scholarly journals Three Putative Types of El Niño Revealed by Spatial Variability in Impact on Australian Wheat Yield

2005 ◽  
Vol 18 (10) ◽  
pp. 1566-1574 ◽  
Author(s):  
A. B. Potgieter ◽  
G. L. Hammer ◽  
H. Meinke ◽  
R. C. Stone ◽  
L. Goddard
Keyword(s):  
Spatial Patterns ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Wheat Yield ◽  
Severe Drought ◽  
Seasonal Forecasts ◽  
El Niño Events ◽  
Australian Wheat ◽  
El Nino Events

Abstract The El Niño–Southern Oscillation (ENSO) phenomenon significantly impacts rainfall and ensuing crop yields in many parts of the world. In Australia, El Niño events are often associated with severe drought conditions. However, El Niño events differ spatially and temporally in their manifestations and impacts, reducing the relevance of ENSO-based seasonal forecasts. In this analysis, three putative types of El Niño are identified among the 24 occurrences since the beginning of the twentieth century. The three types are based on coherent spatial patterns (“footprints”) found in the El Niño impact on Australian wheat yield. This bioindicator reveals aligned spatial patterns in rainfall anomalies, indicating linkage to atmospheric drivers. Analysis of the associated ocean–atmosphere dynamics identifies three types of El Niño differing in the timing of onset and location of major ocean temperature and atmospheric pressure anomalies. Potential causal mechanisms associated with these differences in anomaly patterns need to be investigated further using the increasing capabilities of general circulation models. Any improved predictability would be extremely valuable in forecasting effects of individual El Niño events on agricultural systems.

scholarly journals Climate change and the demise of Minoan civilization

2010 ◽  
Vol 6 (4) ◽  
pp. 525-530 ◽  
Author(s):  
A. A. Tsonis ◽  
K. L. Swanson ◽  
G. Sugihara ◽  
P. A. Tsonis
Keyword(s):  
Climate Change ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Climatic Trend ◽  
Geological Evidence ◽  
Quantitative Evidence ◽  
El Niño Events ◽  
Ancient Civilizations ◽  
El Nino Events

Abstract. Climate change has been implicated in the success and downfall of several ancient civilizations. Here we present a synthesis of historical, climatic, and geological evidence that supports the hypothesis that climate change may have been responsible for the slow demise of Minoan civilization. Using proxy ENSO and precipitation reconstruction data in the period 1650–1980 we present empirical and quantitative evidence that El Nino causes drier conditions in the area of Crete. This result is supported by modern data analysis as well as by model simulations. Though not very strong, the ENSO-Mediterranean drying signal appears to be robust, and its overall effect was accentuated by a series of unusually strong and long-lasting El Nino events during the time of the Minoan decline. Indeed, a change in the dynamics of the El Nino/Southern Oscillation (ENSO) system occurred around 3000 BC, which culminated in a series of strong and frequent El Nino events starting at about 1450 BC and lasting for several centuries. This stressful climatic trend, associated with the gradual demise of the Minoans, is argued to be an important force acting in the downfall of this classic and long-lived civilization.

Monitoring Agricultural Drought Using El Niño and Southern Oscillation Data

2005 ◽  
Author(s):  
Lino Naranjo Díaz
Keyword(s):  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Climatic Variability ◽  
Past Century ◽  
Climatic Data ◽  
Weather Patterns ◽  
El Niño Events ◽  
Ring Analysis ◽  
El Nino Events

Almost all the studies performed during the past century have shown that drought is not the result of a single cause. Instead, it is the result of many factors varying in nature and scales. For this reason, researchers have been focusing their studies on the components of the climate system to explain a link between patterns (regional and global) of climatic variability and drought. Some drought patterns tend to recur frequently, particularly in the tropics. One such pattern is the El Niño and Southern Oscillation (ENSO). This chapter explains the main characteristics of the ENSO and its data forms, and how this phenomenon is related to the occurrence of drought in the world regions. Originally, the name El Niño was coined in the late 1800s by fishermen along the coast of Peru to refer to a seasonal invasion of south-flowing warm currents of the ocean that displaced the north-flowing cold currents in which they normally fished. The invasion of warm water disrupts both the marine food chain and the economies of coastal communities that are based on fishing and related industries. Because the phenomenon peaks around the Christmas season, the fishermen who first observed it named it “El Niño” (“the Christ Child”). In recent decades, scientists have recognized that El Niño is linked with other shifts in global weather patterns (Bjerknes, 1969; Wyrtki, 1975; Alexander, 1992; Trenberth, 1995; Nicholson and Kim, 1997). The recurring period of El Niño varies from two to seven years. The intensity and duration of the event vary too and are hard to predict. Typically, the duration of El Niño ranges from 14 to 22 months, but it can also be much longer or shorter. El Niño often begins early in the year and peaks in the following boreal winter. Although most El Niño events have many features in common, no two events are exactly the same. The presence of El Niño events during historical periods can be detected using climatic data interpreted from the tree ring analysis, sediment or ice cores, coral reef samples, and even historical accounts from early settlers.

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.

Ocean Chlorophyll-Induced Heating Feedbacks on ENSO in a Coupled Ocean Physics–Biology Model Forced by Prescribed Wind Anomalies

2018 ◽  
Vol 31 (5) ◽  
pp. 1811-1832 ◽  
Author(s):  
Rong-Hua Zhang ◽  
Feng Tian ◽  
Xiujun Wang
Keyword(s):  
Solar Radiation ◽  
El Niño ◽  
General Circulation ◽  
El Nino ◽  
Southern Oscillation ◽  
La Niña ◽  
La Nina ◽  
El Niño Events ◽  
Ocean Physics ◽  
El Nino Events

Ocean biology components affect the vertical redistribution of incoming solar radiation in the upper ocean of the tropical Pacific and can significantly modulate El Niño–Southern Oscillation (ENSO). The biophysical interactions in the region were represented by coupling an ocean biology model with an ocean general circulation model (OGCM); the coupled ocean physics–biology model is then forced by prescribed wind anomalies during 1980–2007. Two ocean-only experiments were performed with different representations of chlorophyll (Chl). In an interannual Chl run (referred to as Chlinter), Chl was interannually varying, which was interactively calculated from the ocean biology model to explicitly represent its heating feedback on ocean thermodynamics. The structure and relationship of the related heating terms were examined to understand the Chl-induced feedback effects and the processes involved. The portion of solar radiation penetrating the bottom of the mixed layer ( Qpen) was significantly affected by interannual Chl anomalies in the western-central equatorial Pacific. In a climatological run (Chlclim), the Chl concentration was prescribed to be its seasonally varying climatology derived from the Chlinter run. Compared with the Chlclim run, interannual variability in the Chlinter run tended to be reduced. The sea surface temperature (SST) differences between the two runs exhibited an asymmetric bioeffect: they were stronger during La Niña events but relatively weaker during El Niño events. The signs of the SST differences between the two runs indicated a close relationship with Chl: a cooling effect was associated with a low Chl concentration during El Niño events, and a strong warming effect was associated with a high Chl concentration during La Niña events.

El Niño–Southern Oscillation, Pliocene climate and equifinality

2008 ◽  
Vol 367 (1886) ◽  
pp. 127-156 ◽  
Author(s):  
Sarah G Bonham ◽  
Alan M Haywood ◽  
Daniel J Lunt ◽  
Mathew Collins ◽  
Ulrich Salzmann
Keyword(s):  
Surface Temperature ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Tropical Pacific ◽  
El Nino Southern Oscillation ◽  
Climate Simulations ◽  
El Niño Events ◽  
East West ◽  
El Nino Events

It has been suggested that, during the Pliocene ( ca 5–1.8 Ma), an El Niño state existed as a permanent rather than an intermittent feature; that is, the tropical Pacific Ocean was characterized by a much weaker east–west gradient than today. One line of inquiry used to investigate this idea relates modern El Niño teleconnections to Pliocene proxy data by comparing regional differences in precipitation and surface temperature with climate patterns associated with present-day El Niño events, assuming that agreement between Pliocene data and observations of modern El Niño events supports this interpretation. Here, we examine this assumption by comparing outputs from a suite of Mid-Pliocene climate simulations carried out with the UK Met Office climate model. Regional patterns of climate change associated with changes in model boundary conditions are compared with observed El Niño–Southern Oscillation teleconnection patterns. Our results indicate that many of the proposed ‘permanent El Niño’ surface temperature and precipitation patterns are observable in Mid-Pliocene climate simulations even when they display variability in tropical Pacific sea surface temperatures (SSTs) or when forced with a modern east–west SST gradient. Our experiments highlight the possibility that the same outcome may be achieved through different initial conditions (equifinality); an important consideration for reconstructed patterns of regional Mid-Pliocene climate.

Two Types of El Niño Events: Cold Tongue El Niño and Warm Pool El Niño

2009 ◽  
Vol 22 (6) ◽  
pp. 1499-1515 ◽  
Author(s):  
Jong-Seong Kug ◽  
Fei-Fei Jin ◽  
Soon-Il An
Keyword(s):  
Spatial Patterns ◽  
El Niño ◽  
El Nino ◽  
Warm Pool ◽  
Discharge Process ◽  
Cold Tongue ◽  
El Niño Events ◽  
Sst Anomaly ◽  
Sst Anomalies ◽  
El Nino Events

Abstract In this study, two types of El Niño events are classified based on spatial patterns of the sea surface temperature (SST) anomaly. One is the cold tongue (CT) El Niño, which can be regarded as the conventional El Niño, and the other the warm pool (WP) El Niño. The CT El Niño is characterized by relatively large SST anomalies in the Niño-3 region (5°S–5°N, 150°–90°W), while the WP El Niño is associated with SST anomalies mostly confined to the Niño-4 region (5°S–5°N, 160°E–150°W). In addition, spatial patterns of many atmospheric and oceanic variables are also distinctively different for the two types of El Niño events. Furthermore, the difference in the transition mechanism between the two types of El Niño is clearly identified. That is, the discharge process of the equatorial heat content associated with the WP El Niño is not efficient owing to the spatial structure of SST anomaly; as a result, it cannot trigger a cold event. It is also demonstrated that zonal advective feedback (i.e., zonal advection of mean SST by anomalous zonal currents) plays a crucial role in the development of a decaying SST anomaly associated with the WP El Niño, while thermocline feedback is a key process during the CT El Niño.

scholarly journals Maximizing ENSO as a source of western US hydroclimate predictability

2019 ◽  
Vol 54 (1-2) ◽  
pp. 351-372 ◽  
Author(s):  
Christina M. Patricola ◽  
John P. O’Brien ◽  
Mark D. Risser ◽  
Alan M. Rhoades ◽  
Travis A. O’Brien ◽  
...  
Keyword(s):  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Wave Train ◽  
Global Climate Model ◽  
Western Us ◽  
El Niño Events ◽  
Fixed Region ◽  
Sst Anomalies ◽  
El Nino Events

Abstract Until recently, the El Niño–Southern Oscillation (ENSO) was considered a reliable source of winter precipitation predictability in the western US, with a historically strong link between extreme El Niño events and extremely wet seasons. However, the 2015–2016 El Niño challenged our understanding of the ENSO-precipitation relationship. California precipitation was near-average during the 2015–2016 El Niño, which was characterized by warm sea surface temperature (SST) anomalies of similar magnitude compared to the extreme 1997–1998 and 1982–1983 El Niño events. We demonstrate that this precipitation response can be explained by El Niño’s spatial pattern, rather than internal atmospheric variability. In addition, observations and large-ensembles of regional and global climate model simulations indicate that extremes in seasonal and daily precipitation during strong El Niño events are better explained using the ENSO Longitude Index (ELI), which captures the diversity of ENSO’s spatial patterns in a single metric, compared to the traditional Niño3.4 index, which measures SST anomalies in a fixed region and therefore fails to capture ENSO diversity. The physically-based ELI better explains western US precipitation variability because it tracks the zonal shifts in tropical Pacific deep convection that drive teleconnections through the response in the extratropical wave-train, integrated vapor transport, and atmospheric rivers. This research provides evidence that ELI improves the value of ENSO as a predictor of California’s seasonal hydroclimate extremes compared to traditional ENSO indices, especially during strong El Niño events.

scholarly journals A proxy modelling approach to assess the potential of extracting ENSO signal from tropical Pacific planktonic foraminifera

2020 ◽  
Vol 16 (3) ◽  
pp. 885-910
Author(s):  
Brett Metcalfe ◽  
Bryan C. Lougheed ◽  
Claire Waelbroeck ◽  
Didier M. Roche
Keyword(s):  
El Niño ◽  
Climate Models ◽  
El Nino ◽  
Southern Oscillation ◽  
Accumulation Rate ◽  
Planktonic Foraminifera ◽  
Tropical Pacific ◽  
Sea Floor ◽  
El Niño Events ◽  
El Nino Events

Abstract. A complete understanding of past El Niño–Southern Oscillation (ENSO) fluctuations is important for the future predictions of regional climate using climate models. One approach to reconstructing past ENSO dynamics uses planktonic foraminifera as recorders of past climate to assess past spatio-temporal changes in upper ocean conditions. In this paper, we utilise a model of planktonic foraminifera populations, Foraminifera as Modelled Entities (FAME), to forward model the potential monthly average δ18Oc and temperature signal proxy values for Globigerinoides ruber, Globigerinoides sacculifer, and Neogloboquadrina dutertrei from input variables covering the period of the instrumental record. We test whether the modelled foraminifera population δ18Oc and Tc associated with El Niño events statistically differ from the values associated with other climate states. Provided the assumptions of the model are correct, our results indicate that the values of El Niño events can be differentiated from other climate states using these species. Our model computes the proxy values of foraminifera in the water, suggesting that, in theory, water locations for a large portion of the tropical Pacific should be suitable for differentiating El Niño events from other climate states. However, in practice it may not be possible to differentiate climate states in the sediment record. Specifically, comparison of our model results with the sedimentological features of the Pacific Ocean shows that a large portion of the hydrographically/ecologically suitable water regions coincide with low sediment accumulation rate at the sea floor and/or of sea floor that lie below threshold water depths for calcite preservation.

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 Connection Between the Hadley Circulation and Meridional Structure of Tropical SST during ENSO from 1950 to 1977

2021 ◽  
Author(s):  
Mingxin Yu ◽  
Juan Feng ◽  
Jianping Li ◽  
Ran An
Keyword(s):  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Hadley Circulation ◽  
Tropical Indian Ocean ◽  
Interdecadal Shift ◽  
El Niño Events ◽  
Sst Warming ◽  
Tropical Sea ◽  
El Nino Events

Abstract The connection between the meridional structure of tropical sea surface temperature (SST) and the Hadley circulation (HC) under the effect of ENSO (El Niño Southern Oscillation) from 1950 to 1977 is studied. We decompose the HC and zonal mean SST into equatorially symmetric (HES for HC, SES for SST) and asymmetric variations (HEA for HC, SEA for SST) to discuss the modulation of their connection by ENSO. During El Niño events from 1950 to 1977, the HC is less sensitive to the different SST meridional structures and expressed by response ratio. The ratio in La Niña and neutral events is around 4, which is equivalent to the result in the climatology. The reason for the decreased ratio during El Niño events is explored. The interdecadal variation in the linkage between the HC and tropical SST is due to a clear interdecadal shift in the impacts of ENSO on the tropical Indian Ocean (TIO) SST. For the period 1950–1977, when El Niño events occur, larger SST warming amplitude is observed over the northern TIO (0°–15°N, 50°–100°E). However, the southern TIO (15°S–0°, 50°–100°E) shows greater warming amplitude during 1980–2016. The anomalous SST variation over the TIO linked to El Niño events alters the meridional SST distribution, inducing anomalies in the meridional circulation. These results can help us to understand the interdecadal modulation by ENSO of the relationship between tropical SST and the HC.

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