The Hadley and Walker Regional Circulations and Associated ENSO Impacts on South American Seasonal Rainfall

Ambrizzi, Tércio; Souza, Everaldo Barreiros de; Pulwarty, Roger S.

doi:10.1007/978-1-4020-2944-8_8

Cited by 74 publications

(72 citation statements)

References 45 publications

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“…were consistent with anomalously cold surface waters over the equatorial Pacific (La Nina), with ascending motion in eastern Amazonia, a typical response to the cold water in the equatorial Pacific (Ambrizzi et al 2004). Upper-level divergence was detected over Amazonia, upper-level convergence over NEB during austral summer, with subsidence over NEB during the peak rainy season, FMAM, in that region during 2012.A longitude-height cross section of the anomalous vertical and divergent circulation for the latitude band from 5°N to 5°S (Figure 3 d-f, j-l) shows anomalous sinking motion in the mid-troposphere (400 hPa to 850 hPa) over Northeast Brazil (30°W-40°W) and anomalous rising motion over the Amazon Basin (in 2012) or in the extreme eastern Pacific (in 2014 and, consistent with the patterns of SST anomalies.…”

Section: Resultssupporting

confidence: 55%

Climatic characteristics of the 2010-2016 drought in the semiarid Northeast Brazil region

Marengo

Alves

Alvalá

et al. 2018

An. Acad. Bras. Ciênc.

327

206

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This study discusses the climatological aspects of the most severe drought ever recorded in the semiarid region Northeast Brazil. Droughts are recurrent in the region and while El Nino has driven some of these events others are more dependent on the tropical North Atlantic sea surface temperature fields. The drought affecting this region during the last 5 years shows an intensity and impact not seen in several decades in the regional economy and society. The analysis of this event using drought indicators as well as meteorological fields shows that since the middle 1990s to 2016, 16 out of 25 years experienced rainfall below normal. This suggests that the recent drought may have in fact started in the middle-late 1990s, with the intense droughts of 1993 and 1998, and then the sequence of dry years (interrupted by relatively wet years in 2007, 2008, 2009 and 2011) after that may have affected the levels of reservoirs in the region, leading to a real water crisis that was magnified by the negative rainfall anomalies since 2010.

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Section: Resultssupporting

confidence: 55%

Climatic characteristics of the 2010-2016 drought in the semiarid Northeast Brazil region

Marengo

Alves

Alvalá

et al. 2018

An. Acad. Bras. Ciênc.

327

206

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“…Firstly, the Northeast Brazil is considered to be one of the regions on the globe that has a strong link with warm events in the equatorial Pacific (e.g. Ambrizzi et al 2004). However, there are no previous studies that associate a dynamical link between the Indian Ocean and the Northeast Brazil.…”

Section: Impacts On Observed Rainfallmentioning

confidence: 99%

Can Indian Ocean SST anomalies influence South American rainfall?

Taschetto

Ambrizzi

2011

Clim Dyn

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In this study we examine the impact of Indian Ocean sea surface temperature (SST) variability on South American circulation using observations and a suite of numerical experiments forced by a combination of Indian and Pacific SST anomalies. Previous studies have shown that the Indian Ocean Dipole (IOD) mode can affect climate over remote regions across the globe, including over South America. Here we show that such a link exists not only with the IOD, but also with the Indian Ocean basinwide warming (IOBW). The IOBW, a response to El Niño events, tends to reinforce the South American anomalous circulation in March-to-May associated with the warm events in the Pacific. This leads to increased rainfall in the La Plata basin and decreased rainfall over the northern regions of the continent. In addition, the IOBW is suggested to be an important factor for modulating the persistence of dry conditions over northeastern South America during austral autumn. The link between the IOBW and South American climate occurs via alterations of the Walker circulation pattern and through a mid-latitude wave-train teleconnection.

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“…Evaporation is reduced and, as a result, precipitation increases on land during August-September (Marshall et al, 2001;Robertson and Mechoso, 2002;Wang, 2001). and weaker, respectively, leading to weakened northeast trade winds in the TNA and decreased surface evaporation (Ambrizzi et al, 2005;Marshall et al, 2001). The maximum SSTs in the TNA are reached during December-February and March-May (Marshall et al, 2001;Rajagopolan et al, 1997;Ropelewski and Hapert, 1987, 1989, 1996Wang, 2001).…”

Section: Introductionmentioning

confidence: 99%

“…The above phenomena are caused by the variability in sea-surface temperatures (SSTs). The anomalies in sea-level pressure and winds are leading factors in determining the anomalies in SSTs (Ambrizzi et al, 2005). The different mechanisms are schematically shown in Figure 1.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Rainfall variability in suriname and its relationship with the tropical Pacific ENSO SST anomalies and the Atlantic SST anomalies

Nurmohamed

Naipal

Becker

2006

Intl Journal of Climatology

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Abstract:Spatial correlations in the annual rainfall anomalies are analyzed using principal component analysis (PCA). Cross correlation analysis and composites are used to measure the influence of sea-surface temperature anomalies (SSTAs) in the tropical Atlantic (TA) and the tropical Pacific Ocean on the seasonal rainfall in Suriname. It is shown that the spatial and time variability in rainfall is mainly determined by the meridional movement of the inter-tropical convergence zone (ITCZ). The rainfall anomalies are fairly uniform over the whole country. The strongest correlation in the December-January rainfall (short wet season) at station Cultuurtuin is found to occur with the SSTAs in the Pacific region and is about c k Nino 1+2 = 0.59 at lag 1 month. In the March-May rainfall (beginning of the long wet season), there is a lagged correlation with the SSTAs in the Pacific region (c lag 3 Nino 1+2 = 0.59). The June-August rainfall (end of the long wet season) shows the highest correlation with SSTAs in the TSA region and is about c = −0.52 for lag 0. In the September-November long dry season there is also a lagged correlation with the TSA SSTAs of about c lag 3 = 0.66. These different correlations and predictors can be used for seasonal rainfall predictions.

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The Hadley and Walker Regional Circulations and Associated ENSO Impacts on South American Seasonal Rainfall

Cited by 74 publications

References 45 publications

Climatic characteristics of the 2010-2016 drought in the semiarid Northeast Brazil region

Climatic characteristics of the 2010-2016 drought in the semiarid Northeast Brazil region

Can Indian Ocean SST anomalies influence South American rainfall?

Rainfall variability in suriname and its relationship with the tropical Pacific ENSO SST anomalies and the Atlantic SST anomalies

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