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Climate and environmental changes over ITCZ in Colombia documented by d18O records in speleothems

Grant number: 19/16745-1
Support type:Scholarships in Brazil - Master
Effective date (Start): August 01, 2019
Effective date (End): July 31, 2021
Field of knowledge:Physical Sciences and Mathematics - Geosciences - Geology
Cooperation agreement: National Science Foundation (NSF) and NSF’s Partnership for International Research and Education (PIRE)
Principal Investigator:Francisco William da Cruz Junior
Grantee:Nathalie Melissa Martinez Medina
Home Institution: Instituto de Geociências (IGC). Universidade de São Paulo (USP). São Paulo , SP, Brazil
Associated research grant:17/50085-3 - PIRE: climate research education in the Americas using tree-ring speleothem examples (PIRE-CREATE), AP.TEM

Abstract

The South America Monsoon System (SAMS) and Intertropical Convergence Zone (ITCZ) are the main responsible by convection over tropical and extratropical regions of South America. Despite several studies have shown that both systems are sensitive to solar variability, the interrelationship between SAMS and ITCZ was not well documented for the last millennium over the ITCZ Region in South AmericaReconstructing tropical hydroclimate history has been difficult, particularly in the Amazon Basin, one of Earth's major centers of deep atmospheric convection, largely because most study sites are located on the periphery of the basin (most in the Peruvian Andes) and interpretations can be complicated by sediment preservation, uncertainties in chronology, and topographical setting. Previous reported that peaks in solar forcing increase the energy input to the surface ocean at subtropical latitudes, thereby enhancing evaporation and near-surface moisture, which is carried by the trade winds to the convergence zones. Through this mechanism convective activity in the regions influenced by the upward branches of Hadley cell can be intensified, resulting in strengthened regional tropical precipitation regimes due to enhanced solar forcing. This change in Hadley cell cold modulate the positions of the ITCZ, as well, modulate the intensity of SAMS. To verify the relationship between these convective systems with radiative forcing new paleoclimate records from non-explored study sites is required. The understanding of ITCZ variability during the last millennia needs to be improved by new studies involving ´18O and trace elements on speleothems. For the current project, we propose the study of speleothems collected in caves from Huila State, SW Colombia, a region with a gap of high-resolution records for the last millennium. The stalagmites for this study will be compared with the previously published d18O records from Peruvian Andes and from southern border of Amazon Basin for the understanding of ITCZ evolution over the Andean Cordillera.