scholarly journals Trends and Variabilities of Thunderstorm Days over Bangladesh on the ENSO and IOD Timescales

Atmosphere ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 1176 ◽  
Author(s):  
Md Wahiduzzaman ◽  
Abu Reza Md. Towfiqul Islam ◽  
Jing–Jia Luo ◽  
Shamsuddin Shahid ◽  
Md. Jalal Uddin ◽  
...  
Keyword(s):  
Probability Distribution ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Distribution Model ◽  
Test Results ◽  
Upward Trend ◽  
Significant Upward Trend ◽  
Decadal Scale ◽  
Atmospheric Phenomena

Thunderstorms (TS) are one of the most devastating atmospheric phenomena, which causes massive damage and adverse losses in various sectors, including agriculture and infrastructure. This study investigates the spatiotemporal variabilities of TS days over Bangladesh and their connection with El Niño Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD). The TS, ENSO and IOD years’ data for 42 years (1975–2016) are used. The trend in TS days at the spatiotemporal scale is calculated using Mann Kendall and Spearman’s rho test. Results suggest that the trend in TS days is positive for all months except December and January. The significant trends are found for May and June, particularly in the northern and northeastern regions of Bangladesh. In the decadal scale, most of the regions show a significant upward trend in TS days. Results from the Weibull probability distribution model show the highest TS days in the northeastern region. The connection between TS days and ENSO/IOD indicates a decrease in TS activities in Bangladesh during the El Niño and positive IOD years.

scholarly journals The effect of El Niño Southern Oscillation cycles on the decadal scale suspended sediment behavior of a coastal dry-summer subtropical catchment

2014 ◽  
Vol 40 (2) ◽  
pp. 272-284 ◽  
Author(s):  
Andrew B. Gray ◽  
Gregory B. Pasternack ◽  
Elizabeth B. Watson ◽  
Jonathan A. Warrick ◽  
Miguel A. Goñi
Keyword(s):  
Suspended Sediment ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
El Niño Southern Oscillation ◽  
El Nino Southern Oscillation ◽  
Decadal Scale

A Comparison of the Influence of Additive and Multiplicative Stochastic Forcing on a Coupled Model of ENSO

2005 ◽  
Vol 18 (23) ◽  
pp. 5066-5085 ◽  
Author(s):  
Cristina L. Perez ◽  
Andrew M. Moore ◽  
Javier Zavala-Garay ◽  
Richard Kleeman
Keyword(s):  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Low Frequency ◽  
Coupled Model ◽  
Deterministic System ◽  
Low Frequency Oscillation ◽  
Stochastic Forcing ◽  
Integration Period ◽  
Atmospheric Phenomena

Abstract A currently popular idea is that El Niño–Southern Oscillation (ENSO) can be viewed as a linear deterministic system forced by noise representing processes with periods shorter than ENSO. Also, there is observational evidence to suggest that the Madden–Julian oscillation (MJO) acts to trigger and/or amplify the warm phase of ENSO in this way. The feedback of the slower process, ENSO, to higher-frequency atmospheric phenomena, of which a large part of the variability in the intraseasonal band is due to the MJO, has received little attention. This paper considers the hypothesis that the probability of an El Niño event is modified by high MJO activity and that, in turn, the MJO is regulated by ENSO activity. If this is indeed the case, then viewing ENSO as a low-frequency oscillation forced by additive stochastic noise would not present a complete picture. This paper tests the above hypothesis using a stochastically forced intermediate coupled model by allowing ENSO to directly influence the stochastic forcing. The model response to a variety of stochastic forcing types is found to be sensitive to the type of forcing applied. When the model is operated beyond its intrinsic Hopf bifurcation, its probability distribution function (PDF) is fundamentally altered when the stochastic forcing is changed from additive to multiplicative. The model integration period also influences the shape of the PDF, which is also compared to the PDF derived from observations. It is found that multiplicative stochastic forcing reproduces some measures of the observations better than the additive stochastic forcing.

scholarly journals Tendências no Nível do Rio de Bacias Hidrográficas do Estado do Ceará e Suas Causas Climáticas (Trends in Level River of Basin Hydrographic of the Ceará State and Its Causes Climate)

2015 ◽  
Vol 7 (5) ◽  
pp. 927
Author(s):  
Maria Ângela Cruz Macêdo dos Santos ◽  
Iuri Moreira Costa ◽  
Juliana Alcântara Costa ◽  
Antônio Edgar Mateus ◽  
Rosangela Felesmino de Sousa ◽  
...  
Keyword(s):  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Kendall Test ◽  
River Basins ◽  
Resources Management ◽  
Resource Managers ◽  
The Pacific ◽  
Decadal Scale ◽  
Mann Kendall Test

Utilizando o teste de Mann-Kendall, objetivou-se nesse trabalho, analisar as tendências nas séries de cotas dos rios principais dasbacias hidrográficas do Estado do Ceará. As bacias hidrográficas do Ceará estudadas aqui foram: Bacia do Médio, Alto, Baixo Jaguaribe, Bacia do Salgado, Bacia Acaraú, Bacia Curú, Bacia de Ibiapaba, Bacia do Banabuiú, Bacia Coreaú, Bacia do Litoral. Foram utilizados os dados de cotas dos rios principais dessas bacias hidrográficas, cujos nomes das bacias hidrográficas são os mesmos desses rios cearenses. Os dados foram obtidos por meio da Agência Nacional das Águas para o período de 1973 a 2013. Para identificar as possíveis causas climáticas, utilizou-se a Análise de Ondeleta, a qual identifica as escalas temporais dominantes dos fenômenos e sistemas meteorológicos. Duas dessas Bacias hidrográficas mostraram tendência de diminuição na cota de seus rios principais, enquanto outras duas apresentaram tendência de aumento.Verificou-se que a escala decadal domina sobre as variações de cotas, sugerindo que a Oscilação Decadal do Pacífico tem influência direta sobre o nível dos rios e, associada ao sinal persistente de El Niño Oscilação Sul (7 anos), promoveram aumento e diminuição das cotas, dependendo de suas fases. Desse modo, com acompanhamento hidroclimático, os gestores de recursos hídricos e setores da economia e sociedade podem tirar proveito dessas importantes informações com previsão antecipada.   A B S T R A C T Using the Mann-Kendall test, this study aimed to analyze the trends in the shares of the major rivers of the watershed of the State of Ceará series. Basinhydrographics of Ceará studied here were: Médio, Alto, BaixoJaguaribe Basin, Salgado Basin, Acaraú Basin, BaciaCurú, Ibiapaba Basin, Banabuiú Basin, Coreaú Basin, Litoral Basin. Itsused data levelsof the main rivers of these Basin hydrographics, river basins whose names are the same cearenses these rivers. Data were obtained through the National Water Agency for the period 1973 to 2013 to identify possible causes climate, we used the wavelet analysis, which identifies the dominant temporal scales phenomena and weather systems. Two of these river basins showed declining trend in share of its major rivers, while two others showed a tendency to increase. Checkthat the decadal-scale variations dominates over quota, suggesting that the Pacific Decadal Oscillation has a direct influence on the level rivers and associated with a persistent signal of El Niño Southern Oscillation (7 years), caused an increase and decrease in quotas, depending on their stages. Thus, with climatemonitoring water resource managers and sectors of the economy and society can benefit from this important information with advance forecast.   Keywords: Mann-Kendall test, Water Resources Management, José and Noé effect, Wavelet analisys.   

scholarly journals Warming Patterns Affect El Niño Diversity in CMIP5 and CMIP6 Models

2020 ◽  
Vol 33 (19) ◽  
pp. 8237-8260 ◽  
Author(s):  
Mandy B. Freund ◽  
Josephine R. Brown ◽  
Benjamin J. Henley ◽  
David J. Karoly ◽  
Jaclyn N. Brown
Keyword(s):  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Central Pacific ◽  
Enso Events ◽  
Warming Pattern ◽  
Decadal Scale ◽  
El Niño Events ◽  
Mean State ◽  
El Nino Events

AbstractGiven the consequences and global significance of El Niño–Southern Oscillation (ENSO) events it is essential to understand the representation of El Niño diversity in climate models for the present day and the future. In recent decades, El Niño events have occurred more frequently in the central Pacific (CP). Eastern Pacific (EP) El Niño events have increased in intensity. However, the processes and future implications of these observed changes in El Niño are not well understood. Here, the frequency and intensity of El Niño events are assessed in models from phases 5 and 6 of the Coupled Model Intercomparison Project (CMIP5 and CMIP6), and results are compared to extended instrumental and multicentury paleoclimate records. Future changes of El Niño are stronger for CP events than for EP events and differ between models. Models with a projected La Niña–like mean-state warming pattern show a tendency toward more EP but fewer CP events compared to models with an El Niño–like warming pattern. Among the models with more El Niño–like warming, differences in future El Niño can be partially explained by Pacific decadal variability (PDV). During positive PDV phases, more El Niño events occur, so future frequency changes are mainly determined by projected changes during positive PDV phases. Similarly, the intensity of El Niño is strongest during positive PDV phases. Future changes to El Niño may thus depend on both mean-state warming and decadal-scale natural variability.

Interdecadal Amplitude Modulation of El Niño–Southern Oscillation and Its Impact on Tropical Pacific Decadal Variability*

2013 ◽  
Vol 26 (18) ◽  
pp. 7280-7297 ◽  
Author(s):  
Tomomichi Ogata ◽  
Shang-Ping Xie ◽  
Andrew Wittenberg ◽  
De-Zheng Sun
Keyword(s):  
Amplitude Modulation ◽  
El Niño ◽  
Decadal Variability ◽  
El Nino ◽  
Southern Oscillation ◽  
Tropical Pacific ◽  
Sea Surface ◽  
El Nino Southern Oscillation ◽  
Pacific Decadal Variability ◽  
Decadal Scale

Abstract The amplitude of El Niño–Southern Oscillation (ENSO) displays pronounced interdecadal modulations in observations. The mechanisms for the amplitude modulation are investigated using a 2000-yr preindustrial control integration from the Geophysical Fluid Dynamics Laboratory Climate Model, version 2.1 (GFDL CM2.1). ENSO amplitude modulation is highly correlated with the second empirical orthogonal function (EOF) mode of tropical Pacific decadal variability (TPDV), which features equatorial zonal dipoles in sea surface temperature (SST) and subsurface temperature along the thermocline. Experiments with an ocean general circulation model indicate that both interannual and decadal-scale wind variability are required to generate decadal-scale tropical Pacific temperature anomalies at the sea surface and along the thermocline. Even a purely interannual and sinusoidal wind forcing can produce substantial decadal-scale effects in the equatorial Pacific, with SST cooling in the west, subsurface warming along the thermocline, and enhanced upper-ocean stratification in the east. A mechanism is proposed by which residual effects of ENSO could serve to alter subsequent ENSO stability, possibly contributing to long-lasting epochs of extreme ENSO behavior via a coupled feedback with TPDV.

scholarly journals Streamflow Variability in Colombian Pacific Basins and Their Teleconnections with Climate Indices

Water ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 526 ◽  
Author(s):  
Teresita Canchala ◽  
Wilmar Loaiza Cerón ◽  
Félix Francés ◽  
Yesid Carvajal-Escobar ◽  
Rita Andreoli ◽  
...  
Keyword(s):  
River Basin ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Wavelet Coherence ◽  
Climate Indices ◽  
Decadal Scale ◽  
Streamflow Variability ◽  
Wavelet Coherence Analysis ◽  
Colombian Pacific

Oceanic-atmospheric phenomena of different time scales concurrently might affect the streamflow in several basins around the world. The Atrato River Basin (ARB) and Patía River Basin (PRB) of the Colombian Pacific region are examples of such basins. Nevertheless, the relations between the streamflows in the ARB and PRB and the oceanic-atmospheric factors have not been examined considering different temporal scales. Hence, this article studies the relations of the climate indices and the variability of the streamflows in the ARB and PRB at interannual and decadal timescales. To this, the streamflow variability modes were obtained from the principal component analysis (PCA); furthermore, their linear dependence with indices of the El Niño/Southern Oscillation (ENSO), precipitation (PRP), the Choco low-level jet (CJ), and other indices were quantified through (a) Pearson and Kendall’s tau correlations, and (b) wavelet transform. The PCA presented a single significant mode for each basin, with an explained variance of around 80%. The correlation analyses between the PC1s of the ARB and PRB, and the climate indices showed significant positive (negative) high correlations with PRP, CJ, and Southern Oscillation Index (SOI) (ENSO indices). The wavelet coherence analysis showed significant coherencies between ENSO and ARB: at interannual (2–7 years) and decadal scale (8–14), preferably with the sea surface temperature (SST) in the east and west Tropical Pacific Ocean (TPO). For PRB with the SST in the central and western regions of the TPO in the interannual (4–8 years) and decadal (8–14 years) scales, the decreases (increases) in streamflow precede the El Niño (La Niña) events. These results indicate multiscale relations between the basins’ streamflow and climate phenomena not documented in previous works, relevant to forecast the extreme flow events in the Colombian Pacific rivers and for planning and implementing strategies for the sustainable use of water resources in the basins studied.

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