Air-sea interaction in the South Atlantic and the water paleocycle in eastern South America during the Holocene

Author(s)

Luciana Figueiredo Prado

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto Oceanográfico (IO/DIDC)
• Defense date: 2015-03-02

Examining board members

Ilana Elazari Klein Coaracy Wainer; María Alejandra Gómez Pivel; Abdelfettah Sifeddine; Heitor Evangelista da Silva; Felipe Antonio de Lima Toledo

• Advisor: Ilana Elazari Klein Coaracy Wainer

Abstract

This work investigates the air-sea interaction processes in eastern South America and the adjacent Atlantic Ocean for the Holocene (past 12,000 years). The effects of the natural forcings on climate variability were investigated in three time-scales: (i) millennial-to-centennial: effects of Atlantic meltwater pulses and changes in the solar and orbital forcings on the South Atlantic subtropical dipole, and rainfall impacts during the Holocene; (ii) mid-Holocene scenario: effects of changes in the orbital forcing, in comparison to the present-day conditions, on mean precipitation over the continent, during the mid-Holocene (6,000 years ago). This was achieved through an unpublished multiproxy compilation and comparison with numerical experiments; (iii) multidecadal: effects of changes in the volcanic forcing along the past millennium (850 to 1850 Common Era) on the variability of the Atlantic equatorial mode and consequences on precipitation over South America. Results show effects of the Northern Hemisphere cooling events on the variability of the South Atlantic subtropical dipole, with impacts mainly over Northeastern Brazil\'s rainfall. The mid-Holocene scenario results indicate a water deficit in eastern South America during this period related to a decrease in Southern Hemisphere summer insolation. The difficulty in marine cores sampling is identified as one of the main problems in current paleoclimate studies. The explosive volcanism observed during the past millennium cooled the tropical regions at the year of the volcanic eruption, and weakened the relation between the precipitation in eastern South America and the Atlantic equatorial mode. This thesis shows through data-model approaches the importance of the Atlantic Ocean on South America precipitation regimes in the climate timescales where the anthropogenic forcing was not so relevant. 195 pp. (AU)

• FAPESP's process: 11/06610-0 - Air-sea interaction in Southern Atlantic and the water paleocycle in eastern subtropical South America during Holocene
• Grantee: Luciana Figueiredo Prado
• Support Opportunities: Scholarships in Brazil - Doctorate