Fundamental Behavior of ENSO Phase Locking

2020 ◽  
Vol 33 (5) ◽  
pp. 1953-1968 ◽  
Author(s):  
Han-Ching Chen ◽  
Fei-Fei Jin
Keyword(s):  
Decay Rate ◽  
El Niño ◽  
El Nino ◽  
Phase Locking ◽  
La Niña ◽  
Peak Time ◽  
Linear Frequency ◽  
La Nina ◽  
Noise Forcing ◽  
Phase Preference

AbstractEl Niño–Southern Oscillation (ENSO) events tend to peak at the end of the calendar year, a phenomenon called ENSO phase locking. This phase locking is a fundamental ENSO property that is determined by its basic dynamics. The conceptual ENSO recharge oscillator (RO) model is adopted to examine the ENSO phase-locking behavior in terms of its peak time, strength of phase locking, and asymmetry between El Niño and La Niña events. The RO model reproduces the main phase-locking characteristics found in observations, and the results show that the phase locking of ENSO is mainly dominated by the seasonal modulation of ENSO growth/decay rate. In addition, the linear/nonlinear mechanism of ENSO phase preference/phase locking is investigated using RO model. The difference between the nonlinear phase-locking mechanism and linear phase-preference mechanism is largely smoothed out in the presence of noise forcing. Further, the impact on ENSO phase locking from annual cycle modulation of the growth/decay rate, stochastic forcing, nonlinearity, and linear frequency are examined in the RO model. The preferred month of ENSO peak time depends critically on the phase and strength of the seasonal modulation of the ENSO growth/decay rate. Furthermore, the strength of phase locking is mainly controlled by the linear growth/decay rate, the amplitude of seasonal modulation of growth/decay rate, the amplitude of noise, the SST-dependent factor of multiplicative noise, and the linear frequency. The asymmetry of the sharpness of ENSO phase locking is induced by the asymmetric effect of state-dependent noise forcing in El Niño and La Niña events.

scholarly journals ENSO in the CMIP5 Simulations: Life Cycles, Diversity, and Responses to Climate Change

2017 ◽  
Vol 30 (2) ◽  
pp. 775-801 ◽  
Author(s):  
Chen Chen ◽  
Mark A. Cane ◽  
Andrew T. Wittenberg ◽  
Dake Chen
Keyword(s):  
El Niño ◽  
Natural Variation ◽  
El Nino ◽  
Phase Locking ◽  
Life Cycles ◽  
La Niña ◽  
First Century ◽  
La Nina ◽  
Twenty First Century ◽  
Projected Changes

Focusing on ENSO seasonal phase locking, diversity in peak location, and propagation direction, as well as the El Niño–La Niña asymmetry in amplitude, duration, and transition, a set of empirical probabilistic diagnostics (EPD) is introduced to investigate how the ENSO behaviors reflected in SST may change in a warming climate. EPD is first applied to estimate the natural variation of ENSO behaviors. In the observations El Niños and La Niñas mainly propagate westward and peak in boreal winter. El Niños occur more at the eastern Pacific whereas La Niñas prefer the central Pacific. In a preindustrial control simulation of the GFDL CM2.1 model, the El Niño–La Niña asymmetry is substantial. La Niña characteristics generally agree with observations but El Niño’s do not, typically propagating eastward and showing no obvious seasonal phase locking. So an alternative approach is using a stochastically forced simulation of a nonlinear data-driven model, which exhibits reasonably realistic ENSO behaviors and natural variation ranges. EPD is then applied to assess the potential changes of ENSO behaviors in the twenty-first century using CMIP5 models. Other than the increasing SST climatology, projected changes in many aspects of ENSO reflected in SST anomalies are heavily model dependent and generally within the range of natural variation. Shifts favoring eastward-propagating El Niño and La Niña are the most robust. Given various model biases for the twentieth century and lack of sufficient model agreements for the twenty-first-century projection, whether the projected changes for ENSO behaviors would actually take place remains largely uncertain.

A Simple GCM Study on the Relationship between ENSO and the Southern Annular Mode

2013 ◽  
Vol 70 (6) ◽  
pp. 1821-1832 ◽  
Author(s):  
Tingting Gong ◽  
Steven B. Feldstein ◽  
Dehai Luo
Keyword(s):  
Potential Vorticity ◽  
El Niño ◽  
El Nino ◽  
Southern Annular Mode ◽  
La Niña ◽  
Annular Mode ◽  
La Nina ◽  
The Impact ◽  
The Relationship ◽  
Phase Preference

Abstract This study investigates the relationship between El Niño–Southern Oscillation (ENSO) and southern annular mode (SAM) events with an idealized general circulation model. A series of model calculations are performed to examine why positive (negative) intraseasonal SAM events are observed to occur much more frequently during La Niña (El Niño). Seven different model runs are performed: a control run, three El Niño runs (the first with a zonally symmetric heating field, the second with a zonally asymmetric heating/cooling field, and the third that combines both fields), and three La Niña runs (with heating fields of opposite sign). The model runs with the zonally symmetric and combined heating fields are found to yield the same relationship between the phase of ENSO and the preferred phase for SAM events as is observed in the atmosphere. In contrast, the zonally asymmetric model runs are found to have the opposite SAM–ENSO phase preference characteristics. Since a reduced midlatitude meridional potential vorticity gradient has been linked to a greater frequency of positive-phase SAM events, and vice versa for negative SAM events, the meridional potential vorticity gradient in the various model runs was compared. The results suggest that the phase preference of SAM events during ENSO arises from the impact of the zonal-mean heating on the midlatitude meridional potential vorticity gradient.

ANALISIS DAERAH RAWAN KEKERINGAN LAHAN JAGUNG BERDASARKAN IKLIM OLDEMAN DAN KETERSEDIAN AIR TANAH DI NUSA TENGGARA TIMUR SAAT PERIODE EL NINO DAN LA NINA

2019 ◽  
Vol 3 ◽  
pp. 1219
Author(s):  
Oki Adrianto ◽  
Sudirman Sudirman ◽  
Suwandi Suwandi
Keyword(s):  
El Niño ◽  
El Nino ◽  
La Niña ◽  
La Nina

Perekonomian Provinsi Nusa Tenggara Timur secara sektoral masih didominasi sektor pertanian.Tanaman jagung menjadi salah satu produksi tanaman pangan terbesar berdasarkan data dari Dinas Pertanian dan Perkebunan Provinsi Nusa Tenggara Timur tahun 2015. Peningkatan produksi pertanian dapat dilakukan melalui berbagai strategi adaptasi dan upaya penanganan bencana, salah satu upaya tersebut adalah dengan penyediaan informasi iklim terkait penentuan daerah-daerah rawan kekeringan. Tujuan dari penelitian ini adalah untuk mengetahui sebaran wilayah rawan kekeringan lahan jagung bulanan di Provinsi Nusa Tenggara Timur saat kondisi El Nino dan La Nina dengan periodeisasi bulanan januari hingga desember. Data yang digunakan dalam penelitian ini adalah data curah hujan rata rata bulanan di 19 pos hujan di Provinsi Nusa Tenggara Timur dan suhu udara rata-rata bulanan dihitung menggunakan pendekatan teori Brack dengan titik referensi Stasiun Klimatologi Lasiana Kupang. Periode dari masing-masing data yang digunakan adalah dari tahun 1991 dan 1997 digunakan sebagai tahun El Nino dan tahun 1999 dan 2010 digunakan sebagai tahun La Nina. Metode yang digunakan untuk menentukan tingkat rawan kekeringan dengan menggunakan pembobotan berdasarkan penjumlahan bobot tipe iklim Oldeman dan bobot ketersediaan air tanah. Hasil penelitian menunjukkan sebaran daerah kekeringan di Provinsi Nusa Tenggara Timurpada tahun el nino lebih luas dibandingkan tahun la nina.

A Influência dos fenômenos El Niño e La Niña sobre a dinâmica climática da região Amazônica

2018 ◽  
Vol 1 ◽  
pp. e2018014
Author(s):  
Samya de Freitas MOREIRA ◽  
Cleiciane Silva da CONCEIÇÃO ◽  
Milla Cristina Santos da CRUZ ◽  
Antônio PEREIRA JÚNIOR
Keyword(s):  
El Niño ◽  
El Nino ◽  
La Niña ◽  
La Nina

Caracterização climática da temperatura do ar em Veranópolis, Rio Grande do Sul

Agrometeoros ◽  
2020 ◽  
Vol 26 (2) ◽  
Author(s):  
Amanda Heemann Junges
Keyword(s):  
El Niño ◽  
El Nino ◽  
Rio Grande ◽  
La Niña ◽  
Rio Grande Do Sul ◽  
La Nina

Estudos locais de caraterização e variabilidade climática são fundamentais para geração de informações mais adaptadas às atividades agrícolas desenvolvidas em um município ou região. O objetivo desse trabalho foi caracterizar climaticamente e analisar a influência de eventos El Niño Oscilação Sul (ENOS) na série 1956-2015 de temperatura do ar de Veranópolis, RS. Para caracterização climática foram estabelecidas estatísticas descritivas das temperaturas do ar máximas, mínimas e médias mensais, estacional e anual na série e normal climatológica padrão 1961- 1990. Para identificação de diferenças entre estações e influência de eventos ENOS, os dados foram submetidos à análise de variância e teste de Duncan. Os resultados indicaram que a temperatura média anual é de 17,3ºC, variando entre 12,7ºC (julho) e 21,8ºC (janeiro). O clima é do tipo Cfb, de acordo com a classificação climática de Köppen e TE (temperado) na classificação climática do Estado. Temperaturas mínimas médias mensais inferiores a 10ºC ocorrem de maio a setembro, período de maior variabilidade interanual das temperaturas máximas (desvio padrão entre 1,5º e 1,8ºC), mínimas (1,6-1,8ºC) e médias mensais (1,4-1,7ºC). Anos de La Niña possuem temperaturas médias estacionais inferiores as de El Niño, embora diferenciação em relação a neutros ocorra somente para temperaturas mínimas na primavera e máximas no outono.

Rendimento de grãos de soja e de milho, no Rio Grande do Sul, não difere entre eventos El Niño Oscilação Sul

Agrometeoros ◽  
2018 ◽  
Vol 26 (1) ◽  
Author(s):  
Ronaldo Matzenauer ◽  
Bernadete Radin ◽  
Alberto Cargnelutti Filho
Keyword(s):  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Rio Grande ◽  
La Niña ◽  
Rio Grande Do Sul ◽  
La Nina ◽  
Significant Difference ◽  
Income Data ◽  
The Relationship

O objetivo deste trabalho foi avaliar a relação entre o fenômeno El Niño Oscilação Sul - ENOS e o rendimento de grãos de soja e de milho no Rio Grande do Sul e verificar a hipótese de que os eventos El Niño são favoráveis e os eventos La Niña são prejudiciais ao rendimento de grãos das culturas. Foram utilizados dados de rendimento de grãos dos anos agrícolas de 1974/75 a 2016/17, e relacionados com as ocorrências de eventos ENOS. Foram analisados os dados de rendimento observados na colheita e os dados estimados com a remoção da tendência tecnológica. Os resultados mostraram que não houve diferença significativa do rendimento médio de grãos de soja e de milho na comparação entre os eventos ENOS. Palavras-chave: El Niño, La Niña, safras agrícolas. Abstract – The objective of this work was to evaluate the relationship between the El Niño Southern Oscillation (ENSO) phenomenon with the grain yield of soybean and maize in Rio Grande do Sul state, Brazil and to verify the hypothesis that the El Niño events are favorable and the La Niña events are harmful to the culture’s grain yields. Were used data from the agricultural years of 1974/75 to 2016/17, and related to the occurrence of ENOS events. We analyzed income data observed at harvest and estimated data with technological tendency was removed. The results showed that there was no significant difference in the average yield of soybeans and corn in the comparison between events.

Atmospheric teleconnection patterns associated with severe and mild ice cover on the Great Lakes, 1963–2011

2012 ◽  
Vol 47 (3-4) ◽  
pp. 421-435 ◽  
Author(s):  
Xuezhi Bai ◽  
Jia Wang
Keyword(s):  
North America ◽  
Great Lakes ◽  
El Niño ◽  
El Nino ◽  
Ice Cover ◽  
Reanalysis Data ◽  
Teleconnection Pattern ◽  
La Niña ◽  
Atmospheric Teleconnection ◽  
La Nina

Atmospheric teleconnection circulation patterns associated with severe and mild ice cover over the Great Lakes are investigated using the composite analysis of lake ice data and National Center of Environmental Prediction (NCEP) reanalysis data for the period 1963–2011. The teleconnection pattern associated with the severe ice cover is the combination of a negative North Atlantic Oscillation (NAO) or Arctic Oscillation (AO) and negative phase of Pacific/North America (PNA) pattern, while the pattern associated with the mild ice cover is the combination of a positive PNA (or an El Niño) and a positive phase of the NAO/AO. These two extreme ice conditions are associated with the North American ridge–trough variations. The intensified ridge–trough system produces a strong northwest-to-southeast tilted ridge and trough and increases the anomalous northwesterly wind, advecting cold, dry Arctic air to the Great Lakes. The weakened ridge–trough system produces a flattened ridge and trough, and promotes a climatological westerly wind, advecting warm, dry air from western North America to the Great Lakes. Although ice cover for all the individual lakes responds roughly linearly and symmetrically to both phases of the NAO/AO, and roughly nonlinearly and asymmetrically to El Niño and La Niña events, the overall ice cover response to individual NAO/AO or Niño3.4 index is not statistically significant. The combined NAO/AO and Niño3.4 indices can be used to reliably project severe ice cover during the simultaneous –NAO/AO and La Niña events, and mild ice cover during the simultaneous +NAO/AO and El Niño events.

scholarly journals El Niño, La Niña, and the Forecastability of the Realized Variance of Heating Oil Price Movements

2021 ◽  
Vol 13 (14) ◽  
pp. 7987
Author(s):  
Mehmet Balcilar ◽  
Elie Bouri ◽  
Rangan Gupta ◽  
Christian Pierdzioch
Keyword(s):  
El Niño ◽  
Predictive Value ◽  
El Nino ◽  
Southern Oscillation ◽  
La Niña ◽  
Realized Variance ◽  
La Nina ◽  
Out Of Sample ◽  
Heating Oil ◽  
Price Movements

We use the heterogenous autoregressive (HAR) model to compute out-of-sample forecasts of the monthly realized variance (RV) of movements of the spot and futures price of heating oil. We extend the HAR–RV model to include the role of El Niño and La Niña episodes, as captured by the Equatorial Southern Oscillation Index (EQSOI). Using data from June 1986 to April 2021, we show evidence for several model configurations that both El Niño and La Niña phases contain information useful for forecasting subsequent to the realized variance of price movements beyond the predictive value already captured by the HAR–RV model. The predictive value of La Niña phases, however, seems to be somewhat stronger than the predictive value of El Niño phases. Our results have important implications for investors, as well as from the perspective of sustainable decisions involving the environment.

scholarly journals Wind-Driven Response of the Northern Indian Ocean to Climate Extremes*

2007 ◽  
Vol 20 (13) ◽  
pp. 2978-2993 ◽  
Author(s):  
Tommy G. Jensen
Keyword(s):  
Indian Ocean ◽  
Ocean Circulation ◽  
Bay Of Bengal ◽  
El Niño ◽  
Arabian Sea ◽  
El Nino ◽  
Ocean Model ◽  
La Niña ◽  
Northern Indian Ocean ◽  
La Nina

Abstract Composites of Florida State University winds (1970–99) for four different climate scenarios are used to force an Indian Ocean model. In addition to the mean climatology, the cases include La Niña, El Niño, and the Indian Ocean dipole (IOD). The differences in upper-ocean water mass exchanges between the Arabian Sea and the Bay of Bengal are investigated and show that, during El Niño and IOD years, the average clockwise Indian Ocean circulation is intensified, while it is weakened during La Niña years. As a consequence, high-salinity water export from the Arabian Sea into the Bay of Bengal is enhanced during El Niño and IOD years, while transport of low-salinity waters from the Bay of Bengal into the Arabian Sea is enhanced during La Niña years. This provides a venue for interannual salinity variations in the northern Indian Ocean.

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