Journal of Oceanography

, Volume 68, Issue 1, pp 113–126

Interannual variability of the North Pacific Subtropical Countercurrent: role of local ocean–atmosphere interaction

Special Section: Original Article New developments in mode-water research: Dynamic and climatic effects

DOI: 10.1007/s10872-011-0048-x

Cite this article as:
Kobashi, F. & Xie, SP. J Oceanogr (2012) 68: 113. doi:10.1007/s10872-011-0048-x

Abstract

Seasonal and interannual variability of the Subtropical Countercurrent (STCC) in the western North Pacific are investigated using observations by satellites and Argo profiling floats and an atmospheric reanalysis. The STCC displays a clear seasonal cycle. It is strong in late winter to early summer with a peak in June, and weak in fall. Interannual variations of the spring STCC are associated with an enhanced subtropical front (STF) below the surface mixed layer. In climatology, the SST front induces a band of cyclonic wind stress in May north of the STCC on the background of anticyclonic curls that drive the subtropical gyre. The band of cyclonic wind and the SST front show large interannual variability and are positively correlated with each other, suggesting a positive feedback between them. The cyclonic wind anomaly is negatively correlated with the SSH and SST below. The strong (weak) cyclonic wind anomaly elevates (depresses) the thermocline and causes the fall (rise) in the SSH and SST, accelerating (decelerating) STCC to the south. It is suggested that the anomalies in the SST front and STCC in the preceding winter affect the subsequent development of the cyclonic wind anomaly in May. Results from our analysis of interannual variability support the idea that the local wind forcing in May causes the subsequent variations in STCC.

Keywords

Subtropical countercurrent Interannual variability Ocean–atmosphere interaction Sea surface temperature front 

Copyright information

© The Oceanographic Society of Japan and Springer 2011

Authors and Affiliations

  1. 1.Faculty of Marine TechnologyTokyo University of Marine Science and TechnologyTokyoJapan
  2. 2.Research Institute for Global ChangeJapan Agency for Marine-Earth Science and TechnologyYokosukaJapan
  3. 3.International Pacific Research Center (IPRC) and Department of Meteorology, School of Ocean and Earth Science and Technology (SOEST), University of Hawaii at ManoaHonoluluUSA

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