Ocean Dynamics

, Volume 66, Issue 6–7, pp 893–916 | Cite as

An assessment of the Brazil Current baroclinic structure and variability near 22° S in Distinct Ocean Forecasting and Analysis Systems

  • Mateus O. Lima
  • Mauro Cirano
  • Mauricio M. Mata
  • Marlos Goes
  • Gustavo Goni
  • Molly Baringer
Article
Part of the following topical collections:
  1. Topical Collection on Coastal Ocean Forecasting Science supported by the GODAE OceanView Coastal Oceans and Shelf Seas Task Team (COSS-TT)

Abstract

The Brazil Current (BC) is the Western Boundary Current of the South Atlantic subtropical gyre, the dominant dynamic feature in the South Atlantic Ocean. The importance of this current lies in that it is the main conduit of subtropical waters to higher latitudes in the South Atlantic Ocean. This study assesses the structure and variability of the BC across the nominal latitude of 22° S using data from the high-density eXpendable BathyThermograph (XBT) AX97 transect and from three numerical ocean models with data assimilation. This XBT transect was implemented in 2004 and represents one of the longer-term monitoring systems of the BC in existence. The goal of this work is to enhance the understanding of the temporal and spatial variability of the ocean dynamics in the southwestern South Atlantic Ocean by using a suite of hydrographic observations and numerical model outputs. In the present work, 37 XBT transect realizations using data collected between 2004 and 2012 are used. Daily outputs covering the same time period are evaluated from Hybrid Coordinate Ocean Model with the Navy Coupled Ocean Data Assimilation (HYCOM-NCODA) with a 1/12° horizontal resolution, and GLORYS2V3 and FOAM, both with a 1/4° horizontal resolution. These Ocean Forecasting and Analysis Systems (OFAS) are able to capture the mean observed features in the 22° S region, showing a BC core confined to the west of 39° W and an Intermediate Western Boundary Current between the depths of 200 and 800 m. However, the OFAS tend to overestimate the mean BC baroclinic volume transport across the AX97 reference transect and underestimate its variability. The OFAS show that the coastal region between the coastline and the western edge of the AX97 transect plays an important role in the mean BC total transport, contributing to up to 23 % of its value, and further that this transport is not sampled by the XBT observations with its current sampling strategy. In order to understand the variability of the BC, a statistical classification of the BC is proposed, with the identification of three different events: weak, intermediate, and strong.

Keywords

Western Boundary Current Brazil Current Ocean Forecast and Analysis Systems AX97 reference transect XBT 

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Copyright information

© Springer-Verlag Berlin Heidelberg 2016

Authors and Affiliations

  • Mateus O. Lima
    • 1
    • 2
  • Mauro Cirano
    • 1
    • 2
    • 3
  • Mauricio M. Mata
    • 4
  • Marlos Goes
    • 5
    • 6
  • Gustavo Goni
    • 5
  • Molly Baringer
    • 5
  1. 1.Graduate Program in GeophysicsFederal University of Bahia (UFBA)SalvadorBrazil
  2. 2.Oceanographic Modeling and Observation Network (REMO)Rio de JaneiroBrazil
  3. 3.Institute of GeosciencesFederal University of Rio de Janeiro (UFRJ)Rio de JaneiroBrazil
  4. 4.Institute of OceanographyFederal University of Rio Grande (FURG)Rio GrandeBrazil
  5. 5.Physical Oceanography DivisionAtlantic Oceanographic and Meteorological Laboratory, National Oceanic and Atmospheric Administration (NOAA/AOML)MiamiUSA
  6. 6.Cooperative Institute for Marine and Atmospheric StudiesUniversity of MiamiMiamiUSA

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