Combined performance of September’s Weddell sea ice extent, Southern Annular Mode, and Atlantic SST anomalies over the South American temperature and precipitation

Vasconcellos, Fernanda Cerqueira; Oliva, Fábio Guimarães; Pizzochero, Renan Martins; Silva, Telma Mendes da; Parise, Cláudia Klose; Caldas, Catharine F DE

doi:10.1590/0001-3765202220210803

Cited by 2 publications

(3 citation statements)

References 48 publications

(78 reference statements)

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“…The warmest austral summers showed a significant positive SST dipole over the subtropics and extratropics (Figure 3a), creating a positive meridional SST gradient (northward). Other authors have also discussed this South Atlantic Subtropical Gradient (Bernardino et al, 2018; Vasconcellos et al, 2022). This dipole is associated with increased pressure over the subtropics and decreased pressure over the extratropics (Figure 4a).…”

Section: Resultsmentioning

confidence: 96%

“…According to Ciasto and Thompson (2008), large‐scale atmospheric variability in the Southern Hemisphere is mainly driven by two climate variability modes: the Southern Annular Mode (SAM) and the El Niño–Southern Oscillation (ENSO). On an interannual timescale, the interaction between these modes generates SST anomalies in the South Atlantic Ocean that contribute to the South American climate (Andreoli & Kayano, 2006; Parise et al, 2022; Queiroz et al, 2022; Rudeva & Simmonds, 2015; Silva & Ambrizzi, 2006; Torres et al, 2022; Vasconcellos et al, 2022).…”

Section: Introductionmentioning

confidence: 99%

“…Vasconcellos and Souza (2022) showed that austral summer SST over the SWA is negatively (positively) correlated with rainfall over southeastern Brazil (southeastern South America). Vasconcellos et al (2022) showed relationships among Atlantic SST anomalies, SAM and the South American climate during September. Warmer and drier than normal conditions are observed in most of South America for a negative SAM/positive inter‐hemispheric Atlantic SST gradient and negative SAM/positive extratropical‐subtropical SST gradient, respectively.…”

Section: Introductionmentioning

confidence: 99%

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Warming trends of southwestern Atlantic SST and the summer's warmest SST's impact on South American climate

Vasconcellos

Souza

Dereczynski

et al. 2023

Intl Journal of Climatology

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Several atmospheric variables are directly influenced by oceanic conditions, mainly the sea surface temperature (SST). SST trends and variability over the southwestern Atlantic (SWA) have affected the South American climate, principally the monsoonal period (austral summer). This study analysed the SST trends over the SWA for all seasons. In addition, possible large‐scale triggers of the austral summer's warmest SST over the SWA and the straight impacts of these warmest SSTs on the South American climate were investigated. The results showed a significant positive SST trend of approximately 0.02°C·year−1 over the SWA for all seasons. Since 2000, positive SST anomalies have increased in frequency in all seasons, with the seven warmest summers occurring during the 2010s. The highest SST summers over the SWA have been related to four leading causes: (i) planetary waves triggered by warm anomalies over the subtropical South Pacific; (ii) an omega‐type blocking configuration over the South Atlantic; (iii) a Southern Annular Mode positive phase; and (iv) a strengthening of the Hadley Cell, responding to warm SST over tropical North Atlantic. They all reflected on intensification of the South Atlantic Subtropical High and the western boundary current, heating the SWA. The summer's warmest SST led to positive air temperature anomalies extending in almost all of eastern South America, with significantly highest temperatures over southeastern Brazil, northern Argentina and western Paraguay. Clouds decrease strengthen the incident shortwave in southeastern Brazil, warming the region. Significant reduction of cloudiness and precipitation indicate a low performance of the South Atlantic Convergence Zone. The comparison of the warmest summers in 1980s–1990s in the SWA ratified the role of SST intensification. In conclusion, the positive SST trends over the SWA are related to the summer's warmest SST after 2000s, causing heating and dryness in eastern South America, mainly over southeastern Brazil.

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Section: Resultsmentioning

confidence: 96%