Influence of the Coupling South Atlantic Convergence Zone-El Niño-Southern Oscillation (SACZ-ENSO) on the Projected Precipitation Changes over the Central Andes

In this study, precipitation in Tropical South America in the 1931–2016 period is investigated by means of Principal Component Analysis and composite analysis of circulation fields. The associated dynamics are analyzed using the 20th century ERA-20C reanalysis. It is found that the main climatic processes related to precipitation anomalies in Tropical South America are: (1) the intensity and position of the South Atlantic Convergence Zone (SACZ); (2) El Niño Southern Oscillation (ENSO); (3) the meridional position of the Intertropical Convergence Zone (ITCZ), which is found to be related to Atlantic Sea Surface Temperature (SST) anomalies; and (4) anomalies in the strength of the South American Monsoon System, especially the South American Low-Level Jet (SALLJ). Interestingly, all of the analyzed anomalies are related to processes that operate from the Atlantic Ocean, except for ENSO. Results from the present study are in agreement with the state of the art literature about precipitation anomalies in the region. However, the added strength of the longer dataset and the larger study area improves the knowledge and gives new insights into how climate variability and the resulting dynamics are related to precipitation in Tropical South America.

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“…These data have a 2.5 • spatial resolution and cover the 1979-2022 period. The method to calculate the SACZ index is described in [36].…”

Section: Methodsmentioning

confidence: 99%

Dynamics of Precipitation Anomalies in Tropical South America

2022

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“…The Andes‐Amazon transition region features intricate precipitation patterns influenced by the interplay of large‐scale and local circulation patterns and the region's physio‐geographical characteristics (Espinoza et al., 2020 and references therein). Precipitation patterns across the western Amazon basin typically exhibit a seasonal distribution, although some Peruvian and Ecuadorian Amazon basins display unimodal and bimodal regimes (Espinoza et al., 2009; Laraque et al., 2007; Segura et al., 2019; J. C. Sulca and Rocha, 2021).…”

Section: Introductionmentioning

confidence: 99%

Performance of Regional Climate Model Precipitation Simulations Over the Terrain‐Complex Andes‐Amazon Transition Region

Gutierrez,

Junquas,

Armijos

et al. 2024

JGR Atmospheres

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Regional climate models (RCMs) are widely used to assess future impacts associated with climate change at regional and local scales. RCMs must represent relevant climate variables in the present‐day climate to be considered fit‐for‐purpose for impact assessment. This condition is particularly difficult to meet over complex regions such as the Andes‐Amazon transition region, where the Andean topography and abundance of tropical rainfall regimes remain a challenge for numerical climate models. In this study, we evaluate the ability of 30 regional climate simulations (6 RCMs driven by 10 global climate models) to reproduce historical (1981–2005) rainfall climatology and temporal variability over the Andes‐Amazon transition region. We assess spatio‐temporal features such as spatial distribution of rainfall, focusing on the orographic effects over the Andes‐Amazon “rainfall hotspots” region, and seasonal and interannual precipitation variability. The Eta RCM exhibits the highest spatial correlation (up to 0.6) and accurately reproduces mean annual precipitation and orographic precipitation patterns across the region, while some other RCMs have good performances at specific locations. Most RCMs simulate a wet bias over the highlands, particularly at the eastern Andean summits, as evidenced by the 100%–2,500% overestimations of precipitation in these regions. Annual cycles are well represented by most RCMs, but peak seasons are exaggerated, especially at equatorial locations. No RCM is particularly skillful in reproducing the interannual variability patterns. Results highlight skills and weaknesses of the different regional climate simulations, and can assist in the selection of regional climate simulations for impact studies in the Andes‐Amazon transition zone.

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“…Several studies have predicted a decrease in precipitation over the Altiplano region by the end of the 21st century (Urrutia and Vuille, 2009;Minvielle and Garreaud, 2011;Neukom et al, 2015;Vera et al, 2019;Sulca and da Rocha, 2021;Zubieta et al, 2021). Based on the linear relationship between precipitation (PRE) and 200 hPa zonal wind (U200) anomalies in the current climate, a significant reduction in austral summer precipitation over the central Andes, ranging from 10% to 30%, is projected by the end of this century under the A2 scenario belongs to AR4 (Intergovernmental Panel on Climate Change, IPCC) (Minvielle and Garreaud, 2011).…”

Section: Introductionmentioning

confidence: 99%

New insights into the biennial-to-multidecadal variability of the water level fluctuation in Lake Titicaca in the 20th century

Sulca,

Apaéstegui,

Tacza

2024

Front. Clim.

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The water disponibility of Lake Titicaca is important for local ecosystems, domestic water, industry, fishing, agriculture, and tourism in Peru and Bolivia. However, the water level variability in Lake Titicaca (LTWL) still needs to be understood. The fluctuations of LTWL during the 1921–2018 period are investigated using continuous wavelet techniques on high- and low-pass filters of monthly time series, ERA-20C reanalysis, sea surface temperature (SST), and water level. We also built multiple linear regression (MLR) models based on SST indices to identify the main drivers of the LTWL variability. LTWL features annual (12 months), biennial (22–28 months), interannual (80–108 months), decadal (12.75–14.06 years), interdecadal (24.83–26.50 years), and multidecadal (30–65 years) signals. The high- and low-frequency components of the LTWL are triggered by the humidity transport from the lowland toward the Lake Titicaca basin, although different forcings could cause it. The biennial band is associated with SST anomalies over the southeastern tropical Atlantic Ocean that strengthen the Bolivian High-Nordeste Low system. The interannual band is associated with the southern South Atlantic SST anomalies, which modulate the position of the Bolivian High. According to the MLR models, the decadal and interdecadal components of the LTWL can be explained by the linear combination of the decadal and interdecadal variability of the Pacific and Atlantic SST anomalies (r > 0.83, p < 0.05). In contrast, the multidecadal component of the LTWL is driven by the multidecadal component of the North Atlantic SST anomalies (AMO) and the southern South Atlantic SST anomalies. Moreover, the monthly time series of LTWL exhibits four breakpoints. The signs of the first four trends follow the change of phases of the multidecadal component of LTWL, while the fifth trend is zero attributable to the diminished amplitude of the interdecadal component of LTWL.

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Influence of the Coupling South Atlantic Convergence Zone-El Niño-Southern Oscillation (SACZ-ENSO) on the Projected Precipitation Changes over the Central Andes

Cited by 7 publications

References 66 publications

Dynamics of Precipitation Anomalies in Tropical South America

Dynamics of Precipitation Anomalies in Tropical South America

Performance of Regional Climate Model Precipitation Simulations Over the Terrain‐Complex Andes‐Amazon Transition Region

New insights into the biennial-to-multidecadal variability of the water level fluctuation in Lake Titicaca in the 20th century

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