scholarly journals Attenuation of Central Pacific El Niño Amplitude by North Pacific Sea Surface Temperature Anomalies

2020 ◽  
Vol 33 (15) ◽  
pp. 6673-6688 ◽  
Author(s):  
Kang Xu ◽  
Chi-Yung Tam ◽  
Boqi Liu ◽  
Sheng Chen ◽  
Xiaoyi Yang ◽  
...  
Keyword(s):  
El Niño ◽  
North Pacific ◽  
El Nino ◽  
Sea Surface ◽  
Central Pacific ◽  
Cp El Niño ◽  
The North ◽  
Sea Surface Temperature Anomalies ◽  
Ep El Niño ◽  
The North Pacific

AbstractThere exists a pronounced asymmetry between the amplitudes of central Pacific (CP) and eastern Pacific (EP) El Niño sea surface temperature anomalies (SSTA). The present study examines such an asymmetry and its relationship with the North Pacific SSTA. Results indicate that the weaker CP El Niño amplitude can be attributed to the weaker anomalous zonal wind response to the east–west equatorial SSTA gradient during its growing phase compared with EP El Niño. Furthermore, the occurrence of CP El Niño is closely associated with southwesterly surface wind anomalies in the subtropical North Pacific, as well as ocean warming reminiscent of the North Pacific Gyre Oscillation (NPGO) pattern in its vicinity. Both the observations as well as the pacemaker experiments with a coupled global climate model suggest that the anomalous low-level southwesterlies, induced by the North Pacific Oscillation (NPO)-like atmospheric variability, can enhance anomalously positive SST signals and extend them southwestward to the central equatorial Pacific via the wind–evaporation–SST feedback. This will further attenuate the atmospheric response to zonal SSTA gradient, and hence weaken the amplitude of CP El Niño. Therefore, anomalous low-level southwesterlies over the subtropical North Pacific can effectively act as a conduit for tropical–subtropical air–sea interaction in that region, and can play an important role in limiting the intensity of CP El Niño.

scholarly journals On the Relationship between the North Pacific Climate Variability and the Central Pacific El Niño

2015 ◽  
Vol 28 (2) ◽  
pp. 663-677 ◽  
Author(s):  
Sang-Wook Yeh ◽  
Xin Wang ◽  
Chunzai Wang ◽  
Boris Dewitte
Keyword(s):  
El Niño ◽  
North Pacific ◽  
El Nino ◽  
Atmospheric Variability ◽  
Central Pacific ◽  
Cp El Niño ◽  
The North ◽  
Pacific Climate Variability ◽  
The Relationship ◽  
The North Pacific

Abstract This study examined connections between the North Pacific climate variability and occurrence of the central Pacific (CP) El Niño for the period from 1950 to 2012. A composite analysis indicated that the relationship between the North Pacific sea surface temperature (SST), along with its overlying atmospheric circulation, and the CP El Niño during the developing and mature phases was changed when the occurrence frequency of the CP El Niño significantly increased after 1990. Empirical orthogonal function (EOF) and singular value decomposition (SVD) analyses of variability in the tropical Pacific and its relationship to the North Pacific show that the North Pacific anomalous SST and the atmospheric variability are more closely associated with the occurrence of the CP El Niño after 1990 than before 1990. There were noticeable differences in terms of the atmospheric variability conditions over the North Pacific, such as the North Pacific Oscillation (NPO)-like atmospheric variability during the spring and its associated SST anomalies during the following winter before 1990 and after 1990. In addition, combined EOF analysis also indicated that the NPO-like atmospheric circulation becomes more effective at playing a role in initiating El Niño after 1990. Consequently, such a change might have been associated with the frequent occurrence of the CP El Niño after 1990.

Future Changes to El Niño Teleconnections over the North Pacific and North America

2021 ◽  
pp. 1-43
Author(s):  
Jonathan D. Beverley ◽  
Matthew Collins ◽  
F. Hugo Lambert ◽  
Robin Chadwick
Keyword(s):  
North America ◽  
El Niño ◽  
North Pacific ◽  
El Nino ◽  
Positive Temperature ◽  
Central Pacific ◽  
Wave Source ◽  
The North ◽  
Precipitation Anomalies ◽  
The North Pacific

AbstractThe El Niño-Southern Oscillation (ENSO) is the leading mode of interannual climate variability and it exerts a strong influence on many remote regions of the world, for example in northern North America. Here, we examine future changes to the positive-phase ENSO teleconnection to the North Pacific/North America sector and investigate the mechanisms involved. We find that the positive temperature anomalies over Alaska and northern North America that are associated with an El Niño event in the present day are much weaker, or of the opposite sign, in the CMIP6 abrupt 4×CO2 experiments for almost all models (22 out of 26, of which 15 are statistically significant differences). This is largely related to changes to the anomalous circulation over the North Pacific, rather than differences in the equator-to-pole temperature gradient. Using a barotropic model, run with different background circulation basic states and Rossby wave source forcing patterns from the individual CMIP6 models, we find that changes to the forcing from the equatorial central Pacific precipitation anomalies are more important than changes in the global basic state background circulation. By further decomposing this forcing change into changes associated with the longitude and magnitude of ENSO precipitation anomalies, we demonstrate that the projected overall eastward shift of ENSO precipitation is the main driver of the temperature teleconnection change, rather than the increase in magnitude of El Niño precipitation anomalies which are, nevertheless, seen in the majority of models.

scholarly journals Global Modes of Sea Surface Temperature Variability in Relation to Regional Climate Indices

2011 ◽  
Vol 24 (16) ◽  
pp. 4314-4331 ◽  
Author(s):  
Monique Messié ◽  
Francisco Chavez
Keyword(s):  
El Niño ◽  
North Pacific ◽  
El Nino ◽  
Regional Climate ◽  
Sea Surface ◽  
El Niño Modoki ◽  
The North ◽  
The Pacific ◽  
Global Modes ◽  
The North Pacific

Abstract A century-long EOF analysis of global sea surface temperature (SST) was carried out and the first six modes, independent by construction, were found to be associated with well-known regional climate phenomena: the El Niño–Southern Oscillation (ENSO), the Atlantic multidecadal oscillation (AMO), the Pacific decadal oscillation (PDO), the North Pacific Gyre Oscillation (NPGO), El Niño Modoki, and the Atlantic El Niño. Four of the six global modes are dominated by Pacific changes, the other two (M2 and M6) being associated with the AMO and Atlantic El Niño, respectively. The principal component time series of the ENSO (M1) and North Pacific (M3) modes are coherent at time scales >10 yr, and their interaction results in the traditional PDO pattern and the dominant mode of Pacific multidecadal variability. The M3 and PDO time series are well correlated, but the EOFs have different spatial patterns. The fourth mode (M4) has been strengthening since the 1950s and is related to the NPGO but also to El Niño Modoki, especially at the decadal scale. The fifth global mode (M5) is also spatially and temporally correlated to El Niño Modoki. The Pacific SST modes are further related to atmospheric forcing and the circulation of the North Pacific subpolar and subtropical gyres.

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.

The Influence of ENSO on the Generation of Decadal Variability in the North Pacific*

2007 ◽  
Vol 20 (4) ◽  
pp. 667-680 ◽  
Author(s):  
Soon-Il An ◽  
Jong-Seong Kug ◽  
Axel Timmermann ◽  
In-Sik Kang ◽  
Oliver Timm
Keyword(s):  
El Niño ◽  
North Pacific ◽  
Decadal Variability ◽  
El Nino ◽  
Sea Surface ◽  
Diagnostic Study ◽  
Sea Surface Temperatures ◽  
The North ◽  
Surface Temperatures ◽  
The North Pacific

Abstract This diagnostic study explores the generation of decadal variability in the North Pacific resulting from the asymmetry of the El Niño–Southern Oscillation phenomenon and the nonlinearity of the atmospheric tropical–extratropical teleconnection. Nonlinear regression analysis of the North Pacific sea surface temperatures and atmospheric fields with respect to the ENSO index reveals that the main teleconnection centers shift between El Niño and La Niña years. This asymmetry in the ENSO response, together with the skewed probabilistic distribution of ENSO itself, may contribute to the generation of the long-term decadal variability of sea surface temperatures in the extratropical North Pacific. It is argued that this hypothesis may explain the significant variance of the observed Pacific decadal oscillation in the extratropics.

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.

scholarly journals An Extratropical Air–Sea Interaction over the North Pacific in Association with a Preceding El Niño Episode in Early Summer

2009 ◽  
Vol 137 (11) ◽  
pp. 3771-3785 ◽  
Author(s):  
Yafei Wang ◽  
Anthony R. Lupo
Keyword(s):  
Wave Propagation ◽  
El Niño ◽  
North Pacific ◽  
El Nino ◽  
Wave Train ◽  
The North ◽  
Rossby Wave Propagation ◽  
Okhotsk High ◽  
Wave Flux ◽  
The North Pacific

Abstract Using data for the month of June from 1951 through 2000, this study examined the air–sea interactions over the North Pacific after El Niño matured during the preceding fall season. The principal findings of this work are the following: 1) a coherent region near the international date line (IDL) in the extratropical North Pacific revealed an area of significant negative correlations (SNCs) between the preceding November sea surface temperature (SST) in the Niño-3 region and the June SST in the North Pacific. Also, two indexes of the June Okhotsk high show a significant positive correlation with the November SST in the Niño-3 region during the 1963–2000 period. 2) The strong southeastward wave flux from the upstream area of the Okhotsk Sea over much of the North Pacific in the midlatitudes is associated with a strong preceding El Niño event, the development of the Okhotsk high, and a negative 500-hPa geopotential height/SST anomaly around the coherent region. The stationary wave propagation plays a major part in maintaining the low SSTs in the coherent region and suppressing the northward progress of the subtropical high. This process partially bridges the connection between the central equatorial Pacific warming (CEPW) and the East Asian summer monsoon. 3) A wave train–like anomaly in the SST (tilted northwest–southeast) was established and maintained in the North Pacific during the summer of 1998. This coincided with the direction of the atmospheric Rossby wave propagation as the strong southeastward wave flux was scattered over the midlatitude North Pacific. This event provides solid evidence that Rossby wave propagation plays an important role in forming an oceanic temperature wave train in the extratropical Pacific through the barotropic process.

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