Two different simulations of the Southern Oscillation and El Niño with coupled ocean-atmosphere general circulation models

1989 ◽  
Vol 329 (1604) ◽  
pp. 167-178 ◽  
Keyword(s):  
El Niño ◽  
General Circulation ◽  
El Nino ◽  
Southern Oscillation ◽  
General Circulation Models ◽  
La Niña ◽  
The Other ◽  
La Nina ◽  
Ocean Atmosphere ◽  
Interannual Fluctuations

Two different coupled ocean-atmosphere models simulate irregular interannual fluctuations that in many respects resemble El Niño Southern Oscillation phenomena. For example, the spatial structure of various fields at the peaks of the warm El Niño and cold La Niña phases of the oscillation are realistic. This success indicates that the models capture certain aspects of the interactions between the ocean and atmosphere that cause the Southern Oscillation. The principal difference between the models, namely the prominence of oceanic Kelvin waves in one but not the other, causes the two models to differ significantly in the way El Niño episodes evolve, and in the mechanisms that cause a turnabout from El Niño to La Niña and vice versa. It is possible that the different processes that determine the properties of the simulated oscillations all play a role in reality, at different times and in different regions. Each of the models captures some aspects of what is possible. However, reality is far more complex than any model developed thus far and additional processes not yet included are also likely to have a significant influence on the observed Southern Oscillation.

scholarly journals Role of the Indo-Pacific Interbasin Coupling in Predicting Asymmetric ENSO Transition and Duration

2012 ◽  
Vol 25 (9) ◽  
pp. 3321-3335 ◽  
Author(s):  
Masamichi Ohba ◽  
Masahiro Watanabe
Keyword(s):  
El Niño ◽  
General Circulation ◽  
El Nino ◽  
Southern Oscillation ◽  
La Niña ◽  
La Nina ◽  
The Pacific ◽  
Enso Asymmetry ◽  
Sst Anomalies

Warm and cold phases of El Niño–Southern Oscillation (ENSO) exhibit a significant asymmetry in their transition/duration such that El Niño tends to shift rapidly to La Niña after the mature phase, whereas La Niña tends to persist for up to 2 yr. The possible role of sea surface temperature (SST) anomalies in the Indian Ocean (IO) in this ENSO asymmetry is investigated using a coupled general circulation model (CGCM). Decoupled-IO experiments are conducted to assess asymmetric IO feedbacks to the ongoing ENSO evolution in the Pacific. Identical-twin forecast experiments show that a coupling of the IO extends the skillful prediction of the ENSO warm phase by about one year, which was about 8 months in the absence of the IO coupling, in which a significant drop of the prediction skill around the boreal spring (known as the spring prediction barrier) is found. The effect of IO coupling on the predictability of the Pacific SST is significantly weaker in the decay phase of La Niña. Warm IO SST anomalies associated with El Niño enhance surface easterlies over the equatorial western Pacific and hence facilitate the El Niño decay. However, this mechanism cannot be applied to cold IO SST anomalies during La Niña. The result of these CGCM experiments estimates that approximately one-half of the ENSO asymmetry arises from the phase-dependent nature of the Indo-Pacific interbasin coupling.

Ocean Chlorophyll-Induced Heating Feedbacks on ENSO in a Coupled Ocean Physics–Biology Model Forced by Prescribed Wind Anomalies

2018 ◽  
Vol 31 (5) ◽  
pp. 1811-1832 ◽  
Author(s):  
Rong-Hua Zhang ◽  
Feng Tian ◽  
Xiujun Wang
Keyword(s):  
Solar Radiation ◽  
El Niño ◽  
General Circulation ◽  
El Nino ◽  
Southern Oscillation ◽  
La Niña ◽  
La Nina ◽  
El Niño Events ◽  
Ocean Physics ◽  
El Nino Events

Ocean biology components affect the vertical redistribution of incoming solar radiation in the upper ocean of the tropical Pacific and can significantly modulate El Niño–Southern Oscillation (ENSO). The biophysical interactions in the region were represented by coupling an ocean biology model with an ocean general circulation model (OGCM); the coupled ocean physics–biology model is then forced by prescribed wind anomalies during 1980–2007. Two ocean-only experiments were performed with different representations of chlorophyll (Chl). In an interannual Chl run (referred to as Chlinter), Chl was interannually varying, which was interactively calculated from the ocean biology model to explicitly represent its heating feedback on ocean thermodynamics. The structure and relationship of the related heating terms were examined to understand the Chl-induced feedback effects and the processes involved. The portion of solar radiation penetrating the bottom of the mixed layer ( Qpen) was significantly affected by interannual Chl anomalies in the western-central equatorial Pacific. In a climatological run (Chlclim), the Chl concentration was prescribed to be its seasonally varying climatology derived from the Chlinter run. Compared with the Chlclim run, interannual variability in the Chlinter run tended to be reduced. The sea surface temperature (SST) differences between the two runs exhibited an asymmetric bioeffect: they were stronger during La Niña events but relatively weaker during El Niño events. The signs of the SST differences between the two runs indicated a close relationship with Chl: a cooling effect was associated with a low Chl concentration during El Niño events, and a strong warming effect was associated with a high Chl concentration during La Niña events.

scholarly journals The ENSO–Asian Monsoon Interaction in a Coupled Ocean–Atmosphere GCM

2007 ◽  
Vol 20 (20) ◽  
pp. 5164-5177 ◽  
Author(s):  
Ying Li ◽  
Riyu Lu ◽  
Buwen Dong
Keyword(s):  
El Niño ◽  
Asian Monsoon ◽  
El Nino ◽  
Southern Oscillation ◽  
La Niña ◽  
Enso Cycle ◽  
Central Pacific ◽  
La Nina ◽  
Ocean Atmosphere ◽  
The Relationship

Abstract In this study, the authors evaluate the (El Niño–Southern Oscillation) ENSO–Asian monsoon interaction in a version of the Hadley Centre coupled ocean–atmosphere general circulation model (CGCM) known as HadCM3. The main focus is on two evolving anomalous anticyclones: one located over the south Indian Ocean (SIO) and the other over the western North Pacific (WNP). These two anomalous anticyclones are closely related to the developing and decaying phases of the ENSO and play a crucial role in linking the Asian monsoon to ENSO. It is found that the HadCM3 can well simulate the main features of the evolution of both anomalous anticyclones and the related SST dipoles, in association with the different phases of the ENSO cycle. By using the simulated results, the authors examine the relationship between the WNP/SIO anomalous anticyclones and the ENSO cycle, in particular the biennial component of the relationship. It is found that a strong El Niño event tends to be followed by a more rapid decay and is much more likely to become a La Niña event in the subsequent winter. The twin anomalous anticyclones in the western Pacific in the summer of a decaying El Niño are crucial for the transition from an El Niño into a La Niña. The El Niño (La Niña) events, especially the strong ones, strengthen significantly the correspondence between the SIO anticyclonic (cyclonic) anomaly in the preceding autumn and WNP anticyclonic (cyclonic) anomaly in the subsequent spring, and favor the persistence of the WNP anomaly from spring to summer. The present results suggest that both El Niño (La Niña) and the SIO/WNP anticyclonic (cyclonic) anomalies are closely tied with the tropospheric biennial oscillation (TBO). In addition, variability in the East Asian summer monsoon, which is dominated by the internal atmospheric variability, seems to be responsible for the appearance of the WNP anticyclonic anomaly through an upper-tropospheric meridional teleconnection pattern over the western and central Pacific.

scholarly journals INFLUÊNCIA DO ENOS NAS CHUVAS ANUAIS DA REGIÃO AMAZÔNICA DO MATO GROSSO

Nativa ◽  
2018 ◽  
Vol 6 (1) ◽  
pp. 39
Author(s):  
Adilson Pacheco Souza ◽  
Carla Aparecida Ascoli ◽  
Eduardo Morgan Uliana ◽  
Frederico Terra de Almeida ◽  
Bruno Henrique Casavecchia
Keyword(s):  
El Niño ◽  
General Circulation ◽  
El Nino ◽  
Southern Oscillation ◽  
La Niña ◽  
Annual Rainfall ◽  
Mato Grosso ◽  
La Nina ◽  
Total Annual Rainfall ◽  
River Region

A quantidade e as distribuições espaciais e temporais das chuvas determinam o tipo de vegetação natural, potencialidades de exploração agropecuária e disponibilidade de recursos hídricos. Todavia, as chuvas estão diretamente relacionadas com a circulação geral da atmosfera (CGA) e com as mudanças nos seus comportamentos. Em escala global, a maior influência é decorrente do modo de variabilidade climático denominado de El Niño-Oscilação Sul (ENOS) e suas diferentes fases/intensidades (El Niño – EN; La Niña - LN), que determinam as anomalias de chuva em diversas regiões. Diante da grande aptidão agropecuária do estado de Mato Grosso (MT), objetivou-se avaliar as influências do EN e LN para as bacias hidrográficas dos Rios Juruena, Teles Pires e Xingu, situados na região Amazônica. As regiões das nascentes (Alto) das três bacias apresentam similaridade nos totais anuais de chuva. As diferentes intensidades de EN e LN influenciaram de forma significativa nos índices de chuva anual na bacia do Rio Teles Pires. EN-Forte provoca reduções nos totais anuais de chuvas nas regiões baixas (foz) das três bacias hidrográficas. LN-Forte aumentou as chuvas anuais independentemente da região do rio Teles Pires. LN-moderado reduz os totais anuais de chuva independentemente da bacia hidrográfica.Palavra-chave: bacias hidrográficas, variabilidade climática, distribuição espacial. ENOS INFLUENCE IN THE ANNUAL RAINS OF THE REGION AMAZON OF MATO GROSSO STATE ABSTRACT:The amount and spatial and temporal distributions of rainfall determine the type of natural vegetation, agricultural exploration potential and availability of water resources. However, the rainfall are directly dependents to the general circulation of the atmosphere and changes in your behavior. On a global scale, the major influences are the result of the El Niño-Southern Oscillation (ENSO) and its different phases/intensities (El Niño - EN; La Niña - LN), which determine the precipitation anomalies in several regions. Given the large agricultural faculty of Mato Grosso State, Brazil, aimed to evaluate the influence of EN and LN phenomena for the watershed of the rivers Juruena, Teles Pires and Xingu, located in the Amazon region. The regions of the sources of river (High) of the three watershed have similarity in total annual rainfall. The different intensities of EN and LN cause greater influence in the rates of annual rainfall in the Teles Pires Watershed. EN-Intensive causes reductions in total annual rainfall in the lowlands (mouth rivers) of the three watersheds. LN-Intensive provides increase in annual rainfall regardless of the Teles Pires River region. LN-moderate reduces the total annual rainfall regardless of the watershed.Keywords: watersheds, climatic variability, spatial distribution. DOI:

scholarly journals Thermal Front Variability during The El Nino Southern Oscillation (ENSO) in The Banda Sea Using Remotely Sensed Data

2021 ◽  
Vol 3 (2) ◽  
Author(s):  
Achmad Fachruddin Syah ◽  
Siti Sholehah
Keyword(s):  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
La Niña ◽  
The Other ◽  
El Niño Southern Oscillation ◽  
El Nino Southern Oscillation ◽  
Thermal Front ◽  
La Nina ◽  
Normal Period

The Banda Sea is one of the routes of global ocean currents that move from the Pacific Ocean to the Indian Ocean. This flow is known as Indonesian Through Flow (ITF). The Banda Sea is an area where warm and cold water masses meet, so it has the potential for a thermal front. This study aims to understand the variability of thermal front in the Banda Sea during the El Nino Southern Oscillation period. Southern Oscillation Index (SOI) and sea surface temperature (SST) data in 2010, 2012 and 2015 were used in this study. SOI data was obtained from http://www.bom.gov.au and SST data was obtained from http://oceancolor.gsfc.nasa.gov. The data were processed using ArcGIS 10.4 software and Ms. Office 2013. The results showed the La Nina period occurs in July - December 2010, the Normal period occurs in July - December 2012, and the El Nino period occurs in May - October 2015. In general, during La Nina, the mean SST has higher values than the other periods. On the other hand, the highest thermal front occurs during the El Niño period (10584), followed by the Normal period (7544) and the lowest during the La Niña period (5961), respectively.

scholarly journals The Influence of Wind-Induced Waves on ENSO Simulations

2021 ◽  
Vol 9 (5) ◽  
pp. 457
Author(s):  
Yao Hu ◽  
Xiaoxiao Tan ◽  
Youmin Tang ◽  
Zheqi Shen ◽  
Ying Bao
Keyword(s):  
El Niño ◽  
General Circulation ◽  
El Nino ◽  
Southern Oscillation ◽  
Heat Budget ◽  
Circulation Model ◽  
Wave Model ◽  
La Niña ◽  
La Nina ◽  
Wave Induced

We evaluated the influence of wind-induced waves on El Niño-Southern Oscillation (ENSO) simulations based on the First Institute of Oceanography-Earth System Model version 2 (FIO-ESM 2.0), a global coupled general circulation model (GCM) with a wave component. Two sets of experiments, the GCM, with and without a wave model, respectively, were conducted in parallel. The simulated sea surface temperature (SST) was cooled by introducing the wave model via the enhancement of the vertical mixing in the ocean upper layer. The strength of ENSO was intensified and better simulated with the inclusion of wave-induced mixing, particularly the La Niña amplitude. Furthermore, the simulated amplitude and spatial pattern of El Niño events were slightly altered with the wave model. Heat budget analyses revealed the intensification of La Niña events to be generally attributed to wave-induced vertical advection, followed by the zonal and meridional advection terms.

scholarly journals Impact of Strong Tropical Volcanic Eruptions on ENSO Simulated in a Coupled GCM

2013 ◽  
Vol 26 (14) ◽  
pp. 5169-5182 ◽  
Author(s):  
Masamichi Ohba ◽  
Hideo Shiogama ◽  
Tokuta Yokohata ◽  
Masahiro Watanabe
Keyword(s):  
El Niño ◽  
General Circulation ◽  
El Nino ◽  
Southern Oscillation ◽  
Volcanic Eruptions ◽  
La Niña ◽  
Subsurface Water ◽  
Surface Cooling ◽  
La Nina ◽  
The Impact

Abstract The impact of strong tropical volcanic eruptions (SVEs) on the El Niño–Southern Oscillation (ENSO) and its phase dependency is investigated using a coupled general circulation model (CGCM). This paper investigates the response of ENSO to an idealized SVE forcing, producing a peak perturbation of global-mean surface shortwave radiation larger than −6.5 W m−2. Radiative forcing due to volcanic aerosols injected into the stratosphere induces tropical surface cooling around the volcanic forcing peak. Identical-twin forecast experiments of an ENSO-neutral year in response to an SVE forcing show an El Niño–like warming lagging one year behind the peak forcing. In addition to a reduced role of the mean subsurface water upwelling (known as the dynamical thermostat mechanism), the rapid land surface cooling around the Maritime Continent weakens the equatorial Walker circulation, contributing to the positive zonal gradient of sea surface temperature (SST) and precipitation anomalies over the equatorial Pacific. Since the warm and cold phases of ENSO exhibit significant asymmetry in their transition and duration, the impact of a SVE forcing on El Niño and La Niña is also investigated. In the warm phase of ENSO, the prediction skill of the SVE-forced experiments rapidly drops approximately six months after the volcanic peak. Since the SVE significantly facilitates the duration of El Niño, the following transition from warm to cold ENSO is disrupted. The impact of SVE forcing on La Niña is, however, relatively weak. These results imply that the intensity of a dynamical thermostat-like response to a SVE could be dependent on the phase of ENSO.

scholarly journals Sudden stratospheric warmings during El Niño and La Niña: sensitivity to model biases

2021 ◽  
Author(s):  
Nicholas L. Tyrrell ◽  
Juho M. Koskentausta ◽  
Alexey Yu. Karpechko
Keyword(s):  
El Niño ◽  
General Circulation ◽  
El Nino ◽  
Southern Oscillation ◽  
Circulation Model ◽  
La Niña ◽  
Model Biases ◽  
La Nina ◽  
Modelling Studies ◽  
The Impact

Abstract. The number of sudden stratospheric warmings (SSWs) per year is affected by the phase of the El Niño–Southern Oscillation (ENSO), yet there are discrepancies between the observed and modeled relationship. We investigate how systematic model biases may affect the ENSO-SSW connection. A two-step bias-correction process is applied to the troposphere, stratosphere or full atmosphere of an atmospheric general circulation model. ENSO type sensitivity experiments are then performed to reveal the impact of differing climatologies on the ENSO–SSW teleconnection. The number of SSWs per year is overestimated in the control run, and this statistic is improved when stratospheric biases are reduced. The seasonal cycle of SSWs is also improved by the bias corrections. The composite SSW responses in the stratospheric zonal wind, geopotential height and surface response are well represented in both the control and bias corrected runs. The model response of SSWs to ENSO phase is more linear than in observations, in line with previous modelling studies, and this is not changed by the reduced biases. However, the trend of more wave-1 events during El Niño years than La Niña years is improved in the bias corrected runs.

Rendimento de grãos de soja e de milho, no Rio Grande do Sul, não difere entre eventos El Niño Oscilação Sul

Agrometeoros ◽  
2018 ◽  
Vol 26 (1) ◽  
Author(s):  
Ronaldo Matzenauer ◽  
Bernadete Radin ◽  
Alberto Cargnelutti Filho
Keyword(s):  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Rio Grande ◽  
La Niña ◽  
Rio Grande Do Sul ◽  
La Nina ◽  
Significant Difference ◽  
Income Data ◽  
The Relationship

O objetivo deste trabalho foi avaliar a relação entre o fenômeno El Niño Oscilação Sul - ENOS e o rendimento de grãos de soja e de milho no Rio Grande do Sul e verificar a hipótese de que os eventos El Niño são favoráveis e os eventos La Niña são prejudiciais ao rendimento de grãos das culturas. Foram utilizados dados de rendimento de grãos dos anos agrícolas de 1974/75 a 2016/17, e relacionados com as ocorrências de eventos ENOS. Foram analisados os dados de rendimento observados na colheita e os dados estimados com a remoção da tendência tecnológica. Os resultados mostraram que não houve diferença significativa do rendimento médio de grãos de soja e de milho na comparação entre os eventos ENOS. Palavras-chave: El Niño, La Niña, safras agrícolas. Abstract – The objective of this work was to evaluate the relationship between the El Niño Southern Oscillation (ENSO) phenomenon with the grain yield of soybean and maize in Rio Grande do Sul state, Brazil and to verify the hypothesis that the El Niño events are favorable and the La Niña events are harmful to the culture’s grain yields. Were used data from the agricultural years of 1974/75 to 2016/17, and related to the occurrence of ENOS events. We analyzed income data observed at harvest and estimated data with technological tendency was removed. The results showed that there was no significant difference in the average yield of soybeans and corn in the comparison between events.

scholarly journals El Niño, La Niña, and the Forecastability of the Realized Variance of Heating Oil Price Movements

2021 ◽  
Vol 13 (14) ◽  
pp. 7987
Author(s):  
Mehmet Balcilar ◽  
Elie Bouri ◽  
Rangan Gupta ◽  
Christian Pierdzioch
Keyword(s):  
El Niño ◽  
Predictive Value ◽  
El Nino ◽  
Southern Oscillation ◽  
La Niña ◽  
Realized Variance ◽  
La Nina ◽  
Out Of Sample ◽  
Heating Oil ◽  
Price Movements

We use the heterogenous autoregressive (HAR) model to compute out-of-sample forecasts of the monthly realized variance (RV) of movements of the spot and futures price of heating oil. We extend the HAR–RV model to include the role of El Niño and La Niña episodes, as captured by the Equatorial Southern Oscillation Index (EQSOI). Using data from June 1986 to April 2021, we show evidence for several model configurations that both El Niño and La Niña phases contain information useful for forecasting subsequent to the realized variance of price movements beyond the predictive value already captured by the HAR–RV model. The predictive value of La Niña phases, however, seems to be somewhat stronger than the predictive value of El Niño phases. Our results have important implications for investors, as well as from the perspective of sustainable decisions involving the environment.

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