Hydroclimatic Variability and El Niño Phenomena in South America
Summary
South America’s hydroclimate is profoundly shaped by interannual and decadal patterns of the El Niño–Southern Oscillation (ENSO), which modulates rainfall distribution, river discharges and associated environmental and socio-economic impacts. El Niño phases generally suppress convection over northern and western sectors of the continent, inducing drought, reduced streamflow and heightened fire risk in the Amazon and Andean foothills. Conversely, La Niña tends to intensify precipitation across the Pacific slope and the southern cone, driving flood hazards and soil erosion. These ENSO-driven anomalies interact with regional circulations such as the Chocó and Orinoco low-level jets, as well as the shifting Intertropical Convergence Zone, to produce marked spatial heterogeneity in seasonal and interannual variability. Recent advances in remote sensing, high-resolution modelling and palaeoclimate reconstructions have refined our understanding of teleconnections among sea surface temperature anomalies, moisture transport pathways and orographic effects. Improved hydroclimatic forecasts now support early-warning systems for agriculture, water resources and disaster risk management, underscoring the global importance of accurately characterising ENSO’s influence on South American climates.
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Hydroclimatic Variability and El Niño Phenomena in South America publication trend
The graph below shows the total number of articles in hydroclimatic variability and el niño phenomena in south america across all publications each year (not limited to Nature Index journals).
Technical terms
El Niño–Southern Oscillation (ENSO): A coupled ocean–atmosphere phenomenon in the tropical Pacific characterised by alternating warm (El Niño) and cool (La Niña) sea surface temperature anomalies and associated atmospheric pressure shifts.
Oceanic Niño Index (ONI): A rolling three-month average of sea surface temperature anomalies in the Niño3.4 region of the equatorial Pacific, used to quantify the strength and phase of ENSO.
Low-Level Jet (LLJ): A narrow, fast-moving ribbon of air in the lower troposphere that transports moisture and modulates regional precipitation patterns, such as the Chocó jet along the Pacific coast.
Wavelet coherence: A time–frequency analysis technique that identifies localized covariability between two time series across multiple scales, revealing intermittent teleconnections.
Nonlinear Principal Component Analysis: An extension of principal component analysis that captures non-linear data structures, used to extract dominant modes of variability in hydroclimatic records.
References
- Detection of Coastal Erosion and Progradation in the Colombian ‘Atrato River’ Delta by Using Sentinel-1 Synthetic Aperture Radar Data. Remote Sensing (2024).
- Streamflow Variability in Colombian Pacific Basins and Their Teleconnections with Climate Indices. Water (2020).
- Teleconnections between Monthly Rainfall Variability and Large-Scale Climate Indices in Southwestern Colombia. Water (2020).
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