Flow of bottom and deep water in the amirante passage and mascarene basin

Gregory C. Johnson, David L. Musgrave, Bruce A. Warren, Amy Ffield, Donald Olson

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

In the Indian Ocean the Amirante Passage is the sill through which relatively cold, fresh, oxygen-rich, and nutrient-poor bottom water spreads northward into the Somali Basin from the Mascarene Basin. The passage is also a conduit through which relatively warm, salty, oxygen-poor, and nutrient-rich deep water spreads south. Previous estimates for northward transport of bottom water in the passage have been made from station pairs and sections without benefit of tracer measurements. Previous estimates of southward transport of deep water are scarce. Three hydrographic sections were made across the passage in 1995 and 1996 as part of the World Ocean Circulation Experiment (WOCE). Two WOCE sections were also made perpendicular to the western boundary in the Mascarene Basin, just south of the passage. The geostrophic shear field is used with the salinity, dissolved oxygen, and silica distributions to select a range of zero-velocity surfaces (ZVSs) on potential isotherms from 1.0° to 1.1°C (hence a range of geostrophic transports) for which the flow direction is consistent with the tracer distributions. Objective mapping is used to obtain flux estimates below the deepest common level of station pairs. Estimates in the Mascarene Basin result in a bottom water volume transport from 2.5 to 3.8 × 106 m3 s-1 northward toward the passage below the ZVSs and a deep-water transport between the ZVSs and 2.5°C from 11.6 to 6.4 × 106 m3 s-1 southward. Estimates within the passage result in transports from 1.0 to 1.7 × 106 m3 s-1 northward for the bottom water and from 8.6 to 3.8 × 106 m3 s-1 southward for the deep water.

Original languageEnglish (US)
Article number1998JC900027
Pages (from-to)30973-30984
Number of pages12
JournalJournal of Geophysical Research: Oceans
Volume103
Issue numberC13
StatePublished - Dec 15 1998

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deep water
bottom water
basins
Water
estimates
basin
water
nutrients
tracer
tracers
oceans
oxygen
volume transport
stations
nutrient
sill
Indian Ocean
Nutrients
tracer techniques
dissolved oxygen

ASJC Scopus subject areas

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

Cite this

Johnson, G. C., Musgrave, D. L., Warren, B. A., Ffield, A., & Olson, D. (1998). Flow of bottom and deep water in the amirante passage and mascarene basin. Journal of Geophysical Research: Oceans, 103(C13), 30973-30984. [1998JC900027].

Flow of bottom and deep water in the amirante passage and mascarene basin. / Johnson, Gregory C.; Musgrave, David L.; Warren, Bruce A.; Ffield, Amy; Olson, Donald.

In: Journal of Geophysical Research: Oceans, Vol. 103, No. C13, 1998JC900027, 15.12.1998, p. 30973-30984.

Research output: Contribution to journalArticle

Johnson, GC, Musgrave, DL, Warren, BA, Ffield, A & Olson, D 1998, 'Flow of bottom and deep water in the amirante passage and mascarene basin', Journal of Geophysical Research: Oceans, vol. 103, no. C13, 1998JC900027, pp. 30973-30984.
Johnson GC, Musgrave DL, Warren BA, Ffield A, Olson D. Flow of bottom and deep water in the amirante passage and mascarene basin. Journal of Geophysical Research: Oceans. 1998 Dec 15;103(C13):30973-30984. 1998JC900027.
Johnson, Gregory C. ; Musgrave, David L. ; Warren, Bruce A. ; Ffield, Amy ; Olson, Donald. / Flow of bottom and deep water in the amirante passage and mascarene basin. In: Journal of Geophysical Research: Oceans. 1998 ; Vol. 103, No. C13. pp. 30973-30984.
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