Caracterização do sistema de correntes da região Oeste do Oceano Atlântico Equatorial

Abstract

The present study analyzed the system of currents in the west of the equatorial Atlantic Ocean between latitudes 10oN and 5oS and longitudes 35oW and 60oW. The study region is well documented; however, most of the works are limited spatially or temporally, considering the processes that occur in the region. Thus the present study aims to understand the system of currents acting in an extensive region and using a time series of approximately 10 years. The study was made from OSCAR data, which contains estimates of zonal and meridional velocities, and data of GDP, which contains in situ data of velocities measured by drogues, which made it possible to observe the currents patterns present in the region. For the months of January, February, March, April, May and June, a continuous flow with northwest direction, associated with CNB, near the break of the platform, with speeds varying between 0.5 and 1 m/swas evidenced. Further east, near 50oW, and above latitude 5 o N, less intense velocities were evidenced when compared to the CNB, varying between 0.5 and 0.8 m/s, corresponding to the CCNE. These speeds were more intense in the first quarter compared to the second quarter of the year. However, there were a few months, like January, February and March of the years 2012 and 2017, that there was a small retroflection of the CNB, not common for that time of year. For the months of July, August, September, October, November and December, it is possible to observe the feedback of the CCNE by the CNB, due to the offshore retroflexion of the Northern Brazil Current. Higher intensity, with velocities varying between 0.8 and 1.1 m/s near the latitude of 6 o N and longitude 52 o W, retroflection is an important inter-hemispheric bridge, in which the mass and heat exchange takes place. The eddies generated from the retroflexion of CNB are responsible for the Guianas current which, unlike the other sea currents, is a result of the average translation of the eddies that follow in a northwest direction during the months of July to December. Whereas during the months of January to June the Chain of the Guianas is a continuation of the continuous transport to the northwest of the CNB. In this way, it was possible to observe the pattern of currents in the west equatorial Atlantic, as well as the seasonality that affects currents acting in the region. The quarterly division conducted in this study, as well as the use of 10 years of analysis, proved to be a good resolution and time series for this type of study.