scholarly journals Evolution of ENSO Related Rainfall Anomalies for Lower Tapi River, India

10.29007/vjgz ◽  
2018 ◽  
Author(s):  
Paresha Baria ◽  
Sanjaykumar M. Yadav
Keyword(s):  
El Niño ◽  
El Nino ◽  
Daily Rainfall ◽  
La Niña ◽  
Clear Trend ◽  
Study Region ◽  
Enso Events ◽  
La Nina ◽  
State Water ◽  
Tapi Basin

The present study is an attempt to detect anomalies in rainfall for lower Tapi basin due to ENSO events. Daily rainfall data have been used for the present analysis. The data have been collected from state water data centre from 1961 to 2001. With the availability of suitable data 1982, 1986, 1987, 1991, 1997, 2002 and 2009 are the El Nino years and 1988, 1998, 1999, 2007 and 2010 are the La Nina years analysed for the present study. The yearly extreme precipitation indices have been computed for frequency, intensity and duration for the base period 1981 to 2010. For the El Nino years 1997 and 2009 positive anomalies have been observed in the frequency based indices. In the years 1982, 1987, 1991, 1997, 2002 and 2009, positive anomalies have been observed for the intensity based indices. Positive anomalies results into better rainfall during El Nino events. Negative anomalies have been observed in the years 1998 and 1999 of the La Nina events for the frequency based indices and for the years 1988, 1998, 1999, 1007 and 2010 negative anomalies have been observed in the intensity based indices. The analysis of La Nina events results in a decrease in rainfall. The precipitation duration based indices have not indicated clear trend. The overall analysis showed that ENSO is not directly affecting the rainfall of the study region.

scholarly journals Switch Between El Nino and La Nina is Caused by Subsurface Ocean Waves Likely Driven by Lunar Tidal Forcing

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Jialin Lin ◽  
Taotao Qian
Keyword(s):  
El Niño ◽  
El Nino ◽  
Ocean Waves ◽  
La Niña ◽  
Slow Phase ◽  
Enso Events ◽  
The Past ◽  
La Nina ◽  
Subsurface Ocean ◽  
Sst Anomaly

Abstract The El Nino-Southern Oscillation (ENSO) is the dominant interannual variability of Earth’s climate system, and strongly modulates global temperature, precipitation, atmospheric circulation, tropical cyclones and other extreme events. However, forecasting ENSO is one of the most difficult problems in climate sciences affecting both interannual climate prediction and decadal prediction of near-term global climate change. The key question is what cause the switch between El Nino and La Nina. For the past 30 years, ENSO forecasts have been limited to short lead times after ENSO sea surface temperature (SST) anomaly has already developed, but unable to predict the switch between El Nino and La Nina. Here, we demonstrate that the switch between El Nino and La Nina is caused by a subsurface ocean wave propagating from western Pacific to central and eastern Pacific and then triggering development of SST anomaly. This is based on analysis of all ENSO events in the past 136 years using multiple long-term observational datasets. The wave’s slow phase speed and decoupling from atmosphere indicate that it is a forced wave. Further analysis of Earth’s angular momentum budget and NASA’s Apollo Landing Mirror Experiment suggests that the subsurface wave is likely driven by lunar tidal gravitational force.

Composite Analysis of the Effects of ENSO Events on Antarctica

2016 ◽  
Vol 29 (5) ◽  
pp. 1797-1808 ◽  
Author(s):  
Lee J. Welhouse ◽  
Matthew A. Lazzara ◽  
Linda M. Keller ◽  
Gregory J. Tripoli ◽  
Matthew H. Hitchman
Keyword(s):  
El Niño ◽  
Geopotential Height ◽  
El Nino ◽  
Southern Oscillation ◽  
Southern Annular Mode ◽  
La Niña ◽  
Austral Spring ◽  
Enso Events ◽  
La Nina ◽  
The Relationship

Abstract Previous investigations of the relationship between El Niño–Southern Oscillation (ENSO) and the Antarctic climate have focused on regions that are impacted by both El Niño and La Niña, which favors analysis over the Amundsen and Bellingshausen Seas (ABS). Here, 35 yr (1979–2013) of European Centre for Medium-Range Weather Forecasts interim reanalysis (ERA-Interim) data are analyzed to investigate the relationship between ENSO and Antarctica for each season using a compositing method that includes nine El Niño and nine La Niña periods. Composites of 2-m temperature (T2m), sea level pressure (SLP), 500-hPa geopotential height, sea surface temperatures (SST), and 300-hPa geopotential height anomalies were calculated separately for El Niño minus neutral and La Niña minus neutral conditions, to provide an analysis of features associated with each phase of ENSO. These anomaly patterns can differ in important ways from El Niño minus La Niña composites, which may be expected from the geographical shift in tropical deep convection and associated pattern of planetary wave propagation into the Southern Hemisphere. The primary new result is the robust signal, during La Niña, of cooling over East Antarctica. This cooling is found from December to August. The link between the southern annular mode (SAM) and this cooling is explored. Both El Niño and La Niña experience the weakest signal during austral autumn. The peak signal for La Niña occurs during austral summer, while El Niño is found to peak during austral spring.

scholarly journals Reversed Spatial Asymmetries between El Niño and La Niña and Their Linkage to Decadal ENSO Modulation in CMIP3 Models

2011 ◽  
Vol 24 (20) ◽  
pp. 5423-5434 ◽  
Author(s):  
Jin-Yi Yu ◽  
Seon Tae Kim
Keyword(s):  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Interaction Mechanism ◽  
Tropical Pacific ◽  
La Niña ◽  
Enso Events ◽  
La Nina ◽  
Spatial Asymmetries ◽  
Mean State

Abstract This study examines preindustrial simulations from Coupled Model Intercomparison Project, phase 3 (CMIP3), models to show that a tendency exists for El Niño sea surface temperature anomalies to be located farther eastward than La Niña anomalies during strong El Niño–Southern Oscillation (ENSO) events but farther westward than La Niña anomalies during weak ENSO events. Such reversed spatial asymmetries are shown to force a slow change in the tropical Pacific Ocean mean state that in return modulates ENSO amplitude. CMIP3 models that produce strong reversed asymmetries experience cyclic modulations of ENSO intensity, in which strong and weak events occur during opposite phases of a decadal variability mode associated with the residual effects of the reversed asymmetries. It is concluded that the reversed spatial asymmetries enable an ENSO–tropical Pacific mean state interaction mechanism that gives rise to a decadal modulation of ENSO intensity and that at least three CMIP3 models realistically simulate this interaction mechanism.

scholarly journals PDO–ENSO Effects in the Climate of Mexico

2006 ◽  
Vol 19 (24) ◽  
pp. 6433-6438 ◽  
Author(s):  
Edgar G. Pavia ◽  
Federico Graef ◽  
Jorge Reyes
Keyword(s):  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
La Niña ◽  
Climate Anomalies ◽  
Enso Events ◽  
La Nina ◽  
Mean Temperature ◽  
The Pacific

Abstract The role of the Pacific decadal oscillation (PDO) in El Niño–Southern Oscillation (ENSO)-related Mexican climate anomalies during winter and summer is investigated. The precipitation and mean temperature data of approximately 1000 stations throughout Mexico are considered. After sorting ENSO events by warm phase (El Niño) and cold phase (La Niña) and prevailing PDO phase: warm or high (HiPDO) and cold or low (LoPDO), the authors found the following: 1) For precipitation, El Niño favors wet conditions during summers of LoPDO and during winters of HiPDO. 2) For mean temperature, cooler conditions are favored during La Niña summers and during El Niño winters, regardless of the PDO phase; however, warmer conditions are favored by the HiPDO during El Niño summers.

scholarly journals Study of rainfall departure over catchments of Bihar plains

MAUSAM ◽  
2021 ◽  
Vol 61 (2) ◽  
pp. 187-196
Author(s):  
T. N. JHA ◽  
R. D. RAM
Keyword(s):  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Monsoon Season ◽  
Daily Rainfall ◽  
La Niña ◽  
Rainfall Time Series ◽  
La Nina ◽  
Multivariate Enso Index ◽  
Rainfall Departure

Station wise daily rainfall data of sixty years is used to study rainfall departure and variability  in  Kosi, Kamala/Bagmati/Adhwara and  Gandak/Burhi Gandak catchments during  monsoon  season. Station and catchment wise rainfall time series have been made to compute rainfall departure and Coefficient of Variation (CV). Southern Oscillation Index (SOI), Multivariate ENSO Index (MEI) and ENSO strength based on percentile analysis are used to ascertain their impact on rainfall distribution in the category as excess, normal, deficient and scanty. Results indicate that the variability is greater over Kosi as compared to the other catchments. Probability of normal rainfall is found 0.75 and there is no possibility of scanty rain over the catchments during El Nino and La Nina year. Similarly probabilities of normal, deficient, excess rainfall are found as 0.67, 0.18 and 0.15 respectively during mixed year. SOI has emerged as principal parameter which modifies the departure during El Nino and La Nina year. MEI along with ENSO strength  are more prominent  during  mixed year  particularly to ascertain deficient and excess rain in weak and strong- moderate La Nina  respectively .   

scholarly journals The Pause End and Major Temperature Impacts during Super El Niños are Due to Shortwave Radiation Anomalies

2020 ◽  
pp. 1-20
Author(s):  
Antero Ollila
Keyword(s):  
El Niño ◽  
Climate Model ◽  
El Nino ◽  
La Niña ◽  
Global Temperature ◽  
Temperature Changes ◽  
Simple Climate Model ◽  
Enso Events ◽  
La Nina ◽  
Temperature Impacts

The hiatus or temperature pause during the 21st century has been the subject of numerous research studies with very different results and proposals. In this study, two simple climate models have been applied to test the causes of global temperature changes. The climate change factors have been shortwave (SW) radiation changes, changes in cloudiness and ENSO (El Niño Southern Oscillation) events assessed as the ONI (Oceanic Niño Index) values and anthropogenic climate drivers. The results show that a simple climate model assuming no positive water feedback follows the satellite temperature changes very well, the mean absolute error (MAE) during the period from 2001 to July 2019 being 0.073°C and 0.082°C in respect to GISTEMP. The IPCC’s simple climate model shows for the same period errors of 0.191°C and 0.128°C respectively. The temperature in 2017-2018 was about 0.2°C above the average value in 2002–2014. The conclusion is that the pause was over after 2014 and the SW anomaly forcing was the major reason for this temperature increase. SW anomalies have had their greatest impacts on the global temperature during very strong (super) El Niño events in 1997-98 and 2015-16, providing a new perspective for ENSO events. A positive SW anomaly continued after 2015-16 which may explain the weak La Niña 2016 temperature impacts, and a negative SW anomaly after 1997-98 may have contributed two strong La Niña peaks 1998-2001. No cause and effect connection could be found between the SW radiation and temperature anomalies in Nino areas.

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).

ENSO continuum and its impacts on worldwide precipitation: Observation vs. CMIP5/6

2020 ◽  
Author(s):  
Bastien Dieppois ◽  
Jonathan Eden ◽  
Paul-Arthur Monerie ◽  
Benjamin Pohl ◽  
Julien Crétat ◽  
...  
Keyword(s):  
El Niño ◽  
El Nino ◽  
La Niña ◽  
Boreal Summer ◽  
Central Pacific ◽  
Rainfall Gradient ◽  
Data Set ◽  
Enso Events ◽  
La Nina ◽  
Central Pacific Enso

<p>It is now widely recognized that El Nino-Southern Oscillation (ENSO) occurs in more than one form, e.g. eastern and central Pacific ENSO. Given that these various ENSO flavours may contribute to climate variability and trends in different ways, this study presents a framework that treats ENSO as a continuum to examine its impact on precipitation, and to evaluate the performance of the last two generations of global climate models (GCMs): CMIP5 and CMIP6.</p><p>Uncertainties in the location and intensity of observed El Nino and La Nina events are assessed in various observational and satellite-derived products (ERSSTv5, COBESSTv2, HadSST1 and OISSTv2). The probability distributions of El Nino and La Nina event locations, and intensities, slightly differ from one observational data set to another. For instance, La Nina events are more intense and more likely to occur in the central Pacific using COBESSTv2. All these products also depict consistent decadal variations in the location and intensity of ENSO events: i) central Pacific ENSO events were more likely in the 1940/50s and from the 1980s; ii) eastern Pacific ENSO events were more likely in the 1910/20s and 1960/70s; iii) La Nina events have become more intense during the 20<sup>th</sup> and early 21<sup>st </sup>centuries.</p><p>These fluctuations in ENSO location and intensity are found to impact precipitation consistently across diverse global precipitation products (CRUv4.03, GPCCv8 and UDELv5.01). Over southern Africa, for instance, more intense eastern (central) Pacific El Nino events are found to favour drought conditions over northern (southern) regions during austral summer. By contrast, over the same regions, more intense La Nina events favours wet conditions, while the location of these events has little effect on precipitation. Over West Africa, ENSO locations favour a zonal (E-W) rainfall gradient in precipitation during boreal summer, while changes in ENSO intensity modulate the strength of the meridional (N-S) rainfall gradient.</p><p>Using both historical and pi-Control runs, we demonstrate that most CMIP5 and CMIP6 models favour either eastern or central Pacific ENSO events, but very few models are able to capture the full observed ENSO continuum. Regarding ENSO impacts on worldwide precipitation, contrasted results appear in most models.</p>

scholarly journals Visualizing the Large-Scale Patterns of ENSO-Related Climate Anomalies in North America

2009 ◽  
Vol 13 (3) ◽  
pp. 1-50 ◽  
Author(s):  
Jacqueline J. Shinker ◽  
Patrick J. Bartlein
Keyword(s):  
El Niño ◽  
Large Scale ◽  
El Nino ◽  
Precipitation Anomaly ◽  
La Niña ◽  
Specific Humidity ◽  
Spatial And Temporal Variability ◽  
Climate Anomalies ◽  
Enso Events ◽  
La Nina

Abstract The variations of large-scale climatic controls and surface responses through the annual cycle during strong positive (El Niño) and negative (La Niña) phase ENSO events are analyzed to assess the within-year and among-year variations of climate anomalies. Data from the NCEP–NCAR reanalysis project are presented as small-multiple maps to illustrate the spatial and temporal variability in North American climate associated with extreme phases of ENSO. Temperature, mean sea level pressure, 500-mb geopotential heights, and 850-mb specific humidity have composite-anomaly patterns that exhibit the greatest degree of spatial and temporal coherence. In general, the composite-anomaly patterns for El Niño and La Niña events are of opposite sign, with stronger, more spatially coherent anomalies occurring during El Niño events than during La Niña events. However, the strength and coherency of the precipitation anomaly patterns are reduced in the interior intermountain west during both positive and negative phase of ENSO. The variations in precipitation anomalies are compared to the 500-mb omega and 850-mb specific humidity composite-anomaly patterns, which provide information on the controls of precipitation by large-scale vertical motions and moisture availability thus providing information on the specific mechanisms associated with precipitation variability during ENSO events.

scholarly journals Investigação da Influência do El Niño e da La Niña Sobre a Variabilidade da Precipitação na Cidade de Patos, Paraíba.

2020 ◽  
Vol 13 (1) ◽  
pp. 336
Author(s):  
Shayenny Alves de Medeiros ◽  
Raul Araújo da Nóbrega ◽  
João Miguel De Moraes Neto ◽  
Aldinete Bezerra Barreto ◽  
Gleyka Nóbrega Vasconcelos ◽  
...  
Keyword(s):  
El Niño ◽  
El Nino ◽  
Rainfall Variability ◽  
La Niña ◽  
Area Of Interest ◽  
La Nina ◽  
Total Data ◽  
State Water ◽  
Annual Total ◽  
Precipitation Anomalies

A área de interesse para este estudo foi o município Patos- PB, onde foram utilizados dados totais mensais e anuais (1960-2019) da precipitação, disponibilizados pela Superintendência do Desenvolvimento do Nordeste (SUDENE) e pela Agência Executiva de Gestão das Águas do Estado da Paraíba (AESA). Os dados foram utilizados para estudar a variabilidade da chuva, investigando as anomalias de precipitação em anos de ocorrência El Niño e La Niña. A Técnica utilizada foi a dos Percentis que determinou a classe pluviométrica da precipitação caracterizando os totais nas seguintes classes: Muito Seco (MS), Seco (S), Normal (N), Chuvoso (CH) e Muito Chuvoso (MC). Os resultados destacam os meses de janeiro a abril com as máximas precipitações mensais, representando 86,85% do total anual esperado, e os meses de menor ocorrência de chuvas são de agosto a outubro. Foi utilizada a técnica do Desvio Padronizado de Precipitação (DPP) para investigar a existência de influência dos eventos El Niño e La Niña, na variabilidade das precipitações. Os (DPP) mensais apresentam valores negativos e positivos, entre -1,71 e 5,62. Observou-se que os DPP negativos predominam tanto na época de El Niño (70,21%) quanto de La Niña (59,09%), não representando uma evidência significativa da influência dos fenômenos sobre a variabilidade da chuva.  Investigation of the Influence of El Niño and La Niña on the Variability of Precipitation in the City of Patos, ParaíbaA B S T R A C TThe area of interest for this study was the municipality of Patos-PB, where were used monthly and annual total data (1960-2019) of rainfall, provided by the Northeast Development Superintendence (SUDENE) and the Executive State Water Management Agency Paraíba. Data were used to study rainfall variability, investigating precipitation anomalies in years of occurrence El Niño and La Niña. The technique used was the Percentiles that determined the rainfall class characterizing the totals in the following classes: Very Dry (VD), Dry (D), Normal (N), Rainy (R) and Very Rainy (VR). The results highlight the months from January to April with the highest monthly rainfall, representing 86.85% of the expected annual total, and the months with the lowest rainfall are from August to October. The Standardized Precipitation Deviation (SPD) technique was used to investigate the influence of El Niño and La Niña events on precipitation variability. The monthly (SPD) values  are negative and positive, between -1.71 and 5.62. When analyzing the DPPs separately for the years with the occurrence of the events El Niño and La Niña, it is concluded that there is a predominance of negative DPPs with annual averages of 70.21 and 59.09% respectively, thus, not representing significant evidence of the influence of phenomena on rainfall variability.Keywords: Rainfall, Quantis, Standard Deviation 

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