Western Pacific SST Prediction with an Intermediate El Niño Prediction Model

Abstract To improve forecasting skills in the western Pacific sea surface temperature (SST), the authors utilized and modified an intermediate El Niño prediction model. The original model does not have the major SST thermodynamics for western Pacific SST variability, so it cannot simulate interannual variation in the western Pacific correctly. Therefore, the authors have introduced some modifications, such as heat flux and vertical mixing, into the dynamical model in order to capture SST thermodynamics more realistically. The modified model has better forecast skill than the original one, not only for the western Pacific but also for the eastern-central Pacific. The model has predictive skill up to 6-months lead time as judged by a correlation exceeding 0.5.

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Changes in Independency between Two Types of El Niño Events under a Greenhouse Warming Scenario in CMIP5 Models

Journal of Climate ◽

10.1175/jcli-d-14-00721.1 ◽

2015 ◽

Vol 28 (19) ◽

pp. 7561-7575 ◽

Cited By ~ 2

Author(s):

Yoo-Geun Ham ◽

Yerim Jeong ◽

Jong-Seong Kug

Keyword(s):

Global Warming ◽

El Niño ◽

El Nino ◽

Western Pacific ◽

Cmip5 Models ◽

Greenhouse Warming ◽

Central Pacific ◽

El Niño Events ◽

The Western Pacific ◽

El Nino Events

Abstract This study uses archives from phase 5 of the Coupled Model Intercomparison Project (CMIP5) to investigate changes in independency between two types of El Niño events caused by greenhouse warming. In the observations, the independency between cold tongue (CT) and warm pool (WP) El Niño events is distinctively increased in recent decades. The simulated changes in independency between the two types of El Niño events according to the CMIP5 models are quite diverse, although the observed features are simulated to some extent in several climate models. It is found that the climatological change after global warming is an essential factor in determining the changes in independency between the two types of El Niño events. For example, the independency between these events is increased after global warming when the climatological precipitation is increased mainly over the equatorial central Pacific. This climatological precipitation increase extends convective response to the east, particularly for CT El Niño events, which leads to greater differences in the spatial pattern between the two types of El Niño events to increase the El Niño independency. On the contrary, in models with decreased independency between the two types of El Niño events after global warming, climatological precipitation is increased mostly over the western Pacific. This confines the atmospheric response to the western Pacific in both El Niño events; therefore, the similarity between them is increased after global warming. In addition to the changes in the climatological state after global warming, a possible connection of the changes in the El Niño independency with the historical mean state is discussed in this paper.

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Evolution of the Madden–Julian Oscillation in Two Types of El Niño

Journal of Climate ◽

10.1175/jcli-d-15-0486.1 ◽

2016 ◽

Vol 29 (5) ◽

pp. 1919-1934 ◽

Cited By ~ 30

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.

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Variations of Upper-Ocean Salinity Associated with ENSO from PEODAS Reanalyses

Journal of Climate ◽

10.1175/jcli-d-15-0650.1 ◽

2016 ◽

Vol 29 (6) ◽

pp. 2077-2094 ◽

Cited By ~ 4

Author(s):

Mei Zhao ◽

Harry H. Hendon ◽

Yonghong Yin ◽

Oscar Alves

Keyword(s):

Barrier Layer ◽

El Niño ◽

El Nino ◽

Western Pacific ◽

Upper Ocean ◽

Central Pacific ◽

La Nina ◽

Ocean Salinity ◽

The Western Pacific ◽

Extreme El Niño

Abstract Interannual variations of upper-ocean salinity in the tropical Pacific and relationships with ENSO are investigated using the Bureau of Meteorology (Australia) POAMA Ensemble Ocean Data Assimilation System (PEODAS) reanalyses. Empirical orthogonal function (EOF) analysis reveals the systematic evolution of salinity and temperature during ENSO. EOF1 and EOF2 of both temperature and salinity capture the mature phase of El Niño and the discharge and recharge phase, respectively. Typical El Niño and La Niña evolution captured by the leading pair of EOFs depicts eastward or westward migration of the eastern edge of the warm/fresh pool in the western Pacific. Increased or decreased freshness in the western Pacific mixed layer occurs in the recharge/discharge phase. EOF3 captures extreme El Niño, when the strong positive temperature anomaly extends to the South American coast and the fresh pool detaches from the western Pacific and shifts into the central Pacific. Large loadings on EOF3 occurred only during 1982/83 and 1997/98, which suggests that eastern Pacific El Niño is actually the exception, whereas moderate central Pacific El Niño and La Niña are more typical. The eastward expansion of the warm/fresh pool during El Niño is also associated with a continuous eastward displacement of the barrier layer, indicating an active role of the barrier layer not just at the onset of an event. The barrier layer and fresh pool shift much farther eastward during strong El Niño, which could contribute to the eastward shift of strong events. The prior enhancement of the barrier layer in the western Pacific is also more concentrated and stronger, which might portend development of extreme El Niño.

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ENSO surface longwave radiation forcing over the tropical Pacific

Atmospheric Chemistry and Physics ◽

10.5194/acp-7-2013-2007 ◽

2007 ◽

Vol 7 (8) ◽

pp. 2013-2026 ◽

Cited By ~ 8

Author(s):

K. G. Pavlakis ◽

D. Hatzidimitriou ◽

E. Drakakis ◽

C. Matsoukas ◽

A. Fotiadi ◽

...

Keyword(s):

Time Series ◽

El Niño ◽

El Nino ◽

Longwave Radiation ◽

Western Pacific ◽

Radiative Cooling ◽

Central Pacific ◽

The Mean ◽

Downwelling Longwave Radiation ◽

The Western Pacific

Abstract. We have studied the spatial and temporal variation of the surface longwave radiation (downwelling and net) over a 21-year period in the tropical and subtropical Pacific Ocean (40 S–40 N, 90 E–75 W). The fluxes were computed using a deterministic model for atmospheric radiation transfer, along with satellite data from the ISCCP-D2 database and reanalysis data from NCEP/NCAR (acronyms explained in main text), for the key atmospheric and surface input parameters. An excellent correlation was found between the downwelling longwave radiation (DLR) anomaly and the Niño-3.4 index time-series, over the Niño-3.4 region located in the central Pacific. A high anti-correlation was also found over the western Pacific (15–0 S, 105–130 E). There is convincing evidence that the time series of the mean downwelling longwave radiation anomaly in the western Pacific precedes that in the Niño-3.4 region by 3–4 months. Thus, the downwelling longwave radiation anomaly is a complementary index to the SST anomaly for the study of ENSO events and can be used to asses whether or not El Niño or La Niña conditions prevail. Over the Niño-3.4 region, the mean DLR anomaly values range from +20 Wm−2 during El Niño episodes to −20 Wm−2 during La Niña events, while over the western Pacific (15–0 S, 105–130 E) these values range from −15 Wm−2 to +10 Wm−2, respectively. The long- term average (1984–2004) distribution of the net downwelling longwave radiation at the surface over the tropical and subtropical Pacific for the three month period November-December-January shows a net thermal cooling of the ocean surface. When El Niño conditions prevail, the thermal radiative cooling in the central and south-eastern tropical Pacific becomes weaker by 10 Wm−2 south of the equator in the central Pacific (7–0 S, 160–120 W) for the three-month period of NDJ, because the DLR increase is larger than the increase in surface thermal emission. In contrast, the thermal radiative cooling over Indonesia is enhanced by 10 Wm−2 during the early (August–September–October) El Niño phase.

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A Coupled GCM Analysis of MJO Activity at the Onset of El Niño

Journal of the Atmospheric Sciences ◽

10.1175/2008jas2855.1 ◽

2009 ◽

Vol 66 (4) ◽

pp. 966-983 ◽

Cited By ~ 16

Author(s):

A. G. Marshall ◽

O. Alves ◽

H. H. Hendon

Keyword(s):

El Niño ◽

El Nino ◽

Southern Oscillation ◽

Heat Content ◽

Ocean Dynamics ◽

Western Pacific ◽

Eastern Pacific ◽

Kelvin Wave ◽

Central Pacific ◽

The Western Pacific

Abstract The ocean dynamics of the Madden–Julian oscillation (MJO) and its interaction with El Niño–Southern Oscillation (ENSO) are assessed using a flux-corrected coupled model experiment from the Australian Bureau of Meteorology. The model demonstrates the correct oceanic Kelvin wave response to the MJO-related westerly winds in the western Pacific. Although there may be a role for the MJO in influencing the strength of El Niño, its impact is difficult to separate from that of strong heat content preconditioning of ENSO. Hence, the MJO–ENSO relationship is assessed starting from a background state of low heat content anomalies in the western Pacific that are also characteristic of recent observed El Niño events. The model shows a strong relationship between ENSO and the MJO near the peak of El Niño. At this time, the sea surface temperature (SST) anomaly is largest in the central Pacific, and it is difficult to separate cause and effect. Near the onset of El Niño, however, when Pacific Ocean SST anomalies are near zero, an increase in MJO activity is associated with Kelvin wave activity and stronger subsequent ENSO warming. A significant increase in the number of MJO events, rather than the strength of individual MJO events, leads to stronger eastern Pacific warming; the MJO appears not to be responsible for the occurrence of El Niño itself, but, rather, is important for influencing its development thus. This research supports a role for downwelling oceanic Kelvin waves and subsequent deepening of the thermocline in contributing to eastern Pacific warming during the onset of El Niño.

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Forecasting tropical ENSO-induced drought conditions using sea surface height in the Western Pacific

10.21203/rs.3.rs-926783/v1 ◽

2021 ◽

Author(s):

Carlos Primo David ◽

Manuel Justin Custado ◽

Natasha Sekhon ◽

Daniel Ibarra

Keyword(s):

El Niño ◽

El Nino ◽

Sea Surface Height ◽

The Philippines ◽

Western Pacific ◽

Sea Surface ◽

Central Pacific ◽

Predictive Tool ◽

Drought Conditions ◽

The Western Pacific

Abstract The interannual variability of rainfall caused by the El Niño Southern Oscillation (ENSO) results in significant changes in hydrologic conditions that affect entire countries’ water supply. Forecasting ENSO and its impacts are mainly based on Central Pacific Sea surface temperature (SST) anomalies which satisfactorily correlates with timing and, to a lesser extent, the intensity of drought conditions in the Philippines and the rest of the Western Pacific during the El Niño phase. Changes in sea surface height (SSH) are also brought upon by ENSO through density changes with temperature and oceanographic processes. Here, we report that the associative nature of SSH and drought as measured by surface runoff, has a stronger correlation (r > 0.693, p < 0.05) in terms of the expected timing, with 1 to 3 months lag time, and intensity compared to using traditional ENSO SST indices from the Central Pacific. Furthermore, since SSH is co-located with its corresponding forecasted decrease in runoff, a localized prediction can be made which further increases the accuracy of this predictive tool. In the wake of a changing climate, this work demonstrates the possibility of statistically forecasting the timing of precipitation, and thus the volume of surface water availability, using local SSH as an indicator. A tool which is necessary for time-sensitive management decision making in drought-prone tropical regions.

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ENSO surface longwave radiation forcing over the tropical Pacific

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-6-12895-2006 ◽

2006 ◽

Vol 6 (6) ◽

pp. 12895-12928 ◽

Cited By ~ 1

Author(s):

K. G. Pavlakis ◽

D. Hatzidimitriou ◽

E. Drakakis ◽

C. Matsoukas ◽

A. Fotiadi ◽

...

Keyword(s):

Time Series ◽

El Niño ◽

El Nino ◽

Longwave Radiation ◽

Western Pacific ◽

Radiative Cooling ◽

Central Pacific ◽

The Mean ◽

Downwelling Longwave Radiation ◽

The Western Pacific

Abstract. We have studied the spatial and temporal variation of the surface longwave radiation (downwelling and net) over a 21-year period in the tropical and subtropical Pacific Ocean (40 S–40 N, 90 E–75 W). The fluxes were computed using a deterministic model for atmospheric radiation transfer, along with satellite data from the ISCCP-D2 database and reanalysis data from NCEP/NCAR (acronyms explained in main text), for the key atmospheric and surface input parameters. An excellent correlation was found between the downwelling longwave radiation (DLR) anomaly and the Niño-3.4 index time-series, over the Niño-3.4 region located in the central Pacific. A high anti-correlation was also found over the western Pacific (15–0 S, 105–130 E). There is convincing evidence that the time series of the mean downwelling longwave radiation anomaly in the western Pacific precedes that in the Niño-3.4 region by 3–4 months. Thus, the downwelling longwave radiation anomaly is a complementary index to the SST anomaly for the study of ENSO events and can be used to asses whether or not El Niño or La Niña conditions prevail. Over the Niño-3.4 region, the mean DLR anomaly values range from +20 Wm−2 during El Niño episodes to –20 Wm−2 during La Niña events, while over the western Pacific (15–0 S, 105–130 E) these values range from –15 Wm−2 to +10 Wm−2, respectively. The long- term average (1984–2004) distribution of the net surface longwave radiation to the surface over the tropical and subtropical Pacific for the three month period November-December-January shows a net thermal cooling of the ocean surface. When El Niño conditions prevail, the thermal radiative cooling in the central and south-eastern tropical Pacific becomes weaker by 10 Wm−2 south of the equator in the central Pacific (7–0 S, 160–120 W) for the three-month period of NDJ, because the DLR increase is larger than the increase in surface thermal emission. In contrast, the thermal radiative cooling over Indonesia is enhanced by 10 Wm−2 during the early (August–September–October) El Niño phase.

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CP El Niño and PDO Variability Affect Summer Precipitation over East China

Advances in Meteorology ◽

10.1155/2020/2747194 ◽

2020 ◽

Vol 2020 ◽

pp. 1-15

Author(s):

Wan-Jiao Song ◽

Qi-Guang Wang

Keyword(s):

El Niño ◽

El Nino ◽

Summer Precipitation ◽

Western Pacific Subtropical High ◽

Western Pacific ◽

Subtropical High ◽

East China ◽

Central Pacific ◽

Cp El Niño ◽

Precipitation Anomalies

The summer precipitation produced by the East Asian summer monsoon (EASM) is significantly affecting agriculture and socioeconomics. Based on the Precipitation Reconstruction dataset in East China from 1950 to 2017, we investigate the spatiotemporal variations of summer precipitation, influencing environmental factors and their relation with the EASM and the Pacific Decadal Oscillation (PDO) in both central Pacific (CP) El Niño developing and decaying years. Results indicate the following: (1) The evolutions of CP El Niño events modulate the summer precipitation anomalies in East China. In the cool PDO phase, CP El Niño causes enhanced precipitation anomalies in the decaying years but less precipitation anomalies in the developing years, and vice versa for the warm PDO phase. (2) Atmospheric circulation anomalies drive the moisture transportation and combine the motion of western Pacific subtropical high resulting in the variation of precipitation patterns. Anomalous cyclone over the western North Pacific and the sustained Western Pacific Subtropical High (WPSH) are favorable for the increment of summer precipitation. (3) The different CP El Niño-EASM relationship is caused by the influences of PDO on the evolution of CP El Niño. CP El Niño develops slowly (decays rapidly) and is associated with rapidly developing (slowly decaying) anomalous warming in the north Indian Ocean during the developing (decaying) years.

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Relationship Analysis between Runoff of Dadu River Basin and El Niño

MATEC Web of Conferences ◽

10.1051/matecconf/201824601074 ◽

2018 ◽

Vol 246 ◽

pp. 01074

Author(s):

Zujian Zou ◽

Yubin He

Keyword(s):

River Basin ◽

El Niño ◽

El Nino ◽

Western Pacific Subtropical High ◽

Western Pacific ◽

Subtropical High ◽

Tibet Plateau ◽

Rainfall Runoff ◽

Dadu River ◽

The Western Pacific

The Dadu River Basin is located in the transitional zone between the Qinghai-Tibet Plateau and the Sichuan Basin. It is alternately affected by various weather systems such as the western Pacific subtropical high, the Qinghai-Tibet high (anti-cyclone), the southwest warm and humid air current, and the southeast monsoon. The western Pacific subtropical high is one of the main influencing factors of rainfall runoff in the basin. During the El Niño period, the western Pacific subtropical high moved eastward and the position was southward. The warm and humid airflow and the southeast monsoon northward changed, and the rainfall runoff in the Dadu River Basin changed.By analyzing the development of the El Niño phenomenon, Divide an El Niño process into different stages of occurrence, development, and end. Combining the characteristics of the Dadu River runoff in each stage, Studying the runoff situation of the Dadu River Basin under different strengths and weaknesses of the El Niño phenomenon. Using the correlation method to establish a model of the relationship between the abundance of the Dadu River Basin and the El Niño strength and weakness. Providing new ideas and new methods for the accurate prediction of the incoming water of the Dadu River under the abnormal climatic conditions of El Niño. It provides technical support for reservoir dispatching, flood control dispatching and economic dispatching of cascade hydropower stations, and provides experience for other river basins to cope with complex climate situations and improve water regime forecasting levels.

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