scholarly journals Changes in Sea Salt Emissions Enhance ENSO Variability

2016 ◽  
Vol 29 (23) ◽  
pp. 8575-8588 ◽  
Author(s):  
Yang Yang ◽  
Lynn M. Russell ◽  
Sijia Lou ◽  
Maryam A. Lamjiri ◽  
Ying Liu ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
El Niño ◽  
El Nino ◽  
Sea Salt ◽  
La Niña ◽  
Western Pacific ◽  
Interannual Variations ◽  
Enso Variability ◽  
La Nina ◽  
The Tropical Pacific

Abstract Two 150-yr preindustrial simulations with and without interactive sea salt emissions from the Community Earth System Model (CESM) are performed to quantify the interactions between sea salt emissions and El Niño–Southern Oscillation (ENSO). Variations in sea salt emissions over the tropical Pacific Ocean are affected by changing wind speed associated with ENSO variability. ENSO-induced interannual variations in sea salt emissions result in decreasing (increasing) aerosol optical depth (AOD) by 0.03 over the equatorial central-eastern (western) Pacific Ocean during El Niño events compared to those during La Niña events. These changes in AOD further increase (decrease) radiative fluxes into the atmosphere by +0.2 (−0.4) W m−2 over the tropical eastern (western) Pacific. Thereby, sea surface temperature increases (decreases) by 0.2–0.4 K over the tropical eastern (western) Pacific Ocean during El Niño compared to La Niña events and enhances ENSO variability by 10%. The increase in ENSO amplitude is a result of systematic heating (cooling) during the warm (cold) phase of ENSO in the eastern Pacific. Interannual variations in sea salt emissions then produce the anomalous ascent (subsidence) over the equatorial eastern (western) Pacific between El Niño and La Niña events, which is a result of heating anomalies. Owing to variations in sea salt emissions, the convective precipitation is enhanced by 0.6–1.2 mm day−1 over the tropical central-eastern Pacific Ocean and weakened by 0.9–1.5 mm day−1 over the Maritime Continent during El Niño compared to La Niña events, enhancing the precipitation variability over the tropical Pacific.

scholarly journals Biophysical responses near equatorial islands in the Western Pacific Ocean during El Niño/La Niña transitions

2013 ◽  
Vol 40 (20) ◽  
pp. 5473-5479 ◽  
Author(s):  
Michelle M. Gierach ◽  
Monique Messié ◽  
Tong Lee ◽  
Kristopher B. Karnauskas ◽  
Marie-Hélène Radenac
Keyword(s):  
Pacific Ocean ◽  
El Niño ◽  
El Nino ◽  
La Niña ◽  
Western Pacific ◽  
Western Pacific Ocean ◽  
La Nina ◽  
The Western Pacific

scholarly journals Dipole Structure of Mixed Layer Salinity in Response to El Niño‐La Niña Asymmetry in the Tropical Pacific

2019 ◽  
Vol 46 (21) ◽  
pp. 12165-12172 ◽  
Author(s):  
Cong Guan ◽  
Shijian Hu ◽  
Michael J. McPhaden ◽  
Fan Wang ◽  
Shan Gao ◽  
...  
Keyword(s):  
Mixed Layer ◽  
El Niño ◽  
El Nino ◽  
Tropical Pacific ◽  
La Niña ◽  
Dipole Structure ◽  
La Nina ◽  
The Tropical Pacific

scholarly journals Atmospheric Energetics over the Tropical Pacific during the ENSO Cycle

2017 ◽  
Vol 30 (10) ◽  
pp. 3635-3654 ◽  
Author(s):  
Di Dong ◽  
Jianping Li ◽  
Lidou Huyan ◽  
Jiaqing Xue
Keyword(s):  
El Nino ◽  
Tropical Pacific ◽  
La Niña ◽  
Western Pacific ◽  
Eastern Pacific ◽  
Enso Cycle ◽  
Upper Troposphere ◽  
La Nina ◽  
Central Eastern ◽  
The Tropical Pacific

Abstract The atmospheric perturbation potential energy (PPE) over the tropical Pacific is calculated and analyzed in a composite ENSO cycle. The PPE over the tropical Pacific troposphere increases during El Niño and decreases during La Niña, displaying two centers symmetrical about the equator and delaying the central–eastern Pacific SST anomaly by two months. Generated from atmospheric diabatic heating, the smaller part of PPE in the lower troposphere varies synchronously with the central–eastern Pacific SST through sensible heating, while the larger part of PPE lies in the mid- and upper troposphere and lags the central–eastern Pacific SST about one season because of latent heat release. As the tropical Pacific PPE peaks during the boreal late winter in an El Niño event, two anticyclones form in the upper troposphere as a result of the Gill model response. More PPE is converted to atmospheric kinetic energy (KE) above the central–western Pacific, but less over the eastern Pacific, leading to intensified Hadley circulations over the central–western Pacific and weakened Hadley circulations over the eastern Pacific. The strengthened Hadley circulations cause surface easterly wind bursts through KE convergence in the western equatorial Pacific, which may trigger a La Niña event. The reverse situation occurs during La Niña. Thus, the response of the Hadley circulations in the central–western Pacific provides a negative feedback during the ENSO cycle.

How Many ENSO Flavors Can We Distinguish?*

2013 ◽  
Vol 26 (13) ◽  
pp. 4816-4827 ◽  
Author(s):  
Nathaniel C. Johnson
Keyword(s):  
El Niño ◽  
El Nino ◽  
Warm Pool ◽  
Tropical Pacific ◽  
La Niña ◽  
Western Pacific ◽  
Western Pacific Warm Pool ◽  
La Nina ◽  
Pacific Warm Pool ◽  
Sst Anomalies

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.

Impacts of El Niño and La Niña Cycles: Systems and Sectors

2008 ◽  
Author(s):  
Cynthia Rosenzweig ◽  
Daniel Hillel
Keyword(s):  
Pacific Ocean ◽  
El Niño ◽  
El Nino ◽  
Terrestrial Ecosystem ◽  
Terrestrial Ecosystems ◽  
La Niña ◽  
Enso Events ◽  
La Nina ◽  
The Pacific ◽  
The Pacific Ocean

Perturbations of the climate system caused by El Niño and La Niña events affect natural and managed systems in vast areas of the Pacific Ocean and far beyond it. (Other oscillations affect systems and sectors in wide swaths of the world as well.)1 El Niño–Southern Oscillation (ENSO) events have been associated with ecosystem disruptions and forest fires, crop failures and famines, disease epidemics, and even market fluctuations in various regions. The forms and degrees of impact depend not only on the strength and duration of an El Niño or La Niña event and its associated teleconnections, but also on the state, sensitivity, and vulnerability of the affected system and its biotic community, as well as its human population. The underlying characteristics of ecosystems and human societies in each region are important factors in their susceptibility to ENSO-related damages. Variation may be enhanced as ENSO effects ripple through natural and managed ecosystems. The underlying health of the affected biota, interrelationships among different biotic associations, and pressure by humans all affect marine as well as terrestrial ecosystem responses to ENSO events. Impacts on human systems can be both direct and indirect. Some ENSO phenomena, such as severe storms, affect human lives and infrastructures directly. Other impacts occur through alterations in the marine and terrestrial ecosystems and water supplies upon which human populations ultimately depend. In this chapter we consider some of the impacts that ENSO and other oscillations (described with their teleconnections in chapter 1) have on marine and terrestrial ecosystems and on human-managed systems apart from agriculture. The significant and geographically widespread changes that El Niño events induce in the Pacific Ocean alter conditions for various marine communities. These alterations include dramatic changes in the abundance and distribution of organisms, associated collapses of commercial fisheries, and ensuing consequences affecting human livelihood (Glantz, 2004; Lehodey et al., 2006). Some of the effects are well documented. Reductions in primary production of up to 95% were measured in the eastern equatorial Pacific in 1982–83 (Barber and Chavez, 1983.) Large changes in ecosystem structure and productivity have also been recorded in other parts of the Pacific Ocean, including the western Pacific and in the North Pacific subtropical gyre (north of the Hawaiian Islands) (Karl et al., 1995).

Two Tropical Routes for the Remote Influence of the Northern Tropical Atlantic on the Indo−western Pacific Summer Climate

2020 ◽  
pp. 1-51
Author(s):  
Yuhei Takaya ◽  
Naoaki Saito ◽  
Ichiro Ishikawa ◽  
Shuhei Maeda
Keyword(s):  
El Niño ◽  
El Nino ◽  
Walker Circulation ◽  
La Niña ◽  
Western Pacific ◽  
Tropical Atlantic ◽  
Summer Climate ◽  
La Nina ◽  
The Impact ◽  
Northern Tropical Atlantic

AbstractThis study investigates the influence of sea surface temperature (SST) in the northern tropical Atlantic (NTA) on the Indo−western Pacific summer climate by analyzing record-high NTA SSTs summer in 2010. In that time, a decaying El Niño and developing La Niña were accompanied by widespread anomalous climate conditions in the Indo-western Pacific. These conditions are typical of summers that follow El Niño events and are often explained as being due to the influence of Indian Ocean warming induced by the El Niño. Meanwhile, the record high NTA SSTs that also resulted from the influence of the El Niño, the negative phase of the North Atlantic Oscillation as well as the interdecadal-and-longer NTA SST variability, is one of possible causes of anomalous conditions in the Indo−western Pacific. The results of sensitivity experiments using a coupled atmosphere−ocean model clearly indicate that the high NTA SSTs had a considerable influence on the summer weather in the Indo−western Pacific via two tropical routes: an eastbound route that involved a reinforcement of the atmospheric equatorial Kelvin wave and a westbound route that involved altering the Walker circulation over the Atlantic−Pacific region. The altered Walker circulation facilitated the transition to La Niña, amplifying the impact on the western North Pacific monsoon. Further evaluation reveals that both the interannual and interdecadal-and-longer variability of the NTA SST contributed to the anomalous Indo−western Pacific summer. The results highlight the interannual to multidecadal predictability of the Indo−western Pacific summer climate that originates in the NTA.

scholarly journals El Niño in a changing climate: a multi-model study

Ocean Science ◽  
2005 ◽  
Vol 1 (2) ◽  
pp. 81-95 ◽  
Author(s):  
G. J. van Oldenborgh ◽  
S. Y. Philip ◽  
M Collins
Keyword(s):  
Standard Deviation ◽  
Pacific Ocean ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Tropical Pacific ◽  
Enso Cycle ◽  
Tropical Pacific Ocean ◽  
Enso Variability ◽  
The Tropical Pacific

Abstract. In many parts of the world, climate projections for the next century depend on potential changes in the properties of the El Niño - Southern Oscillation (ENSO). The current staus of these projections is assessed by examining a large set of climate model experiments prepared for the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Firstly, the patterns and time series of present-day ENSO-like model variability in the tropical Pacific Ocean are compared with that observed. Next, the strength of the coupled atmosphere-ocean feedback loops responsible for generating the ENSO cycle in the models are evaluated. Finally, we consider the projections of the models with, what we consider to be, the most realistic ENSO variability. Two of the models considered do not have interannual variability in the tropical Pacific Ocean. Three models show a very regular ENSO cycle due to a strong local wind feedback in the central Pacific and weak sea surface temperature (SST) damping. Six other models have a higher frequency ENSO cycle than observed due to a weak east Pacific upwelling feedback loop. One model has much stronger upwelling feedback than observed, and another one cannot be described simply by the analysis technique. The remaining six models have a reasonable balance of feedback mechanisms and in four of these the interannual mode also resembles the observed ENSO both spatially and temporally. Over the period 2051-2100 (under various scenarios) the most realistic six models show either no change in the mean state or a slight shift towards El Niño-like conditions with an amplitude at most a quarter of the present day interannual standard deviation. We see no statistically significant changes in amplitude of ENSO variability in the future, with changes in the standard deviation of a Southern Oscillation Index that are no larger than observed decadal variations. Uncertainties in the skewness of the variability are too large to make any statements about the future relative strength of El Niño and La Niña events. Based on this analysis of the multi-model ensemble, we expect very little influence of global warming on ENSO.

scholarly journals Upper equatorial Pacific Ocean current and salinity variability during the 1996-1998 El Niño-La Niña cycle

2000 ◽  
Vol 105 (C1) ◽  
pp. 1037-1053 ◽  
Author(s):  
Gregory C. Johnson ◽  
Michael J. McPhaden ◽  
G. Dail Rowe ◽  
Kristene E. McTaggart
Keyword(s):  
Pacific Ocean ◽  
El Niño ◽  
El Nino ◽  
Equatorial Pacific ◽  
La Niña ◽  
Ocean Current ◽  
Equatorial Pacific Ocean ◽  
La Nina ◽  
Salinity Variability
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