La Niña-driven flooding in the Indo-Pacific warm pool during the past millennium

Abstract It is now widely recognized that El Niño–Southern Oscillation (ENSO) occurs in more than one form, with the canonical eastern Pacific (EP) and more recently recognized central Pacific (CP) ENSO types receiving the most focus. Given that these various ENSO “flavors” may contribute to climate variability and long-term trends in unique ways, and that ENSO variability is not limited to these two types, this study presents a framework that treats ENSO as a continuum but determines a finite maximum number of statistically distinguishable representative ENSO patterns. A neural network–based cluster analysis called self-organizing map (SOM) analysis paired with a statistical distinguishability test determines nine unique patterns that characterize the September–February tropical Pacific SST anomaly fields for the period from 1950 through 2011. These nine patterns represent the flavors of ENSO, which include EP, CP, and mixed ENSO patterns. Over the 1950–2011 period, the most significant trends reflect changes in La Niña patterns, with a shift in dominance of La Niña–like patterns with weak or negative western Pacific warm pool SST anomalies until the mid-1970s, followed by a dominance of La Niña–like patterns with positive western Pacific warm pool SST anomalies, particularly after the mid-1990s. Both an EP and especially a CP El Niño pattern experienced positive frequency trends, but these trends are indistinguishable from natural variability. Overall, changes in frequency within the ENSO continuum contributed to the pattern of tropical Pacific warming, particularly in the equatorial eastern Pacific and especially in relation to changes of La Niña–like rather than El Niño–like patterns.

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Impacts of Two Types of El Niño and La Niña Events on Typhoon Activity

Advances in Meteorology ◽

10.1155/2013/632470 ◽

2013 ◽

Vol 2013 ◽

pp. 1-8 ◽

Cited By ~ 4

Author(s):

Po-Chun Hsu ◽

Chung-Ru Ho ◽

Shin-Jye Liang ◽

Nan-Jung Kuo

Keyword(s):

Correlation Coefficient ◽

El Niño ◽

El Nino ◽

Warm Pool ◽

La Niña ◽

El Niño Modoki ◽

La Nina ◽

Pacific Warm Pool ◽

Highly Correlated ◽

Hadley Centre

The HadISST (Hadley Centre Sea Ice and Sea Surface Temperature) dataset is used to define the years of El Niño, El Niño Modoki, and La Niña events and to find out the impacts of these events on typhoon activity. The results show that the formation positions of typhoon are farther eastward moving in El Niño years than in La Niña years and much further eastward in El Niño Modoki years. The lifetime and the distance of movement are longer, and the intensity of typhoons is stronger in El Niño and in El Niño Modoki years than in La Niña years. The Accumulated Cyclone Energy of typhoon is highly correlated with the Oceanic Niño Index with a correlation coefficient of 0.79. We also find that the typhoons anomalously decrease during El Niño years but increase during El Niño Modoki years. Besides, there are two types of El Niño Modoki, I and II. The intensity of typhoon in El Niño Modoki I years is stronger than in El Niño Modoki II years. Furthermore, the centroid position of the Western Pacific Warm Pool is strongly related to the area of typhoon formation with a correlation coefficient of 0.95.

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Switch Between El Nino and La Nina is Caused by Subsurface Ocean Waves Likely Driven by Lunar Tidal Forcing

Scientific Reports ◽

10.1038/s41598-019-49678-w ◽

2019 ◽

Vol 9 (1) ◽

Author(s):

Jialin Lin ◽

Taotao Qian

Keyword(s):

El Niño ◽

El Nino ◽

Ocean Waves ◽

La Niña ◽

Slow Phase ◽

Enso Events ◽

The Past ◽

La Nina ◽

Subsurface Ocean ◽

Sst Anomaly

Abstract The El Nino-Southern Oscillation (ENSO) is the dominant interannual variability of Earth’s climate system, and strongly modulates global temperature, precipitation, atmospheric circulation, tropical cyclones and other extreme events. However, forecasting ENSO is one of the most difficult problems in climate sciences affecting both interannual climate prediction and decadal prediction of near-term global climate change. The key question is what cause the switch between El Nino and La Nina. For the past 30 years, ENSO forecasts have been limited to short lead times after ENSO sea surface temperature (SST) anomaly has already developed, but unable to predict the switch between El Nino and La Nina. Here, we demonstrate that the switch between El Nino and La Nina is caused by a subsurface ocean wave propagating from western Pacific to central and eastern Pacific and then triggering development of SST anomaly. This is based on analysis of all ENSO events in the past 136 years using multiple long-term observational datasets. The wave’s slow phase speed and decoupling from atmosphere indicate that it is a forced wave. Further analysis of Earth’s angular momentum budget and NASA’s Apollo Landing Mirror Experiment suggests that the subsurface wave is likely driven by lunar tidal gravitational force.

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Hydroclimate of the western Indo-Pacific Warm Pool during the past 24,000 years

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1323585111 ◽

2014 ◽

Vol 111 (26) ◽

pp. 9402-9406 ◽

Cited By ~ 39

Author(s):

Eva M. Niedermeyer ◽

Alex L. Sessions ◽

Sarah J. Feakins ◽

Mahyar Mohtadi

Keyword(s):

Warm Pool ◽

The Past ◽

Pacific Warm Pool

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Precipitation variability within the West Pacific Warm Pool over the past 120 ka: Evidence from the Davao Gulf, southern Philippines

Paleoceanography ◽

10.1002/2013pa002599 ◽

2014 ◽

Vol 29 (11) ◽

pp. 1094-1110 ◽

Cited By ~ 23

Author(s):

Nicholas Fraser ◽

Wolfgang Kuhnt ◽

Ann Holbourn ◽

Timothé Bolliet ◽

Nils Andersen ◽

...

Keyword(s):

Warm Pool ◽

Precipitation Variability ◽

The West ◽

West Pacific ◽

The Past ◽

Pacific Warm Pool

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The influence of radiation flux in Northwest Pacific on the Western Pacific warm pools and typhoons over the past 170 years

Environmental Research Communications ◽

10.1088/2515-7620/ac3ef5 ◽

2021 ◽

Author(s):

Chai Boyu ◽

Feng Xu ◽

Jianjun Xu ◽

Han Li-guo ◽

CHEN Si-qi ◽

...

Keyword(s):

Radiation Flux ◽

Longwave Radiation ◽

Warm Pool ◽

Western Pacific ◽

Shortwave Radiation ◽

Northwest Pacific ◽

Western Pacific Warm Pool ◽

The Past ◽

Pacific Warm Pool ◽

The Western Pacific

Abstract Based on various statistical methods and empirical orthogonal function (EOF) analysis, this study analyzes the correlation of radiation flux of Northwest Pacific in the 100 years scale with the western Pacific warm pool and typhoon development. The key results are as follows. First, the surface downwelling longwave radiation (SDLR) received by key areas in Northwest Pacific significantly increased over the past 170 years. The surface downwelling shortwave radiation (SDSR) decreased, and TOA (Top of Atmosphere) incident shortwave radiation (TISR) slightly fluctuated and increased in the 11a (11 years) period. Second, there was the strongest correlation between the Western Pacific warm pool and SDLR, and both increased continuously. Third, since 1945, there has been a tendency of increasing after decreasing in the annual frequency and the share of severe typhoons, and the formation area distribution of typhoons has turned more even. Taking 1998 as a cut-off point, before 1998, there was no obvious correlation between the strong typhoon frequency and SDLR. However, such correction became stronger after 1998. They were affected by the changes of SDLR, SDSR, TISR, vapor, vorticity, vertical velocity, SST and h100 . Forth, the SDLR and TISR are major factors influencing the Western Pacific warm pool, typhoon motion and other varieties. While SDLR mainly increases in the tropical areas, TISR tends to fluctuate and increase slightly. Their changes are consistent with the change general characteristics of strengthening of typhoon.

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On the Physics of the Warm Water Volume and El Niño/La Niña Predictability

Journal of Physical Oceanography ◽

10.1175/jpo-d-18-0144.1 ◽

2019 ◽

Vol 49 (6) ◽

pp. 1541-1560 ◽

Cited By ~ 3

Author(s):

Allan J. Clarke ◽

Xiaolin Zhang

Keyword(s):

El Niño ◽

El Nino ◽

Warm Pool ◽

Equatorial Pacific ◽

La Niña ◽

Warm Water ◽

Water Volume ◽

La Nina ◽

Eastern Equatorial Pacific ◽

Warm Water Volume

AbstractPrevious work has shown that warm water volume (WWV), usually defined as the volume of equatorial Pacific warm water above the 20°C isotherm between 5°S and 5°N, leads El Niño. In contrast to previous discharge–recharge oscillator theory, here it is shown that anomalous zonal flow acceleration right at the equator and the movement of the equatorial warm pool are crucial to understanding WWV–El Niño dynamics and the ability of WWV to predict ENSO. Specifically, after westerly equatorial wind anomalies in a coupled ocean–atmosphere instability push the warm pool eastward during El Niño, the westerly anomalies follow the warmest water south of the equator in the Southern Hemisphere summer in December–February. With the wind forcing that causes El Niño in the eastern Pacific removed, the eastern equatorial Pacific sea level and thermocline anomalies decrease. Through long Rossby wave dynamics this decrease results in an anomalous westward equatorial flow that tends to push the warm pool westward and often results in the generation of a La Niña during March–June. The anomalously negative eastern equatorial Pacific sea level typically does not change as much during La Niña, the negative feedback is not as strong, and El Niños tend to not follow La Niñas the next year. This El Niño/La Niña asymmetry is seen in the WWV/El Niño phase diagram and decreased predictability during “La Niña–like” decades.

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Why Do Similar Patterns of Tropical Convection Yield Extratropical Circulation Anomalies of Opposite Sign?

Journal of the Atmospheric Sciences ◽

10.1175/jas-d-16-0067.1 ◽

2017 ◽

Vol 74 (2) ◽

pp. 487-511 ◽

Cited By ~ 13

Author(s):

Michael Goss ◽

Steven B. Feldstein

Keyword(s):

North America ◽

El Niño ◽

North Pacific ◽

El Nino ◽

Opposite Sign ◽

Phase 1 ◽

Warm Pool ◽

Tropical Convection ◽

La Niña ◽

La Nina

Abstract Tropical precipitation anomalies associated with El Niño and Madden–Julian oscillation (MJO) phase 1 (La Niña and MJO phase 5) are characterized by a tripole, with positive (negative) centers over the Indian Ocean and central Pacific and a negative (positive) center over the warm pool region. However, their midlatitude circulation responses over the North Pacific and North America tend to be of opposite sign. To investigate these differences in the extratropical response to tropical convection, the dynamical core of a climate model is used, with boreal winter climatology as the initial flow. The model is run using the full heating field for the above four cases, and with heating restricted to each of seven small domains located near or over the equator, to investigate which convective anomalies may be responsible for the different extratropical responses. An analogous observational study is also performed. For both studies, it is found that, despite having a similar tropical convective anomaly spatial pattern, the extratropical response to El Niño and MJO phase 1 (La Niña and MJO phase 5) is quite different. Most notably, responses with opposite-signed upper-tropospheric geopotential height anomalies are found over the eastern North Pacific, northwestern North America, and the southeastern United States. The extratropical response for each convective case most closely resembles that for the domain associated with the largest-amplitude precipitation anomaly: the central equatorial Pacific for El Niño and La Niña and the warm pool region for MJO phases 1 and 5.

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