A note on boundary conditions for salt and freshwater balances

F. J. Beron-Vera, J. Ochoa, P. Ripa

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

The derivation of surface boundary conditions for salt and freshwater budgets, in the presence of an imbalance of evaporation and precipitation, is revisited in order to: (i) clarify the physical concepts involved and (ii) derive consistent approximations. Proper surface boundary conditions can be obtained by assuming that the air-sea interface is a material surface for the salt continuum. This requires all the mass exchange at the air-sea interface to be fulfilled by the freshwater continuum. The need of diffusive fluxes is crucial for this assumption to hold. If the air-sea interface varies in time (either by seawater advection, an imbalance of evaporation minus precipitation, or a combination of both) there must be a corresponding salt flux, in order for the transport across such moving surface to be nil. Here it is essential to distinguish the flux vector of a property from its transport across a (possibly moving) surface. Only in a motionless ocean surface approximation, which includes the classical rigid lid approximation, the advective and diffusive salt fluxes perpendicular to the surface cancel out exactly.

Original languageEnglish (US)
Pages (from-to)111-118
Number of pages8
JournalOcean Modelling
Volume1
Issue number2-4
DOIs
StatePublished - Oct 1 1999
Externally publishedYes

Keywords

  • Balance
  • Boundary condition
  • Flux
  • Freshwater
  • Salt

ASJC Scopus subject areas

  • Computer Science (miscellaneous)
  • Oceanography
  • Geotechnical Engineering and Engineering Geology
  • Atmospheric Science

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