古水温変動からみた北太平洋の軌道強制力に対する応答(<特集>後期新生代の環境指標としての微古生物学と古海洋学の進展)

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We present a palaeoceanographic perspective of the North Pacific during the last two glacial cycles based on U^<K'>_<37>-derived palaeotemperature records from Japan and California margins. At the Japan margin, the sea surface temperature (SST) in the Kuroshio-Oyashio transition has varied in response to precessional cycle. At the California margin, SST has varied in response to ice volume changes, but the SST difference between inshore and offshore sites (ΔSST_<northeastern Pacific (NEP)>=SST_<ODP1014>-SST_<ODP1016>) has responded to precessional cycle. Comparison of ΔSST_<NEP> and the SST_<MD01-2421> of the central Japan margin revealed anti-phase variation; high ΔSST_<NEP> (indicating weakening of the California Current) corresponded to low SST at the Japan margin (indicating the southward displacement of the northwestern Pacific subarctic boundary and weakening of the Kuroshio Extension), and vice versa. This finding suggests that the intensity of the North Pacific subtropical gyre circulation has varied in response to precessional forcing.
2009-10-16