Pliocene-Pleistocene evolution of sea surface and intermediate water temperatures from the southwest Pacific.
Pliocene-Pleistocene evolution of sea surface and intermediate water temperatures from the southwest Pacific.
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DOI：
10.1002/2016pa002954
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发表时间：
2016-06
期刊：
影响因子：
--
通讯作者：
Elderfield H
中科院分区：
文献类型：
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作者：
McClymont EL;Elmore AC;Kender S;Leng MJ;Greaves M;Elderfield H
在过去的500万年里，全球气候系统已经朝着一个更冷的平均状态发展，其标志是大陆冰量的大幅振荡。极地沃茨向赤道方向扩张，温度梯度增强。然而，南半球中纬度和高纬度地区的响应没有得到很好的记录，尽管对气候反馈（包括海冰分布和低高纬度热量输送）具有潜在的重要性。在这里，我们重建的海洋表面和南极中层水（AAIW）温度的轨道时间尺度从深海钻探项目站点593在塔斯曼海，西南太平洋的上新世更新世的历史。我们确认了表层海洋和AAIW的上新世-更新世总体冷却趋势，尽管模式很复杂。上新世比现代温暖，但我们的数据表明，赤道位移的副热带锋相对于目前和南极绕极流（ACC）的subanastertic前向极位移。两个主要的冷却间隔，从~3 Ma和~1.5 Ma，与其他地方注意到的冷却和冰盖扩张是同期的，并表明极地水团向赤道扩张也是西南太平洋通过上新世-更新世的特征。然而，尽管与ACC有潜在的联系，但观测到的海洋表面温度和AAIW温度的趋势并不相同，并且异常的表面海洋温暖（~2 Ma）和AAIW温度的大幅变化（~1 Ma）突出了与ACC相关的锋面向赤道位移和/或来自副热带的变化的极向热传输之间的复杂相互作用。重建的塔斯曼海表面和南极中层水温从~3.0到2.6 Ma和从1.5 Ma到现在的长期冷却趋势上新世以来复杂的副热带锋位移和亚南极冷却趋势
Over the last 5 million years, the global climate system has evolved toward a colder mean state, marked by large‐amplitude oscillations in continental ice volume. Equatorward expansion of polar waters and strengthening temperature gradients have been detected. However, the response of the mid latitudes and high latitudes of the Southern Hemisphere is not well documented, despite the potential importance for climate feedbacks including sea ice distribution and low‐high latitude heat transport. Here we reconstruct the Pliocene‐Pleistocene history of both sea surface and Antarctic Intermediate Water (AAIW) temperatures on orbital time scales from Deep Sea Drilling Project Site 593 in the Tasman Sea, southwest Pacific. We confirm overall Pliocene‐Pleistocene cooling trends in both the surface ocean and AAIW, although the patterns are complex. The Pliocene is warmer than modern, but our data suggest an equatorward displacement of the subtropical front relative to present and a poleward displacement of the subantarctic front of the Antarctic Circumpolar Current (ACC). Two main intervals of cooling, from ~3 Ma and ~1.5 Ma, are coeval with cooling and ice sheet expansion noted elsewhere and suggest that equatorward expansion of polar water masses also characterized the southwest Pacific through the Pliocene‐Pleistocene. However, the observed trends in sea surface temperature and AAIW temperature are not identical despite an underlying link to the ACC, and intervals of unusual surface ocean warmth (~2 Ma) and large‐amplitude variability in AAIW temperatures (from ~1 Ma) highlight complex interactions between equatorward displacements of fronts associated with the ACC and/or varying poleward heat transport from the subtropics. Reconstructed Tasman Sea surface and Antarctic Intermediate Water temperatures Long‐term cooling trends from ~3.0 to 2.6 Ma and from 1.5 Ma to present Complex subtropical front displacement and subantarctic cooling trends since Pliocene