Asymmetric evolution of El Niño and La Niña: the recharge/discharge processes and role of the off-equatorial sea surface height anomaly

2016 ◽  
Vol 49 (7-8) ◽  
pp. 2737-2748 ◽  
Author(s):  
Zeng-Zhen Hu ◽  
Arun Kumar ◽  
Bohua Huang ◽  
Jieshun Zhu ◽  
Rong-Hua Zhang ◽  
...  
Keyword(s):  
El Niño ◽  
El Nino ◽  
Sea Surface Height ◽  
La Niña ◽  
Sea Surface ◽  
Height Anomaly ◽  
La Nina ◽  
Sea Surface Height Anomaly

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.

scholarly journals Improved Simulation of Tropical Cyclone Responses to ENSO in the Western North Pacific in the High-Resolution GFDL HiFLOR Coupled Climate Model*

2016 ◽  
Vol 29 (4) ◽  
pp. 1391-1415 ◽  
Author(s):  
Wei Zhang ◽  
Gabriel A. Vecchi ◽  
Hiroyuki Murakami ◽  
Thomas Delworth ◽  
Andrew T. Wittenberg ◽  
...  
Keyword(s):  
High Resolution ◽  
Tropical Cyclone ◽  
El Niño ◽  
North Pacific ◽  
Western North Pacific ◽  
El Nino ◽  
Walker Circulation ◽  
La Niña ◽  
Sea Surface ◽  
La Nina

Abstract This study aims to assess whether, and the extent to which, an increase in atmospheric resolution of the Geophysical Fluid Dynamics Laboratory (GFDL) Forecast-Oriented Low Ocean Resolution version of CM2.5 (FLOR) with 50-km resolution and the High-Resolution FLOR (HiFLOR) with 25-km resolution improves the simulation of the El Niño–Southern Oscillation (ENSO)–tropical cyclone (TC) connections in the western North Pacific (WNP). HiFLOR simulates better ENSO–TC connections in the WNP including TC track density, genesis, and landfall than FLOR in both long-term control experiments and sea surface temperature (SST)- and sea surface salinity (SSS)-restoring historical runs (1971–2012). Restoring experiments are performed with SSS and SST restored to observational estimates of climatological SSS and interannually varying monthly SST. In the control experiments of HiFLOR, an improved simulation of the Walker circulation arising from more realistic SST and precipitation is largely responsible for its better performance in simulating ENSO–TC connections in the WNP. In the SST-restoring experiments of HiFLOR, more realistic Walker circulation and steering flow during El Niño and La Niña are responsible for the improved simulation of ENSO–TC connections in the WNP. The improved simulation of ENSO–TC connections with HiFLOR arises from a better representation of SST and better responses of environmental large-scale circulation to SST anomalies associated with El Niño or La Niña. A better representation of ENSO–TC connections in HiFLOR can benefit the seasonal forecasting of TC genesis, track, and landfall; improve understanding of the interannual variation of TC activity; and provide better projection of TC activity under climate change.

scholarly journals PDO–ENSO Effects in the Climate of Mexico

2006 ◽  
Vol 19 (24) ◽  
pp. 6433-6438 ◽  
Author(s):  
Edgar G. Pavia ◽  
Federico Graef ◽  
Jorge Reyes
Keyword(s):  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
La Niña ◽  
Climate Anomalies ◽  
Enso Events ◽  
La Nina ◽  
Mean Temperature ◽  
The Pacific

Abstract The role of the Pacific decadal oscillation (PDO) in El Niño–Southern Oscillation (ENSO)-related Mexican climate anomalies during winter and summer is investigated. The precipitation and mean temperature data of approximately 1000 stations throughout Mexico are considered. After sorting ENSO events by warm phase (El Niño) and cold phase (La Niña) and prevailing PDO phase: warm or high (HiPDO) and cold or low (LoPDO), the authors found the following: 1) For precipitation, El Niño favors wet conditions during summers of LoPDO and during winters of HiPDO. 2) For mean temperature, cooler conditions are favored during La Niña summers and during El Niño winters, regardless of the PDO phase; however, warmer conditions are favored by the HiPDO during El Niño summers.

Sea Surface Temperature in the Subtropical Pacific Boosted the 2015 El Niño and Hindered the 2016 La Niña

2018 ◽  
Vol 31 (2) ◽  
pp. 877-893 ◽  
Author(s):  
Jingzhi Su ◽  
Renhe Zhang ◽  
Xinyao Rong ◽  
Qingye Min ◽  
Congwen Zhu
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
El Niño ◽  
El Nino ◽  
Heat Content ◽  
Equatorial Region ◽  
La Niña ◽  
Sea Surface ◽  
La Nina ◽  
Super El Niño

After the quick decaying of the 2015 super El Niño, the predicted La Niña unexpectedly failed to materialize to the anticipated standard in 2016. Diagnostic analyses, as well as numerical experiments, showed that this ENSO evolution of the 2015 super El Niño and the hindered 2016 La Niña may be essentially caused by sea surface temperature anomalies (SSTAs) in the subtropical Pacific. The self-sustaining SSTAs in the subtropical Pacific tend to weaken the trade winds during boreal spring–summer, leading to anomalous westerlies along the equatorial region over a period of more than one season. Such long-lasting wind anomalies provide an essential requirement for ENSO formation, particularly before a positive Bjerknes feedback is thoroughly built up between the oceanic and atmospheric states. Besides the 2015 super El Niño and the hindered La Niña in 2016, there were several other El Niño and La Niña events that cannot be explained only by the oceanic heat content in the equatorial Pacific. However, the questions related to those eccentric El Niño and La Niña events can be well explained by suitable SSTAs in the subtropical Pacific. Thus, the leading SSTAs in the subtropical Pacific can be treated as an independent indicator for ENSO prediction, on the basis of the oceanic heat content inherent in the equatorial region. Because ENSO events have become more uncertain under the background of global warming and the Pacific decadal oscillation during recent decades, thorough investigation of the role of the subtropical Pacific in ENSO formation is urgently needed.

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