Paleoclimatic variability and extreme events since the last deglaciation in Peru : sedimentary record and model simulations

• Main Author: Yseki, Marco
• Other Authors: Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Sorbonne Université, Bruno Turcq, Dimitri Gutiérrez
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: HAL CCSD 2022
• Subjects: Paleoclimatology; Peruvian Upwelling System; Wind; Precipitation; ENSO; Paléoclimatologie; Système d'Upwelling Péruvien; Vent côtier; Précipitations; [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; Ice Sheet
• Online Access: https://theses.hal.science/tel-03993752; https://theses.hal.science/tel-03993752/document; https://theses.hal.science/tel-03993752/file/YSEKI_Marco_these_2022.pdf

Reconstructing precipitation and wind from the geological record could help to understand the potential changes in precipitation and wind dynamics in response to climate change in Peru. The objectives of this thesis were: 1) To reconstruct the millennial variability of fluvial and aeolian inputs and to infer changes in precipitation and surface wind in Peru during the last deglaciation. 2) Reconstruct the interannual variability of precipitation-dependent fluvial discharges and infer the variability of ENSO during the last deglaciation and 3) Reconstruct the millennial variability of aeolian inputs dependent of surface wind during the Holocene. For this purpose, grain-size distribution and end-member analysis were used to infer the sources of terrigenous material. In addition, the titanium concentration obtained by high-resolution XRF was used to infer ENSO variability. During the last deglaciation, our results suggest that variations in river discharge in the western margin of South America deglaciation were sensitive to Atlantic Meridional Overturning Circulation on millennial timescales. In addition, we find that the amplitude of ENSO events was 50 to 190 % larger during the deglaciation compared to the Late Holocene, which supports the hypothesis that ENSO in the Eastern Pacific is strengthened by ice sheet meltwater discharge. Concerning to surface wind, during the Holocene, our results suggest an increase in aeolian inputs linked to stronger surface wind during the Mid-Holocene. Although there remains uncertainty about the effects of current climate change on wind and upwelling dynamics in Peruvian Upwelling System, our results and previous studies suggest that a northern (southern) shift of the Intertropical Convergence Zone-South Pacific Subtropical High system may generate an intensification (weakening) of upwelling-favorable wind and upwelling in Peruvian Upwelling System at different times-scale. La reconstruction des précipitations et des vents à partir des archives géologiques pourrait aider à ...