Reconstruction of PALeo-sea water properties in the tropical western Indian Ocean for the last 470 kyrs using Mg/Ca and stable isotopes on planktonic foraminifera: atmospheric versus oceanographic influences (PALIO).

热带西印度洋是受不同海洋和大气过程影响的古气候研究的关键区域。每年的气候变化受到印度季风的强烈控制，其特征是两年一次的逆风。沃克环流的年际气候变化是由印度洋偶极子和厄尔尼诺Niño-Southern振荡引起的，导致严重的洪水或严重的干旱，如2011年东非的饥荒。海洋学上，热带西印度洋接收来自印度尼西亚门户地区的水团，赤道以南的亚南极水域，以及来自高盐红海的流出水。另一方面，热带西印度洋是向阿古拉斯海流系统提供水团的主要来源。因此，热带西印度洋有可能提供这些不同因素在过去如何变化以及将来可能如何变化的重要信息。不幸的是，到目前为止，还没有覆盖几个冰期-间冰期旋回的长沉积物岩心。GeoB 12613-1是在坦桑尼亚奔巴岛以东的RV流星巡航M75/2期间发现的，它提供了一个保存完好的开放海洋岩心，覆盖了最后五个冰期-间冰期旋回。本文的研究目的是利用不同种类浮游有孔虫的Mg/Ca和稳定同位素，验证海温和相对海盐在轨道时间尺度上解耦的假设；由于Walker环流的变化，印度洋两岸水柱分层（包括跨盆地梯度）在千年时间尺度上发生了变化；对阿古拉斯海流系统的盐供应主要由红海流出水提供。

The tropical western Indian Ocean is a key location for paleoclimate research affected by different oceanographic and atmospheric processes. Annual climate variations are strongly controlled by the Indian Monsoon characterized by bi-annually reversing trade winds. Inter-annual climate variations in the Walker circulation are caused by the Indian Ocean Dipole and El Niño-Southern Oscillation resulting in either heavy flooding or severe droughts like the famine of 2011 in eastern Africa. Oceanographically the tropical western Indian Ocean receives water masses from the Indonesian Gateway area, sub-Antarctic waters that upwell south of the equator, and the outflow waters from the highly saline Red Sea. On the other hand, the tropical western Indian Ocean is a major source for providing water masses to the Agulhas Current system. Thus, the tropical western Indian Ocean has the potential to provide important information on how these different factors have changed in the past, and possibly will change in the future. Unfortunately, until now there were no long sediment cores available covering several glacial-interglacial cycles. GeoB 12613-1, recovered during RV Meteor Cruise M75/2 east of the island of Pemba off Tanzania, provides an open-ocean core with well-preserved sediments covering the last five glacial-interglacial cycles. The research objective of this proposal is to use Mg/Ca and stable isotopes on different species of planktonic foraminifera to test the hypotheses that changes in sea surface temperatures and relative sea surface salinity were de-coupled on orbital time scales; that the water column stratification on both sides of the Indian Ocean including the cross-basin gradients varied on millennial time scales due to changes in the Walker circulation; and that the salt supply to the Agulhas Current system was mainly provided by the Red Sea Outflow Water.