Variabilidade da camada de mistura a partir de dados de XBT no Oceano Atlântico de 2008 a 2011

Abstract

The Mixed Layer Depth (MLD) is the result of several active processes at the ocean surface (Keerthi et al., 2012), and presents the physical properties such as temperature, salinity and density, considered homogeneous. This layer is important for various processes occurring in the ocean and in the ocean-atmosphere exchanges (Levitus, 1982; BRAINERD and GREGG, 1995; THOMPSON AND FINE, 2002; KARA et al., 2003; HOLTE and TALLEY, 2008; Keerthi et al., 2012). Being determined by the difference in temperature, salinity or density, at a given depth, compared with that measured at surface. In this study we used the difference of 0.5 °C of temperature at depth relative to the reference depth temperature. The reference depth was defined as the minimal layer collected by XBT (eXpendable BathyThermograph), equipment used in this study as the data source. This study was conducted in the Atlantic Ocean, mainly in the north tropical Atlantic. Through the realized analyzes it was found that the depth of the mixed layer will be higher during the winter months, because in these months there is little stratification temperature in the ocean as well as in the middle latitudes. At the equator the variation of the depth of the mixed layer within the annual cycle is small, not trespassing 30 meters. It was performed the correlation between the XBT temperature data and SST (Sea Surface Temperature) retrieval from AQUA satellite /MODIS sensor, which showed a good correlation between these data, with R ² = 0.96 was also performed. The MLD variation in the annual cycle for the Equatorial Atlantic ocean region is small, while at the middle latitudes greater variations are observed, with higher values occurring in the boreal winter. The MLD values estimated in this work presenting good agreement with climatological MLD for the Atlantic.