earth science

Tropical Atlantic SST Dipole

Tropical Atlantic SST Dipole is a earth science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Tropical Atlantic SST Dipole rather than just read about it. In short: The Tropical Atlantic SST Dipole refers to a cross-equatorial sea surface temperature (SST) pattern that appears dominant on decadal timescales. It has a period of about 12 years, with the SST anomalies manifesting their most pronounced features around 10–15 degrees of latitude off of the Equator.

Key takeaways

Tropical Atlantic SST Dipole belongs to earth science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Tropical Atlantic SST Dipole to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Tropical Atlantic SST Dipole from memory before moving on to harder problems.

Reference excerpt

The Tropical Atlantic SST Dipole refers to a cross-equatorial sea surface temperature (SST) pattern that appears dominant on decadal timescales. It has a period of about 12 years, with the SST anomalies manifesting their most pronounced features around 10–15 degrees of latitude off of the Equator. It is also referred to as the interhemispheric SST gradient or the Meridional Atlantic mode. This decadal-scale SST pattern constitutes one of the key features of SST variability in the Tropical Atlantic Ocean. Another one is the Atlantic Equatorial Mode, which occurs in the zonal (east-west) direction at interannual timescales, with sea surface temperature and heat content anomalies being observed in the eastern equatorial basin. Its importance in climate dynamics and decadal-scale climate prediction is evident when investigating its impact on adjacent continental regions such as the Northeast Brazil, the Sahel as well as its influence on North Atlantic cyclogenesis.

Structure and key features of the interhemispheric SST dipole Early studies have focused on the connection between the enhancement (decrease) of tropical rainfall in regions such as Northeast Brazil, the Western Sub-Saharan Africa etc. and perturbations in the tropical Atlantic sea surface temperatures (Moura and Shukla (1981), Nobre and Shukla (1996).) Such research efforts have concentrated on the role of the interhemispheric (meridional) SST mode as a dynamical driver of the tropical Atlantic overlying atmosphere, by analyzing perturbations of this coupled tropical ocean-atmosphere system while examining local as well as remote influences (i.e. the tropical -mid-latitude N. Atlantic connection (Tanimoto and Xie (1999), Tourre et al. (1999)), the tropical Pacific influence via El Nino/La Nina events (Enfield and Mayer (1997)). Other studies, however, such as the ones carried out by Houghton and Tourre (1992) and Enfield and Mayer (1997), have questioned the very existence of this interhemispheric gradient (or SST dipole) as a statistical mode of climate variability. These studies suggest that the principal component analysis used to analyze the tropical Atlantic variability (TAV) and extract these statistical SST modes imposes a constraint on the analysis (due to the requirement of the orthogonality of the principal components that are associated with the different SST modes), without which the connection between the SST anomaly patterns in the Northern and Southern hemispheres appears to be insignificant. Ruiz-Barradas et al. (2001) proposed that the aforementioned controversy potentially exists due to the fact that most of the previously-cited studies have attempted to identify tropical Atlantic SST patterns of variability based solely on ocean data, instead of making use of a combined analysis of observed or modeled perturbations in both the ocean and the atmosphere. Following such an additive approach, Ruiz-Barradas et al. noted that a positive Northern Hemisphere (NH) SST anomaly is associated with a northward, wind-stress anomaly and a subsequent cyclonic (counterclockwise) circulation in the subtropics, which interferes with the background flow easterlies; the opposite is true for the southern hemisphere, where the wind stress anomaly acts to enhance the south-easterlies. Such interference with the background flow subsequently leads to a decrease (enhancement) of the heat fluxes from the ocean toward the atmosphere and therefore an intensification of the positive(negative) SST anomalies, in the warm (cool) hemisphere.

Other discernible features of the interhemispheric dipole noted in the aforementioned study, include a strengthened, anomalous downwelling in the hemisphere that is characterized by positive SST anomalies and a respective, less prevalent upwelling in the negative SST anomalies-hemisphere. Furthermore, diabatic heating perturbations are also shown to be linked to cross-equatorial SST changes, with positive anomalies being observed over the warmer Northern hemisphere waters and negative ones over the Southern hemisphere. A strong connection is also found between the tropical Atlantic SST dipole and the overlying atmosphere; enhanced convective patterns and anomalous precipitation appear correlated with warm NH SSTs, whereas the opposite phase is observed across the equator, over the cooler SH waters. Finally, a connection is discerned between the surface and sub-surface interhemispheric pattern-related SSTs. Northern SST anomalies appear to permeate vertically below the ocean surface reaching thermocline (THC) depths and inciting in this way THC anomalies of up to 3m. This provides additional evidence of the critical role of surface ocean currents in transporting warm waters and heat meridionally, since surface wind-induced Ekman pumping appears to be the key contributor for such THC and heat content anomalies.

… excerpt ends here. Continue reading the full article.

Worked examples

Example 1 — a first encounter with Tropical Atlantic SST Dipole

Start with the simplest possible case. Write down what Tropical Atlantic SST Dipole claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In earth science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Tropical Atlantic SST Dipole before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Tropical Atlantic SST Dipole ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Tropical Atlantic SST Dipole

In research: Tropical Atlantic SST Dipole appears in earth science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Tropical Atlantic SST Dipole in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Tropical Atlantic SST Dipole is common in secondary-school and first-year university syllabi. It links to neighbouring topics Atlantic Ocean, Physical oceanography, Regional climate effects, so understanding it makes those chapters shorter.
In everyday life: Look for Tropical Atlantic SST Dipole outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Tropical Atlantic SST Dipole in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Tropical Atlantic SST Dipole means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Tropical Atlantic SST Dipole out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Tropical Atlantic SST Dipole in simple terms?

Why does Tropical Atlantic SST Dipole matter?

Because it connects several earth science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Tropical Atlantic SST Dipole?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Tropical Atlantic SST Dipole.