scholarly journals The Pacific Meridional Mode as an ENSO Precursor and Predictor in the North American Multimodel Ensemble

2014 ◽  
Vol 27 (18) ◽  
pp. 7018-7032 ◽  
Author(s):  
Sarah M. Larson ◽  
Ben P. Kirtman
Keyword(s):  
El Niño ◽  
El Nino ◽  
Multimodel Ensemble ◽  
Enso Events ◽  
The North ◽  
The Pacific ◽  
El Niño Events ◽  
Pacific Meridional Mode ◽  
North American Multimodel Ensemble ◽  
El Nino Events

Abstract Although modeling and observational studies have highlighted a robust relationship between the Pacific meridional mode (PMM) and El Niño–Southern Oscillation (ENSO)—namely, that the PMM is often a precursor to El Niño events—it remains unclear if this relationship has any real predictive use. Bridging the gap between theory and practical application is essential, because the potential use of the PMM precursor as a supplemental tool for ENSO prediction has been implied but not yet implemented into a realistic forecast setting. In this paper, a suite of sea surface temperature hindcasts is utilized from the North American Multimodel Ensemble (NMME) prediction experiment between 1982 and 2010. The goal is first to assess the NMME’s ability to forecast the PMM precursor and second to examine the relationship between PMM and ENSO within a forecast framework. In terms of model performance, results are optimistic in that not only is PMM variability captured well by the multimodel ensemble mean, but it also appears as a precursor to ENSO events in the NMME. In forecast mode, positive PMM events predict eastern Pacific El Niño events in both observations and model forecasts with some skill, yet with less skill for central Pacific El Niño events. Conversely, negative PMM events poorly predict La Niña events in observations, yet the model forecasts fail to capture this observed representation. There proves to be considerable opportunity for improvement of the PMM–ENSO relationship in the forecast models; accordingly, the predictive use of PMM for certain types of ENSO events may also see improvement.

scholarly journals ENSO flavors in a tree-ring δ<sup>18</sup>O record of <i>Tectona grandis</i> from Indonesia

2015 ◽  
Vol 11 (10) ◽  
pp. 1325-1333 ◽  
Author(s):  
K. Schollaen ◽  
C. Karamperidou ◽  
P. Krusic ◽  
E. Cook ◽  
G. Helle
Keyword(s):  
Tree Ring ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Central Pacific ◽  
Central Pacific El Niño ◽  
Enso Events ◽  
Proxy Records ◽  
El Niño Events ◽  
El Nino Events

Abstract. Indonesia's climate is dominated by the equatorial monsoon system, and has been linked to El Niño-Southern Oscillation (ENSO) events that often result in extensive droughts and floods over the Indonesian archipelago. In this study we investigate ENSO-related signals in a tree-ring δ18O record (1900–2007) of Javanese teak. Our results reveal a clear influence of Warm Pool (central Pacific) El Niño events on Javanese tree-ring δ18O, and no clear signal of Cold Tongue (eastern Pacific) El Niño events. These results are consistent with the distinct impacts of the two ENSO flavors on Javanese precipitation, and illustrate the importance of considering ENSO flavors when interpreting palaeoclimate proxy records in the tropics, as well as the potential of palaeoclimate proxy records from appropriately selected tropical regions for reconstructing past variability of. ENSO flavors.

scholarly journals Seasonal and interannual (ENSO) climate variabilities and trends in the South China Sea over the last three decades

2018 ◽  
Author(s):  
Violaine Piton ◽  
Thierry Delcroix
Keyword(s):  
South China Sea ◽  
El Niño ◽  
El Nino ◽  
The South ◽  
The North ◽  
Meridional Winds ◽  
El Niño Events ◽  
The Mean ◽  
Increasing Trends ◽  
El Nino Events

Abstract. We present a short overview of the long-term mean and variability of five Essential Climate Variables observed in the South China Sea over the last 3 decades, including sea surface temperature (SST), sea level anomaly (SLA), precipitation (P), surface wind and water discharge (WD) from the Mekong and Red Rivers. At the seasonal time scale, SST and SLAs increase in the summer (up to 4.2 °C and 14 cm, respectively), and P increases in the north. The summer zonal and meridional winds reverse and intensify (mostly over the ocean), and the WD shows positive anomalies. At the interannual time scale, each variable appears to be correlated with El Niño Southern Oscillation (ENSO) indices. Eastern Pacific El Niño events produce basin-wide SST warming (up to 1.4 °C) with a 6-month lag. The SLAs fall basin-wide (by up to 9 cm) during an El Niño event (all types), with a 3-month lag. The zonal and meridional winds strengthen (up to 4 m/s) in the north (weaken in the south) during all types of El Niño events, with a 3–5-month lag. A rainfall deficit of approximately 30 % of the mean occurs during all types of El Niño phases. The Mekong River WD is reduced by 1/3 of the mean 7–8 months after all types of El Niño events. We also show increasing trends of SST as high as 0.24 °C/decade and SLAs by 41 mm/decade. Increasing trends are observed for zonal wind, which is possibly linked to the phase of the Pacific Decadal Oscillation, and decreasing trends are observed for P in the north and both WD stations that were analyzed. The likely driving mechanisms and some of the relationships between all observed anomalies are discussed

Coastal upwelling along the north coast of Papua New Guinea and El Niño events during 1981–2005

2010 ◽  
Vol 60 (5) ◽  
pp. 1255-1269 ◽  
Author(s):  
Takuya Hasegawa ◽  
Kentaro Ando ◽  
Keisuke Mizuno ◽  
Roger Lukas ◽  
Bunmei Taguchi ◽  
...  
Keyword(s):  
Papua New Guinea ◽  
El Niño ◽  
Coastal Upwelling ◽  
El Nino ◽  
New Guinea ◽  
North Coast ◽  
The North ◽  
El Niño Events ◽  
El Nino Events

The Late Fall Extratropical Response to ENSO: Sensitivity to Coupling and Convection in the Tropical West Pacific

2008 ◽  
Vol 21 (23) ◽  
pp. 6101-6118 ◽  
Author(s):  
Ileana Bladé ◽  
Matthew Newman ◽  
Michael A. Alexander ◽  
James D. Scott
Keyword(s):  
El Niño ◽  
El Nino ◽  
Tropical Indian Ocean ◽  
Surface Cooling ◽  
West Pacific ◽  
The North ◽  
Late Fall ◽  
El Niño Events ◽  
Sst Anomalies ◽  
El Nino Events

Abstract The extratropical response to El Niño in late fall departs considerably from the canonical El Niño signal. Observational analysis suggests that this response is modulated by anomalous forcing in the tropical west Pacific (TWP), so that a strong fall El Niño teleconnection is more likely when warm SST conditions and/or enhanced convection prevail in the TWP. While these TWP SST anomalies may arise from noise and/or long-term variability, they may also be generated by differences between El Niño events, through variations in the tropical “atmospheric bridge.” This bridge typically drives subsidence west of the date line and enhanced trade winds over the far TWP, which cool the ocean. In late fall, however, some relatively weaker and/or more eastward-shifted El Niño events produce a correspondingly weakened and displaced tropical bridge, which results in no surface cooling and enhanced convection in the TWP. Because the North Pacific circulation is very sensitive to forcing from the TWP at this time of year, the final outcome is a strong extratropical El Niño teleconnection. This hypothesis is partly supported by regionally coupled ensemble GCM simulations for the 1950–99 period, in which prescribed observed El Niño SST anomalies in the eastern/central equatorial Pacific and an oceanic mixed layer model elsewhere coexist, so that the TWP is allowed to interact with the El Niño atmospheric bridge. To separate the deterministic signal driven by TWP coupling from that associated with inter–El Niño differences and from the “noise” due to intrinsic TWP convection variability (not induced by local SST anomalies), a second large-ensemble (100) simulation of the 1997/98 El Niño event, with coupling limited to the TWP and tropical Indian Ocean, is carried out. Together, the model findings suggest that the extratropical El Niño teleconnection during late fall is very sensitive to convective forcing in the TWP and that coupling-induced warming in the TWP may enhance this El Niño teleconnection by promoting convection in this critical TWP region. A more general implication is that diagnostic studies using December–February (DJF) seasonal averages may obscure some important aspects of climate anomalies associated with forcing in the tropical Pacific.

scholarly journals North–South Discrepancy of Interannual Sea Surface Temperature Anomalies over the South China Sea Associated with Eastern Pacific El Niño Events in the Spring

Atmosphere ◽  
2020 ◽  
Vol 11 (10) ◽  
pp. 1135
Author(s):  
Yujie Liu ◽  
Shuang Li
Keyword(s):  
Heat Flux ◽  
El Niño ◽  
El Nino ◽  
Sea Surface ◽  
Major Contributor ◽  
The North ◽  
El Niño Events ◽  
Ep El Niño ◽  
Sst Anomalies ◽  
El Nino Events

This paper discovers a spatial feature of interannual sea surface temperature (SST) anomalies over the South China Sea (SCS) in the boreal spring, based on the Simple Ocean Data Assimilation (SODA) monthly data in the period from January 1958 to December 2010. The Empirical Orthogonal Function (EOF) analysis of interannual SST anomalies shows a north–south discrepant pattern of the first mode, which is characterized by higher (lower) anomalies in the northern (southern) SCS and possessing seasonal phase locking (in the boreal spring). Besides, the high correlation coefficient between the time series of the first EOF mode and the Nino 3 SST anomalies during winter reveals that this discrepant pattern is likely caused by El Niño events. The composites of SST anomalies show that this discrepant pattern appears in the eastern Pacific (EP) El Niño events, while it does not exist in the Central Pacific (CP) El Niño events. It is believed that the western North Pacific anticyclone (WNPA) plays a key role in conveying the El Niño impact on the interannual variabilities of SCS SST in the EP El Niño events. The anomalous anticyclone in the Philippine Sea weakens the northeasterly monsoon over the SCS by its southwest portion during the mature phases of the EP El Niño events. This anomalous atmospheric circulation contributes to the north–south discrepant pattern of the wind stress anomalies over the SCS in the EP El Niño mature winters, and then leads to the north–south dipole pattern of the contemporaneous latent heat flux anomalies. The latent heat flux is a major contributor to the surface net heat flux, and heat budget analysis shows that the net heat flux is the major contributor to the SCS SST anomalies during the spring for the EP El Niño events, and the north–south discrepancy of SCS SST anomalies in the succeeding spring is ultimately formed.

scholarly journals Tropical warming and the dynamics of endangered primates

2009 ◽  
Vol 6 (2) ◽  
pp. 257-260 ◽  
Author(s):  
Ruscena Wiederholt ◽  
Eric Post
Keyword(s):  
Population Dynamics ◽  
Global Warming ◽  
El Niño ◽  
Large Scale ◽  
El Nino ◽  
Southern Oscillation ◽  
Primate Species ◽  
Enso Events ◽  
El Niño Events ◽  
El Nino Events

Many primate species are severely threatened, but little is known about the effects of global warming and the associated intensification of El Niño events on primate populations. Here, we document the influences of the El Niño southern oscillation (ENSO) and hemispheric climatic variability on the population dynamics of four genera of ateline (neotropical, large-bodied) primates. All ateline genera experienced either an immediate or a lagged negative effect of El Niño events. ENSO events were also found to influence primate resource levels through neotropical arboreal phenology. Furthermore, frugivorous primates showed a high degree of interspecific population synchrony over large scales across Central and South America attributable to the recent trends in large-scale climate. These results highlight the role of large-scale climatic variation and trends in ateline primate population dynamics, and emphasize that global warming could pose additional threats to the persistence of multiple species of endangered primates.

scholarly journals The 2015/16 El Niño Event in Context of the MERRA-2 Reanalysis: A Comparison of the Tropical Pacific with 1982/83 and 1997/98

2017 ◽  
Vol 30 (13) ◽  
pp. 4819-4842 ◽  
Author(s):  
Young-Kwon Lim ◽  
Robin M. Kovach ◽  
Steven Pawson ◽  
Guillaume Vernieres
Keyword(s):  
El Niño ◽  
El Nino ◽  
Tropical Pacific ◽  
Equatorial Pacific ◽  
Eastern Pacific ◽  
Subsurface Water ◽  
Central Pacific ◽  
Enso Events ◽  
El Niño Events ◽  
El Nino Events

The 2015/16 El Niño is analyzed using atmospheric and oceanic analysis produced using the Goddard Earth Observing System (GEOS) data assimilation systems. As well as describing the structure of the event, a theme of this work is to compare and contrast it with two other strong El Niños, in 1982/83 and 1997/98. These three El Niño events are included in the Modern-Era Retrospective Analysis for Research and Applications (MERRA) and in the more recent MERRA-2 reanalyses. MERRA-2 allows a comparison of fields derived from the underlying GEOS model, facilitating a more detailed comparison of physical forcing mechanisms in the El Niño events. Various atmospheric and oceanic structures indicate that the 2015/16 El Niño maximized in the Niño-3.4 region, with a large region of warming over most of the Pacific and Indian Oceans. The eastern tropical Indian Ocean, Maritime Continent, and western tropical Pacific are found to be less dry in boreal winter, compared to the earlier two strong events. Whereas the 2015/16 El Niño had an earlier occurrence of the equatorial Pacific warming and was the strongest event on record in the central Pacific, the 1997/98 event exhibited a more rapid growth due to stronger westerly wind bursts and the Madden–Julian oscillation during spring, making it the strongest El Niño in the eastern Pacific. Compared to 1982/83 and 1997/98, the 2015/16 event had a shallower thermocline over the eastern Pacific with a weaker zonal contrast of subsurface water temperatures along the equatorial Pacific. While the three major ENSO events have similarities, each is unique when looking at the atmosphere and ocean surface and subsurface.

scholarly journals The North Equatorial Countercurrent East of the Dateline, Its Variations, and Its Relationship to the El Niño Event

2021 ◽  
Vol 9 (10) ◽  
pp. 1041
Author(s):  
Yusuf Jati Wijaya ◽  
Ulung Jantama Wisha ◽  
Yukiharu Hisaki
Keyword(s):  
El Niño ◽  
El Nino ◽  
Thermocline Depth ◽  
Central Pacific ◽  
Ocean Reanalysis ◽  
Central Pacific El Niño ◽  
The North ◽  
El Niño Events ◽  
Ep El Niño ◽  
El Nino Events

Using forty years (1978–2017) of Ocean Reanalysis System 4 (ORAS4) dataset, the purpose of this study is to investigate the fluctuation of the North Equatorial Countercurrent (NECC) to the east of the dateline in relation to the presence of three kinds of El Niño events. From spring (MAM) through summer (JJA), we found that the NECC was stronger during the Eastern Pacific El Niño (EP El Niño) and the MIX El Niño than during the Central Pacific El Niño (CP El Niño). When it comes to winter (DJF), on the other hand, the NECC was stronger during the CP and MIX El Niño and weaker during the EP El Niño. This NECC variability was affected by the fluctuations of thermocline depth near the equatorial Pacific. Moreover, we also found that the seasonal southward shift of the NECC occurred between winter and spring, but the shift was absent during the CP and MIX El Niño events. This meridional shift was strongly affected by the local wind stress.

scholarly journals Volcanic and ENSO effects in China in simulations and reconstructions: Tambora eruption 1815

2011 ◽  
Vol 7 (3) ◽  
pp. 2061-2088 ◽  
Author(s):  
D. Zhang ◽  
R. Blender ◽  
K. Fraedrich
Keyword(s):  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Standardized Precipitation Index ◽  
Volcanic Eruptions ◽  
La Niña ◽  
The North ◽  
La Nina ◽  
El Niño Events ◽  
El Nino Events

Abstract. The co-operative effects of volcanic eruptions and ENSO (El Niño/Southern Oscillation) on the climate in China are analyzed in a millennium simulation for 800–2005 AD using the earth system model (ESM) ECHAM5/MPIOM/JSBACH subject to anthropogenic and natural forcings. The experiment includes two ensembles with weak (5 members) and strong (3 members) total solar irradiance variability. In the absence of El Niño and La Niña events, volcanoes, which are the dominant forcing in both ensembles, cause a dramatic cooling in West China (−2 °C) and a drought in East China during the year after the eruption. The recovery times for the volcano induced cooling vary globally between one and 12 yr; in China these values are mostly within 1–4 yr, but reach 10 yr in the Northeast. Without volcanoes, after El Niño events the summer precipitation is reduced in the North, while South China becomes wetter (indicated by the Standardized Precipitation Index, SPI, for summers, JJA); La Niña events cause opposite effects. El Niño events in the winters after eruptions compensate the cooling in most regions of China, while La Niña events intensify the cooling (up to −2.5 °C). The simulated impact of the eruption of the Tambora in 1815, which caused the "year without summer" 1816 in Europe and North America and coldness and famines for several years in the Chinese province Yunnan, depends crucially on the ENSO state of the coupled model. A comparison with reconstructed El Niño events shows a moderate cool climate with wet (in the South) and extreme dry anomalies (in the North) persisting for several years.

Sign in / Sign up

Export Citation Format

Share Document