scholarly journals CMIP5 Projections of Two Types of El Niño and Their Related Tropical Precipitation in the Twenty-First Century

2017 ◽  
Vol 30 (3) ◽  
pp. 849-864 ◽  
Author(s):  
Kang Xu ◽  
Chi-Yung Tam ◽  
Congwen Zhu ◽  
Boqi Liu ◽  
Weiqiang Wang

Abstract Future projections of the eastern-Pacific (EP) and central-Pacific (CP) types of El Niño in the twenty-first century, as well as their associated tropical circulation and precipitation variability, are investigated using historical runs and representative concentration pathway 8.5 (RCP8.5) simulations from 31 coupled models in phase 5 of the Coupled Model Intercomparison Project (CMIP5). As inferred from CMIP5 models that best capture both El Niño flavors, EP El Niño sea surface temperature (SST) variability will become weaker in the future climate, while no robust change of CP El Niño SST is found. Models also reach no consensus on the future change of relative frequency from CP to EP El Niño. However, there are robust changes in the tropical overturning circulation and precipitation associated with both types of El Niño. Under a warmer climate, magnitudes of precipitation anomalies during EP El Niño are projected to increase, presenting significant enhancement of the dry (wet) signal over the western (central–eastern) Pacific. This is consistent with an accelerated hydrological cycle in the deep tropics; hence, a “wet get wetter” picture appears under global warming, accompanied by a weakened anomalous Walker circulation. For CP El Niño, drier-than-normal conditions will be intensified over the tropical central–eastern Pacific in the future climate, with stronger anomalous sinking related to the strengthened North Pacific local Hadley cell. These results suggest that, besides the enhanced basic-state hydrological cycle over the tropics, other elements, such as the anomalous overturning circulation, might also play a role in determining the ENSO precipitation response to a warmer background climate.

Atmosphere ◽  
2018 ◽  
Vol 9 (7) ◽  
pp. 266
Author(s):  
Jinshuang Zhu ◽  
Yudi Liu ◽  
Ruiqing Xie ◽  
Haijie Chang

The precipitation data from the Global Precipitation Climatology Project (GPCP) and CPC Merged Analysis of Precipitation (CMAP) were used to investigate the discrepancy of Centre and Eastern Pacific ITCZ (CEP-ITCZ) during two types of El Niño years. Two models of the heat source distribution during two types of El Niño events were constructed, and the causes of different CEP-ITCZ anomalies for two types of El Niño events were analyzed through the Gill model. The results show that the CEP-ITCZ precipitation is approximately 4.0° southward, and the intensity is enhanced by 3.6 mm/day during the mature period of Eastern Pacific El Niño (EP-El Niño), while during the mature period of Central Pacific El Niño (CP-El Niño), it is only 0.8° southward, and the intensity is enhanced by 3.2 mm/day. The meridional mode of the SST anomaly by means of EOF (Empirical Orthogonal Function) can indirectly affect the CEP-ITCZ by influencing the atmospheric Rossby wave response. In CP-El Niño years, the meridional mode of the SST anomaly is weak, and the atmospheric Rossby wave response enhances the northern and southern trade-wind zones at the same time. The anomaly of cross-equatorial flow is weak and the CEP-ITCZ moves southward a little. At the same time, the wind convergence zone is enhanced, and it is more conducive to the vertical transport of water vapor. In EP-El Niño years, the meridional mode of the SST anomaly is strong, and the atmospheric Rossby wave response strengthens the meridional wind on the northern side of the equator, leading to the southward shift of the CEP-ITCZ. At the same time, the wind convergence zone is weakened and widened, and to a certain extent, it suppresses the vertical transport increase of water vapor caused by the sea surface evaporation.


2016 ◽  
Vol 29 (5) ◽  
pp. 1919-1934 ◽  
Author(s):  
Xiong Chen ◽  
Jian Ling ◽  
Chongyin Li

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.


2012 ◽  
Vol 140 (11) ◽  
pp. 3669-3681 ◽  
Author(s):  
Daria Gushchina ◽  
Boris Dewitte

ABSTRACT The characteristics of intraseasonal tropical variability (ITV) associated with the two flavors of El Niño [i.e., the canonical or eastern Pacific (EP) El Niño and the Modoki or central Pacific (CP) El Niño] are documented using composite and regression analysis. Double space–time Fourier analysis is applied to the NCEP–NCAR zonal wind at 850 hPa (U850) to separate the different components of the ITV in the tropical troposphere, which is then used to define indices of wave activity, and document the spatial pattern of the waves. It is shown that the ITV characteristics are altered during CP El Niño compared to the typical seasonal dependence of the ITV–ENSO relationship. In particular, while EP El Niño is characterized by enhanced MJO and equatorial Rossby (ER) wave activity during spring–summer prior to the ENSO peak, during CP El Niño, the ITV activity is increased during the mature and decaying phases. It is suggested that ITV is more propitious to the triggering of the EP event; while during the CP event, it contributes mostly to the persistence of positive SST anomalies. The oceanic response of these ITV anomalous patterns is further investigated in the Simple Ocean Data Assimilation (SODA) reanalysis by documenting the seasonal evolution of the intraseasonal equatorial oceanic Kelvin wave (IEKW) activity during the two flavors of El Niño. It is shown that anomalous westerlies associated with ITV may generate the corresponding response in the ocean in the form of anomalous IEKW activity.


2018 ◽  
Vol 15 (2) ◽  
pp. 73
Author(s):  
Budi Prasetyo ◽  
Nikita Pusparini

Pulau Sulawesi dipengaruhi oleh fenomena Central Pacific (CP) dan Eastern Pacific (EP) El Niño. Curah hujan Sulawesi mencakup ketiga pola hujan yang ada di Indonesia yaitu Monsunal, equatorial, dan lokal. Variabilitas ketiga pola curah hujan tersebut akan memberikan respon yang berbeda terhadap pengaruh dari kedua tipe El Niño tersebut. Maka, Kajian ini akan membahas pengaruh dari kedua tipe El Niño  terhadap curah hujan Sulawesi. Penelitian ini Menggunakan data curah hujan bulanan berasal dari Climate Prediction Center (CPC) National Oceanic and Atmospheric Administration (NOAA), Suhu Permukaan Laut (SPL) bulanan dari System Ocean Data Assimilation (SODA) versi 2.2.4 dan oceanic Niño Indeks (ONI) dengan periode  Januari 1950 hingga Desember 2010 (60 tahun). Perhitungan statistik sederhana berupa perata-rataan, korelasi, dan analisa komposit digunakan dalam kajian ini. Penentuan tipe El Niño menggunakan tiga buah indeks yang berbeda. Hasilnya diperoleh bahwa Curah hujan Sulawesi berkurang saat kedua tipe El Niño. Penurunan curah hujan akibat EP El Niño berkisar antara 5 – 20 mm sedangkan akibat CP El Niño berkisar antara 2-12 mm. Wilayah Sulawesi dengan pola curah hujan monsunal merupakan wilayah yang mengalami penurunan curah hujan terbesar akibat kedua tipe El Niño tersebut, kemudian diikuti dengan pola curah hujan equatorial dan terakhir Lokal.


2019 ◽  
Vol 4 (1) ◽  
pp. 15
Author(s):  
Budi Prasetyo ◽  
Nikita Pusparini ◽  
Ivonne Milichristi Radjawanne

<strong>Vertical Profile of Banda Sea Temperature Related to El Niño Events in the East Pacific and Central Pacific</strong>.Eastern Pacific (EP) and Central Pacific El Niño have different characteristics such as mechanism, evolution, impact to Sea Surface Temperature (SST), and rainfall. The character of two types of El Nino affect the temperature of the sea, on the near-surface as well as in deeper layer, in other regions including Banda Sea. This study is aimed to understand the response of Banda Sea vertical sea temperature profile to both El Niño types using sea temperature data from Simple Ocean Data Assimilation (SODA) v.2.2.4 from January 1950 until December 2010 (60 years), Oceanic Nino Index (ONI), and mixed layer depth (MLD) from SODA3. Eastern Pacific El Niño and CP El Niño cooled Banda Sea about -1.5°C and 0.9°C, respectively. The maximum cooling due to both El Niño occurred in the thermocline layer (at the depth of 90 to 120m). The maximum temperature decrease during EP El Niño occurred at the depth of 90 to 120 m, while during CP El Niño the maximum temperature decrease was at 140 to 160 m and 160 to 200m in western and eastern Banda Sea, respectively. The temperature of the near-surface layer responded rapidly to CP El Niño while in the deep layer the temperature responded more to EP El Niño. The Banda deep sea layer was cooling after both types of El Niño extinct while the temperature of near-surface layer was increasing when CP El Niño extinct.


2021 ◽  
Vol 8 ◽  
Author(s):  
Wenxu Liao ◽  
Yi Fan ◽  
Shoupeng Zhu ◽  
Yanyan Huang ◽  
Yang Lv

The influence of ENSO events on winter precipitation anomalies in the Philippines has been well known since decades, but whether this effect is different between months needs further exploration. In this study, the monthly variations of precipitation over the Philippines in winter during the mature phases of ENSO events are investigated with datasets of reanalysis and observations from 1979 to 2019. Results indicate that only the eastern Pacific (EP) El Niño shows different influences on the Philippines winter precipitation among different months. In December during mature EP El Niño events, precipitation deficiency is not significant over the whole Philippines, whereas in January and February, precipitation decreases significantly over the southern Philippines as well as the areas to the southeast of the Philippines. Besides, the correlation between consecutive dry days over the southeast Philippines and ENSO is significantly positive in January and February but not in December. The eastward propagation of EP El Niño–related anomalous anticyclone over the western North Pacific (WNPAC) from December to February is proved responsible for the changed relationship between EP El Niño and precipitation. In December, the center of the WNPAC is located to the southeast of the Indo-China Peninsula, inducing weak lower-level wind anomalies and, consequently, weak vertical movement and water vapor transport anomalies over the Philippines, which exerts limited influence on the local precipitation. In January and February, by contrast, the center of WNPAC is located to the southeast of the Philippines, and therefore the southern Philippines is occupied by anticyclonic moisture transports and downward vertical motions, favoring less precipitations and larger than normal consecutive dry days over there.


2013 ◽  
Vol 26 (2) ◽  
pp. 361-379 ◽  
Author(s):  
Pei-Hsuan Chung ◽  
Tim Li

Abstract The interdecadal change of the mean state and two types of El Niño was investigated based on the analysis of observational data from 1980 to 2010. It was found that easterly trades and sea surface temperature (SST) gradients across the equatorial Pacific undergo a regime change in 1998/99, with enhanced trades and a significant cooling (warming) over tropical eastern (western) Pacific in the later period. Accompanying this mean state change is more frequent occurrence of central Pacific (CP) El Niño during 1999–2010. The diagnosis of air–sea feedback strength showed that atmospheric precipitation and wind responses to CP El Niño are greater than those to the eastern Pacific (EP) El Niño for given a unit SST anomaly (SSTA) forcing. The oceanic response to the same wind forcing, however, is greater in the EP El Niño than in the CP El Niño. A mixed layer heat budget analysis reveals that zonal advection (thermocline change induced vertical advection) primarily contributes to the CP (EP) El Niño growth. The role of the mean SST zonal gradient in El Niño selection was investigated through idealized numerical experiments. With the increase of the background zonal SST gradient, the anomalous wind and convection response to a specified EP or CP SSTA shift to the west. Such a difference results in a bifurcation of maximum SSTA tendency, as shown from a simple ocean model. The numerical results support the notion that a shift to the La Niño–like interdecadal mean state is responsible for more frequent occurrence of CP-type El Niño.


2017 ◽  
Vol 30 (4) ◽  
pp. 1397-1415 ◽  
Author(s):  
Pang-Chi Hsu ◽  
Ting Xiao

Abstract The influences of different types of Pacific warming, often classified as the eastern Pacific (EP) and central Pacific (CP) El Niño events, on Madden–Julian oscillation (MJO) activity over the Indian Ocean were investigated. Accompanied by relatively unstable (stable) atmospheric stratification induced by enhanced (reduced) moisture and moist static energy (MSE) in the lower troposphere, strengthened (weakened) MJO convection was observed in the initiation and eastward-propagation stages during CP (EP) El Niño events. To examine the key processes resulting in the differences in low-level moistening and column MSE anomalies over the Indian Ocean associated with the two types of El Niño, the moisture and column MSE budget equations were diagnosed using the reanalysis dataset ERA-Interim. The results indicate that the enhanced horizontal advection in the CP El Niño years plays an important role in causing a larger moisture and MSE growth rate over the MJO initiation area during CP El Niño events than during EP El Niño events. The increases in horizontal moisture and MSE advection primarily result from advection by mean flow across the enhanced intraseasonal moisture and MSE gradient, as well as by intraseasonal circulation across the mean moisture and MSE gradient associated with the CP El Niño. In the eastward development stage, the enhanced preconditioning comes from positive moisture and MSE advection anomalies in the CP El Niño events. Meanwhile, the strengthened MJO-related convection over the central-eastern Indian Ocean is maintained by increased atmospheric radiative heating and surface latent heat flux during the CP El Niño compared to the EP El Niño events.


2016 ◽  
Vol 73 (10) ◽  
pp. 4203-4214 ◽  
Author(s):  
Sebastian Schemm ◽  
Laura M. Ciasto ◽  
Camille Li ◽  
Nils Gunnar Kvamstø

Abstract This study investigates the relationship between tropical Pacific sea surface temperature (SST) variability and cyclogenesis over the Gulf Stream region of the North Atlantic. A cyclone identification scheme and Lagrangian trajectories are used to compare preferred cyclogenesis locations and precyclogenesis flow paths associated with three patterns of tropical Pacific SST variability: eastern Pacific (EP) El Niño, central Pacific (CP) El Niño, and La Niña. During EP El Niño and La Niña winters, the upper-level precyclogenesis flow takes a subtropical path over North America and Gulf Stream cyclogenesis predominantly occurs under the North Atlantic jet entrance, which is the climatologically preferred location. In contrast, during CP El Niño winters, when the warmest SST anomalies occur in the central tropical Pacific, the precyclogenesis flow takes a northern path across North America and Gulf Stream cyclogenesis tends to occur farther north under the jet exit. The shift in preferred cyclogenesis is consistent with changes in transient upstream flow perturbations, detected using potential vorticity (PV) streamer frequencies, which are associated with the stationary wave response. Compared to EP El Niño winters, CP El Niño winters exhibit fewer southward-extending streamers and cyclonic (LC2) flow behavior, resulting in precyclogenesis air bypassing the right entrance of the North Atlantic jet. Downstream, Gulf Stream cyclones penetrate deeper into high Arctic latitudes during CP El Niño winters than in other cases. The results highlight distinct signatures of tropical SST anomalies on synoptic-scale atmospheric features and could help constrain future changes in the North Atlantic storm track and the associated poleward heat transport.


2012 ◽  
Vol 25 (21) ◽  
pp. 7702-7722 ◽  
Author(s):  
Yuan Yuan ◽  
Song Yang

Using multiple datasets and a partial correlation method, the authors analyze the different impacts of eastern Pacific (EP) and central Pacific (CP) El Niño on East Asian climate, focusing on the features from El Niño developing summer to El Niño decaying summer. Unlike the positive–negative–positive (+/−/+) anomalous precipitation pattern over East Asia and the equatorial Pacific during EP El Niño, an anomalous −/+/− rainfall pattern appears during CP El Niño. The anomalous dry conditions over southeastern China and the northwestern Pacific during CP El Niño seem to result from the anomalous low-level anticyclone over southern China and the South China Sea, which is located more westward than the Philippine Sea anticyclone during EP El Niño. The continuous anomalous sinking motion over southeastern China, as part of the anomalous Walker circulation associated with CP El Niño, also contributes to these dry conditions. During the developing summer, the impact of CP El Niño on East Asian climate is more significant than the influence of EP El Niño. During the decaying summer, however, EP El Niño exerts a stronger influence on East Asia, probably due to the long-lasting anomalous warming over the tropical Indian Ocean accompanying EP El Niño. Temperatures over portions of East Asia and the northwestern Pacific tend to be above normal during EP El Niño but below normal from the developing autumn to the next spring during CP El Niño. A possible reason is the weakened (enhanced) East Asian winter monsoon related to EP (CP) El Niño.


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