Southern hemisphere circulation anomalies and impacts over subtropical South America due to different El Niño flavours

Martín-Gómez, Verónica; Barreiro, Marcelo; Losada, Teresa; Rodríguez‐Fonseca, Belén

doi:10.1002/joc.6577

Cited by 3 publications

(1 citation statement)

References 51 publications

(96 reference statements)

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“…Several studies have evaluated the effects of the warm pool location in the Pacific Ocean in South America. In southeast South America, while circulation and precipitation anomalies are related to canonical and Modoki El Niño events, the strongest anomalies are related to Modoki El Niño (Tedeschi et al 2015;Barreiro 2017;Martín-Gómez et al 2020).…”

Section: Relationships Between Pc1 Pdo Enso Qbo and Aaomentioning

confidence: 97%

The combined influence of ENSO and PDO on the spring UTLS ozone variability in South America

2020

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Ozone in the upper troposphere-lower stratosphere (UTLS) is primarily regulated by tropospheric dynamics. Understanding mechanisms driving ozone variability at the UTLS is crucial to evaluate the transport of mass to and from the lower stratosphere. The El Niño-Southern Oscillation (ENSO) is the primary coupled mode acting on interannual timescales modulating tropospheric circulation worldwide. ENSO teleconnections can depend on the phases of the Pacific Decadal Oscillation (PDO) and on the characteristics of the warming over central and eastern tropical Pacific. This study investigates the role of ENSO on UTLS ozone variability with focus on South America and examines patterns of teleconnections in the two recent warm (1980)(1981)(1982)(1983)(1984)(1985)(1986)(1987)(1988)(1989)(1990)(1991)(1992)(1993)(1994)(1995)(1996)(1997) and cool (1998-2012) PDO phases. The dominant mode of ozone variability is identified by applying a principal component analysis (PCA) to modern-era retrospective analysis for research and applications, Version 2 (MERRA-2) ozone data from September-November (SON). SON is the season with the largest UTLS ozone variance over South America. The first mode resembles a Rossby wave train across South America with spatial patterns dependent on PDO phase. We show that the ENSO teleconnections and respective influences on SON UTLS ozone are stronger during the cool PDO when ENSO and PDO are mostly in phase. Additionally, the strength of the ENSO teleconnection appears to depend on patterns of SST anomalies over tropical Pacific. The decadal variability in the ENSO-PDO relationships and teleconnections with the Southern Hemisphere resulted in a shift in upper tropospheric circulation in tropical and subtropical regions of South America.

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Section: Relationships Between Pc1 Pdo Enso Qbo and Aaomentioning

confidence: 97%

The combined influence of ENSO and PDO on the spring UTLS ozone variability in South America

2020

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Enhanced interaction between ENSO and the South Atlantic subtropical dipole over the past four decades

Yu,

Zhong,

Vihma

et al. 2024

Intl Journal of Climatology

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This study investigates the relationship between sea surface temperature (SST) anomalies in the subtropical Atlantic Ocean, as represented by the Southern Atlantic subtropical dipole (SASD), and SST anomalies in the tropical Pacific Ocean, identified by the El Niño‐Southern Oscillation (ENSO). Contrary to the previously held notion of a weak relationship between SASD and ENSO as suggested by earlier literature, our analysis reveals a substantial inverse correlation between the two. This correlation exhibits significant multi‐decadal variability, which has notably intensified over the most recent two decades compared with the preceding two decades. This intensification in the SASD–ENSO inverse correlation may be attributed to the shift in ENSO regime from predominance of eastern Pacific El Niño to central Pacific El Niño events around the turn of the century. This transition triggers wavetrains that propagate along different paths, consequently influencing the South Atlantic subtropical high and inducing alterations in anomalous SST patterns in the subtropical Atlantic Ocean. These findings advance our comprehension of the interactions between South Atlantic and Pacific SST variations, which strongly influence rainfall patterns, particularly in South America and southern Africa. Understanding such teleconnection holds promise for improving sub‐seasonal to seasonal precipitation predictions in these regions.

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Enso influence on water vapor transport and thermodynamics over Northwestern South America

Ruiz-Vásquez,

Arias,

Martínez

2024

Theor Appl Climatol

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The interannual variability of hydroclimatic conditions in Northwestern South America, especially precipitation, is mainly influenced by the El Niño–Southern Oscillation (ENSO). We explore potential mechanisms that affect precipitation occurrence in Northwestern South America during El Niño and La Niña events over the period 1980–2019, using data from the ERA5 reanalysis. We look at the atmospheric moisture contribution from different sources using the Dynamic Recycling Model to track water vapor trajectories. Interestingly, conditions with reduced precipitation during El Niño events can take place along with increased precipitable water. To understand this, we analyze thermodynamic conditions in the atmosphere that are necessary for precipitation to occur over the region, such as convective available potential energy, convective inhibition, lifting condensation level, and low-level relative humidity. With this approach, we find more favorable thermodynamic conditions for the occurrence of precipitation during La Niña events, even if the content of water vapor is equal or even less than during El Niño events. We also look at the structure of the regional Hadley and Walker circulation in both types of events and find that a weaker ascending motion during El Niño events also inhibits convection. This study provides an integral picture of how precipitation anomalies over Northwestern South America during ENSO events are related to dynamic and thermodynamic conditions and sources of atmospheric moisture.

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Southern hemisphere circulation anomalies and impacts over subtropical South America due to different El Niño flavours

Cited by 3 publications

References 51 publications

The combined influence of ENSO and PDO on the spring UTLS ozone variability in South America

The combined influence of ENSO and PDO on the spring UTLS ozone variability in South America

Enhanced interaction between ENSO and the South Atlantic subtropical dipole over the past four decades

Enso influence on water vapor transport and thermodynamics over Northwestern South America

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