Heat transport variation due to change of North Pacific subtropical gyre interior flow during 1993–2012

Akira Nagano, Shoichi Kizu, Kimio Hanawa, Dean Roemmich

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6 Citations (Scopus)


Applying segment-wise altimetry-based gravest empirical mode method to expendable bathythermograph temperature, Argo salinity, and altimetric sea surface height data in March, June, and November from San Francisco to near Japan (30 N, 145 E) via Honolulu, we estimated the component of the heat transport variation caused by change in the southward interior geostrophic flow of the North Pacific subtropical gyre in the top 700 m layer during 1993–2012. The volume transport-weighted temperature (TI) is strongly dependent on the season. The anomaly of TI from the mean seasonal variation, whose standard deviation is 0.14C, was revealed to be caused mainly by change in the volume transport in a potential density layer of 25.0−25.5σαθ. The anomaly of TI was observed to vary on a decadal or shorter, i.e., quasi-decadal (QD), timescale. The QD-scale variation of TI had peaks in 1998 and 2007, equivalent to the reduction in the net heat transport by 6 and 10 TW, respectively, approximately 1 year before those of sea surface temperature (SST) in the warm pool region, east of the Philippines. This suggests that variation in TI affects the warm pool SST through modification of the heat balance owing to the entrainment of southward transported water into the mixed layer.

Original languageEnglish
Pages (from-to)1637-1649
Number of pages13
JournalOcean Dynamics
Issue number12
Publication statusPublished - 2016 Dec 1


  • AGEM
  • Heat transport
  • North Pacific subtropical gyre interior flow
  • Quasi-decadal timescale variation
  • Volume transport-weighted temperature

ASJC Scopus subject areas

  • Oceanography


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