An intensified East Asian winter monsoon in the Japan Sea between 7.9 and 6.6 Ma.
An intensified East Asian winter monsoon in the Japan Sea between 7.9 and 6.6 Ma.
复制标题
7.9 Ma 至 6.6 Ma 期间日本海东亚冬季风增强。
作者：
Matsuzaki;K.M.;Suzuki;N.;and Tada;R.
日本海是一个半封闭的边缘海，在中新世晚期主要通过浅水航道与亚北极西北太平洋相连。我们对现存的常见放射虫种群进行了多元回归分析，估计了9.1-5.3 Ma期间的海表面温度(SST)。结果表明，当海温从24℃下降到16℃时，在7.9~6.6 Ma之间有8℃的降温。我们推测，这种降温主要反映了与东亚冬季风增强有关的冬季降温。另一方面，夏季海温降温发生在6.6~5.8 Ma，表明晚中新世全球降温由7.9~6.6 Ma的冬季降温阶段和6.6~5.8 Ma的夏季降温阶段组成。
The Japan Sea was a semi-closed marginal sea mainly connected to the subarctic northwestern Pacific via shallow seaways during the late Miocene. We use a multiple regression analysis with common extant radiolarian species groups to estimate the sea-surface temperature (SST) for the period between 9.1 and 5.3 Ma. Our results show a cooling of 8 C between 7.9 and 6.6 Ma, when the SST dropped from 24 C to 16 C. We infer that this cooling dominantly reflects wintertime cooling related to an intensified East Asian winter monsoon. On the other hand, cooling of the summertime SST occurred from 6.6 to 5.8 Ma, suggesting that the late Miocene global cooling is composed of a wintertime cooling phase from 7.9 to 6.6 Ma and summertime cooling phase from 6.6 to 5.8 Ma.