Midsummer Low-Level Circulation and Precipitation in Subtropical South America and Related Sea Surface Temperature Anomalies in the South Atlantic

Doyle, Moira Evelina; Barros, Vicente

doi:10.1175/1520-0442(2002)015<3394:mllcap>2.0.co;2

Cited by 159 publications

(160 citation statements)

References 26 publications

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“…More recently the SACZ has received attention, with Liebmann et al (1999) and Carvalho et al (2002Carvalho et al ( , 2004 examining ENSO-induced changes in its position and intensity and the effect of such changes on convective rainfall. These studies, along with Doyle and Barros (2002), highlight the importance of SSTs in the western South Atlantic in influencing the SACZ. The South American summer monsoon has received particular attention, as this season is generally the wettest period over most of the northern and central part of the continent.…”

Section: Introductionmentioning

confidence: 83%

Trends in Total and Extreme South American Rainfall in 1960–2000 and Links with Sea Surface Temperature

et al. 2006

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A weeklong workshop in Brazil in August 2004 provided the opportunity for 28 scientists from southern South America to examine daily rainfall observations to determine changes in both total and extreme rainfall. Twelve annual indices of daily rainfall were calculated over the period 1960 to 2000, examining changes to both the entire distribution as well as the extremes. Maps of trends in the 12 rainfall indices showed large regions of coherent change, with many stations showing statistically significant changes in some of the indices. The pattern of trends for the extremes was generally the same as that for total annual rainfall, with a change to wetter conditions in Ecuador and northern Peru and the region of southern Brazil, Paraguay, Uruguay, and northern and central Argentina. A decrease was observed in southern Peru and southern Chile, with the latter showing significant decreases in many indices. A canonical correlation analysis between each of the indices and sea surface temperatures (SSTs) revealed two large-scale patterns that have contributed to the observed trends in the rainfall indices. A coupled pattern with ENSO-like SST loadings and rainfall loadings showing similarities with the pattern of the observed trend reveals that the change to a generally more negative Southern Oscillation index (SOI) has had an important effect on regional rainfall trends. A significant decrease in many of the rainfall indices at several stations in southern Chile and Argentina can be explained by a canonical pattern reflecting a weakening of the continental trough leading to a southward shift in storm tracks. This latter signal is a change that has been seen at similar latitudes in other parts of the Southern Hemisphere. A similar analysis was carried out for eastern Brazil using gridded indices calculated from 354 stations from the Global Historical Climatology Network (GHCN) database. The observed trend toward wetter conditions in the southwest and drier conditions in the northeast could again be explained by changes in ENSO.

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Section: Introductionmentioning

confidence: 83%

Trends in Total and Extreme South American Rainfall in 1960–2000 and Links with Sea Surface Temperature

et al. 2006

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“…Nogués-Paegle and Mo (1997) found evidence of a seesaw pattern in the convection over the SACZ, with each phase lasting no more than 10 days and that the intensification (weakening) of the SACZ is associated with rainfall deficit (abundance) over the subtropical plains of South America, including eastern Argentina and Uruguay. Doyle and Barros (2002) showed that this dipole behavior appears also as a distinctive feature of the interannual variability of rainfall, and that in western Argentina, precipitation tends to vary in phase with SACZ rainfall. Gandu and Silva Dias (1998) explored the physics of this dipole with numerical experiments, showing that a strong SACZ activity is associated with enhanced subsidence to the south of it.…”

Section: The South Atlantic Sstmentioning

confidence: 96%

“…However, it abounds the literature with respect to South Atlantic Convergence Zone (SACZ). Since interannual variability of rainfall in subtropical Argentina and Uruguay during summertime is closely related to this system (Doyle and Barros, 2002), it is convenient to briefly introduce some aspects of the SACZ The SACZ is one important climatological feature of the austral summer in South America. This band of intense convective activity emanates from the Amazon region extending from the tropical South America southeastward into the South Atlantic Ocean (Kodama, 1992;Figueroa et al, 1995).…”

Section: The South Atlantic Sstmentioning

confidence: 99%

Seasonal-to-Decadal Predictability and Prediction of South American Climate

et al. 2006

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The dynamical basis for seasonal to decadal climate predictions and predictability over South America is reviewed. It is shown that, while global tropical SSTs affect both predictability and predictions over South America, the current lack of SST predictability over the tropical Atlantic represents a limiting factor to seasonal climate predictions over some parts of the continent. The model’s skill varies with the continental region: the highest skill is found in the “Nordeste” region and the lowest skill over southeastern Brazil. It is also suggested that current two-tier approaches to predict seasonal climate variations might represent a major limitation to forecast coupled ocean–atmosphere phenomena like the South Atlantic convergence zone. Also discussed are the possible effects of global climate change on regional predictability of seasonal climate.

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“…5e) was seen to predominate along the SBB, evolving as a response to increased cloud cover (note the negative OLRA in Figure 6e) and reduced incidence of short wave radiation (in the region of SACZ). During the summer months, when the SACZ occurs, it is enhanced and displaced to the north with negative SSTA observed south of 20°S and, conversely, it shifts southward followed by positive SSTA (Doyle and Barros, 2002). In the latter case, the wind-induced Ekman transport and mixing anomalies are near zero or slightly negative (Fig.…”

Section: Discussionmentioning

confidence: 92%

Oceanic and atmospheric patterns during spawning periods prior to extreme catches of the Brazilian sardine (<i>Sardinella brasiliensis</i>) in the southwest Atlantic

et al. 2011

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SUMMARY: Relative maxima and minima of landings of Brazilian sardine captured in the Southeast Brazil Bight (SBB) were compared with oceanic and atmospheric composites relative to the spawning period in December and January, prior to these landings. Atmospheric and oceanic variables such as wind stress, Ekman transport, mixing index, sea surface temperature (SST), precipitation, outgoing long wave radiation and geopotential height were analyzed, revealing distinct climatological patterns in the SBB for these extreme catches that have not been described before. The system could be characterized by cooler SST composite anomaly (SSTA) along the SBB as a response to increased cloud cover and reduced incidence of short-wave radiation, predominating one year before the Brazilian sardine catch maxima. This system can take on a different configuration in which positive SSTA condition in the SBB is associated with a less intense South Atlantic Convergence Zone displaced southwards one year before the period of minimum catch. Our results indicate that the spatial structure of the spawning habitat is influenced by specific ocean-atmosphere interactions rather than simply resulting from the choice of a stable environment. This climatic constraint strongly affects the interannual variability of the Brazilian sardine production.Keywords: Brazilian sardine, southwest Atlantic climate, air-sea interaction, South Atlantic Convergence Zone, sea surface temperature, Southeast Brazil Bight.RESUMEN: Patrones oceánicos y atmosféricos durante períodos de puesta previos a capturas extremas de la sardina brasilera (Sardinella braSilienSiS) en el océano Atlántico sudoeste. -Los desembarcos máximos y mínimos de capturas de la sardina brasileña en la Plataforma Sudeste Brasilera (SBB) se compararon con los patrones climáticos oceánicos y atmosféricos durante períodos de puesta, en diciembre y enero. Se analizó el comportamiento climático de variables oceanicas y atmosféricas como la influencia del viento, el transporte de Ekman, el índice de mezcla, la temperatura superficial del mar (SST), las precipitaciones, la radiación ascendente de ondas largas (OLR) y la altura geopotencial. Este análisis permitió la identificación de patrones climatológicos característicos sobre la SBB, no observados en trabajos previos. Los análisis revelaron que el sistema se caracteriza por SSTA más fríos sobre la sardina como respuesta a un incremento de la nebulosidad y la reducción de la incidencia de las radiaciones de onda corta, que predominan un año antes de las máximas capturas de sardina. Este sistema puede asumir una configuración distinta en la que SSTA positivos sobre la SBB se asocian con una SACZ desplazada hacia el sur un año antes del periodo de capturas mínimas. Nuestros resultados indican que la estructura espacial del hábitat de puesta es una consecuencia de las interacciones específicas océano-atmósfera, más que de una elección de ambiente estable y que ello influencia fuertemente la variabilidad interanual en la producción de sardina brasile...

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Midsummer Low-Level Circulation and Precipitation in Subtropical South America and Related Sea Surface Temperature Anomalies in the South Atlantic

Cited by 159 publications

References 26 publications

Trends in Total and Extreme South American Rainfall in 1960–2000 and Links with Sea Surface Temperature

Trends in Total and Extreme South American Rainfall in 1960–2000 and Links with Sea Surface Temperature

Seasonal-to-Decadal Predictability and Prediction of South American Climate

Oceanic and atmospheric patterns during spawning periods prior to extreme catches of the Brazilian sardine (<i>Sardinella brasiliensis</i>) in the southwest Atlantic

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