Investigation of Brazil current rings in the confluence region

Carlos A.D. Lentini, Gustavo J. Goni, Donald B. Olson

Research output: Contribution to journalArticle

27 Scopus citations

Abstract

TOPEX/Poseidon-derived along track SHA, climatological temperature, and salinity fields were used within a two-layer scheme to estimate the depth of the 8°C isotherm in the southwestern Atlantic. These fields were used to monitor the formation and characteristic of the Brazil Current warm-core anticyclonic rings shed by the first meander trough after poleward excursions of the Brazil Current (BC). Results reveal that 40 warm-core rings were shed by the BC between January 1993 and October 1998. The observe lifetime ranges between 1 and 4 months, with a mean value of approximately 2 months. At any given time, two to three anticyclonic rings coexisted in the Brazil-Malivinas confluence region. Most of the rings drifted southward without coalescing with their parent current. Only four rings were identified as being reabsorbed by the BC front after they were shed. No evidence of propagation or absorption of these anticyclones into the eastern limb of the subtropical gyre was observed. These rings have a mean horizontal length scale of 55 km, d-1. Volume anomaly and available potential energy computations showed a mean value of 3.6 × 1012 m3 and 2.5 × 1015 J, respectively. The upper layer transport of the BC was also computed, and a relationship between variations in the southward transport and ring shedding activity was examined. Computation of the heat flux anomaly of the BC rings is estimated to be approximately 0.045 PW per annum. Compilation of these results indicates that warm-core rings created by meandering boundary current extentions in different regions are generally similar.

Original languageEnglish (US)
Article numberC06013
JournalJournal of Geophysical Research: Oceans
Volume111
Issue number6
DOIs
StatePublished - Jun 8 2006

ASJC Scopus subject areas

  • Geophysics
  • Forestry
  • Oceanography
  • Aquatic Science
  • Ecology
  • Water Science and Technology
  • Soil Science
  • Geochemistry and Petrology
  • Earth-Surface Processes
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Palaeontology

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