The role of Atlantic-Arctic exchange in North Atlantic multidecadal climate variability

Abstract A three-part study of the anomalously cold European winter of 2005/06 is undertaken. Climatological analysis indicates that the dominant pattern of climate variability in the Euro–Atlantic sector during this winter was not a negative phase of the North Atlantic Oscillation (NAO), but a pattern with a “blocklike” center located immediately upstream of the continent. Synoptic-dynamical diagnosis of the winter indicates the frequent occurrence of long-lasting blocks in this region, and a Lagrangian trajectory analysis points to the significant role of cloud-diabatic effects in the dynamics of block inception. A series of heuristic numerical simulations lend credence to the hypothesis that the occurrence of the blocks was sensitive to, and significantly influenced by, the warm surface temperature anomalies upstream over the western Atlantic Ocean and North America. Brief comments are made on the significance of the foregoing results for seasonal numerical weather prediction and also their relevance to the consideration of interannual climate variability.

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Interrelationships of the North Atlantic multidecadal climate variability characteristics

Russian Journal of Earth Sciences ◽

10.2205/2018es000653 ◽

2019 ◽

Vol 19 (3) ◽

pp. 1-11

Author(s):

Roman V. Bekryaev

Keyword(s):

Climate Variability ◽

North Atlantic ◽

The North ◽

The North Atlantic ◽

Multidecadal Climate Variability

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The Role of Natural Factors on Major Climate Variability in Northern Winter

10.20944/preprints201608.0025.v2 ◽

2017 ◽

Cited By ~ 2

Author(s):

Indrani Roy

Keyword(s):

Climate Variability ◽

North Atlantic ◽

Southern Oscillation ◽

Volcanic Eruptions ◽

Solar Variability ◽

The Sun ◽

The North ◽

Natural Factors ◽

The North Atlantic

The role of natural factors mainly solar eleven-year cycle variability, and volcanic eruptions on two major modes of climate variability the North Atlantic Oscillation (NAO) and El Niño Southern Oscillation (ENSO) are studied for around last 150 years period. The NAO is the primary factor to regulate Central England Temperature (CET) during winter throughout the period, though NAO is impacted differently by other factors in various time periods. Solar variability indicates a strong positive influence on NAO during 1978-1997, though suggests opposite in earlier period. Solar NAO lag relationship is also shown sensitive to the chosen times of reference and thus points towards the previously proposed mechanism/ relationship related to the sun and NAO. The ENSO is influenced strongly by solar variability and volcanic eruptions in certain periods. This study observes a strong negative association between the sun and ENSO before the 1950s, which is even opposite during the second half of 20th century. The period 1978-1997, when two strong eruptions coincided with active years of strong solar cycles, the ENSO, and volcano suggested a stronger association, and we discussed the important role played by ENSO. That period showed warming in central tropical Pacific while cooling in the North Atlantic with reference to the later period (1999-2017) and also from chosen earlier period. Here we show that the mean atmospheric state is important for understanding the connection between solar variability, the NAO and ENSO and associated mechanism. It presents a critical analysis to improve knowledge about major modes of variability and their role in climate. We also discussed the importance of detecting the robust signal of natural variability, mainly the sun.

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Observed and Simulated Fingerprints of Multidecadal Climate Variability and Their Contributions to Periods of Global SST Stagnation

Journal of Climate ◽

10.1175/jcli-d-16-0443.1 ◽

2017 ◽

Vol 30 (2) ◽

pp. 721-737 ◽

Cited By ~ 13

Author(s):

Monika J. Barcikowska ◽

Thomas R. Knutson ◽

Rong Zhang

Keyword(s):

Climate Variability ◽

North Atlantic ◽

Climate Model ◽

Tropical Pacific ◽

Eastern Tropical Pacific ◽

Multidecadal Variability ◽

The North ◽

Tropical North Atlantic ◽

The North Atlantic ◽

Multidecadal Climate Variability

This study investigates spatiotemporal features of multidecadal climate variability using observations and climate model simulation. Aside from a long-term warming trend, observational SST and atmospheric circulation records are dominated by an almost 65-yr variability component. Although its center of action is over the North Atlantic, it manifests also over the Pacific and Indian Oceans, suggesting a tropical interbasin teleconnection maintained through an atmospheric bridge. An analysis shows that simulated internal climate variability in a coupled climate model (CSIRO Mk3.6.0) reproduces the main spatiotemporal features of the observed component. Model-based multidecadal variability includes a coupled ocean–atmosphere teleconnection, established through a zonally oriented atmospheric overturning circulation between the tropical North Atlantic and eastern tropical Pacific. During the warm SST phase in the North Atlantic, increasing SSTs over the tropical North Atlantic strengthen locally ascending air motion and intensify subsidence and low-level divergence in the eastern tropical Pacific. This corresponds with a strengthening of trade winds and cooling in the tropical central Pacific. The model’s derived component substantially shapes its global climate variability and is tightly linked to multidecadal variability of the Atlantic meridional overturning circulation (AMOC). This suggests potential predictive utility and underscores the importance of correctly representing North Atlantic variability in simulations of global and regional climate. If the observations-based component of variability originates from internal climate processes, as found in the model, the recently observed (1970s–2000s) North Atlantic warming and eastern tropical Pacific cooling might presage an ongoing transition to a cold North Atlantic phase with possible implications for near-term global temperature evolution.

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