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地点。年气候变化受到印度季风的强烈控制，其特点是每两年逆转一次信风。沃克环流的年际气候变化是由印度洋偶极子和厄尔尼诺-南方涛动造成的，导致严重的洪水或严重的干旱，如2011年东非的饥荒。在海洋方面，热带西印度洋接受来自印度尼西亚关口地区的水团，赤道以南的亚南极水域，以及高度含盐量的红海的流出水。另一方面，热带西印度洋是为阿古拉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重要信息，说明这些不同因素过去是如何变化的，未来也可能是如何变化的。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岩芯。在坦桑尼亚附近奔巴岛以东的RV Meteor邮轮M75/2期间发现的GEOB 12613-1，提供了一个开阔的海洋核心，具有保存完好的沉积物，覆盖了过去五个冰川-间冰期旋回。这一建议的研究目标是利用不同种类浮游有孔虫的镁/钙和稳定同位素来检验以下假设：海面温度和相对海面盐度的变化在轨道时间尺度上是分离的；由于Walker环流的变化，印度洋两岸的水柱分层，包括跨盆地的梯度，在千年尺度上是不同的；以及对Agulhas洋流系统的盐分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.