On the relationship between Atlantic Niño variability and ocean dynamics

Dippe, Tina; Greatbatch, Richard John; Ding, Hui

doi:10.1007/s00382-017-3943-z

Cited by 44 publications

(48 citation statements)

References 52 publications

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“…While the (total) Bjerknes feedback is asymmetrical in winter, it does not project onto the observed SST variability—indicating that the Bjerknes feedback plays a minor role in establishing the Atlantic winter Niño. This agrees with Dippe et al () who have found that dynamical, Bjerknes feedback‐related contributions to Atl3 SST variability do increase in winter, but are much smaller in magnitude than in summer. Rather than being a dynamically driven phenomenon as in the Pacific, the Atlantic winter Niño appears to be much more susceptible to atmospheric noise forcing.…”

Section: Discussionsupporting

confidence: 92%

“…While the (total) Bjerknes feedback is asymmetrical in winter, it does not project onto the observed SST variability-indicating that the Bjerknes feedback plays a minor role in establishing the Atlantic winter Niño. This agrees with Dippe et al (2018) who have found that dynamical, Bjerknes feedback-related contributions to Atl3 SST variability do increase in winter, Figure 13. Decadal variations of ERSST-SST event strengths along the equator (x axis) for running subperiods (y axis, shown dates label the start of each analysis period) in the Pacific (left column, a-c) and the Atlantic (right column, d-f).…”

Section: Discussionsupporting

confidence: 92%

“…In the case of the negative composite, it changes from being weakly positive to negative in August, indicating that it blocks anomaly growth and hence effectively contributes to the breakdown of the Atlantic Bjerknes feedback. This agrees with Dippe et al (), who show that the closed Atlantic Bjerknes feedback collapses in August. Differences between the negative and positive composites are generally small, with the positive composite prevailing slightly.…”

Section: Symmetry Of the Atlantic And Pacific Bjerknes Feedbacks 1993supporting

confidence: 93%

“…In the equatorial Atlantic and Pacific Oceans, the Bjerknes feedback supports the growth of coupled air-sea anomalies associated with the Atlantic and Pacific Niños (Bjerknes, 1969;Burls et al, 2012;Deppenmeier et al, 2016;Dippe et al, 2018;Keenlyside & Latif, 2007;Lübbecke & McPhaden, 2013). While the phrase "Pacific Niño" in a strict sense refers to the SST manifestation of a positive El Niño-Southern Oscillation (ENSO) event, we use the name to refer to the entire coupled process.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Discussionsupporting

confidence: 92%

Section: Discussionsupporting

confidence: 92%

Section: Symmetry Of the Atlantic And Pacific Bjerknes Feedbacks 1993supporting

confidence: 93%

Section: Introductionmentioning

confidence: 99%

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

2019

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“…Despite the large biases of climatological SST in the region, models are able to reproduce reasonably the Atlantic Niño and the Bjerknes feedback (Deppenmeier et al, ). Ding et al () and Dippe et al () show that an improved mean state of the TA can lead to better representation of interannual variability in the Kiel climate model, suggesting that error in the climatological SST could be related with errors in the interannual variability.…”

Section: Introductionmentioning

confidence: 99%

How Does the Seasonal Cycle Control Equatorial Atlantic Interannual Variability?

Prodhomme

Voldoire

Exarchou

et al. 2019

Geophysical Research Letters

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It has long been thought that reducing mean‐state biases would lead to improvements in variability. However, so far, there is no confirmation of a relation between model mean biases and variability. While most coupled models exhibit substantial sea surface temperature (SST) biases in the Tropical Atlantic, they are still able to reproduce reasonable SST variability in the basin. We investigate the relationship between the first‐ and second‐order moments of the SST distribution in the equatorial Atlantic using Coupled Model Intercomparison Project Phase 5 simulations. Results suggest that the ability of the coupled models to properly reproduce the interannual variability is linked to their ability to simulate a realistic seasonal cycle evolution, that is, a realistic cold tongue development and a realistic Bjerknes feedback during the beginning of summer, rather than to their ability to represent the summer SST climatology.

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Seasonal prediction of equatorial Atlantic sea surface temperature using simple initialization and bias correction techniques

Dippe

Greatbatch

Ding

2019

Atmospheric Science Letters

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Due to strong mean state‐biases most coupled models are unable to simulate equatorial Atlantic variability. Here, we use the Kiel Climate Model to assess the impact of bias reduction on the seasonal prediction of equatorial Atlantic sea surface temperature (SST). We compare a standard experiment (STD) with an experiment that employs surface heat flux correction to reduce the SST bias (FLX) and, in addition, apply a correction for initial errors in SST. Initial conditions for both experiments are generated in partially coupled mode, and seasonal hindcasts are initialized at the beginning of February, May, August and November for 1981–2012. Surface heat flux correction generally improves hindcast skill. Hindcasts initialized in February have the least skill, even though the model bias is not particularly strong at that time of year. In contrast, hindcasts initialized in May achieve the highest skill. We argue this is because of the emergence of a closed Bjerknes feedback loop in boreal summer in FLX that is a feature of observations but is missing in STD.

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On the relationship between Atlantic Niño variability and ocean dynamics

Cited by 44 publications

References 52 publications

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

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

How Does the Seasonal Cycle Control Equatorial Atlantic Interannual Variability?

Seasonal prediction of equatorial Atlantic sea surface temperature using simple initialization and bias correction techniques

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