Distinctive MJO Activity during the Boreal Winter of the 2015/16 Super El Niño in Comparison with Other Super El Niño Events

2021 ◽  
Vol 38 (4) ◽  
pp. 555-568
Author(s):  
Xuben Lei ◽  
Wenjun Zhang ◽  
Pang-Chi Hsu ◽  
Chao Liu
Keyword(s):  
El Niño ◽  
El Nino ◽  
Boreal Winter ◽  
El Niño Events ◽  
Super El Niño ◽  
El Nino Events

scholarly journals Influence of the Seasonal Cycle on the Termination of El Niño Events in a Coupled General Circulation Model

2006 ◽  
Vol 19 (9) ◽  
pp. 1850-1868 ◽  
Author(s):  
Matthieu Lengaigne ◽  
Jean-Philippe Boulanger ◽  
Christophe Menkes ◽  
Hilary Spencer
Keyword(s):  
El Niño ◽  
General Circulation ◽  
El Nino ◽  
Circulation Model ◽  
Coupled System ◽  
Equatorial Pacific ◽  
Boreal Winter ◽  
Coupled General Circulation Model ◽  
El Niño Events ◽  
El Nino Events

Abstract In this study, the mechanisms leading to the El Niño peak and demise are explored through a coupled general circulation model ensemble approach evaluated against observations. The results here suggest that the timing of the peak and demise for intense El Niño events is highly predictable as the evolution of the coupled system is strongly driven by a southward shift of the intense equatorial Pacific westerly anomalies during boreal winter. In fact, this systematic late-year shift drives an intense eastern Pacific thermocline shallowing, constraining a rapid El Niño demise in the following months. This wind shift results from a southward displacement in winter of the central Pacific warmest SSTs in response to the seasonal evolution of solar insolation. In contrast, the intensity of this seasonal feedback mechanism and its impact on the coupled system are significantly weaker in moderate El Niño events, resulting in a less pronounced thermocline shallowing. This shallowing transfers the coupled system into an unstable state in spring but is not sufficient to systematically constrain the equatorial Pacific evolution toward a rapid El Niño termination. However, for some moderate events, the occurrence of intense easterly wind anomalies in the eastern Pacific during that period initiate a rapid surge of cold SSTs leading to La Niña conditions. In other cases, weaker trade winds combined with a slightly deeper thermocline allow the coupled system to maintain a broad warm phase evolving through the entire spring and summer and a delayed El Niño demise, an evolution that is similar to the prolonged 1986/87 El Niño event. La Niña events also show a similar tendency to peak in boreal winter, with characteristics and mechanisms mainly symmetric to those described for moderate El Niño cases.

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 Impacts of Different Onset Time El Niño Events on Winter Precipitation over South China

Atmosphere ◽  
2018 ◽  
Vol 9 (10) ◽  
pp. 366 ◽  
Author(s):  
Lingli Fan ◽  
Jianjun Xu ◽  
Huade Guan
Keyword(s):  
South China ◽  
El Niño ◽  
El Nino ◽  
Wave Train ◽  
Onset Time ◽  
Winter Precipitation ◽  
Hadley Cell ◽  
Boreal Winter ◽  
El Niño Events ◽  
El Nino Events

Winter precipitation over South China tended to be much higher than normal for the spring El Niño events during 1979–2016. For the spring El Niño events, the meridional and zonal circulations served as a bridge, linking the warmer sea surface temperature (SST) in the eastern equatorial Pacific (EEP) and South China winter precipitation. This possible physical process can be described as follows: During boreal winter, a positive SST anomaly in the EEP was concurrent with strong anomalous convection activity over South China via anomalous Walker circulation, an anomalous Hadley Cell along 110°–130° E, and a zonal westward teleconnection wave train pattern at 700 hPa in the Northern Hemisphere. In addition, an anomalous pumping effect at 200 hPa contributed to the convective activity. Meanwhile, the western Pacific subtropical high moved southwards and strengthened at 500 hPa, and abnormal southwesterly winds brought plentiful water vapor to South China at 850 hPa. All these factors favored an increase in precipitation over South China. For the summer El Niño events, the aforementioned anomalies were weaker, which resulted in a precipitation close to normal over South China.

scholarly journals Evolution of Global Lightning in the Transition from Cold to Warm Phase Preceding Two Super El Niño Events

2020 ◽  
Author(s):  
E. Williams ◽  
T. Bozóki ◽  
G. Sátori ◽  
C. Price ◽  
P. Steinbach ◽  
...  
Keyword(s):  
El Niño ◽  
El Nino ◽  
El Niño Events ◽  
Super El Niño ◽  
El Nino Events

scholarly journals Multi-year El Niño events tied to the North Pacific Oscillation

2021 ◽  
Author(s):  
Ruiqiang Ding ◽  
YU-HENG TSENG ◽  
Emanuele Di Lorenzo ◽  
Liang Shi ◽  
Jianping Li ◽  
...  
Keyword(s):  
El Niño ◽  
North Pacific ◽  
El Nino ◽  
Boreal Winter ◽  
North Pacific Oscillation ◽  
Central Pacific ◽  
The North ◽  
El Niño Events ◽  
The North Pacific ◽  
El Nino Events

Abstract Multi-year El Niño events induce severe and persistent floods and droughts worldwide, with significant socioeconomic impacts, but the causes of their long-lasting behaviors are still not fully understood. Here we present a two-way feedback mechanism between the tropics and extratropics to argue that extratropical atmospheric variability associated with the North Pacific Oscillation (NPO) is a key source of multi-year El Niño events. The NPO during boreal winter can trigger a Central Pacific (CP) El Niño during the subsequent winter, which excites atmospheric teleconnections to the extratropics that project onto the NPO variability, then re-triggers another El Niño event in the following winter, finally resulting in persistent El Niño-like states. Model experiments, with the NPO forcing assimilated to constrain atmospheric circulation, replicate the observed connection between NPO forcing and the occurrence of multi-year El Niño events. Future projections of Coupled Model Intercomparison Project phases 5 and 6 (CMIP5 and CMIP6) models demonstrate that if the projected NPO variability becomes enhanced under future anthropogenic forcing, then more frequent multi-year El Niño events should be expected. We conclude that properly accounting for the effects of the NPO on the evolution of El Niño events may improve multi-year El Niño prediction and projection.

scholarly journals Southeastern China Boreal Winter Precipitation Anomalies are Dependent on Intensity of El Niño

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Zongjian Ke ◽  
Xingwen Jiang ◽  
Zunya Wang
Keyword(s):  
El Niño ◽  
El Nino ◽  
Winter Precipitation ◽  
Tropical Pacific ◽  
Boreal Winter ◽  
Southeastern China ◽  
Anomalous Anticyclone ◽  
El Niño Events ◽  
Sst Anomalies ◽  
El Nino Events

AbstractPrevious studies reported that boreal winter precipitation in southeastern China (SEC) tends to increase during El Niño. In this study, however, we find that most weak El Niño events are accompanied by below-normal precipitation in SEC, although strong El Niño events are accompanied by above-normal precipitation in SEC for both eastern Pacific El Niño and central Pacific El Niño. Both the cold SST anomalies in the western North Pacific (WNP) and the warm SST anomalies in the central tropical Pacific are important for the formation of anomalous anticyclone over the WNP, which favors above-normal precipitation over SEC by transporting more water vapor to SEC. The cold SST anomalies in the WNP only excite a weak anomalous anticyclone locally when the weak warm SST anomalies in the central tropical Pacific are accompanied by weak enhanced convection anomalies. In such condition, El Niño does not affect precipitation in SEC apparently.

Late onsets of tropical cyclones in the decaying years of super El Niño events

2019 ◽  
Vol 38 (7) ◽  
pp. 67-73
Author(s):  
Zhiqiang Li ◽  
Runyu Zhang ◽  
Kai Liu ◽  
Changling Zheng ◽  
Zhikun Chen
Keyword(s):  
Tropical Cyclones ◽  
El Niño ◽  
El Nino ◽  
El Niño Events ◽  
Super El Niño ◽  
El Nino Events
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