South atlantic subtropical mode waters in the Levitus database

Abstract

Mode waters are layers of vertically homogeneous water found over a large geographical area, occur within or near the top of the permanent pycnocline. The mode waters are characterized by the conservation of their properties of the formation area (temperature, salinity, potential vorticity). In South Atlantic Ocean, the subtropical mode waters are formed within the Brazil-Malvinas Confluence region, and keep their properties along the subtropical gyre. The objective of this work is to identify and to characterize subtropical mode waters from data of temperature and salinity of the Levitus database. The applied methodology consisted on the construction and analysis of zonal and meridional sections of potential temperature and salinity and volumetric T-S diagrams. Two mode waters were identified on the analysis, one with potential temperature (q) ~14-16°C and another one with q ~ 11-12°C. These results were verified with information of hydrographic data collected presented in literature and will be used for future comparison with numerical models simulation.