Corresponding author address:

• Main Authors: Masami Nonaka, Youichi Tanimoto, Hideharu Sasaki
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2005
• Subjects: Oyashio; Subarctic
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.96.8357; http://eprints.lib.hokudai.ac.jp/dspace/bitstream/2115/13482/1/Nonaka_etal2006.pdf

Through analysis of a hindcast integration of an eddy-resolving quasi-global ocean general circulation model, decadal variability in the Kuroshio-Oyashio Extension region is investigated, with particular emphasis on that of the subarctic (Oyashio) and the Kuroshio Extension (KE) fronts. The KE front is deep and accompanied by sharp sea surface height (SSH) gradient with modest sea surface temperature (SST) gradient. In contrast, the subarctic front is shallow and recognized as a zone of tight gradient in SST but not SSH. As a decadal-scale change from a warm period around 1970 to a cool period in the mid-1980s, those fronts in the model migrate southward as observed, and the associated pronounced cooling is confined mainly to those frontal zones. Reflecting the distinctive vertical structures of the fronts, the mixed-layer cooling is the strongest along the subarctic front, whereas the subsurface cooling and the associated salinity changes are the most pronounced along the KE front. Concomitantly with their southward migration, the two fronts have undergone decadal-scale intensification. Associated with reduced heat release into the atmosphere, the cooling in the frontal zones can be attributed neither to the direct atmospheric thermal forcing nor