scholarly journals Precipitation Anomalies in Southern Brazil Associated with El Niño and La Niña Events

1998 ◽  
Vol 11 (11) ◽  
pp. 2863-2880 ◽  
Author(s):  
Alice M. Grimm ◽  
Simone E. T. Ferraz ◽  
Júlio Gomes
Keyword(s):  
El Niño ◽  
El Nino ◽  
La Niña ◽  
Southern Brazil ◽  
La Nina ◽  
Precipitation Anomalies

scholarly journals Diversity of East China Summer Rainfall Change in Post-El Niño Summers

2020 ◽  
Vol 8 ◽  
Author(s):  
Wen Zhang ◽  
Xiaoye Zhou ◽  
Pang-Chi Hsu ◽  
Fei Liu
Keyword(s):  
El Niño ◽  
North China ◽  
El Nino ◽  
Summer Rainfall ◽  
La Niña ◽  
East China ◽  
La Nina ◽  
Huaihe River Valley ◽  
Precipitation Anomalies ◽  
Cluster 2

East China has experienced positive precipitation anomalies in post-El Niño summers, mainly in the Yangtze-Huaihe River Valley. This kind of monsoonal rainfall change induced by El Niño, however, is not always the same due to El Niño diversity and mean state change. Here, we use cluster analysis on the post-El Niño (PE) East China summer precipitation anomalies to identify the diversity of this El Niño-induced monsoon change. The result shows that PE East China summer rainfall anomalies mainly display three different modes for all selected 20 El Niño events from 1957 to 2016. Cluster 1 shows the middle and lower reaches of the Yangtze River demonstrate strong wet anomalies, while South and North China are dominated by dry anomalies, similar to a sandwich mode. Cluster 2 is distinguished by dry anomalies over South China and wet anomalies over North China, exhibiting a dipole mode. Compared with Cluster 1, the change caused by Cluster 3 is different, showing negative anomalies over the Yangtze-Huaihe River Valley. The three clusters are correlated with successive events of El Niño, a quick transfer to a strong La Niña and a quick transfer to a weak La Niña respectively. The associated anomalous anticyclone (AAC) focuses on (120°E, 20°N) in Cluster 1, which expands southward for Cluster 2 and moves eastward for Cluster 3. The feedback of AAC-sea surface temperature (SST) mainly works for supporting the AAC in Cluster 1, but it is weak for Cluster 2; the strong easterly anomalies related to La Niña contribute to the AAC location change for Cluster 2. Both AAC-SST feedback and easterly anomalies support the AAC of Cluster 3. The CMIP5 output can capture these diverse responses in circulation except that their simulated AAC for Cluster 1 is significant to the east of the observed.

scholarly journals On the influences of the El Niño, La niña and Atlantic Dipole Paterni on the Amazonian Rainfall during 1960-1998

2000 ◽  
Vol 30 (2) ◽  
pp. 305-318 ◽  
Author(s):  
Everaldo B de SOUZA ◽  
Mary T KAYANO ◽  
Julio TOTA ◽  
Luciano PEZZI ◽  
Gilberto FISCH ◽  
...  
Keyword(s):  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Austral Summer ◽  
La Niña ◽  
Tropical Atlantic ◽  
La Nina ◽  
Precipitation Anomalies ◽  
Dipole Pattern ◽  
Sst Anomalies

The influence of the large-scale climatic variability dominant modes in the Pacific and in the Atlantic on Amazonian rainfall is investigated. The composite technique of the Amazon precipitation anomalies is used in this work. The basis years for these composites arc those in the period 1960-1998 with occurrences of extremes in the Southern Oscillation (El Niño or La Niña) and the north/south warm (or cold) sea surface temperature (SST) anomalies dipole pattern in the tropical Atlantic. Warm (cold) dipole means positive (negative) anomalies in the tropical North Atlantic and negative (positive) anomalies in the tropical South Atlantic. Austral summer and autumn composites for extremes in the Southern Oscillation (El Niño or La Niña) and independently for north/south dipole pattern (warm or cold) of the SST anomalies in the tropical Atlantic present values (magnitude and sign) consistent with those found in previous works on the relationship between Amazon rainfall variations and the SST anomalies in the tropical Pacific and Atlantic. However, austral summer and autumn composites for the years with simultaneous occurrences of El Niño and warm north/south dipole of the SST anomalies in the tropical Atlantic show negative precipitation anomalies extending eastward over the center-eastern Amazon. This result indicates the important role played by the tropical Atlantic in the Amazon anomalous rainfall distribution.

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 

scholarly journals Asymmetric Relationship between Indian Ocean SST and the Western North Pacific Summer Monsoon

2015 ◽  
Vol 28 (4) ◽  
pp. 1383-1395 ◽  
Author(s):  
Riyu Lu ◽  
Shu Lu
Keyword(s):  
Indian Ocean ◽  
El Niño ◽  
North Pacific ◽  
Western North Pacific ◽  
El Nino ◽  
Summer Precipitation ◽  
La Niña ◽  
La Nina ◽  
Precipitation Anomalies ◽  
Sst Anomalies

Abstract The summer precipitation anomalies over the tropical western North Pacific (WNP), which greatly affect East Asian climate, are closely related to Indian Ocean (IO) SST anomalies, and this WNP–IO relationship is widely assumed to be linear. This study indicates that the IO SST–WNP precipitation relationship is generally linear only when the IO SST anomalies are positive and not when the IO SST anomalies are negative, that is, a strongly cooler IO, in comparison with a moderately cooler IO, does not correspond to stronger precipitation enhancement over the WNP. Further analysis suggests that the phases of ENSO play a crucial role in modifying the impacts of IO SSTs on WNP anomalies. The reverse IO SST–WNP precipitation relationship, which exists without apparent ENSO development/decay, is intensified by El Niño decay through the enhancement of IO SST anomalies, but weakened by El Niño development and La Niña decay through the concurrence of SST anomalies in the tropical central and eastern Pacific. After removing El Niño developing and La Niña decaying cases, the IO SST and WNP precipitation anomalies show a clear linear relationship. Because of the effects of the phases of ENSO, the years of negative precipitation or anticyclonic anomalies over the WNP are highly concentrated over strongly warmer IO and El Niño decaying years, which is consistent with previous studies. However, the years of positive precipitation anomalies are scattered over cooler IO and moderately warmer IO years, implying a complexity of tropical SST forcing on positive WNP precipitation anomalies.

Identification of small summers in Southern Brazil and its relation with El Niño and La Niña events

2015 ◽  
Author(s):  
Lucas da Conceição ◽  
Humberto Conrado ◽  
Glauber Mariano ◽  
Ericka Mariano
Keyword(s):  
El Niño ◽  
El Nino ◽  
La Niña ◽  
Southern Brazil ◽  
La Nina

scholarly journals Sensitivity of RegCM3 Simulated Precipitation over Southern Brazil with Different Boundary Conditions: ENSO Case

2013 ◽  
Vol 2013 ◽  
pp. 1-6
Author(s):  
Simone Erotildes Teleginski Ferraz ◽  
Diego Pedroso
Keyword(s):  
Boundary Conditions ◽  
El Niño ◽  
Climate Model ◽  
El Nino ◽  
Regional Climate ◽  
La Niña ◽  
Southern Brazil ◽  
Different Boundary Conditions ◽  
La Nina ◽  
Simulated Precipitation

This paper investigates the capability of a regional climate model (RegCM3) to simulate the Southern Brazil rainfall during three periods: the El Niño (1982), the neutral intermediary phase (1985), and the La Niña (1988). Each integration has used three of different boundary conditions available: NCEP-NCAR Reanalysis (I and II) and ECMWF Reanalysis—ERA-40. The simulations were performed covering a South America domain and some descriptive statistics analyses have been applied, like arithmetic mean, median, standard deviation and Pearson’s correlation; and frequencies histogram over Southern Brazil. The main results show that the model satisfactorily reproduces the rainfall in this region during the El Niño, neutral, and La Niña events, indicating that the boundary conditions which were tested adequately describe this simulations type.

scholarly journals Assessing ENSO Summer Teleconnections, Impacts, and Predictability in North America

2021 ◽  
pp. 1-47
Author(s):  
Bor-Ting Jong ◽  
Mingfang Ting ◽  
Richard Seager
Keyword(s):  
North America ◽  
El Niño ◽  
General Circulation ◽  
Climate Models ◽  
El Nino ◽  
The United States ◽  
La Niña ◽  
Coupled Models ◽  
La Nina ◽  
Precipitation Anomalies

AbstractDuring the summer when an El Niño is transitioning to a La Niña, the extratropical teleconnections exert robust warming anomalies over the United States Midwest threatening agricultural production. This study assesses the performance of current climate models in capturing the prominent observed extratropical responses over North America during the transitioning La Niña summer, based on Atmospheric General Circulation Model experiments and coupled models from the North American Multimodel Ensemble (NMME). The ensemble mean of the SST-forced experiments across the transitioning La Niña summers does not capture the robust warming in the Midwest. The SST-forced experiments do not produce consistent subtropical western Pacific (WP) negative precipitation anomalies and this leads to the poor simulations of extratropical teleconnections over North America. In the NMME models, with active air-sea interaction, the negative WP precipitation anomalies show better agreement across the models and with observations. However, the downstream wave-train pattern and the resulting extratropical responses over North America exhibit large disagreement across the models and are consistently weaker than in observations. Furthermore, in these climate models, an anomalous anticyclone does not robustly translate into warm anomaly over the Midwest, in disagreement with observations. This work suggests that, during the El Niño to La Niña transitioning summer, active air-sea interaction is important in simulating tropical precipitation over the WP. Nevertheless, skillful representations of the Rossby wave propagation and land-atmosphere processes in climate models are also essential for skillful simulations of extratropical responses over North America.

The Modulation of Daily Southern Africa Precipitation by the El Niño Southern Oscillation Across the Summertime Wet Season

2020 ◽  
pp. 1-63
Author(s):  
Andrew Hoell ◽  
Andrea E. Gaughan ◽  
Tamuka Magadzire ◽  
Laura Harrison
Keyword(s):  
Southern Africa ◽  
El Niño ◽  
El Nino ◽  
La Niña ◽  
Wet Season ◽  
Spatiotemporal Evolution ◽  
La Nina ◽  
Precipitation Characteristics ◽  
Precipitation Anomalies ◽  
Mass Divergence

AbstractThe spatiotemporal evolution of daily Southern Africa precipitation characteristics, and associated atmospheric circulation, related to El Niño and La Niña are examined across the region’s November-April wet season. Precipitation characteristics are examined in terms of monthly changes in daily average precipitation, the number of precipitation days, and the number of heavy precipitation days in three independently constructed estimates of observed precipitation during 1983-2018. Mechanisms related to precipitation changes, including contributions from mass divergence, water vapor transports, and transient eddies, are diagnosed using the atmospheric moisture budget based on the ERA5 reanalysis.El Niño is related to precipitation anomalies that build during December-March, the core of the rainy season, culminating in significantly below average values stretching across a semiarid region from central Mozambique to southeastern Angola. A broad anticyclone centered over Botswana drives these precipitation anomalies primarily through anomalous mass divergence, with moisture advection and transient eddies playing secondary roles. La Niña is related to significantly above average daily precipitation characteristics over all Africa south of 20°S in February and much less so during the other five months. February precipitation anomalies are primarily driven through mass divergence due to a strong anomalous cyclonic circulation, whereas a similar circulation is more diffuse during the other months. The spatiotemporal evolution of anomalies in daily precipitation characteristics across Southern Africa related to El Niño and La Niña are not equal and opposite. The robustness of an asymmetric evolution, which could have implications for subseasonal forecasts, needs to be confirmed with analysis of additional empirical data and established with climate model experimentation.

Global Seasonal Precipitation Anomalies Robustly Associated with El Niño and La Niña Events—An OLR Perspective*,+

2015 ◽  
Vol 28 (15) ◽  
pp. 6133-6159 ◽  
Author(s):  
Andrew M. Chiodi ◽  
D. E. Harrison
Keyword(s):  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
La Niña ◽  
Seasonal Precipitation ◽  
Seasonal Forecasts ◽  
Enso Events ◽  
La Nina ◽  
Precipitation Anomalies ◽  
Weather Anomalies

Abstract El Niño–Southern Oscillation (ENSO) events are associated with particular seasonal weather anomalies in many regions around the planet. When the statistical links are sufficiently strong, ENSO state information can provide useful seasonal forecasts with varying lead times. However, using conventional sea surface temperature or sea level pressure indices to characterize ENSO state leads to many instances of limited forecast skill (e.g., years identified as El Niño or La Niña with weather anomalies unlike the average), even in regions where there is considerable ENSO-associated anomaly, on average. Using outgoing longwave radiation (OLR) conditions to characterize ENSO state identifies a subset of the conventional ENSO years, called OLR El Niño and OLR La Niña years herein. Treating the OLR-identified subset of years differently can both usefully strengthen the level of statistical significance in the average (composite) and also greatly reduce the year-to-year deviations in the composite precipitation anomalies. On average, over most of the planet, the non-OLR El Niño and non-OLR La Niña years have much more limited statistical utility for precipitation. The OLR El Niño and OLR La Niña indices typically identify years in time to be of use to boreal wintertime and later seasonal forecasting efforts, meaning that paying attention to tropical Pacific OLR conditions may offer more than just a diagnostic tool. Understanding better how large-scale environmental conditions during ENSO events determine OLR behavior (and deep atmospheric convection) will lead to improved seasonal precipitation forecasts for many areas.

Sign in / Sign up

Export Citation Format

Share Document