Northward and southward migrations of frontal zones during the past 40 kyr in the Kuroshio-Oyashio transition area
Northward and southward migrations of frontal zones during the past 40 kyr in the Kuroshio-Oyashio transition area
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DOI：
10.1029/2004gc000740
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发表时间：
2004-09-01
影响因子：
3.5
通讯作者：
Murayama, M
中科院分区：
文献类型：
--
作者：
Harada, N;Ahagon, N;Murayama, M
利用长链不饱和烷基酮（alkenones）估算了近40年来黑潮-冈潮过渡区和鄂霍次克海海温的变化。在黑潮-漂潮过渡区，当前冰期与末次冰期的温差约为5 -6度，略大于先前报道的4度。此外，在公元前18kyr之前，在鄂霍次克海或其附近没有检测到烯酮，这可能是因为几乎全年的海冰扩张，这可能会阻止烯酮生成物的生长，或者是因为在冰期，烯酮在地表沉积物中保存得不太好。利用亚北极锋（SAF）、亚北极边界（SAB）和黑潮分岔锋（KBF）附近站点间的烯烃温度差异评估锋面区向北和向南迁移。三个锋面带在冰期均有向南迁移的趋势，全新世与冰期的相对位置存在差异。特别是在冰期，与现在相比，SAF和SAB之间的距离减小了。锋面区向北和向南的迁移可能与中低空大气环流和极地大气环流有关。
The variation of sea surface temperature (SST) in the Kuroshio-Oyashio transition area and the Okhotsk Sea during the last 40 kyr was estimated using long-chain unsaturated alkyl ketones (alkenones). The temperature difference between the present and the last glacial period was about 5degrees-6degreesC in the Kuroshio-Oyashio transition area, slightly larger than the 4degreesC previously reported. Moreover, alkenones were not detected before 18 kyr B. P. in or near the Okhotsk Sea, perhaps because of nearly year-round sea-ice expansion, which would have prevented the growth of alkenone producers, or because alkenones were less well preserved in surface sediments during the glacial period. The northward and southward migrations of frontal zones were evaluated using differences in alkenone temperatures between stations located in the vicinity of the Subarctic Front (SAF), Subarctic Boundary (SAB), and Kuroshio Bifurcation Front (KBF). All three frontal zones migrated southward during the glacial period, compared with their present positions, and their relative positions were different between the Holocene and glacial periods. In particular, the distance between the SAF and the SAB was reduced during the glacial period compared with at present. The northward and southward migration of the frontal zones may relate to both mid to low atmospheric circulation and polar atmospheric circulation.