North Brazil Current rings and transport of southern waters in a high resolution numerical simulation of the North Atlantic

Zulema D. Garraffo, William E. Johns, Eric P.Chassignet, Gustavo J. Goni

Research output: Contribution to journalArticle

25 Scopus citations

Abstract

Output from a very high resolution (1/12 deg.) North Atlantic simulation with the Miami Isopycnic Coordinate Ocean Model (MICOM) is analyzed in a region of the Tropical Atlantic characterized by the presence of the North Brazil Current (NBC) retroflection and North Brazil Current rings. The model mean and seasonal circulations present a good qualitative agreement with observations. Quantitatively, the modeled NBC in summer and fall does not completely retroflect into the North Equatorial Counter Current, and the model upper 100 m NBC is more intense than the observed values by 3-4 Sv. The modeled NBC generates a variety of rings, which we classify as 'shallow', 'intermediate', 'deep', and 'subsurface'. An average of 8.3 rings of all types are generated per year, of which 6 are surface intensified, in good agreement with altimetry (5.7 rings per year, Goni and Johns, 2001). The transport of southern origin water by the the rings was estimated using two methods. First, the transport was computed kinematically from the rings' volume, resulting in an average transport of 6.6 Sv. Second, an estimation of southern water transport based on an explicit calculation of water mass content was done, resulting in an average transport of 7.5 Sv. The rings' contribution represents 0% of the total meridional transport from the surface to the intermediate water layers. Possible mechanisms operating in the model ring generation are briefly discussed.

Original languageEnglish (US)
Pages (from-to)375-409
Number of pages35
JournalElsevier Oceanography Series
Volume68
Issue numberC
DOIs
StatePublished - Dec 1 2003

ASJC Scopus subject areas

  • Oceanography

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