Linkages between Summer Rainfall Variability over South America and Sea Surface Temperature Anomalies

Nesse estudo foi aplicada uma metodologia de classificação dos eventos de El Niño em seus diferentes tipos (Central, Leste e, quando ambos ocorrem concomitantemente, MIX) no período de janeiro de 1950 a março de 2019. Além disso, os tipos de El Niño foram separados por estação do ano e considerando as diferentes condições de anomalias de temperatura da superfície do mar no oceano Atlântico Tropical Sul (neutras quando ocorrem anomalias de temperatura entre -0,5º e 0,5ºC; quentes quando as anomalias são superiores a 0,5ºC e frias quando as anomalias são inferiores a -0,5ºC). Com base nas combinações de ocorrência de cada tipo de EN e anomalias de temperatura da superfície do mar no Atlântico Tropical Sul, foram determinadas as anomalias de precipitação na América do Sul. Os diferentes tipos de El Niño são mais frequentes quando há condições neutras no Atlântico Tropical Sul. Com relação às anomalias de precipitação na América do Sul, os eventos de El Niño Leste e MIX, em geral, mostram padrão similar na distribuição espacial das anomalias, mas com os eventos MIX mostrando sinal mais fraco. As anomalias de temperatura da superfície do mar no Atlântico Tropical Sul quando negativas ajudam a fortalecer as condições secas entre o norte das regiões norte e nordeste do Brasil propiciadas pelos eventos de El Niño. Influence of the Different Types of El Niño in the Precipitation over South America A B S T R A C TIn this study, a specific methodology was applied to classify El Niño events into their different types (Central, East and when both occur at the same time, MIX) from January 1950 to March 2019. In addition, the types of El Niño were separated by season and considering the conditions of sea surface temperature anomalies on the South Tropical Atlantic Ocean (neutrality: temperature anomalies between -0.5º and 0.5ºC, warm: anomalies above 0.5ºC and cold: anomalies below -0.5ºC). Based on in the combination of different types of El Niño and sea surface temperature anomalies on the South Atlantic Tropical Ocean, precipitation anomalies over South America were computed. The different types El Niño occur, in general, under neutral conditions on the Atlantic Ocean. The events of El Niño - East and MIX, in general, present a similar pattern in the spatial distribution of the precipitation anomalies over South America, but with the MIX events showing weaker signal. Sea surface temperature anomalies in the Tropical South Atlantic when negative, they help to strengthen the dry conditions between the north of the north and northeast regions of Brazil caused by the El Niño events.Keywords: atmospheric circulation, anomaly conditions, tropical oceans, climate

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Interannual Indian Rainfall Variability and Indian Ocean Sea Surface Temperature Anomalies

Earth's Climate - Geophysical Monograph Series ◽

10.1029/147gm14 ◽

2013 ◽

pp. 247-259 ◽

Cited By ~ 25

Author(s):

Gabriel A. Vecchi ◽

D. E. Harrison

Keyword(s):

Indian Ocean ◽

Surface Temperature ◽

Sea Surface Temperature ◽

Rainfall Variability ◽

Sea Surface ◽

Temperature Anomalies ◽

Sea Surface Temperature Anomalies ◽

Indian Rainfall

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Rainfall variability related to sea surface temperature anomalies in a Pacific–Andean basin into Ecuador and Peru

Advances in Geosciences ◽

10.5194/adgeo-33-53-2013 ◽

2013 ◽

Vol 33 ◽

pp. 53-62 ◽

Cited By ~ 13

Author(s):

L. Pineda ◽

V. Ntegeka ◽

P. Willems

Keyword(s):

Surface Temperature ◽

Sea Surface Temperature ◽

Coastal Plain ◽

Southern Oscillation ◽

Rainfall Variability ◽

Sea Surface ◽

Atmospheric Forcing ◽

Temperature Anomalies ◽

Sea Surface Temperature Anomalies ◽

Instrumental Records

Abstract. The spatiotemporal modes of seasonal rainfall variability and their relation with sea surface temperature anomalies (SSTA 1.2 indices) are examined in the transition from the coastal plain towards the western Andes cordillera in southern Ecuador/northwestern Peru using instrumental records (1970–2000) collected from the Catamayo–Chira basin. A multi-criteria data analysis is conducted within different elevation ranges. The criteria involve rotated principal components, cross correlations and temporal changes of anomalies in rainfall quantiles. The results confirm that SSTA 1.2 indices influence rainfall variability over the coastal plain (< 510 m a.s.l.) where forcing is dominant within December–May. The El Niño Southern Oscillation also plays a role inland of the coastal plain where a region of ENSO-like rainfall variability is found on the southeastern part of the basin (4°30'–5° S/79°15'–80° W) within March–May (MAM). This suggests that inland distance and elevation are only partial controls of ocean–atmospheric forcing up to ~ 1300 m a.s.l. Our analysis also provides evidence of the SSTA 1.2 indices influence in a large altitudinal range ~ 1400–2700 m a.s.l. confined to the southeastern basin. This region is found consistently perturbed by ENSO within MAM. We conclude that geo-morphological features of the southwestern Ecuadorian Andean ridges play a twofold role in the control of ocean–atmospheric forcing. They can modulate the atmospheric circulation, leading to a dissipation of the signal, or they might favor meteorological processes, leading to enhancement of orographic precipitation. This would explain the observed ENSO signals in instrumental records at locations as high as 2700 m a.s.l.

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