Moisture transport and intraseasonal variability in the South America monsoon system

Carvalho, Leila M. V.; Silva, Ana E.; Jones, Charles; Liebmann, Brant; Dias, Pedro Leite da Silva; Rocha, Humberto Ribeiro da

doi:10.1007/s00382-010-0806-2

Cited by 93 publications

(83 citation statements)

References 58 publications

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“…Marengo et al, 2001;Liebmann and Marengo, 2001;Carvalho et al, 2011). In the southern part of the basin, the rainy season occurs between austral spring and autumn, while over the western and the northern Amazon it extends from austral autumn to spring.…”

Section: Introductionmentioning

confidence: 99%

The role of the Amazon Basin moisture in the atmospheric branch of the hydrological cycle: a Lagrangian analysis

Drumond

Marengo

Ambrizzi

et al. 2014

Hydrol. Earth Syst. Sci.

130

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Abstract. We used a Lagrangian model (FLEXPART) together with the 1979-2012 ERA-Interim reanalysis data to investigate the role of the moisture in the Amazon Basin in the regional hydrological budget over the course of the year. FLEXPART computes budgets of evaporation minus precipitation by calculating changes in the specific humidity along forward and backward trajectories. The tropical Atlantic is the most important remote moisture source for the Amazon Basin. The tropical North Atlantic (NA) mainly contributed during the austral summer, while the contribution of the tropical South Atlantic (SA) prevailed for the remainder of the year. At the same time, the moisture contribution from the Amazon Basin itself is mainly for moisture supplying the southeastern South America. The 33-year temporal domain allowed the investigation of some aspects of the interannual variability of the moisture transport over the basin, such as the role of the El Niño Southern Oscillation (ENSO) and the Atlantic Meridional Mode (AMM) on the hydrological budget. During the peak of the Amazonian rainy season (from February to May, FMAM) the AMM is associated more with the interannual variations in the contribution from the tropical Atlantic sources, while the transport from the basin towards the subtropics responds more to the ENSO variability. The moisture contribution prevailed from the SA (NA) region in the years dominated by El Niño/positive AMM (La Niña/negative AMM) conditions. The transport from the Amazon towards the subtropics increased (reduced) during El Niño (La Niña) years.

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Section: Introductionmentioning

confidence: 99%

The role of the Amazon Basin moisture in the atmospheric branch of the hydrological cycle: a Lagrangian analysis

Drumond

Marengo

Ambrizzi

et al. 2014

Hydrol. Earth Syst. Sci.

130

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“…It shows seesaw or dipole variations with a similar precipitation zone over southern Brazil, Uruguay, and Argentina on intraseasonal and interannual time scales (Nogues-Paegle and Mo 1997;Liebmann et al 1999;Nogues-Paegle and Mo 2002;Carvalho et al 2004;Grimm and Zilli 2009). Moisture sources also differ between the portions (Muza et al 2009;Carvalho et al 2010), being northerly from the equatorial Atlantic and northeasterly from the Amazon for the continental portion, and northerly from eastern South America and from over the Atlantic for the oceanic portion. Moisture sources also differ between the portions (Muza et al 2009;Carvalho et al 2010), being northerly from the equatorial Atlantic and northeasterly from the Amazon for the continental portion, and northerly from eastern South America and from over the Atlantic for the oceanic portion.…”

Section: Introductionmentioning

confidence: 95%

“…The SACZ develops in austral summer and is an important component of the South American summer monsoon (SASM) (Zhou and Lau 1998;Kodama 1992Kodama , 1993Figueroa et al 1995;Carvalho et al 2004;Vera et al 2006). The SACZ develops in austral summer and is an important component of the South American summer monsoon (SASM) (Zhou and Lau 1998;Kodama 1992Kodama , 1993Figueroa et al 1995;Carvalho et al 2004;Vera et al 2006).…”

Section: Introductionmentioning

confidence: 99%

“…This is in contrast to the BFZ, which migrates northward from 258 to 408N with a seasonal march between June and August (Ding 1992), and to the SPCZ, which shifts in an east-west direction in accordance with the El Niñ o-Southern Oscillation (ENSO) (Murakami et al 1986;Streten 1975;Kodama 1993). It shows seesaw or dipole variations with a similar precipitation zone over southern Brazil, Uruguay, and Argentina on intraseasonal and interannual time scales (Nogues-Paegle and Mo 1997;Liebmann et al 1999;Nogues-Paegle and Mo 2002;Carvalho et al 2004;Grimm and Zilli 2009). It shows seesaw or dipole variations with a similar precipitation zone over southern Brazil, Uruguay, and Argentina on intraseasonal and interannual time scales (Nogues-Paegle and Mo 1997;Liebmann et al 1999;Nogues-Paegle and Mo 2002;Carvalho et al 2004;Grimm and Zilli 2009).…”

Section: Introductionmentioning

confidence: 99%

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Roles of the Brazilian Plateau in the Formation of the SACZ

et al. 2012

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The role of the Brazilian Plateau (BP) in maintaining the South Atlantic convergence zone (SACZ) has been examined by statistical analysis and numerical experiments. Statistical analysis using 27 years of data showed that the SACZ is most intense when it is over the BP. In this case, low-level cyclonic circulation appears over the southwestern part of the BP and forms westerly flow, which intensifies low-level convergence along the SACZ with northeasterly flow from the Amazon and northerly flow along the western edge of the South Atlantic subtropical high. A vorticity budget analysis indicates that precipitation over the BP that accompanies stretching maintains the cyclonic circulation.Sensitivity experiments using a regional atmospheric model for two different cases indicate that precipitation over the BP plays a dominant role as an atmospheric heat source in maintaining the cyclonic circulation and the SACZ. In model experiments in which rain was stopped around the BP but the topography was kept, the cyclonic circulation disappeared, and the SACZ shifted southward away from its original position. In comparison with a control run, precipitation over the BP was weakened and the SACZ shifted southward in experiments in which the BP was removed or its complex, multiple-valley terrain was smoothed out. The results of this study support the ideas suggested in previous studies (i.e., that the BP has an anchor effect on the SACZ): Precipitation is intensified over the complex terrain of the BP, and mechanisms of conditional instability of the second kind occur between the precipitation over the BP and the cyclonic circulation to its southwest, which intensifies moisture convergence over the plateau. * Current affiliation: Seiai Junior and Senior High School, Hirosaki, Aomori, Japan.

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“…Intra-seasonal and decadal variability in rainfall and streamflow have also been the subject of many studies (Robertson and Mechoso, 2000;Robertson et al, 2001;Zhou and Lau, 2001;Paegle and Mo, 2002;Carvalho et al, 2004). Most of the moisture that reaches UPRB is from the Amazon region (Drumond et al, 2008;Carvalho et al, 2011), and the rainfall mechanisms are also associated with MCSs along the South American low-level jet (SALLJ; see Velasco and Fritsch, 1987;Marengo et al, 2004;Salio et al, 2007) and transient systems related to extratropical cyclones and cold fronts (Mendes et al, 2007;Silva and Ambrizzi, 2010). El Niño events have also been linked to extreme rainfalls and floods in the UPRB (Camilloni and Barros, 2003;Grimm and Tedeschi, 2009;Muza et al, 2009;Cavalcanti et al, 2015;Antico et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

Classification of mechanisms, climatic context, areal scaling, and synchronization of floods: the hydroclimatology of floods in the Upper Paraná River basin, Brazil

2017

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Abstract. Floods are the main natural disaster in Brazil, causing substantial economic damage and loss of life. Studies suggest that some extreme floods result from a causal climate chain. Exceptional rain and floods are determined by large-scale anomalies and persistent patterns in the atmospheric and oceanic circulations, which influence the magnitude, extent, and duration of these extremes. Moreover, floods can result from different generating mechanisms. These factors contradict the assumptions of homogeneity, and often stationarity, in flood frequency analysis. Here we outline a methodological framework based on clustering using self-organizing maps (SOMs) that allows the linkage of large-scale processes to local-scale observations. The methodology is applied to flood data from several sites in the flood-prone Upper Paraná River basin (UPRB) in southern Brazil. The SOM clustering approach is employed to classify the 6-day rainfall field over the UPRB into four categories, which are then used to classify floods into four types based on the spatiotemporal dynamics of the rainfall field prior to the observed flood events. An analysis of the vertically integrated moisture fluxes, vorticity, and high-level atmospheric circulation revealed that these four clusters are related to known tropical and extratropical processes, including the South American low-level jet (SALLJ); extratropical cyclones; and the South Atlantic Convergence Zone (SACZ). Persistent anomalies in the sea surface temperature fields in the Pacific and Atlantic oceans are also found to be associated with these processes. Floods associated with each cluster present different patterns in terms of frequency, magnitude, spatial variability, scaling, and synchronization of events across the sites and subbasins. These insights suggest new directions for flood risk assessment, forecasting, and management.

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Moisture transport and intraseasonal variability in the South America monsoon system

Cited by 93 publications

References 58 publications

The role of the Amazon Basin moisture in the atmospheric branch of the hydrological cycle: a Lagrangian analysis

The role of the Amazon Basin moisture in the atmospheric branch of the hydrological cycle: a Lagrangian analysis

Roles of the Brazilian Plateau in the Formation of the SACZ

Classification of mechanisms, climatic context, areal scaling, and synchronization of floods: the hydroclimatology of floods in the Upper Paraná River basin, Brazil

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