The Experts below are selected from a list of 71568 Experts worldwide ranked by ideXlab platform
D E Harrison - One of the best experts on this subject based on the ideXlab platform.
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global seasonal temperature and precipitation anomalies during El Nino autumn and winter
Geophysical Research Letters, 2005Co-Authors: Narasimhan K Larkin, D E HarrisonAbstract:[1] One of the consequences of the new NOAA definition of El Nino is the identification of a number of boreal autumns and winters as El Nino seasons that are not conventionally so identified. In these periods SST anomalies are concentrated significantly more toward the International DatEline than usual. We show here that the seasonal weather anomalies typically associated with these additional “DatEline El Nino” seasons are different in useful respects over much of the world, and suggest that it is useful to treat these as different types of “El Nino” for purposes of seasonal weather forecasting.
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on the definition of El Nino and associated seasonal average u s weather anomalies
Geophysical Research Letters, 2005Co-Authors: Narasimhan K Larkin, D E HarrisonAbstract:[1] A new NOAA definition of El Nino identifies a number of additional El Nino seasons beyond those conventionally agreed. These additional seasons are characterized by SST anomalies primarily in the western central equatorial Pacific. We show here that the seasonal weather anomalies over the U.S. associated with these additional DatEline El Nino seasons are substantially different from those associated with conventional El Nino seasons. Although some regions have similar associated anomalies, most of the major regional anomalies are quite different. Treating the two as a single phenomenon yiElds weaker overall seasonal weather associations and does not take advantage of the stronger associations available when the two are treated separatEly.
Wenju Cai - One of the best experts on this subject based on the ideXlab platform.
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El Nino southern oscillation complexity
Nature, 2018Co-Authors: Antonietta Capotondi, Axel Timmermann, Jong-seong Kug, Fei-fei Jin, Wenju Cai, Kim M. CobbAbstract:El Nino events are characterized by surface warming of the tropical Pacific Ocean and weakening of equatorial trade winds that occur every few years. Such conditions are accompanied by changes in atmospheric and oceanic circulation, affecting global climate, marine and terrestrial ecosystems, fisheries and human activities. The alternation of warm El Nino and cold La Nina conditions, referred to as the El Nino-Southern Oscillation (ENSO), represents the strongest year-to-year fluctuation of the global climate system. Here we provide a synopsis of our current understanding of the spatio-temporal complexity of this important climate mode and its influence on the Earth system.
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the defining characteristics of enso extremes and the strong 2015 2016 El Nino
Reviews of Geophysics, 2017Co-Authors: Wenju Cai, Michael J Mcphaden, Agus SantosoAbstract:The year 2015 was special for climate scientists, particularly for the El Nino Southern Oscillation (ENSO) research community, as a major El Nino finally materialized after a long pause since the 1997/1998 extreme El Nino. It was scientifically exciting since, due to the short observational record, our knowledge of an extreme El Nino has been based only on the 1982/1983 and 1997/1998 events. The 2015/2016 El Nino was marked by many environmental disasters that are consistent with what is expected for an extreme El Nino. Considering the dramatic impacts of extreme El Nino, and the risk of a potential increase in frequency of ENSO extremes under greenhouse warming, it is timEly to evaluate how the recent event fits into our understanding of ENSO extremes. Here we provide a review of ENSO, its nature and dynamics, and through analysis of various observed key variables, we outline the processes that characterize its extremes. The 2015/2016 El Nino brings a useful perspective into the state of understanding of these events and highlights areas for future research. While the 2015/2016 El Nino is characteristically distinct from the 1982/1983 and 1997/1998 events, it still can be considered as the first extreme El Nino of the 21st century. Its extremity can be attributed in part to unusually warm condition in 2014 and to long-term background warming. In effect, this study provides a list of physically meaningful indices that are straightforward to compute for identifying and tracking extreme ENSO events in observations and climate modEls.
Toshio Yamagata - One of the best experts on this subject based on the ideXlab platform.
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interaction between El Nino and extreme indian ocean dipole
Journal of Climate, 2010Co-Authors: Jingjia Luo, Fei-fei Jin, Swadhin K Behera, Ruochao Zhang, Yukio Masumoto, Roger Lukas, Toshio YamagataAbstract:Abstract Climate variability in the tropical Indo-Pacific sector has undergone dramatic changes under global ocean warming. Extreme Indian Ocean dipole (IOD) events occurred repeatedly in recent decades with an unprecedented series of three consecutive episodes during 2006–08, causing vast climate and socioeconomic effects worldwide and weakening the historic El Nino–Indian monsoon rElationship. Major attention has been paid to the El Nino influence on the Indian Ocean, but how the IOD influences El Nino and its predictability remained an important issue to be understood. On the basis of various forecast experiments activating and suppressing air–sea coupling in the individual tropical ocean basins using a state-of-the-art coupled ocean–atmosphere modEl with demonstrated predictive capability, the present study shows that the extreme IOD plays a key role in driving the 1994 pseudo–El Nino, in contrast with traditional El Nino theory. The pseudo–El Nino is more frequently observed in recent decades, coinci...
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climate change the El Nino with a difference
Nature, 2009Co-Authors: Karumuri Ashok, Toshio YamagataAbstract:Patterns of sea-surface warming and cooling in the tropical Pacific seem to be changing, as do the associated atmospheric effects. Increased global warming is implicated in these shifts in El Nino phenomena.
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El Nino modoki and its possible tEleconnection
Journal of Geophysical Research, 2007Co-Authors: Karumuri Ashok, Swadhin K Behera, Hengyi Weng, Toshio YamagataAbstract:[1] Using observed data sets mainly for the period 1979–2005, we find that anomalous warming events different from conventional El Nino events occur in the central equatorial Pacific. This unique warming in the central equatorial Pacific associated with a horseshoe pattern is flanked by a colder sea surface temperature anomaly (SSTA) on both sides along the equator. empirical orthogonal function (EOF) analysis of monthly tropical Pacific SSTA shows that these events are represented by the second mode that explains 12% of the variance. Since a majority of such events are not part of El Nino evolution, the phenomenon is named as El Nino Modoki (pseudo-El Nino) (“Modoki” is a classical Japanese word, which means “a similar but different thing”). The El Nino Modoki involves ocean-atmosphere coupled processes which include a unique tripolar sea levEl pressure pattern during the evolution, analogous to the Southern Oscillation in the case of El Nino. Hence the total entity is named as El Nino–Southern Oscillation (ENSO) Modoki. The ENSO Modoki events significantly influence the temperature and precipitation over many parts of the globe. Depending on the season, the impacts over regions such as the Far East including Japan, New Zealand, western coast of United States, etc., are opposite to those of the conventional ENSO. The difference maps between the two periods of 1979–2004 and 1958–1978 for various oceanic/atmospheric variables suggest that the recent weakening of equatorial easterlies rElated to weakened zonal sea surface temperature gradient led to more flattening of the thermocline. This appears to be a cause of more frequent and persistent occurrence of the ENSO Modoki event during recent decades.
Zuntao Fu - One of the best experts on this subject based on the ideXlab platform.
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percolation phase transition of surface air temperature networks under attacks of El Nino la nina
Scientific Reports, 2016Co-Authors: Zhenghui Lu, Naiming Yuan, Zuntao FuAbstract:In this study, sea surface air temperature over the Pacific is constructed as a network, and the influences of sea surface temperature anomaly in the tropical central eastern Pacific (El Nino/La Nina) are regarded as a kind of natural attack on the network. The results show that El Nino/La Nina leads an abrupt percolation phase transition on the climate networks from stable to unstable or metastable phase state, corresponding to the fact that the climate condition changes from normal to abnormal significantly during El Nino/La Nina. By simulating three different forms of attacks on an idealized network, including Most connected Attack (MA), Localized Attack (LA) and Random Attack (RA), we found that both MA and LA lead to stepwise phase transitions, while RA leads to a second-order phase transition. It is found that most attacks due to El Nino/La Nina are close to the combination of MA and LA, and a percolation critical threshold Pc can be estimated to determine whether the percolation phase transition happens. Therefore, the findings in this study may renew our understandings of the influence of El Nino/La Nina on climate, and further hElp us in better predicting the subsequent events triggered by El Nino/La Nina.
Naiming Yuan - One of the best experts on this subject based on the ideXlab platform.
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percolation phase transition of surface air temperature networks under attacks of El Nino la nina
Scientific Reports, 2016Co-Authors: Zhenghui Lu, Naiming Yuan, Zuntao FuAbstract:In this study, sea surface air temperature over the Pacific is constructed as a network, and the influences of sea surface temperature anomaly in the tropical central eastern Pacific (El Nino/La Nina) are regarded as a kind of natural attack on the network. The results show that El Nino/La Nina leads an abrupt percolation phase transition on the climate networks from stable to unstable or metastable phase state, corresponding to the fact that the climate condition changes from normal to abnormal significantly during El Nino/La Nina. By simulating three different forms of attacks on an idealized network, including Most connected Attack (MA), Localized Attack (LA) and Random Attack (RA), we found that both MA and LA lead to stepwise phase transitions, while RA leads to a second-order phase transition. It is found that most attacks due to El Nino/La Nina are close to the combination of MA and LA, and a percolation critical threshold Pc can be estimated to determine whether the percolation phase transition happens. Therefore, the findings in this study may renew our understandings of the influence of El Nino/La Nina on climate, and further hElp us in better predicting the subsequent events triggered by El Nino/La Nina.
