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Long-term reconstruction of Indian Ocean Dipole variability by coral and lake sediment cores

通过珊瑚和湖泊沉积岩芯长期重建印度洋偶极子变率

基本信息

批准号：
14253005
负责人：
KAYANNE Hajime
金额：
$ 25.96万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-14253005/
关键词：
Indian Ocean Indian Dipole variability coral annual band lake sediment paleoceanography Seychelles Kenya Egypt ケニヤ

项目摘要

Variability of tropical and subtropical climate has often been explained in relation to ENSO not only in the Pacific but also in the Indian Ocean. However, correlation between ENSO and climate variability in the Indian Ocean is not always high. Recently, Indian Ocean Dipole(IOD) was discovered, which is a mirror image but acts independently of ENSO (Saji et al., Nature, 401,360-363,1999 followed by a series of papers). Many anomalous climates (droughts and floods) around Indian Ocean and other areas of the world have shown to be better understood in relation to IOD. However, IOD has been analyzed by instrumental observation records, which usually extend only for the last 40 years. Therefore, its decadal and longer time-scale variability in relation to ENSO and monsoon remains to be solved.In this research project, we intended to reconstruct long-term variability of IOD and related climate for the last several decades to a hundred years by coral annual bands, and for the last several thousand years by lake sediment cores. We succeeded in obtaining 16 coral cores (maximum length : 234 cm) from six colonies in Seychelles and Kenya, and five lake sediment cores (maximum length : 617.5 cm) at Lake Qarun in Egypt. We expect that coral cores record precipitation changes for the last one hundred years, and that lake sediment cores record changing history of River Nile discharge for the last several thousand years, both of which are closely related to IOD. The analysis of the cores is in progress, but we have found that the quality of both the coral and lake sediment cores are very high. We expect to obtain high-quality record of IOD variability and paleoclimate change after the analysis finishes.

不仅在太平洋，而且在印度洋，热带和亚热带气候的多变性常常被解释为与厄尔尼诺/南方涛动有关。然而，厄尔尼诺/南方涛动与印度洋气候变率之间的相关性并不总是很高。最近，印度洋偶极子（IOD）被发现，它是一个镜像，但独立于ENSO（Saji等人，Nature，401，360 - 363，1999，随后是一系列论文）。印度洋和世界其他地区的许多异常气候（干旱和洪水）与印度洋日积月累的关系已被证明是更好的理解。然而，IOD是通过仪器观测记录进行分析的，这些记录通常只延续到最近40年。本研究计划利用珊瑚年谱和湖泊沉积物柱样重建近几十年到一百年IOD及其相关气候的长期变化。我们成功地获得了16个珊瑚芯（最大长度：234厘米），从塞舌尔和肯尼亚的6个殖民地，和5个湖泊沉积物芯（最大长度：617.5厘米）在Qarun湖在埃及。我们认为珊瑚岩芯记录了近百年来的降水变化，湖泊沉积物岩芯记录了近几千年来尼罗河流量的变化历史，两者都与IOD密切相关。岩心分析正在进行中，但我们发现珊瑚和湖泊沉积物岩心的质量都很高。我们期望在分析完成后，获得高质量的IOD变化和古气候变化的记录。