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Journal ArticleDOI

Sea surface temperature in the north tropical Atlantic as a trigger for El Niño/Southern Oscillation events

TL;DR: The El Nino/Southern Oscillation in the Pacific Ocean influences temperature in other tropical ocean basins as discussed by the authors, and temperature anomalies in the north tropical Atlantic may also influence the development of La Nina events.
Abstract: The El Nino/Southern Oscillation in the Pacific Ocean influences temperature in other tropical ocean basins. Reanalysis data and model simulations suggest that temperature anomalies in the north tropical Atlantic may also influence the development of La Nina events.
Citations
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Journal ArticleDOI
TL;DR: A review of the state of knowledge on the El Nino/Southern Oscillation (ENSO), a natural climate phenomenon, can be found in this article, where the authors discuss recent advances and insights into how climate change will affect this natural climate varibility cycle.
Abstract: This Review looks at the state of knowledge on the El Nino/Southern Oscillation (ENSO), a natural climate phenomenon. It discusses recent advances and insights into how climate change will affect this natural climate varibility cycle. The El Nino/Southern Oscillation (ENSO) is the dominant climate phenomenon affecting extreme weather conditions worldwide. Its response to greenhouse warming has challenged scientists for decades, despite model agreement on projected changes in mean state. Recent studies have provided new insights into the elusive links between changes in ENSO and in the mean state of the Pacific climate. The projected slow-down in Walker circulation is expected to weaken equatorial Pacific Ocean currents, boosting the occurrences of eastward-propagating warm surface anomalies that characterize observed extreme El Nino events. Accelerated equatorial Pacific warming, particularly in the east, is expected to induce extreme rainfall in the eastern equatorial Pacific and extreme equatorward swings of the Pacific convergence zones, both of which are features of extreme El Nino. The frequency of extreme La Nina is also expected to increase in response to more extreme El Ninos, an accelerated maritime continent warming and surface-intensified ocean warming. ENSO-related catastrophic weather events are thus likely to occur more frequently with unabated greenhouse-gas emissions. But model biases and recent observed strengthening of the Walker circulation highlight the need for further testing as new models, observations and insights become available.

604 citations

Journal ArticleDOI
26 Jul 2018-Nature
TL;DR: A synopsis of the current understanding of the spatio-temporal complexity of this important climate mode and its influence on the Earth system is provided and a unifying framework that identifies the key factors for this complexity is proposed.
Abstract: El Nino events are characterized by surface warming of the tropical Pacific Ocean and weakening of equatorial trade winds that occur every few years Such conditions are accompanied by changes in atmospheric and oceanic circulation, affecting global climate, marine and terrestrial ecosystems, fisheries and human activities The alternation of warm El Nino and cold La Nina conditions, referred to as the El Nino–Southern Oscillation (ENSO), represents the strongest year-to-year fluctuation of the global climate system Here we provide a synopsis of our current understanding of the spatio-temporal complexity of this important climate mode and its influence on the Earth system

598 citations

Journal ArticleDOI
01 Mar 2019-Science
TL;DR: Advances in the understanding of pantropical interbasin climate interactions are reviewed and their implications for both climate prediction and future climate projections are reviewed.
Abstract: The El Nino-Southern Oscillation (ENSO), which originates in the Pacific, is the strongest and most well-known mode of tropical climate variability. Its reach is global, and it can force climate variations of the tropical Atlantic and Indian Oceans by perturbing the global atmospheric circulation. Less appreciated is how the tropical Atlantic and Indian Oceans affect the Pacific. Especially noteworthy is the multidecadal Atlantic warming that began in the late 1990s, because recent research suggests that it has influenced Indo-Pacific climate, the character of the ENSO cycle, and the hiatus in global surface warming. Discovery of these pantropical interactions provides a pathway forward for improving predictions of climate variability in the current climate and for refining projections of future climate under different anthropogenic forcing scenarios.

420 citations

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the role of the Atlantic Ocean in tropical sea surface temperature (SST) teleconnection and found that the Atlantic plays a key role in initiating the tropical wide teleconnection, and the Atlantic-induced anomalies contribute ∼55-75% of the tropical SST and circulation changes during the satellite era.
Abstract: The dipole-like trend of tropical sea surface temperature is investigated and this study finds it to be initiated in the Atlantic Ocean. Atlantic warming drives wind and circulation changes and influences Pacific Ocean surface temperatures. During the past three decades, tropical sea surface temperature (SST) has shown dipole-like trends, with warming over the tropical Atlantic and Indo-western Pacific but cooling over the eastern Pacific. Competing hypotheses relate this cooling, identified as a driver of the global warming hiatus1,2, to the warming trends in either the Atlantic3,4 or Indian Ocean5. However, the mechanisms, the relative importance and the interactions between these teleconnections remain unclear. Using a state-of-the-art climate model, we show that the Atlantic plays a key role in initiating the tropical-wide teleconnection, and the Atlantic-induced anomalies contribute ∼55–75% of the tropical SST and circulation changes during the satellite era. The Atlantic warming drives easterly wind anomalies over the Indo-western Pacific as Kelvin waves and westerly anomalies over the eastern Pacific as Rossby waves. The wind changes induce an Indo-western Pacific warming through the wind–evaporation–SST effect6,7, and this warming intensifies the La Nina-type response in the tropical Pacific by enhancing the easterly trade winds and through the Bjerknes ocean dynamical processes8. The teleconnection develops into a tropical-wide SST dipole pattern. This mechanism, supported by observations and a hierarchy of climate models, reveals that the tropical ocean basins are more tightly connected than previously thought.

331 citations

Journal ArticleDOI
10 Apr 2020
TL;DR: In this paper, the authors synthesize the understanding of ENSO teleconnections to South America, focusing on the mechanisms and diversity of resulting Teleconnections, and outline the impacts of the El Nino-Southern Oscillation on South America. But, while the understanding has improved, with implications for prediction and projection, uncertainty remains in regards to the robustness of the impacts, interbasin climate interactions and interplay with greenhouse warming.
Abstract: The climate of South America (SA) has long held an intimate connection with El Nino, historically describing anomalously warm sea-surface temperatures off the coastline of Peru. Indeed, throughout SA, precipitation and temperature exhibit a substantial, yet regionally diverse, relationship with the El Nino–Southern Oscillation (ENSO). For example, El Nino is typically accompanied by drought in the Amazon and north-eastern SA, but flooding in the tropical west coast and south-eastern SA, with marked socio-economic effects. In this Review, we synthesize the understanding of ENSO teleconnections to SA. Recent efforts have sought improved understanding of ocean–atmosphere processes that govern the impact, inter-event and decadal variability, and responses to anthropogenic warming. ENSO’s impacts have been found to vary markedly, affected not only by ENSO diversity, but also by modes of variability within and outside of the Pacific. However, while the understanding of ENSO–SA relationships has improved, with implications for prediction and projection, uncertainty remains in regards to the robustness of the impacts, inter-basin climate interactions and interplay with greenhouse warming. A coordinated international effort is, therefore, needed to close the observational, theoretical and modelling gaps currently limiting progress, with specific efforts in extending palaeoclimate proxies further back in time, reducing systematic model errors and improving simulations of ENSO diversity and teleconnections. The El Nino–Southern Oscillation exerts a strong influence on the global climate, including South America, where understanding of the phenomenon first emerged. This Review outlines the impacts of the El Nino–Southern Oscillation on South America, focusing on the mechanisms and diversity of resulting teleconnections.

256 citations

References
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Journal ArticleDOI
TL;DR: The Modern-Era Retrospective Analysis for Research and Applications (MERRA) was undertaken by NASA's Global Modeling and Assimilation Office with two primary objectives: to place observations from NASA's Earth Observing System satellites into a climate context and to improve upon the hydrologic cycle represented in earlier generations of reanalyses as mentioned in this paper.
Abstract: The Modern-Era Retrospective Analysis for Research and Applications (MERRA) was undertaken by NASA’s Global Modeling and Assimilation Office with two primary objectives: to place observations from NASA’s Earth Observing System satellites into a climate context and to improve upon the hydrologic cycle represented in earlier generations of reanalyses. Focusing on the satellite era, from 1979 to the present, MERRA has achieved its goals with significant improvements in precipitation and water vapor climatology. Here, a brief overview of the system and some aspects of its performance, including quality assessment diagnostics from innovation and residual statistics, is given.By comparing MERRA with other updated reanalyses [the interim version of the next ECMWF Re-Analysis (ERA-Interim) and the Climate Forecast System Reanalysis (CFSR)], advances made in this new generation of reanalyses, as well as remaining deficiencies, are identified. Although there is little difference between the new reanalyses i...

4,572 citations

Journal ArticleDOI
TL;DR: In this article, a simple analytic model is constructed to elucidate some basic features of the response of the tropical atmosphere to diabatic heating, showing that there is considerable east-west asymmetry which can be illustrated by solutions for heating concentrated in an area of finite extent.
Abstract: A simple analytic model is constructed to elucidate some basic features of the response of the tropical atmosphere to diabatic heating. In particular, there is considerable east-west asymmetry which can be illustrated by solutions for heating concentrated in an area of finite extent. This is of more than academic interest because heating in practice tends to be concentrated in specific areas. For instance, a model with heating symmetric about the equator at Indonesian longitudes produces low-level easterly flow over the Pacific through propagation of Kelvin waves into the region. It also produces low-level westerly inflow over the Indian Ocean (but in a smaller region) because planetary waves propagate there. In the heating region itself the low-level flow is away from the equator as required by the vorticity equation. The return flow toward the equator is farther west because of planetary wave propagation, and so cyclonic flow is obtained around lows which form on the western margins of the heating zone. Another model solution with the heating displaced north of the equator provides a flow similar to the monsoon circulation of July and a simple model solution can also be found for heating concentrated along an inter-tropical convergence line.

3,799 citations

Journal ArticleDOI
TL;DR: In this article, the authors found that anomalous warming events different from conventional El Nino events occur in the central equatorial Pacific, where a horseshoe pattern is flanked by a colder sea surface temperature anomaly (SSTA) on both sides along the equator.
Abstract: [1] Using observed data sets mainly for the period 1979–2005, we find that anomalous warming events different from conventional El Nino events occur in the central equatorial Pacific. This unique warming in the central equatorial Pacific associated with a horseshoe pattern is flanked by a colder sea surface temperature anomaly (SSTA) on both sides along the equator. empirical orthogonal function (EOF) analysis of monthly tropical Pacific SSTA shows that these events are represented by the second mode that explains 12% of the variance. Since a majority of such events are not part of El Nino evolution, the phenomenon is named as El Nino Modoki (pseudo-El Nino) (“Modoki” is a classical Japanese word, which means “a similar but different thing”). The El Nino Modoki involves ocean-atmosphere coupled processes which include a unique tripolar sea level pressure pattern during the evolution, analogous to the Southern Oscillation in the case of El Nino. Hence the total entity is named as El Nino–Southern Oscillation (ENSO) Modoki. The ENSO Modoki events significantly influence the temperature and precipitation over many parts of the globe. Depending on the season, the impacts over regions such as the Far East including Japan, New Zealand, western coast of United States, etc., are opposite to those of the conventional ENSO. The difference maps between the two periods of 1979–2004 and 1958–1978 for various oceanic/atmospheric variables suggest that the recent weakening of equatorial easterlies related to weakened zonal sea surface temperature gradient led to more flattening of the thermocline. This appears to be a cause of more frequent and persistent occurrence of the ENSO Modoki event during recent decades.

2,340 citations

Journal ArticleDOI
TL;DR: In this paper, the formulation and simulation characteristics of two new global coupled climate models developed at NOAA's Geophysical Fluid Dynamics Laboratory (GFDL) are described and two versions of the coupled model are described.
Abstract: The formulation and simulation characteristics of two new global coupled climate models developed at NOAA's Geophysical Fluid Dynamics Laboratory (GFDL) are described. The models were designed to simulate atmospheric and oceanic climate and variability from the diurnal time scale through multicentury climate change, given our computational constraints. In particular, an important goal was to use the same model for both experimental seasonal to interannual forecasting and the study of multicentury global climate change, and this goal has been achieved. Two versions of the coupled model are described, called CM2.0 and CM2.1. The versions differ primarily in the dynamical core used in the atmospheric component, along with the cloud tuning and some details of the land and ocean components. For both coupled models, the resolution of the land and atmospheric components is 2° latitude × 2.5° longitude; the atmospheric model has 24 vertical levels. The ocean resolution is 1° in latitude and longitude, wi...

1,711 citations

Journal ArticleDOI
TL;DR: In this article, a new conceptual model for ENSO has been constructed based upon the positive feedback of tropical ocean atmosphere interaction proposed by Bjerknes as the growth mechanism and the recharge discharge of the equatorial heat content as the phase transition mechanism suggested by Cane and Zebiak and by Wyrtki.
Abstract: A new conceptual model for ENSO has been constructed based upon the positive feedback of tropical ocean‐ atmosphere interaction proposed by Bjerknes as the growth mechanism and the recharge‐discharge of the equatorial heat content as the phase-transition mechanism suggested by Cane and Zebiak and by Wyrtki. This model combines SST dynamics and ocean adjustment dynamics into a coupled basinwide recharge oscillator that relies on the nonequilibrium between the zonal mean equatorial thermocline depth and wind stress. Over a wide range of the relative coupling coefficient, this recharge oscillator can be either self-excited or stochastically sustained. Its period is robust in the range of 3‐5 years. This recharge oscillator model clearly depicts the slow physics of ENSO and also embodies the delayed oscillator (Schopf and Suarez; Battisti and Hirst) without requiring an explicit wave delay. It can also be viewed as a mixed SST‐ocean dynamics oscillator due to the fact that it arises from the merging of two uncoupled modes, a decaying SST mode and a basinwide ocean adjustment mode, through the tropical ocean‐atmosphere coupling. The basic characteristics of this recharge oscillator, including the relationship between the equatorial western Pacific thermocline depth and the eastern Pacific SST anomalies, are in agreement with those of ENSO variability in the observations and simulations with the Zebiak‐Cane model.

1,322 citations