HR: 1340h
AN: OS13A-0996    [Abstracts]
TI: Decadal Variations of the Subtropical Front in a North Pacific Eddy Resolving OGCM
AU: * Yamanaka, G
EM: gyamanak@mri-jma.go.jp
AF: Meteorological Research Institute, Nagamine 1-1, Tsukuba, 3050052, Japan
AU: Ishizaki, H
EM: hishizak@mri-jma.go.jp
AF: Meteorological Research Institute, Nagamine 1-1, Tsukuba, 3050052, Japan
AU: Hirabara, M
EM: mhirabar@mri-jma.go.jp
AF: Meteorological Research Institute, Nagamine 1-1, Tsukuba, 3050052, Japan
AU: Ishikawa, I
EM: iishikawa@met.kishou.go.jp
AF: Japan Meteorological Agency, Otemachi 1-3-4, Chiyoda-ku, Tokyo, 1008122, Japan
AB: Variations of both the subtropical front (STF) and the subarctic front (SAF) are related to the two dominant modes of the North Pacific SST on decadal timescale. Although there have been many studies on the variation of the SAF, the variation of the STF has not been well understood because of temporal and spatial scarcity of observed data. In this study, decadal variations of the STF are examined with a North Pacific ocean general circulation model (OGCM). The OGCM we employed is based on the Meteorological Research Institute Community Ocean Model (MRI.COM). The model domain is the North Pacific north of 15{°}S. The model is driven by the daily surface fluxes of momentum, heat, and freshwater derived from the NCEP/NCAR atmospheric reanalysis data for the period 1949- 2005. Three types of simulations with different horizontal resolutions are compared. On the long-term mean fields, an eddy resolving model (1/12°) was able to simulate the distributions of the STF and the associated subtropical counter current (STCC) between 20{°}N and 30{°}N, better than a non-eddy resolving model (1°) and an eddy-permitting model (1/4° x 1/6°), reflecting the more realistic representation of the simulated Kuroshio recirculation gyre in the eddy resolving model. The simulated STF showed a significant decadal variation; the strength of the STF was relatively strong in 1975/79, while it was relatively weak in 1990/94. The decadal-scale STF change was largely explained by the corresponding variability of the mode waters, which were formed in the western North Pacific and advected to the north of the STF by the subtropical gyre. The relationship between the decadal variation of the STF and surface fluxes is also discussed.
DE: 4215 Climate and interannual variability (1616, 1635, 3305, 3309, 4513)
DE: 4283 Water masses
DE: 4513 Decadal ocean variability (1616, 1635, 3305, 4215)
DE: 4532 General circulation (1218, 1222)
DE: 4534 Hydrodynamic modeling
SC: Ocean Sciences [OS]
MN: 2007 Fall Meeting