scholarly journals An Analysis of the Energetics of Tropical and Extra-Tropical Regions for Warm ENSO Composite Episodes

2017 ◽  
Vol 32 (1) ◽  
pp. 39-51
Author(s):  
Zayra Christine Sátyro ◽  
José Veiga
Keyword(s):  
Kinetic Energy ◽  
Potential Energy ◽  
El Niño ◽  
Energy Production ◽  
El Nino ◽  
Southern Oscillation ◽  
Stable Condition ◽  
The Other ◽  
Tropical Regions ◽  
Using Data

Abstract This study focuses on the quantification and evaluation of the effects of ENSO (El Niño Southern Oscillation) warm phases, using a composite of five intense El Niño episodes between 1979 – 2011 on the Energetic Lorenz Cycle for four distinct regions around the globe: 80° S – 5° N (region 1), 50° S – 5° N (region 2), 30° S – 5° N (region 3), and 30° S – 30° N (region 4), using Data from NCEP reanalysis-II. Briefly, the results showed that zonal terms of potential energy and kinetic energy were intensified, except for region 1, where zonal kinetic energy weakened. Through the analysis of the period in which higher energy production is observed, a strong communication between the available zonal potential and the zonal kinetic energy reservoirs can be identified. This communication weakened the modes linked to eddies of potential energy and kinetic energy, as well as in the other two baroclinic conversions terms. Furthermore, the results indicate that for all the regions, the system itself works to regain its stable condition.

scholarly journals Precipitação na América do Sul: Médias Climáticas e Padrões da Variabilidade no Período entre 1979 e 2008

2016 ◽  
Vol 9 (1) ◽  
pp. 032
Author(s):  
Éder Leandro Maier ◽  
Juliana Costi ◽  
Sandra Barreira ◽  
Jefferson Cardia Simões
Keyword(s):  
South America ◽  
North Atlantic ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Principal Component ◽  
Monthly Precipitation ◽  
Tropical Regions ◽  
The North ◽  
North Atlantic Variability

Este artigo discute os principais padrões médios e anômalos da precipitação sobre a América do Sul no período 1979–2008. Para isso foram manipulados dados mensais da precipitação observada em 890 estações meteorológicas localizadas na Argentina, Bolívia, Brasil, Paraguai e Uruguai ao longo desse período de trinta anos. As médias climáticas foram subtraídas das amostras, originando as anomalias, as quais foram agrupadas por meio da Análise das Componentes Principais em dois modos. No modo T se identificou 6 componentes principais, que explicam 35% da variância e representam 12 padrões espaciais anômalos originados, principalmente, pelo fenômeno El Niño–Oscilação Sul (ENOS) e pela variabilidade do Atlântico Norte. No modo S foram identificadas 8 zonas em que a variabilidade temporal das séries anômalas é semelhante, sendo que o ENOS prevalece no controle das anomalias nas zonas situadas na região equatorial e extratropical, além disso, a variabilidade do Atlântico Norte pode maximizar ou minimizar os impactos do ENOS. A frequência de recorrência desses estresses hídrico variam entre 20 e 60 meses.  This article discusses mean and anomalous rainfall patterns over South America in the period 1979–2008. For that we handled monthly precipitation data observed at 890 meteorological stations located in Argentina, Bolivia, Brazil, Paraguay and Uruguay over this thirty years period. Climatic means were subtracted from the data, resulting in anomalies that were grouped by Principal Component Analysis in two modes. We identified 6 main components in the T mode, which explain 35% of the variance and represent 12 anomalous spatial patterns originated mainly by El Niño–Southern Oscillation (ENSO) phenomenon and the North Atlantic variability. In mode S, we identified eight zones where the series temporal variability is also anomalous, and the ENOS prevails as the anomalies controller in the equatorial and extra tropical regions. Further, North Atlantic variability may maximize or minimize the ENSO impact. The frequency of these recurrent water stresses range from 20 to 60 months. Keywords: Precipitation, South America, PCA  

scholarly journals Spatio-temporal patterns of thermal anomalies and drought over tropical forests driven by recent extreme climatic anomalies

2018 ◽  
Vol 373 (1760) ◽  
pp. 20170300 ◽  
Author(s):  
Juan C. Jimenez ◽  
Jonathan Barichivich ◽  
Cristian Mattar ◽  
Ken Takahashi ◽  
Andrés Santamaría-Artigas ◽  
...  
Keyword(s):  
Tropical Forests ◽  
Spatial Patterns ◽  
El Niño ◽  
El Nino ◽  
The Other ◽  
Extreme Drought ◽  
Drought Severity ◽  
Tropical Regions ◽  
Temperature Anomalies ◽  
The Impact

The recent 2015–2016 El Niño (EN) event was considered as strong as the EN in 1997–1998. Given such magnitude, it was expected to result in extreme warming and moisture anomalies in tropical areas. Here we characterize the spatial patterns of temperature anomalies and drought over tropical forests, including tropical South America (Amazonia), Africa and Asia/Indonesia during the 2015–2016 EN event. These spatial patterns of warming and drought are compared with those observed in previous strong EN events (1982–1983 and 1997–1998) and other moderate to strong EN events (e.g. 2004–2005 and 2009–2010). The link between the spatial patterns of drought and sea surface temperature anomalies in the central and eastern Pacific is also explored. We show that indeed the EN2015–2016 led to unprecedented warming compared to the other EN events over Amazonia, Africa and Indonesia, as a consequence of the background global warming trend. Anomalous accumulated extreme drought area over Amazonia was found during EN2015–2016, but this value may be closer to extreme drought area extents in the other two EN events in 1982–1983 and 1997–1998. Over Africa, datasets disagree, and it is difficult to conclude which EN event led to the highest accumulated extreme drought area. Our results show that the highest values of accumulated drought area over Africa were obtained in 2015–2016 and 1997–1998, with a long-term drying trend not observed over the other tropical regions. Over Indonesia, all datasets suggest that EN 1982–1983 and EN 1997–1998 (or even the drought of 2005) led to a higher extreme drought area than EN2015–2016. Uncertainties in precipitation datasets hinder consistent estimates of drought severity over tropical regions, and improved reanalysis products and station records are required.This article is part of a discussion meeting issue ‘The impact of the 2015/2016 El Niño on the terrestrial tropical carbon cycle: patterns, mechanisms and implications’.

scholarly journals Thermal Front Variability during The El Nino Southern Oscillation (ENSO) in The Banda Sea Using Remotely Sensed Data

2021 ◽  
Vol 3 (2) ◽  
Author(s):  
Achmad Fachruddin Syah ◽  
Siti Sholehah
Keyword(s):  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
La Niña ◽  
The Other ◽  
El Niño Southern Oscillation ◽  
El Nino Southern Oscillation ◽  
Thermal Front ◽  
La Nina ◽  
Normal Period

The Banda Sea is one of the routes of global ocean currents that move from the Pacific Ocean to the Indian Ocean. This flow is known as Indonesian Through Flow (ITF). The Banda Sea is an area where warm and cold water masses meet, so it has the potential for a thermal front. This study aims to understand the variability of thermal front in the Banda Sea during the El Nino Southern Oscillation period. Southern Oscillation Index (SOI) and sea surface temperature (SST) data in 2010, 2012 and 2015 were used in this study. SOI data was obtained from http://www.bom.gov.au and SST data was obtained from http://oceancolor.gsfc.nasa.gov. The data were processed using ArcGIS 10.4 software and Ms. Office 2013. The results showed the La Nina period occurs in July - December 2010, the Normal period occurs in July - December 2012, and the El Nino period occurs in May - October 2015. In general, during La Nina, the mean SST has higher values than the other periods. On the other hand, the highest thermal front occurs during the El Niño period (10584), followed by the Normal period (7544) and the lowest during the La Niña period (5961), respectively.

Two different simulations of the Southern Oscillation and El Niño with coupled ocean-atmosphere general circulation models

1989 ◽  
Vol 329 (1604) ◽  
pp. 167-178 ◽  
Keyword(s):  
El Niño ◽  
General Circulation ◽  
El Nino ◽  
Southern Oscillation ◽  
General Circulation Models ◽  
La Niña ◽  
The Other ◽  
La Nina ◽  
Ocean Atmosphere ◽  
Interannual Fluctuations

Two different coupled ocean-atmosphere models simulate irregular interannual fluctuations that in many respects resemble El Niño Southern Oscillation phenomena. For example, the spatial structure of various fields at the peaks of the warm El Niño and cold La Niña phases of the oscillation are realistic. This success indicates that the models capture certain aspects of the interactions between the ocean and atmosphere that cause the Southern Oscillation. The principal difference between the models, namely the prominence of oceanic Kelvin waves in one but not the other, causes the two models to differ significantly in the way El Niño episodes evolve, and in the mechanisms that cause a turnabout from El Niño to La Niña and vice versa. It is possible that the different processes that determine the properties of the simulated oscillations all play a role in reality, at different times and in different regions. Each of the models captures some aspects of what is possible. However, reality is far more complex than any model developed thus far and additional processes not yet included are also likely to have a significant influence on the observed Southern Oscillation.

An LTER Network Overview and Introduction to El Niño–Southern Oscillation (ENSO) Climatic Signal and Response

2003 ◽  
Author(s):  
David Greenland
Keyword(s):  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
The Other ◽  
El Niño Southern Oscillation ◽  
El Nino Southern Oscillation ◽  
Ecological Responses ◽  
Climatic Signal ◽  
Monthly Total ◽  
Human Ecosystems

Part II of this book deals with the quasi-quintennial timescale that is dominated by the El Niño–Southern Oscillation (ENSO) phenomenon. During the last 50 years, ENSO has operated with a recurrence interval between peak values of 2–7 years. The term quasi-quintennial is chosen to recognize that climatic events other than ENSO-related ones might occur at this timescale. The general significance of the ENSO phenomenon lies in its influence on natural and human ecosystems. It has been estimated that severe El Niño–related flooding and droughts in Africa, Latin America, North America, and Southeast Asia resulted in more than 22,000 lives lost and more than $36 billion in damages during 1997– 1998 (Buizer et al. 2000). The specific significance of ENSO within the context of this book is that it provides fairly well-bounded climatic events for which specific ecological responses may be identified. In the other chapters in part II, we first look at the U.S. Southwest. The Southwest is home to an urban LTER site, the Central Arizona-Phoenix (CAP) site. Tony Brazel and Andrew Ellis describe the clear ENSO climatic signal at this site and identify surprising responses that cascade into the human/economic system. Ray Smith, Bill Fraser, and Sharon Stammerjohn provide more details of the fascinating ecological responses of the Palmer Antarctic ecosystem to ENSO. World maps of ENSO climatic signals do not usually show the Antarctic, and the LTER program provides some groundbreaking results at this location, with Smith and coworkers (see the Synthesis at the end of this part) providing such maps (figures S.1 and S.2). Kathy Welch and her colleagues present equally new discoveries related to freshwater aquatic ecosystems from the other Antarctic LTER site at the McMurdo Dry Valleys. This chapter gives a general introduction to ENSO and its climatic effects. How ever, these general patterns may mask the detailed responses that occur at individual locations. This is one reason for presenting the principal results of previous findings related to El Niños and LTER sites and one particular analysis focused on LTER sites. This analysis for the period 1957–1990 investigates the response of monthly mean temperature and monthly total precipitation standardized anomaly values to El Niño and La Niña events as indicated by the Southern Oscillation Index (SOI) (Greenland 1999).

scholarly journals Radiative and microphysical responses of clouds to an anomalous increase in fire particles over the Maritime Continent in 2015

2021 ◽  
Author(s):  
Azusa Takeishi ◽  
Chien Wang
Keyword(s):  
Biomass Burning ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Cloud Microphysics ◽  
The Other ◽  
Maritime Continent ◽  
Peak Biomass ◽  
Clear Sign ◽  
Ice Phase

Abstract. The year of 2015 was an extremely dry year for Southeast Asia where the direct impact of strong El Niño was in play. As a result of this dryness and the relative lack of rainfall, an extraordinary amount of aerosol particles from biomass burning remained in the atmosphere over the Maritime Continent during the fire season. This study uses the Weather Research and Forecasting model coupled with Chemistry to understand the impacts of these fire particles on cloud microphysics and radiation during the peak biomass burning season in September. Our simulations, one with fire particles and the other without them, cover the entire Maritime Continent region at a cloud-resolving resolution (4 km) for the entire month of September in 2015. The comparison of the simulations shows a clear sign of precipitation enhancement by fire particles through microphysical effects; smaller cloud droplets remain longer in the atmosphere to later form ice crystals, and/or they are more easily collected by ice-phase hydrometeors, in comparison to droplets under no fire influences. As a result, mass of ice-phase hydrometeors increases in the simulation with fire particles, so does rainfall. On the other hand, we see no clear sign of temperature differences between the two simulations that could stem from the semi-direct effects of aerosols by absorbing the incoming solar radiation. Clouds are more reflective in the simulation with fire particles as ice mass increases. Combined with the direct scattering of sunlight by aerosols, the simulation with fire particles shows higher albedo over the simulation domain on average. The simulated response of clouds to fire particles in our simulations clearly differs from what was presented by two previous studies that modeled aerosol-cloud interaction in years with different phases of El Niño-Southern Oscillation (ENSO), suggesting a further need for an investigation on the possible modulation of fire-aerosol-convection interaction by ENSO.

scholarly journals Prediction of southern oscillation index using spectral components

MAUSAM ◽  
2022 ◽  
Vol 53 (2) ◽  
pp. 165-176
Author(s):  
R. P. KANE
Keyword(s):  
El Niño ◽  
Southern Oscillation Index ◽  
El Nino ◽  
Southern Oscillation ◽  
Spectral Characteristics ◽  
Singular Spectrum Analysis ◽  
Dependent Data ◽  
Simple Method ◽  
Single Wave ◽  
Using Data

The time series of SOI (Southern Oscillation Index, Tahiti minus Darwin sea-level atmospheric pressure difference) was spectrally analysed by a simple method MEM-MRA, where periodicities are detected by MEM (Maximum Entropy Method) and used in MRA (Multiple Regression Analysis) to get the estimates of their amplitudes and phases. From these, the three or four most prominent ones were used for reconstruction and prediction. Using data for 1935-80 as dependent data, the reconstructed values of SOI matched well with observed values and most of the El Niños (SOI minima) and La Niñas (SOI maxima) were located correctly. But for the independent data (1980 onwards), the matching was poor. Omitting earlier data, 1945- 80, 1955-80, 1965-80 as dependent data again gave poor matching for 1980 onwards. When data for 1980 onwards only were used as dependent data, the matching was better, indicating that the spectral characteristics have changed considerably with time and recent data were more appropriate for further predictions. The 1997 El Niño was reproduced only in data for 1985 onwards. For 1990 onwards, only a single wave of 3.5 years was appropriate and explained the 1997 and 1994 events but only one (1991) of the 3 complex and quick events that occurred during 1989-95. The UCLA group of Dr. Ghil has been using the SSA (Singular Spectrum Analysis)-MEM combination for SOI analysis. For the 1980s, they got very good matching, but the 1989-95 structures were not reproduced. For recent years, their SSA-filtered SOI (used for prediction) is a simple sinusoid of ~3.5 years. It predicted the El Niño of 1997 only at its peak and even after using data up to February 1997, the abrupt commencement of the event in March 1997 and its abrupt end in June 1998 could not be predicted.   Using only a 3.5 years wave, an El Niño was expected for 2000-2001. However, a very long-lasting La Niña seems to be operative and there are no indications as yet (September of 2001) of any El Niño like conditions.

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