Interannual relations between South American rainfall and tropical sea surface temperature anomalies before and after 1976

Kayano, Mary Toshie; Oliveira, Cristiano Prestrelo de; Andreoli, Rita V.

doi:10.1002/joc.1824

Cited by 57 publications

(49 citation statements)

References 61 publications

(95 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…To further investigate the changes in correlation between ENSO indexes and precipitation in SESA during summer reported by Kayano et al (2008), we computed the correlation between the N3.4 index in DJF (defined as the average SST in the area enclosed by 5° S, 5° N, 170° W and 120° W) and the simultaneous precipitation over South America (according to PREC/L data) for 2 periods : 1948−1978 and 1979− 2009. These periods split the data from the late 1940s to the present into halves.…”

Section: Sst Anomalies During La Niña Eventsmentioning

confidence: 99%

La Niña events before and after 1979 and their impact in southeastern South America during austral summer: role of the Indian Ocean

Cazes-Boezio¹,

Talento²

2016

Clim. Res.

View full text Add to dashboard Cite

In this study, we analyzed the influence of interannual variability in sea surface temperature (SST) on the climate of southeastern South America (SESA) during austral summer. We found that the correlation between the El Niño Southern Oscillation (ENSO) and rainfall over southern Brazil-northern Uruguay (SB-NU) was not statistically significant between 1949 and 1978, but it was significant between 1979 and 2009. The results show that this change in correlation was largely due to the modified rainfall response over SB-NU to La Niña events. A cluster analysis for all summers between 1949 and 2009 identified a turning point of La Niña events in 1979. We document the atmospheric circulation patterns associated with the strong correlation between ENSO and the rainfall over SB-NU after 1979 and hypothesize causes of the weaker correlation in the earlier period. In particular, numerical simulations produced using the UCLA atmospheric general circulation model showed important differences between upper tropo spheric circulation patterns during ENSO cold episodes after the late 1970s relative to the earlier period. Such differences were consistent with changes in the impacts of La Niña events on SESA. The differences in Indian Ocean SST anomalies largely explained these results.

show abstract

Section: Sst Anomalies During La Niña Eventsmentioning

confidence: 99%

La Niña events before and after 1979 and their impact in southeastern South America during austral summer: role of the Indian Ocean

Cazes-Boezio¹,

Talento²

2016

Clim. Res.

View full text Add to dashboard Cite

show abstract

“…(Reynolds et al 2002). Kayano et al (2008) show changes in the relationship between ENSO and SESA after the late 70's, but does not discuss specifically about austral summer. An elementary way to assess the relationship between ENSO and the inter annual variability of the precipitation over South America is to compute correlations between the precipitation and the Niño 3.4 index (N3.4, which is defined as the SST averaged between 5ºS and 5ºN, and between 170ºW and 120ºW).…”

Section: Description Of the Cfs V2 And The Data Sets Usedmentioning

confidence: 99%

“…We propose a statistical downscaling technique that allows obtaining a forecast of probabilities for the precipitation in the region and the season of interest, and we analyze in which cases the forecast of probabilities proposed can be distinguished from a climatological forecast with some level of statistical significance. In a forthcoming work we will analyze physical processes that may have contributed to changes in the correlation between the precipitation in SESA and ENSO, as the ones observed by Kayano et al (2008).…”

Section: Introductionmentioning

confidence: 99%

“…During recent years there have been several studies that documented physical mechanisms relevant to the interannual climatic variability of Southeastern South America (SESA) during austral summer: regional anomalies of atmospheric circulation (Robertson and Mechoso 2000), impact of ENSO on the regional climate (Ropelewski and Halpert 1987, 1989, Aceituno 1988, Pisciottano et al 1994, Grimm et al 1998, Grimm 2003, 2004, Cazes Boezio et al 2003, Silva et al 2009, Kayano et al 2008, influence of sea surface temperature (SST) anomalies in the Atlantic Ocean , Barreiro et al 2002, 2005, Barreiro and Tippmann 2008, effects of soil conditions in regions close to SESA (Grimm at al. 2007, Grimm andZilli 2009), and effects of low level circulation (Nogués and Mo 1997, Salio et al 2002, Liebmann et al 2004, Silva et al 2009).…”

Section: Introductionmentioning

confidence: 99%

“…(Grimm et al 1998, Grimm et al 2000, Pisciottano et al 1994, Cazes Boezio et al 2003, Robertson and Mechoso 2000. On the other hand, Kayano et al (2008) analyze inter-annual relationships between precipitation over South America and SST indices defined in certain oceanic regions, for two periods: 1948-1976 and 1977-2002. They find that the most pronounced differences between these periods occur in an area centered around 10ºS-50ºW and in Southern Brazil and Uruguay.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Seasonal probability forecasts of december-january-february precipitation in northern Uruguay and Rio Grande do Sul obtained with the coupled forecast system v2 of NOAA and statistical downscaling

Boezio

Talento

Jalabert

2012

Rev. bras. meteorol.

View full text Add to dashboard Cite

The present work analyses the inter-seasonal predictability of precipitation during the austral summer in a subregion of Southeastern South America that includes Rio Grande do Sul and Northern Uruguay (RGS-NU), and proposes a methodology to produce probabilistic precipitation forecasts for this region, based on the use of NOAA CFS v2. It is found that the correlation between ENSO and the precipitation over RGS-NU during December-January-February is statistically significant after the late 70's, but not before. Considering that this relationship changes in different multidecadal periods, it is useful to explore a forecast system based on numerical models. We studied the hindcasts from NOAA CFS v2 initialized during October of the years 1983 to 2009, and found that the hindcasts of meridional wind at 850 hPa averaged over certain region of South America have statistically significant skill, in terms of correlation, to predict the observed precipitation over RGS-NU. The proposed forecasts are based on this relationship. The CFS v2 hindcasts also show realistic anomalous circulation patterns associated with the anomalous precipitation in the region and the season considered. This suggests that the forecasts may be further improved by using regional models combined with the CFS v2 outputs. Keywords: Seasonal forecast, Statistical downscaling, Southeastern South America, Hindcasts RESUMO: PREVISÃO PROBABILISTICA SAZONAL DA PRECIPITAÇÃO DE DEZEMBRO-JANEIRO-FEVEREIRO NO NORTE DO URUGUAI E RIO GRANDE DO SUL OBTIDA COM O MODELO ACOPLADO DE PREVISÃO DA NOAA E DOWNSCALING ESTATÍSTICA: O presente trabalho analisa a previsibilidade inter-sazonal da precipitação durante o verão austral em uma sub-região do Sudeste da América do Sul, que inclui Rio Grande do Sul e o Norte do Uruguai (RGS-NU), e propõe uma metodologia para produzir previsões probabilísticas da precipitação baseada no uso do CFS v2 da NOAA. Verifica-se que a correlação entre o ENOS e a precipitação sobre RGS-NU em dezembro-janeiro-fevereiro é estatisticamente significativa nos últimos 30 anos, mas não nos 30 anos anteriores a estes. Em vista desta mudança na relação em diferentes períodos multi-decenais, consideramos útil explorar um sistema de prognósticos baseados em modelo numérico, o CFS v2 da NOAA. Estudamos as previsões retrospectivas do CFS v2 iniciadas em outubro dos anos 1983 a 2009, e achamos que o valor médio das previsões retrospectivas de vento meridional em 850 hPa sobre determinada região da América do Sul, têm habilidade estatisticamente significativa, em termos de coeficiente de correlação, de prever a precipitação observada em RGS-NU. Esta relação é a base da metodologia para produzir previsões da precipitação. As previsões retrospectivas do CFS v2 também mostram padrões de circulação anômala realistas, associados com as precipitações na região e na época considerada. Isto é encorajador, no sentido de que há potencial para melhorar ainda mais as previsões através do uso de modelos regionais combinados com as saídas do CFS v2.

show abstract

Validation of 40 year multimodel seasonal precipitation forecasts: The role of ENSO on the global skill

Manzanas

Frías

Cofiño

et al. 2014

J. Geophys. Res. Atmos.

View full text Add to dashboard Cite

The skill of seasonal precipitation forecasts is assessed worldwide-grid point by grid point-for the 40 year period 1961-2000, considering the ENSEMBLES multimodel hindcast and applying a tercile-based probabilistic approach in terms of the relative operating characteristic skill score (ROCSS). Although predictability varies with region, season, and lead time, results indicate that (1) significant skill is mainly located in the tropics-20 to 40% of the total land areas; (2) overall, September-October (March-May) is the most (least) skillful season; and (3) the skill weakens (with respect to the 1 month lead case) at 4 months lead-especially in June-August-although the ROCSS spatial patterns are broadly preserved-particularly in Northern South America and the Malay Archipelago. The contribution of El Niño-Southern Oscillation (ENSO) events to this 40 year skill is also analyzed, based on the idea that the seasonal predictability may be mainly driven by El Niño and La Niña precipitation teleconnections and, consequently, limited by the ability of the different seasonal forecasting models to accurately reproduce them. Results show that the ROCSS spatial patterns for (1) the full period 1961-2000 and (2) El Niño and La Niña events are highly correlated-over 0.85. Moreover, the observed teleconnection patterns are properly simulated (predicted)-with spatial correlations around 0.8-by most of the models at both 1 and 4 months lead time.

show abstract

Interannual relations between South American rainfall and tropical sea surface temperature anomalies before and after 1976

Cited by 57 publications

References 61 publications

La Niña events before and after 1979 and their impact in southeastern South America during austral summer: role of the Indian Ocean

La Niña events before and after 1979 and their impact in southeastern South America during austral summer: role of the Indian Ocean

Seasonal probability forecasts of december-january-february precipitation in northern Uruguay and Rio Grande do Sul obtained with the coupled forecast system v2 of NOAA and statistical downscaling

Validation of 40 year multimodel seasonal precipitation forecasts: The role of ENSO on the global skill

Contact Info

Product

Resources

About