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.

热带和亚热带气候的可变性经常与ENSO有关，不仅在太平洋，而且在印度洋。但是，印度洋的ENSO与气候变化之间的相关性并不总是很高。最近，发现了印度洋偶极子（IOD），这是镜像，但独立于ENSO（Saji等人，自然，401,360-363，1999，然后是一系列论文）。印度洋和世界其他地区周围的许多异常气候（干旱和洪水）已证明与IOD有关。但是，IOD已通过仪器观察记录进行了分析，该记录通常仅在过去40年中扩展。因此，它与ENSO和季风相关的衰老和更长的时间尺度变化仍然有待解决。在这项研究项目中，我们打算通过珊瑚年度乐队重建iod和相关气候的长期变化，并由湖泊岩心在过去的几千年中重建一百年。我们成功地从塞舌尔和肯尼亚的6个殖民地获得了16个珊瑚岩心（最大长度：234厘米），并在埃及的卡伦湖（Lake Qarun）获得了5个湖泊沉积物核心（最大长度：617.5厘米）。我们预计岩心岩心在过去一百年中创造了降水的变化，而湖泊沉积物岩心在过去的几千年中记录了变化的尼罗河河河流历史，这两者都与IOD密切相关。对核心的分析正在进行中，但我们发现珊瑚和湖泊沉积物岩心的质量都很高。分析完成后，我们希望获得IOD变异性和古气候变化的高质量记录。