One mystery of the North Atlantic multidecadal variability. An attempt of simple explanation

Abstract Atlantic multidecadal variability (AMV) is the term used to describe the pattern of variability in North Atlantic sea surface temperatures (SSTs) that is characterized by decades of basinwide warm or cool anomalies, relative to the global mean. AMV has been associated with numerous climate impacts in many regions of the world including decadal variations in temperature and rainfall patterns, hurricane activity, and sea level changes. Given its importance, understanding the physical processes that drive AMV and the extent to which its evolution is predictable is a key challenge in climate science. A leading hypothesis is that natural variations in ocean circulation control changes in ocean heat content and consequently AMV phases. However, this view has been challenged recently by claims that changing natural and anthropogenic radiative forcings are critical drivers of AMV. Others have argued that changes in ocean circulation are not required. Here, we review the leading hypotheses and mechanisms for AMV and discuss the key debates. In particular, we highlight the need for a holistic understanding of AMV. This perspective is a key motivation for a major new U.K. research program: the North Atlantic Climate System Integrated Study (ACSIS), which brings together seven of the United Kingdom’s leading environmental research institutes to enable a broad spectrum approach to the challenges of AMV. ACSIS will deliver the first fully integrated assessment of recent decadal changes in the North Atlantic, will investigate the attribution of these changes to their proximal and ultimate causes, and will assess the potential to predict future changes.

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Evolution of the Atlantic Multidecadal Variability in a Model with an Improved North Atlantic Current

Journal of Climate ◽

10.1175/jcli-d-16-0790.1 ◽

2017 ◽

Vol 30 (14) ◽

pp. 5491-5512 ◽

Cited By ~ 17

Author(s):

Annika Drews ◽

Richard J. Greatbatch

Keyword(s):

North Atlantic ◽

Heat Supply ◽

Heat Content ◽

Atlantic Multidecadal Variability ◽

North Atlantic Current ◽

Multidecadal Variability ◽

Eastern Side ◽

The North ◽

The North Atlantic ◽

Atlantic Current

This article investigates the dynamics and temporal evolution of the Atlantic multidecadal variability (AMV) in a coupled climate model. The model contains a correction to the North Atlantic flow field to improve the path of the North Atlantic Current, thereby alleviating the surface cold bias, a common problem with climate models, and offering a unique opportunity to study the AMV in a model. Changes in greenhouse gas forcing or aerosol loading are not considered. A striking feature of the results is the contrast between the western and eastern sides of the subpolar gyre in the model. On the western side, anomalous heat supply by the ocean plays a major role, with most of this heat being given up to the atmosphere in the warm phase, largely symmetrically about the time of the AMV maximum. By contrast, on the eastern side, the ocean anomalously gains heat from the atmosphere, with relatively little role for ocean heat supply in the years before the AMV maximum. Thereafter, the balance changes with heat now being anomalously removed from the eastern side by the ocean, leading to a reduced ocean heat content, behavior associated with the establishment of an intergyre gyre at the time of the AMV maximum. In the warm phase, melting sea ice leads to a freshening of surface waters northeast of Greenland that travel southward into the Irminger and Labrador Seas, shutting down convection and terminating the AMV warm phase.

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The impact of Atlantic and Pacific Ocean sea surface temperature anomalies on the North Atlantic multidecadal variability

Tellus A Dynamic Meteorology and Oceanography ◽

10.1111/j.1600-0870.2008.00304.x ◽

2008 ◽

Vol 60 (4) ◽

pp. 728-741 ◽

Cited By ~ 9

Author(s):

KLAUS GROSFELD ◽

GERRIT LOHMANN ◽

NOREL RIMBU

Keyword(s):

Pacific Ocean ◽

Surface Temperature ◽

North Atlantic ◽

Sea Surface ◽

Atlantic Multidecadal Variability ◽

Multidecadal Variability ◽

The North ◽

Sea Surface Temperature Anomalies ◽

The North Atlantic ◽

The Impact

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The impact of Atlantic and Pacific Ocean sea surface temperature anomalies on the North Atlantic multidecadal variability

Tellus A Dynamic Meteorology and Oceanography ◽

10.3402/tellusa.v60i4.15300 ◽

2008 ◽

Cited By ~ 2

Author(s):

Klaus Grosfeld ◽

Gerrit Lohmann ◽

Norel Rimbu

Keyword(s):

Pacific Ocean ◽

Surface Temperature ◽

North Atlantic ◽

Sea Surface ◽

Atlantic Multidecadal Variability ◽

Multidecadal Variability ◽

The North ◽

Sea Surface Temperature Anomalies ◽

The North Atlantic ◽

The Impact

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The Atlantic Multidecadal Variability phase-dependence of teleconnection between the North Atlantic Oscillation in February and the Tibetan Plateau in March

Journal of Climate ◽

10.1175/jcli-d-20-0157.1 ◽

2021 ◽

pp. 1-40

Author(s):

Jingyi Li ◽

Fei Li ◽

Shengping He ◽

Huijun Wang ◽

Yvan J Orsolini

Keyword(s):

Tibetan Plateau ◽

Rossby Wave ◽

North Atlantic ◽

Wave Train ◽

The Tibetan Plateau ◽

Atlantic Multidecadal Variability ◽

Multidecadal Variability ◽

The North ◽

Rossby Wave Train ◽

The North Atlantic

AbstractThe Tibetan Plateau (TP), referred to as the “Asian water tower”, contains one of the largest land ice masses on Earth. The local glacier shrinkage and frozen-water storage are strongly affected by variations in surface air temperature over the TP (TPSAT), especially in springtime. This study reveals that the relationship between the February North Atlantic Oscillation (NAO) and March TPSAT is unstable with time and regulated by the phase of the Atlantic Multidecadal Variability (AMV). The significant out-of-phase connection occurs only during the warm phase of AMV (AMV+). The results show that during the AMV+, the negative phase of the NAO persists from February to March, and is accompanied by a quasi-stationary Rossby wave train trapped along a northward-shifted subtropical westerly jet stream across Eurasia, inducing an anomalous adiabatic descent that warms the TP. However, during the cold phase of the AMV, the negative NAO can not persist into March. The Rossby wave train propagates along the well-separated polar and subtropical westerly jets, and the NAO−TPSAT connection is broken. Further investigation suggests that the enhanced synoptic eddy and low frequency flow (SELF) interaction over the North Atlantic in February and March during the AMV+, caused by the enhanced and southward-shifted storm track, help maintain the NAO anomaly pattern via positive eddy feedback. This study provides a new detailed perspective on the decadal variability of the North Atlantic−TP connection in late winter−early spring.

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Impact of Seasonality in the North Atlantic Jet Stream and Storm Migration on the Seasonality of Hurricane Translation Speed Changes

Journal of Climate ◽

10.1175/jcli-d-20-0642.1 ◽

2021 ◽

pp. 1-38

Author(s):

Xi Guo ◽

James P. Kossin ◽

Zhe-Min Tan

Keyword(s):

North Atlantic ◽

Atlantic Coast ◽

Jet Stream ◽

Translation Speed ◽

Multidecadal Variability ◽

The Past ◽

The North ◽

Term Variation ◽

The North Atlantic

AbstractTropical cyclone (TC) translation speed (TCTS) can affect the duration of TC-related disasters, which is critical to coastal and inland areas. The long-term variation of TCTS and their relationship to the variability of the mid-latitude jet stream and storm migration are discussed here for storms near the North Atlantic coast during 1948-2019. Our results reveal the prominent seasonality in the long-term variation of TCTS, which can be largely explained by the seasonality in the covariations of the mid-latitude jet stream and storm locations. Specifically, significant increases of TCTS occur in June and October during the past decades, which may result from the equatorward displacement of the jet stream and poleward migration of storm locations. Prominent slowdown of TCTS is found in August, which is related to the weakened jet strength and equatorward storm migration. In September, the effects of poleward displacement and weakening of the jet stream on TCTS are largely compensated by the poleward storm migration, therefore, no significant change in TCTS is observed. Meanwhile, the multidecadal variability of the Atlantic may contribute to the multidecadal variability of TCTS. Our findings emphasize the significance in taking a seasonality view in discussing the variability and trends of near-coast Atlantic TCTS under climate change.

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Multidecadal Variability of the Hydrothermodynamic Characteristics of the North Atlantic Subpolar Gyre

Processes in GeoMedia - Volume II - Springer Geology ◽

10.1007/978-3-030-53521-6_32 ◽

2021 ◽

pp. 293-300

Author(s):

N. A. Diansky ◽

P. A. Sukhonos

Keyword(s):

North Atlantic ◽

Subpolar Gyre ◽

Multidecadal Variability ◽

The North ◽

North Atlantic Subpolar Gyre ◽

The North Atlantic

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The Impact of North Atlantic–Arctic Multidecadal Variability on Northern Hemisphere Surface Air Temperature

Journal of Climate ◽

10.1175/2010jcli3347.1 ◽

2010 ◽

Vol 23 (21) ◽

pp. 5668-5677 ◽

Cited By ~ 98

Author(s):

Vladimir A. Semenov ◽

Mojib Latif ◽

Dietmar Dommenget ◽

Noel S. Keenlyside ◽

Alexander Strehz ◽

...

Keyword(s):

Climate Variability ◽

Northern Hemisphere ◽

North Atlantic ◽

The Arctic ◽

Decadal Climate Variability ◽

Multidecadal Variability ◽

The North ◽

Hemisphere Surface ◽

The North Atlantic ◽

Decadal Climate

Abstract The twentieth-century Northern Hemisphere surface climate exhibits a long-term warming trend largely caused by anthropogenic forcing, with natural decadal climate variability superimposed on it. This study addresses the possible origin and strength of internal decadal climate variability in the Northern Hemisphere during the recent decades. The authors present results from a set of climate model simulations that suggest natural internal multidecadal climate variability in the North Atlantic–Arctic sector could have considerably contributed to the Northern Hemisphere surface warming since 1980. Although covering only a few percent of the earth’s surface, the Arctic may have provided the largest share in this. It is hypothesized that a stronger meridional overturning circulation in the Atlantic and the associated increase in northward heat transport enhanced the heat loss from the ocean to the atmosphere in the North Atlantic region and especially in the North Atlantic portion of the Arctic because of anomalously strong sea ice melt. The model results stress the potential importance of natural internal multidecadal variability originating in the North Atlantic–Arctic sector in generating interdecadal climate changes, not only on a regional scale, but also possibly on a hemispheric and even a global scale.

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Modeled and Observed Multidecadal Variability in the North Atlantic Jet Stream and Its Connection to Sea Surface Temperatures

Journal of Climate ◽

10.1175/jcli-d-18-0168.1 ◽

2018 ◽

Vol 31 (20) ◽

pp. 8313-8338 ◽

Cited By ~ 16

Author(s):

Isla R. Simpson ◽

Clara Deser ◽

Karen A. McKinnon ◽

Elizabeth A. Barnes

Keyword(s):

North Atlantic ◽

Sea Surface ◽

Late Winter ◽

Jet Stream ◽

Sea Surface Temperatures ◽

Multidecadal Variability ◽

The North ◽

Surface Temperatures ◽

The North Atlantic ◽

North Atlantic Jet

Multidecadal variability in the North Atlantic jet stream in general circulation models (GCMs) is compared with that in reanalysis products of the twentieth century. It is found that almost all models exhibit multidecadal jet stream variability that is entirely consistent with the sampling of white noise year-to-year atmospheric fluctuations. In the observed record, the variability displays a pronounced seasonality within the winter months, with greatly enhanced variability toward the late winter. This late winter variability exceeds that found in any GCM and greatly exceeds expectations from the sampling of atmospheric noise, motivating the need for an underlying explanation. The potential roles of both external forcings and internal coupled ocean–atmosphere processes are considered. While the late winter variability is not found to be closely connected with external forcing, it is found to be strongly related to the internally generated component of Atlantic multidecadal variability (AMV) in sea surface temperatures (SSTs). In fact, consideration of the seasonality of the jet stream variability within the winter months reveals that the AMV is far more strongly connected to jet stream variability during March than the early winter months or the winter season as a whole. Reasoning is put forward for why this connection likely represents a driving of the jet stream variability by the SSTs, although the dynamics involved remain to be understood. This analysis reveals a fundamental mismatch between late winter jet stream variability in observations and GCMs and a potential source of long-term predictability of the late winter Atlantic atmospheric circulation.

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