Regional modeling of the water masses and circulation annual variability at the Southern Brazilian Continental Shelf

• Published in: Journal of geophysical research. Oceans Vol. 122; no. 2; pp. 1232 - 1253
• Main Authors: Mendonça, L. F., Souza, R. B., Aseff, C. R. C., Pezzi, L. P., Möller, O. O., Alves, R. C. M.
• Format: Journal Article
• Language: English
• Published: Washington Blackwell Publishing Ltd 01-02-2017
• Subjects: Annual variations; Brazil Current; Climatology; Coastal currents; Coastal environments; Computer simulation; Continental shelves; currents; Eddy Kinetic Energy; Estimates; Fisheries; Geophysics; Kinetic energy; Marine; Mass distribution; Modelling; Ocean circulation; Ocean models; Oceanography; Oceans; Plankton; regional modeling; Satellite data; Satellite observation; Satellites; Shelf dynamics; Shelves; Southern Brazilian Continental Shelf; Subtropical Shelf Front; Variability; Vortices; Water circulation; Water column; Water mass distribution; Water masses; Winter; Brazil; PSW, Argentina; ASW, Atlantic, Brazil Current
• ISSN: 2169-9275; 2169-9291
• DOI: 10.1002/2016JC011780

The Southern Brazilian Continental Shelf (SBCS) is one of the more productive areas for fisheries in Brazilian waters. The water masses and the dynamical processes of the region present a very seasonal behavior that imprint strong effects in the ecosystem and the weather of the area and its vicinity. This paper makes use of the Regional Ocean Modeling System (ROMS) for studying the water mass distribution and circulation variability in the SBCS during the year of 2012. Model outputs were compared to in situ, historical observations and to satellite data. The model was able to reproduce the main thermohaline characteristics of the waters dominating the SBCS and the adjacent region. The mixing between the Subantarctic Shelf Water and the Subtropical Shelf Water, known as the Subtropical Shelf Front (STSF), presented a clear seasonal change in volume. As a consequence of the mixing and of the seasonal oscillation of the STSF position, the stability of the water column inside the SBCS also changes seasonally. Current velocities and associated transports estimated for the Brazil Current (BC) and for the Brazilian Coastal Current (BCC) agree with previous measurements and estimates, stressing the fact that the opposite flow of the BCC occurring during winter in the study region is about 2 orders of magnitude smaller than that of the BC. Seasonal maps of simulated Mean Kinetic Energy and Eddy Kinetic Energy demonstrate the known behavior of the BC and stressed the importance of the mean coastal flow off Argentina throughout the year.
Key Points
The annual variability of water masses and circulation at the SBCS are studied using regional modeling
The Subtropical Shelf Front (STSF) presented a clear change in volume between summer and winter
Water masses, current velocities and transports, MKE and EKE estimates, and variability are consistent with previous measurements.