Numerical study of the meridional overturning circulation with "mixing hotspots"' in the Pacific Ocean

Takahiro Endoh, Toshiyuki Hibiya

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

Using an idealized ocean general circulation model, we examine the effect of "mixing hotspots" (localized regions of intense diapycnal mixing) predicted based on internal wave-wave interaction theory (Hibiya et al., 2006) on the meridional overturning circulation of the Pacific Ocean. Although the assumed diapycnal diffusivity in the mixing hotspots is a little larger than the predicted value, the upwelling in the mixing hotspots is not sufficient to balance the deep-water production; out of 17 Sv of the downwelled water along the southern boundary, only 9.2 Sv is found to upwell in the mixing hotspots. The imbalance as much as 7.8 Sv is compensated by entrainment into the surface mixed layer in the vicinity of the downwelling region. As a result, the northward transport of the deep water crossing the equator is limited to 5.5 Sv, much less than estimated from previous current meter moorings and hydrographic surveys. One plausible explanation for this is that the magnitude of the meridional overturning circulation of the Pacific Ocean has been overestimated by these observations. We raise doubts about the validity of the previous ocean general circulation models where diapycnal diffusivity is assigned ad hoc to attain the current magnitude suggested from current meter moorings and hydrographic surveys.

Original languageEnglish
Pages (from-to)259-266
Number of pages8
JournalJournal of Oceanography
Volume62
Issue number3
DOIs
Publication statusPublished - Jun 2006
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Oceanography

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