Investigating the formation and maintenance of Subtropical Mode Water in the South Atlantic (SAMOWA)

• Grant number: 15/26450-8
• Support Opportunities: Regular Research Grants
• Start date: April 01, 2016
• End date: March 31, 2019
• Field of knowledge: Physical Sciences and Mathematics - Oceanography - Physical Oceanography
• Principal Investigator: Olga Tiemi Sato
• Grantee: Olga Tiemi Sato
• Host Institution: Instituto Oceanográfico (IO). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated researchers: Marcelo Dottori ; Paulo Henrique Rezende Calil ; Paulo Simionatto Polito

Abstract

In this project we aim the understanding of the mechanisms that control the presence of the subtropical mode water in the South Atlantic. The distinct characteristic of the mode water is the homogeneity of parameters such as temperature and salinity, in both vertical structure and along its horizontal extension. This particular type of subtropical mode water ocupies a region between 30S and 40S at the western boundary of the subtropical gyre, it has a zonal extention of 3000 km and on average is 160 m deep. This massive amount of water is formed between July and October as a consequence of the ocean and atmosphere interaction processes. During these months, the ocean releases heat to the atmosphere in exchange to the formation of a deeper than expected mixing layer. After the mode water is formed at the surface, convective mixing promotes its subduction to lower layers until it finds its resting place at an equilibrium isopycnal but still close to the region of formation. The formation process is strongly linked to the heat loss from the surface. However, the variability in the formed volume is not directly related to the variations in the heat flux. Speculations include that other processes that occur outside the region of formation affect the amount of mode water formed or destructed. Among these factors there are the by interaction with the Brazil Current and turbulent processes associated with mesoscale vortices and anomalies due to the wind stress in the form of Ekman transport. For a comprehensive understanding of its formation it is crucial that a precise description of the state of the ocean before and after its formation be available. For that purpose, we draw an unprecedented strategy to understand these processes by obtaining synoptic in situ profiles together with a continuous and high resolution sampling through glider in combination of fields derived by satellite data. (AU)

Scientific publications

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

BERNARDO, PIERO S.; SATO, OLGA T.. Volumetric Characterization of the South Atlantic Subtropical Mode Water Types. Geophysical Research Letters, v. 47, n. 8, APR 28 2020. (15/26450-8)

FERREIRA, M. B.; SATO, O. T.; POLITO, P. S.; BERNARDO, P. S.. Examining the Subtropical Mode Water in the Southwestern Atlantic From in Situ Observations. JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS, v. 124, n. 4, p. 2513-2526, APR 2019. (15/26450-8)