scholarly journals Changes in Independency between Two Types of El Niño Events under a Greenhouse Warming Scenario in CMIP5 Models

2015 ◽  
Vol 28 (19) ◽  
pp. 7561-7575 ◽  
Author(s):  
Yoo-Geun Ham ◽  
Yerim Jeong ◽  
Jong-Seong Kug
Keyword(s):  
Global Warming ◽  
El Niño ◽  
El Nino ◽  
Western Pacific ◽  
Cmip5 Models ◽  
Greenhouse Warming ◽  
Central Pacific ◽  
El Niño Events ◽  
The Western Pacific ◽  
El Nino Events

Abstract This study uses archives from phase 5 of the Coupled Model Intercomparison Project (CMIP5) to investigate changes in independency between two types of El Niño events caused by greenhouse warming. In the observations, the independency between cold tongue (CT) and warm pool (WP) El Niño events is distinctively increased in recent decades. The simulated changes in independency between the two types of El Niño events according to the CMIP5 models are quite diverse, although the observed features are simulated to some extent in several climate models. It is found that the climatological change after global warming is an essential factor in determining the changes in independency between the two types of El Niño events. For example, the independency between these events is increased after global warming when the climatological precipitation is increased mainly over the equatorial central Pacific. This climatological precipitation increase extends convective response to the east, particularly for CT El Niño events, which leads to greater differences in the spatial pattern between the two types of El Niño events to increase the El Niño independency. On the contrary, in models with decreased independency between the two types of El Niño events after global warming, climatological precipitation is increased mostly over the western Pacific. This confines the atmospheric response to the western Pacific in both El Niño events; therefore, the similarity between them is increased after global warming. In addition to the changes in the climatological state after global warming, a possible connection of the changes in the El Niño independency with the historical mean state is discussed in this paper.

scholarly journals Historical change of El Niño properties sheds light on future changes of extreme El Niño

2019 ◽  
Vol 116 (45) ◽  
pp. 22512-22517 ◽  
Author(s):  
Bin Wang ◽  
Xiao Luo ◽  
Young-Min Yang ◽  
Weiyi Sun ◽  
Mark A. Cane ◽  
...  
Keyword(s):  
El Niño ◽  
El Nino ◽  
Historical Change ◽  
Western Pacific ◽  
Intensity Change ◽  
Cmip5 Models ◽  
Central Pacific ◽  
El Niño Events ◽  
Extreme El Niño ◽  
El Nino Events

El Niño’s intensity change under anthropogenic warming is of great importance to society, yet current climate models’ projections remain largely uncertain. The current classification of El Niño does not distinguish the strong from the moderate El Niño events, making it difficult to project future change of El Niño’s intensity. Here we classify 33 El Niño events from 1901 to 2017 by cluster analysis of the onset and amplification processes, and the resultant 4 types of El Niño distinguish the strong from the moderate events and the onset from successive events. The 3 categories of El Niño onset exhibit distinct development mechanisms. We find El Niño onset regime has changed from eastern Pacific origin to western Pacific origin with more frequent occurrence of extreme events since the 1970s. This regime change is hypothesized to arise from a background warming in the western Pacific and the associated increased zonal and vertical sea-surface temperature (SST) gradients in the equatorial central Pacific, which reveals a controlling factor that could lead to increased extreme El Niño events in the future. The Coupled Model Intercomparison Project phase 5 (CMIP5) models’ projections demonstrate that both the frequency and intensity of the strong El Niño events will increase significantly if the projected central Pacific zonal SST gradients become enhanced. If the currently observed background changes continue under future anthropogenic forcing, more frequent strong El Niño events are anticipated. The models’ uncertainty in the projected equatorial zonal SST gradients, however, remains a major roadblock for faithful prediction of El Niño’s future changes.

scholarly journals Stronger Increase in the Frequency of Extreme Convective than Extreme Warm El Niño Events under Greenhouse Warming

2020 ◽  
Vol 33 (2) ◽  
pp. 675-690 ◽  
Author(s):  
Guojian Wang ◽  
Wenju Cai ◽  
Agus Santoso
Keyword(s):  
El Niño ◽  
El Nino ◽  
South Pacific Convergence Zone ◽  
Boreal Winter ◽  
Greenhouse Warming ◽  
Convergence Zone ◽  
Central Pacific ◽  
Mixed Regime ◽  
El Niño Events ◽  
El Nino Events

AbstractSince 1979, three extreme El Niño events occurred, in 1982/83, 1997/98, and 2015/16, with pronounced impacts that disrupted global weather patterns, agriculture, fisheries, and ecosystems. Although all three episodes are referred to as strong equatorial eastern Pacific (EP) El Niño events, the 2015/16 event is considered a mixed regime of both EP and central Pacific (CP) El Niño. During such extreme events, sea surface temperature (SST) anomalies peak over the EP region, hereafter referred to as an extreme warm El Niño (ExtWarmEN) event. Simultaneously, the intertropical convergence zone (ITCZ) moves southward to the usually dry and cold Niño-3 region, resulting in dramatic rainfall increases to more than 5 mm day−1 averaged over boreal winter, referred to as an extreme convective El Niño (ExtConEN) event. However, in climate models from phase 5 of the Coupled Model Intercomparison Project (CMIP5) that are able to simulate both types of events, ExtConEN events are found not to always coincide with ExtWarmEN events and the disassociation becomes more distinct under greenhouse warming when the increased frequency of ExtConEN events is notably larger than that of ExtWarmEN events. The disassociation highlights the role of eastward migration of western Pacific convection and equatorward shift of the South Pacific convergence zone associated with the faster warming over the EP region as a result of greenhouse warming.

scholarly journals Northern Hemisphere Stratospheric Pathway of Different El Niño Flavors in Stratosphere-Resolving CMIP5 Models

2017 ◽  
Vol 30 (12) ◽  
pp. 4351-4371 ◽  
Author(s):  
N. Calvo ◽  
M. Iza ◽  
M. M. Hurwitz ◽  
E. Manzini ◽  
C. Peña-Ortiz ◽  
...  
Keyword(s):  
Northern Hemisphere ◽  
El Niño ◽  
El Nino ◽  
Cmip5 Models ◽  
Eastern Canada ◽  
Central Pacific ◽  
Cp El Niño ◽  
El Niño Events ◽  
Ep El Niño ◽  
El Nino Events

The Northern Hemisphere (NH) stratospheric signals of eastern Pacific (EP) and central Pacific (CP) El Niño events are investigated in stratosphere-resolving historical simulations from phase 5 of the Coupled Model Intercomparison Project (CMIP5), together with the role of the stratosphere in driving tropospheric El Niño teleconnections in NH climate. The large number of events in each composite addresses some of the previously reported concerns related to the short observational record. The results shown here highlight the importance of the seasonal evolution of the NH stratospheric signals for understanding the EP and CP surface impacts. CMIP5 models show a significantly warmer and weaker polar vortex during EP El Niño. No significant polar stratospheric response is found during CP El Niño. This is a result of differences in the timing of the intensification of the climatological wavenumber 1 through constructive interference, which occurs earlier in EP than CP events, related to the anomalous enhancement and earlier development of the Pacific–North American pattern in EP events. The northward extension of the Aleutian low and the stronger and eastward location of the high over eastern Canada during EP events are key in explaining the differences in upward wave propagation between the two types of El Niño. The influence of the polar stratosphere in driving tropospheric anomalies in the North Atlantic European region is clearly shown during EP El Niño events, facilitated by the occurrence of stratospheric summer warmings, the frequency of which is significantly higher in this case. In contrast, CMIP5 results do not support a stratospheric pathway for a remote influence of CP events on NH teleconnections.

scholarly journals Effects of Excessive Equatorial Cold Tongue Bias on the Projections of Tropical Pacific Climate Change. Part II: The Extreme El Niño Frequency in CMIP5 Multi-Model Ensemble

Atmosphere ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 851
Author(s):  
Gen Li ◽  
Zhiyuan Zhang ◽  
Bo Lu
Keyword(s):  
El Niño ◽  
Climate Models ◽  
El Nino ◽  
Equatorial Pacific ◽  
Western Pacific ◽  
Warming Pattern ◽  
El Niño Events ◽  
Rcp 8.5 ◽  
Extreme El Niño ◽  
El Nino Events

Under increased greenhouse gas (GHG) forcing, climate models tend to project a warmer sea surface temperature in the eastern equatorial Pacific than in the western equatorial Pacific. This El Niño-like warming pattern may induce an increase in the projected occurrence frequency of extreme El Niño events. The current models, however, commonly suffer from an excessive westward extension of the equatorial Pacific cold tongue accompanied by insufficient equatorial western Pacific precipitation. By comparing the Representative Concentration Pathway (RCP) 8.5 experiments with the historical simulations based on the Coupled Model Intercomparison Project phase 5 (CMIP5), a “present–future” relationship among climate models was identified: models with insufficient equatorial western Pacific precipitation error would have a weaker mean El Niño-like warming pattern as well as a lower increase in the frequency of extreme El Niño events under increased GHG forcing. Using this “present–future” relationship and the observed precipitation in the equatorial western Pacific, this study calibrated the climate projections in the tropical Pacific. The corrected projections showed a stronger El Niño-like pattern of mean changes in the future, consistent with our previous study. In particular, the projected increased occurrence of extreme El Niño events under RCP 8.5 forcing are underestimated by 30–35% in the CMIP5 multi-model ensemble before the corrections. This implies an increased risk of the El Niño-related weather and climate disasters in the future.

scholarly journals Decadal Change of Combination Mode Spatiotemporal Characteristics due to an ENSO Regime Shift

2020 ◽  
Vol 33 (12) ◽  
pp. 5239-5251
Author(s):  
Feng Jiang ◽  
Wenjun Zhang ◽  
Malte F. Stuecker ◽  
Fei-Fei Jin
Keyword(s):  
El Niño ◽  
Regime Shift ◽  
El Nino ◽  
Surface Wind ◽  
Climate Impacts ◽  
Decadal Change ◽  
Central Pacific ◽  
El Niño Events ◽  
Combination Mode ◽  
El Nino Events

AbstractPrevious studies have shown that nonlinear atmospheric interactions between ENSO and the warm pool annual cycle generates a combination mode (C-mode), which is responsible for the termination of strong El Niño events and the development of the anomalous anticyclone over the western North Pacific (WNP). However, the C-mode has experienced a remarkable decadal change in its characteristics around the early 2000s. The C-mode in both pre- and post-2000 exhibits its characteristic anomalous atmospheric circulation meridional asymmetry but with somewhat different spatial structures and time scales. During 1979–99, the C-mode pattern featured prominent westerly surface wind anomalies in the southeastern tropical Pacific and anticyclonic anomalies over the WNP. In contrast, the C-mode-associated westerly anomalies were shifted farther westward to the central Pacific and the WNP anticyclone was farther westward extended and weaker after 2000. These different C-mode patterns were accompanied by distinct climate impacts over the Indo-Pacific region. The decadal differences of the C-mode are tightly connected with the ENSO regime shift around 2000; that is, the occurrence of central Pacific (CP) El Niño events with quasi-biennial and decadal periodicities increased while the occurrence of eastern Pacific (EP) El Niño events with quasi-quadrennial periodicity decreased. The associated near-annual combination tone periodicities of the C-mode also changed in accordance with these changes in the dominant ENSO frequency between the two time periods. Numerical model experiments further confirm the impacts of the ENSO regime shift on the C-mode characteristics. These results have important implications for understanding the C-mode dynamics and improving predictions of its climate impacts.

scholarly journals ENSO flavors in a tree-ring δ<sup>18</sup>O record of <i>Tectona grandis</i> from Indonesia

2015 ◽  
Vol 11 (10) ◽  
pp. 1325-1333 ◽  
Author(s):  
K. Schollaen ◽  
C. Karamperidou ◽  
P. Krusic ◽  
E. Cook ◽  
G. Helle
Keyword(s):  
Tree Ring ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Central Pacific ◽  
Central Pacific El Niño ◽  
Enso Events ◽  
Proxy Records ◽  
El Niño Events ◽  
El Nino Events

Abstract. Indonesia's climate is dominated by the equatorial monsoon system, and has been linked to El Niño-Southern Oscillation (ENSO) events that often result in extensive droughts and floods over the Indonesian archipelago. In this study we investigate ENSO-related signals in a tree-ring δ18O record (1900–2007) of Javanese teak. Our results reveal a clear influence of Warm Pool (central Pacific) El Niño events on Javanese tree-ring δ18O, and no clear signal of Cold Tongue (eastern Pacific) El Niño events. These results are consistent with the distinct impacts of the two ENSO flavors on Javanese precipitation, and illustrate the importance of considering ENSO flavors when interpreting palaeoclimate proxy records in the tropics, as well as the potential of palaeoclimate proxy records from appropriately selected tropical regions for reconstructing past variability of. ENSO flavors.

scholarly journals A study of the effects of westerly wind bursts on ENSO based on CESM

2019 ◽  
Vol 54 (1-2) ◽  
pp. 885-899 ◽  
Author(s):  
Xiaoxiao Tan ◽  
Youmin Tang ◽  
Tao Lian ◽  
Zhixiong Yao ◽  
Xiaojing Li ◽  
...  
Keyword(s):  
El Niño ◽  
El Nino ◽  
Eastern Pacific ◽  
Parameterization Scheme ◽  
Westerly Wind ◽  
Central Pacific ◽  
El Niño Events ◽  
Wind Bursts ◽  
Westerly Wind Bursts ◽  
El Nino Events

AbstractNumerous works have indicated that westerly wind bursts (WWBs) have a significant contribution to the development of El Niño events. However, the simulation of WWBs commonly suffers from large biases in the current generation of coupled general circulation models (CGCMs), limiting our ability to predict El Niño events. In this study, we introduce a WWBs parameterization scheme into the global coupled Community Earth System Model (CESM) to improve the representation of WWBs and to study the impacts of WWBs on El Niño-Southern Oscillation (ENSO) characteristics. It is found that CESM with the WWBs parameterization scheme can generate more realistic characteristics of WWBs, in particular their location and seasonal variation of occurrence. With the parameterized WWBs, the skewness of the Niño 3 index is increased, in better agreement with observation. Eastern Pacific El Niño and central Pacific El Niño events could be successfully reproduced in the model run with WWBs parameterization. Further diagnoses show that the enhanced horizontal advection in the central Pacific and vertical advection in the eastern Pacific, both of which are triggered by WWBs, are crucial factors responsible for the improvements in ENSO simulation. Clearly, WWBs have important effects on ENSO asymmetry and ENSO diversity.

scholarly journals Western Pacific SST Prediction with an Intermediate El Niño Prediction Model

2005 ◽  
Vol 133 (5) ◽  
pp. 1343-1352 ◽  
Author(s):  
Jong-Seong Kug ◽  
In-Sik Kang ◽  
Jong-Ghap Jhun
Keyword(s):  
Prediction Model ◽  
El Niño ◽  
El Nino ◽  
Vertical Mixing ◽  
Western Pacific ◽  
Central Pacific ◽  
Modified Model ◽  
Sst Variability ◽  
Predictive Skill ◽  
The Western Pacific

Abstract To improve forecasting skills in the western Pacific sea surface temperature (SST), the authors utilized and modified an intermediate El Niño prediction model. The original model does not have the major SST thermodynamics for western Pacific SST variability, so it cannot simulate interannual variation in the western Pacific correctly. Therefore, the authors have introduced some modifications, such as heat flux and vertical mixing, into the dynamical model in order to capture SST thermodynamics more realistically. The modified model has better forecast skill than the original one, not only for the western Pacific but also for the eastern-central Pacific. The model has predictive skill up to 6-months lead time as judged by a correlation exceeding 0.5.

scholarly journals Evolution of the Madden–Julian Oscillation in Two Types of El Niño

2016 ◽  
Vol 29 (5) ◽  
pp. 1919-1934 ◽  
Author(s):  
Xiong Chen ◽  
Jian Ling ◽  
Chongyin Li
Keyword(s):  
El Niño ◽  
El Nino ◽  
Moisture Flux ◽  
Early Summer ◽  
Western Pacific ◽  
Madden Julian Oscillation ◽  
Central Pacific ◽  
Cp El Niño ◽  
Ep El Niño ◽  
The Western Pacific

Abstract Evolution characteristics of the Madden–Julian oscillation (MJO) during the eastern Pacific (EP) and central Pacific (CP) types of El Niño have been investigated. MJO activities are strengthened over the western Pacific during the predeveloping and developing phases of EP El Niño, but suppressed during the mature and decaying phases. In contrast, MJO activities do not show a clear relationship with CP El Niño before their occurrence over the western Pacific, but they increase over the central Pacific during the mature and decaying phases of CP El Niño. Lag correlation analyses further confirm that MJO activities over the western Pacific in boreal spring and early summer are closely related to EP El Niño up to 2–11 months later, but not for CP El Niño. EP El Niño tends to weaken the MJO and lead to a much shorter range of its eastward propagation. Anomalous descending motions over the Maritime Continent and western Pacific related to El Niño can suppress convection and moisture flux convergence there and weaken MJO activities over these regions during the mature phase of both types of El Niño. MJO activities over the western Pacific are much weaker in EP El Niño due to the stronger anomalous descending motions. Furthermore, the MJO propagates more continuously and farther eastward during CP El Niño because of robust moisture convergence over the central Pacific, which provides adequate moisture for the development of MJO convection.

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