Coherent South American Monsoon Variability During the Last Millennium Revealed Through High‐Resolution Proxy Records

2019 ◽  
Vol 46 (14) ◽  
pp. 8261-8270 ◽  
Author(s):  
J. L. P. S. Campos ◽  
F. W. Cruz ◽  
T. Ambrizzi ◽  
M. Deininger ◽  
M. Vuille ◽  
...  
Keyword(s):  
High Resolution ◽  
South American ◽  
Last Millennium ◽  
South American Monsoon ◽  
Proxy Records ◽  
Monsoon Variability

Reconstruction of the last three millennia South American Monsoon variability over the Amazon basin using speleothem isotope records 

2021 ◽  
Author(s):  
Marcela Eduarda Della Libera de Godoy ◽  
Valdir F. Novello ◽  
Francisco William Cruz
Keyword(s):  
High Resolution ◽  
Amazon Basin ◽  
Rainfall Variability ◽  
Isotope Analysis ◽  
Core Region ◽  
South American ◽  
The South ◽  
Continuous Increase ◽  
South American Monsoon ◽  
The Core

<p>South American Monsoon System (SAMS) and its main feature, the South American Convergence Zone (SACZ) are responsible for the major distribution of moisture in South America. The current work presents a novel high-resolution oxygen isotope record (δ<sup>18</sup>O) based on speleothems from southwest Amazon basin (Brazil), right at SAMS' core region and SACZ onset, where there is still a gap of high resolution paleoclimate records. The novel δ<sup>18</sup>O record presents an average of 3 year-resolution, composed by 1344 stable isotope analysis performed in two speleothems with a well-resolved chronology (37 U/Th ages) with average errors <1%. This work aims to describe the rainfall variability of the core region of the South American monsoon for the last 3k years and to take a broader look at precipitation patterns over Amazon basin. The Rondônia δ18O record shows three main stages throughout this time period. The first is from -1000 to ~400 CE, where it’s in accordance with most of other paleorecords from the Amazon basin. the second segment  is from ~400 to 1200 CE, when there is a continuous increase in the δ18O record until it reaches its highest values around 850 CE during the MCA (800-1200 CE), which is in accordance with western Amazon records, whilst the record in eastern Amazon presents an opposite trend. Thus, a precipitation dipole over Amazon emerges from ~400 CE onwards, majorly triggered by anomalous climate changes such as MCA, where western (eastern) Amazon is drier (wetter). During LIA (1450-1800 CE), on the other hand, Rondônia record presents its lowest values, also agreeing with western records and with records under the influence of SACZ whilst on eastern Amazon a drier period is established. Therefore, with this novel paleoclimate record located at the core region of SAMS, it's possible to evidence the dynamics of the precipitation dipole over the Amazon region, as well as understand the SACZ intensity variations.</p>

scholarly journals A high-resolution history of the South American Monsoon from Last Glacial Maximum to the Holocene

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Valdir F. Novello ◽  
Francisco W. Cruz ◽  
Mathias Vuille ◽  
Nicolás M. Stríkis ◽  
R. Lawrence Edwards ◽  
...  
Keyword(s):  
High Resolution ◽  
Last Glacial Maximum ◽  
Glacial Maximum ◽  
South American ◽  
The South ◽  
The Holocene ◽  
South American Monsoon ◽  
Last Glacial ◽  
History Of ◽  
History Of The South

scholarly journals The South American Monsoon Variability over the Last Millennium in CMIP5/PMIP3 simulations

2015 ◽  
Vol 11 (6) ◽  
pp. 5651-5681 ◽  
Author(s):  
M. Rojas ◽  
P. A. Arias ◽  
V. Flores-Aqueveque ◽  
A. Seth ◽  
M. Vuille
Keyword(s):  
South America ◽  
Large Scale ◽  
Model Simulation ◽  
Ice Age ◽  
South American ◽  
Last Millennium ◽  
The South ◽  
South American Monsoon ◽  
The Past ◽  
Intercomparison Project

Abstract. In this paper we assess South American Monsoon System (SAMS) variability throughout the Last Millennium as depicted by the Coupled Modelling Intercomparison Project version 5/Paleo Modelling Intercomparison Project version 3 (CMIP5/PMIP3) simulations. High-resolution proxy records for the South American monsoon over this period show a coherent regional picture of a weak monsoon during the Medieval Climate Anomaly period and a stronger monsoon during the Little Ice Age (LIA). Due to the small forcing during the past 1000 years, CMIP5/PMIP3 model simulations do not show very strong temperature anomalies over these two specific periods, which in turn do not translate into clear precipitation anomalies, as suggested by rainfall reconstructions in South America. However, with an ad-hoc definition of these two periods for each model simulation, several coherent large-scale atmospheric circulation anomalies were identified. The models feature a stronger Monsoon during the LIA associated with: (i) an enhancement of the rising motion in the SAMS domain in austral summer, (ii) a stronger monsoon-related upper-troposphere anticyclone, (iii) activation of the South American dipole, which results to a certain extent in a poleward shift in the South Atlantic Convergence Zone and (iv) a weaker upper-level sub tropical jet over South America, this providing important insights into the mechanisms of these climate anomalies over South America during the past millennium.

scholarly journals High-resolution Holocene South American monsoon history recorded by a speleothem from Botuverá Cave, Brazil

2016 ◽  
Vol 450 ◽  
pp. 186-196 ◽  
Author(s):  
J.P. Bernal ◽  
Francisco W. Cruz ◽  
Nicolás M. Stríkis ◽  
Xianfeng Wang ◽  
Michael Deininger ◽  
...  
Keyword(s):  
High Resolution ◽  
South American ◽  
South American Monsoon

scholarly journals Environmental variability at the margin of the South American Monsoon System recorded by a high-resolution sediment record from Lagoa Dourada (South Brazil)

2021 ◽  
Author(s):  
Bernd Zolitschka ◽  
An-Sheng Lee ◽  
Daniela Piraquive Bermúdez ◽  
Thomas Giesecke
Keyword(s):  
High Resolution ◽  
Catchment Area ◽  
Future Climate Change ◽  
South American ◽  
Sediment Record ◽  
The South ◽  
South American Monsoon ◽  
Monsoon System ◽  
South American Monsoon System ◽  
South Brazil

High-resolution geochemical and sedimentological data were analyzed for a lacustrine sediment record from Lagoa Dourada (South Brazil). Four distinctly different depositional processes were determined: (1) Suspension fallout of fine-grained minerogenic particles transferred via fluvial activity dominates the Early Holocene and relates to open grassland in the catchment area; (2) Activation of the karst hydrological system with deposition of massive sand layers indicates increased precipitation at the onset of the Middle Holocene; (3) Minerogenic sediments are replaced by organic deposition due to wetter climatic conditions with the development of forests, which together fostered pedogenesis with the release of dissolved nutrients during the Middle to Late Holocene; (4) Human-induced land-use change caused destabilization of soils in the catchment area with resulting cultural soil erosion between AD 1800 and 1950. These depositional trends are linked to intensity variations of the South American Monsoon System (SAMS). Two century-long climatic events detected by high-resolution XRF scanning data confirm this relationship and probably provide signals of the 8.2 ka event and the Little Ice Age (LIA). Both events document increased rainfall with complex responses of the environmental system. Our SAMS-induced consequences of past hydroclimatic variability on the environment of South Brazil provide background information for better evaluating model projections of future climate change.

scholarly journals The South American monsoon variability over the last millennium in climate models

2016 ◽  
Vol 12 (8) ◽  
pp. 1681-1691 ◽  
Author(s):  
Maisa Rojas ◽  
Paola A. Arias ◽  
Valentina Flores-Aqueveque ◽  
Anji Seth ◽  
Mathias Vuille
Keyword(s):  
South America ◽  
Large Scale ◽  
Model Simulation ◽  
Ice Age ◽  
South American ◽  
Last Millennium ◽  
The South ◽  
Model Simulations ◽  
South American Monsoon ◽  
The Past

Abstract. In this paper we assess South American monsoon system (SAMS) variability in the last millennium as depicted by global coupled climate model simulations. High-resolution proxy records for the South American monsoon over this period show a coherent regional picture of a weak monsoon during the Medieval Climate Anomaly and a stronger monsoon during the Little Ice Age (LIA). Due to the small external forcing during the past 1000 years, model simulations do not show very strong temperature anomalies over these two specific periods, which in turn do not translate into clear precipitation anomalies, in contrast with the rainfall reconstructions in South America. Therefore, we used an ad hoc definition of these two periods for each model simulation in order to account for model-specific signals. Thereby, several coherent large-scale atmospheric circulation anomalies are identified. The models feature a stronger monsoon during the LIA associated with (i) an enhancement of the rising motion in the SAMS domain in austral summer; (ii) a stronger monsoon-related upper-tropospheric anticyclone; (iii) activation of the South American dipole, which results in a poleward shift of the South Atlantic Convergence Zone; and (iv) a weaker upper-level subtropical jet over South America. The diagnosed changes provide important insights into the mechanisms of these climate anomalies over South America during the past millennium.

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