The modern AMO index4 is defined by subtracting the global mean SST anomalies (a) from the North Atlantic SST anomalies (b). Five-year running means are shown by heavy black lines with fill in all panels.

Mentions: The Atlantic multidecadal oscillation (AMO) has been identified as a coherent pattern of oscillatory changes in North Atlantic sea-surface temperature (SST) with a period of about 60–90 years12. Indices of the AMO have traditionally been based on average annual SST anomalies in the North Atlantic region3. To account for the influence of the recent global warming trend on North Atlantic SST, revised AMO indices have subsequently been defined by including global mean SSTs45 (Fig. 1).


Tracking the Atlantic Multidecadal Oscillation through the last 8,000 years.

Knudsen MF, Seidenkrantz MS, Jacobsen BH, Kuijpers A - Nat Commun (2011)

Global and North Atlantic climate trends over the past ∼150 years.(a) Global annual mean sea-surface temperature (SST) anomalies from HadISST for the period 1870–2008 (Ref. 58)(thin black line). (b) Annual mean North Atlantic SST anomalies for the period 1870–2008 (ref. 58; thin black line). (c) The Atlantic multidecadal oscillation (AMO) index for the period 1870–2008. The modern AMO index4 is defined by subtracting the global mean SST anomalies (a) from the North Atlantic SST anomalies (b). Five-year running means are shown by heavy black lines with fill in all panels.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3105344&req=5

f1: Global and North Atlantic climate trends over the past ∼150 years.(a) Global annual mean sea-surface temperature (SST) anomalies from HadISST for the period 1870–2008 (Ref. 58)(thin black line). (b) Annual mean North Atlantic SST anomalies for the period 1870–2008 (ref. 58; thin black line). (c) The Atlantic multidecadal oscillation (AMO) index for the period 1870–2008. The modern AMO index4 is defined by subtracting the global mean SST anomalies (a) from the North Atlantic SST anomalies (b). Five-year running means are shown by heavy black lines with fill in all panels.
Mentions: The Atlantic multidecadal oscillation (AMO) has been identified as a coherent pattern of oscillatory changes in North Atlantic sea-surface temperature (SST) with a period of about 60–90 years12. Indices of the AMO have traditionally been based on average annual SST anomalies in the North Atlantic region3. To account for the influence of the recent global warming trend on North Atlantic SST, revised AMO indices have subsequently been defined by including global mean SSTs45 (Fig. 1).

Bottom Line: Understanding the internal ocean variability and its influence on climate is imperative for society.The nature and origin of the AMO is uncertain, and it remains unknown whether it represents a persistent periodic driver in the climate system, or merely a transient feature.We therefore conjecture that a quasi-persistent ∼55- to 70-year AMO, linked to internal ocean-atmosphere variability, existed during large parts of the Holocene.

View Article: PubMed Central - PubMed

Affiliation: Centre for Past Climate Studies, Department of Earth Sciences, Aarhus University, HÃøegh-Guldbergs Gade 2, Aarhus DK-8000, Denmark. mfk@geo.au.dk

ABSTRACT
Understanding the internal ocean variability and its influence on climate is imperative for society. A key aspect concerns the enigmatic Atlantic Multidecadal Oscillation (AMO), a feature defined by a 60- to 90-year variability in North Atlantic sea-surface temperatures. The nature and origin of the AMO is uncertain, and it remains unknown whether it represents a persistent periodic driver in the climate system, or merely a transient feature. Here, we show that distinct, ∼55- to 70-year oscillations characterized the North Atlantic ocean-atmosphere variability over the past 8,000 years. We test and reject the hypothesis that this climate oscillation was directly forced by periodic changes in solar activity. We therefore conjecture that a quasi-persistent ∼55- to 70-year AMO, linked to internal ocean-atmosphere variability, existed during large parts of the Holocene. Our analyses further suggest that the coupling from the AMO to regional climate conditions was modulated by orbitally induced shifts in large-scale ocean-atmosphere circulation.

Show MeSH
Related in: MedlinePlus