Recent subsurface North Atlantic cooling trend in context of Atlantic decadal-to-multidecadal variability

Abstract Analyses of a 500-yr control integration with the non-flux-adjusted coupled atmosphere–sea ice–ocean model ECHAM5/Max-Planck-Institute Ocean Model (MPI-OM) show pronounced multidecadal fluctuations of the Atlantic overturning circulation and the associated meridional heat transport. The period of the oscillations is about 70–80 yr. The low-frequency variability of the meridional overturning circulation (MOC) contributes substantially to sea surface temperature and sea ice fluctuations in the North Atlantic. The strength of the overturning circulation is related to the convective activity in the deep-water formation regions, most notably the Labrador Sea, and the time-varying control on the freshwater export from the Arctic to the convection sites modulates the overturning circulation. The variability is sustained by an interplay between the storage and release of freshwater from the central Arctic and circulation changes in the Nordic Seas that are caused by variations in the Atlantic heat and salt transport. The relatively high resolution in the deep-water formation region and the Arctic Ocean suggests that a better representation of convective and frontal processes not only leads to an improvement in the mean state but also introduces new mechanisms determining multidecadal variability in large-scale ocean circulation.

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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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Contribution of SST change to multidecadal global and continental surface air temperature trends between 1910 and 2013

Climate Dynamics ◽

10.1007/s00382-019-05060-0 ◽

2019 ◽

Vol 54 (3-4) ◽

pp. 1295-1313

Author(s):

Yidan Xu ◽

Jianping Li ◽

Cheng Sun ◽

Xiaopei Lin ◽

Hailong Liu ◽

...

Keyword(s):

Air Temperature ◽

North Atlantic ◽

Surface Air Temperature ◽

Western Pacific ◽

Multidecadal Variability ◽

The North ◽

Temperature Trends ◽

Community Atmosphere Model ◽

Community Earth System Model ◽

Goddard Institute

AbstractThe global mean surface air temperature (GMST) shows multidecadal variability over the period of 1910–2013, with an increasing trend. This study quantifies the contribution of hemispheric surface air temperature (SAT) variations and individual ocean sea surface temperature (SST) changes to the GMST multidecadal variability for 1910–2013. At the hemispheric scale, both the Goddard Institute for Space Studies (GISS) observations and the Community Earth System Model (CESM) Community Atmosphere Model 5.3 (CAM5.3) simulation indicate that the Northern Hemisphere (NH) favors the GMST multidecadal trend during periods of accelerated warming (1910–1945, 1975–1998) and cooling (1940–1975, 2001–2013), whereas the Southern Hemisphere (SH) slows the intensity of both warming and cooling processes. The contribution of the NH SAT variation to the GMST multidecadal trend is higher than that of the SH. We conduct six experiments with different ocean SST forcing, and find that all the oceans make positive contributions to the GMST multidecadal trend during rapid warming periods. However, only the Indian, North Atlantic, and western Pacific oceans make positive contributions to the GMST multidecadal trend between 1940 and 1975, whereas only the tropical Pacific and the North Pacific SSTs contribute to the GMST multidecadal trend between 2001 and 2013. The North Atlantic and western Pacific oceans have important impacts on modulating the GMST multidecadal trend across the entire 20th century. Each ocean makes different contributions to the SAT multidecadal trend of different continents during different periods.

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Changes of Decadal SST Variations in the Subpolar North Atlantic under Strong CO2 Forcing as an Indicator for the Ocean Circulation’s Contribution to Atlantic Multidecadal Variability

Journal of Climate ◽

10.1175/jcli-d-18-0739.1 ◽

2020 ◽

Vol 33 (8) ◽

pp. 3213-3228 ◽

Cited By ~ 3

Author(s):

Ralf Hand ◽

Jürgen Bader ◽

Daniela Matei ◽

Rohit Ghosh ◽

Johann H. Jungclaus

Keyword(s):

Heat Transport ◽

North Atlantic ◽

Meridional Overturning Circulation ◽

Ocean Dynamics ◽

Northwestern Part ◽

Atlantic Multidecadal Variability ◽

Ocean Heat Transport ◽

Multidecadal Variability ◽

Sst Variability ◽

Basin Scale

AbstractThe question of whether ocean dynamics are relevant for basin-scale North Atlantic decadal temperature variability is the subject of ongoing discussions. Here, we analyze a set of simulations with a single climate model consisting of a 2000-yr preindustrial control experiment, a 100-member historical ensemble, and a 100-member ensemble forced with an incremental CO2 increase by 1% yr−1. Compared to previous approaches, our setup offers the following advantages: First, the large ensemble size allows us to robustly separate internally and externally forced variability and to robustly detect statistical links between different quantities. Second, the availability of different scenarios allows us to investigate the role of the background state for drivers of the variability. We find strong evidence that ocean dynamics, particularly ocean heat transport variations, form an important contribution to generate the Atlantic multidecadal variability (AMV) in the Max Planck Institute Earth System Model (MPI-ESM). Particularly the northwest North Atlantic is substantially affected by ocean circulation for the historical and preindustrial simulations. Anomalies of the Labrador Sea deep ocean density precede a change of the Atlantic meridional overturning circulation (AMOC) and heat advection to the region south of Greenland. Under strong CO2 forcing, the AMV–SST regression pattern shows crucial changes: SST variability in the northwestern part of the North Atlantic is strongly reduced, so that the AMV pattern in this scenario is dominated by the low-latitude branch. We found a connection to changes in the deep-water formation that cause a strong reduction of the mean AMOC and its variability. Consequently, ocean heat transport convergence becomes less important for the SST variability south of Greenland.

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Atlantic Multidecadal Variability in a model with an improved North Atlantic Current

Geophysical Research Letters ◽

10.1002/2016gl069815 ◽

2016 ◽

Vol 43 (15) ◽

pp. 8199-8206 ◽

Cited By ~ 31

Author(s):

Annika Drews ◽

Richard J. Greatbatch

Keyword(s):

North Atlantic ◽

Atlantic Multidecadal Variability ◽

North Atlantic Current ◽

Multidecadal Variability ◽

Atlantic Current

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Correcting North Atlantic sea surface salinity biases in the Kiel Climate Model: influences on ocean circulation and Atlantic Multidecadal Variability

Climate Dynamics ◽

10.1007/s00382-016-2982-1 ◽

2016 ◽

Vol 47 (7-8) ◽

pp. 2543-2560 ◽

Cited By ~ 17

Author(s):

T. Park ◽

W. Park ◽

M. Latif

Keyword(s):

Ocean Circulation ◽

North Atlantic ◽

Climate Model ◽

Sea Surface ◽

Sea Surface Salinity ◽

Atlantic Multidecadal Variability ◽

Surface Salinity ◽

Multidecadal Variability

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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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