Is the decadal variability in the tropical Atlantic a precursor to the NAO?

Wainer, Ilana; Servain, Jacques; Clauzet, Gabriel

doi:10.5194/angeo-26-4075-2008

Cited by 11 publications

(5 citation statements)

References 35 publications

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“…The variability of the South Atlantic Ocean comprises time frequencies ranging from interannual to multidecadal periods (Enfield and Mayer, 1997;Venegas et al, 1998;Czaja and Frankignoul, 2002;Wainer et al, 2008).…”

Section: South Atlantic Ocean Circulationmentioning

confidence: 99%

Mid-Holocene climate reconstruction for eastern South America

Prado¹,

Wainer²,

Chiessi³

et al. 2012

Preprint

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The Mid-Holocene (6 ka BP) is a key period to the study of climate, since it presented lower than present incoming summer insolation in the Southern Hemisphere, and the opposite in the Northern Hemisphere. This happened due to a different than present configuration of the orbital parameters. To investigate the effects of insolation on the Mid-Holocene climate, some global and regional multiproxy palaeodata compilations have been elaborated. However, few global studies have focused on the Southern Hemisphere, and none of the regional ones have characterized the Mid-Holocene climate in South America through a multiproxy approach. Here we present the first multiproxy compilation to the Mid-Holocene climate in eastern South America. We have compiled 120 palaeoclimatological data, published in 84 different papers. The palaeodata analyzed suggest a water deficit scenario in great part of eastern South America during Mid-Holocene, except for Northeastern Brazil. Nonetheless, further sampling is mandatory in South America and in the adjacent ocean basins

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Section: South Atlantic Ocean Circulationmentioning

confidence: 99%

Mid-Holocene climate reconstruction for eastern South America

Prado¹,

Wainer²,

Chiessi³

et al. 2012

Preprint

Self Cite

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show abstract

Section: South Atlantic Ocean Circulationmentioning

confidence: 99%

A mid-Holocene climate reconstruction for eastern South America

Prado¹,

Wainer²,

Chiessi³

et al. 2013

Clim. Past

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The mid-Holocene (6000 calibrated years before present) is a key period in palaeoclimatology because incoming summer insolation was lower than during the late Holocene in the Southern Hemisphere, whereas the opposite happened in the Northern Hemisphere. However, the effects of the decreased austral summer insolation over South American climate have been poorly discussed by palaeodata syntheses. In addition, only a few of the regional studies have characterised the mid-Holocene climate in South America through a multiproxy approach. Here, we present a multiproxy compilation of mid-Holocene palaeoclimate data for eastern South America. We compiled 120 palaeoclimatological datasets, which were published in 84 different papers. The palaeodata analysed here suggest a water deficit scenario in the majority of eastern South America during the mid-Holocene if compared to the late Holocene, with the exception of northeastern Brazil. Low mid-Holocene austral summer insolation caused a reduced land–sea temperature contrast and hence a weakened South American monsoon system circulation. This scenario is represented by a decrease in precipitation over the South Atlantic Convergence Zone area, saltier conditions along the South American continental margin, and lower lake levels

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“…For the tropical Atlantic, earlier studies on decadal time scales focused mainly on the variability of the interhemispheric SST gradient (Mehta, ; Mehta & Delworth, ; Wainer et al, ), while recent work started to address decadal variations in the eastern equatorial Atlantic SST variability with bearings on the Atlantic Niño. Losada and Rodríguez‐Fonseca () describe differences in the spatial pattern of the Atlantic Niño before and after the 1970s, with positive SST anomalies restricted to the eastern equatorial Atlantic in the earlier and a more basin‐wide SST signal in the later period.…”

Section: Discussionmentioning

confidence: 99%

A Comparison of the Atlantic and Pacific Bjerknes Feedbacks: Seasonality, Symmetry, and Stationarity

2019

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The Bjerknes feedback is the dominant positive feedback in the equatorial ocean basins. To examine the seasonality, symmetry, and stationarity of the Pacific and Atlantic Bjerknes feedbacks we decompose them into three feedback elements that relate thermocline depth, sea surface temperature, and western basin wind stress variability to each other. We partition feedback elements into composites associated with positive or negative anomalies. Using robust regression, we diagnose the strength of each composite. For the recent period 1993–2012, composites of the Pacific Bjerknes feedback elements agree well with previous work. Positive composites are generally stronger than negative composites, and all feedback elements are weakest in late boreal spring. In the Atlantic, differences between positive and negative composites are less consistent across feedback elements. Specifically, wind variability seems to play a less important role in shaping atmosphere‐ocean coupling in the Atlantic when compared to the Pacific. However, a clear seasonality emerges: Feedback elements are generally strong in boreal summer and, for the negative composites, again in boreal winter. The Atlantic Bjerknes feedback is dominated by subsurface‐surface coupling. Applying our analysis to overlapping 25‐year periods for 1958–2009 shows that the strengths of feedback elements in both ocean basins vary on decadal time scales. While the overall asymmetry of the Pacific Bjerknes feedback is robust, the strength and symmetry of Atlantic feedback elements vary considerably between decades. Our results indicate that the Atlantic Bjerknes feedback is nonstationary on decadal time scales.

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Is the decadal variability in the tropical Atlantic a precursor to the NAO?

Cited by 11 publications

References 35 publications

Mid-Holocene climate reconstruction for eastern South America

Mid-Holocene climate reconstruction for eastern South America

A mid-Holocene climate reconstruction for eastern South America

A Comparison of the Atlantic and Pacific Bjerknes Feedbacks: Seasonality, Symmetry, and Stationarity

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