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The tropical rain belt of South America during Plio-Pleistocene cooling

上里奥-更新世冷却期间的南美洲热带雨带

基本信息

批准号：
260717210
负责人：
Dr. Lydie Madeleine Dupont
金额：
--
依托单位：
Alfred-Wegener-Institut (AWI) Helmholtz-Zentrum für Polar- und Meeresforschung
依托单位国家：
德国
项目类别：
Infrastructure Priority Programmes
财政年份：
2014
资助国家：
德国
起止时间：
2013-12-31 至 2017-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/260717210?language=en
关键词：
tropical rain belt South America

项目摘要

The proposal focusses on the timing of the atmospheric circulation intensification and the position of the Intertropical Convergence Zone (ITCZ) over South America during the Pliocene. Pliocene cooling involves the intensification of the atmospheric circulation related to temperature changes in the Equatorial Pacific Ocean. Pliocene sea surface temperature (SST) records of the Pacific indicate that increases of the zonal and meridional SST gradients intensified the atmospheric Walker and Hadley circulations, respectively. Restriction of the surface water exchange between the Atlantic and Pacific oceans recorded by the salinity divergence between oceans indicates that the final closure of the Central American Seaway (CAS) occurred between 4.7 and 4.2 Ma. The closure had a strong impact on the circulation in the Equatorial Pacific and the development of the eastern Equatorial Pacific cold tongue. Closure of the CAS also influenced the latitudinal position of the ITCZ, but models and data indicate shifts in opposite directions. The proposal aims at a palynological record of Pliocene vegetation change in west equatorial South America and the western Andean Cordillera for three key periods of the Pliocene using marine sediments of ODP Site 1239 offshore of Ecuador. We aim at a record of changes in climate and terrestrial hydrology of northwest South America related to an early shift of the ITCZ between 4.7 and 4.2 and the timing of the intensification of the Walker circulation between 3.6 and 1.7 Ma. In the first year we approached the early Pliocene period. We could demonstrate that the ITCZ shifted southwards in line with the data confirming the hypothesis of its southward shift during CAS closure.

该建议的重点是大气环流加强的时间和位置的热带辐合带（ITCZ）在南美洲上新世。上新世冷却涉及到与赤道太平洋温度变化有关的大气环流的加强。太平洋上新世海表温度（SST）记录表明，纬向和纬向SST梯度的增加分别加强了大气步行者和Hadley环流。大西洋和太平洋之间的表面水交换的限制记录的海洋之间的盐度差异表明，中美洲航道（CAS）的最终关闭发生在4.7和4.2 Ma之间。这次关闭对赤道太平洋环流和赤道东太平洋冷舌的发展有强烈的影响。CAS的关闭也影响了ITCZ的纬度位置，但模型和数据表明，在相反的方向上的变化。该提案旨在利用厄瓜多尔近海ODP 1239号站点的海洋沉积物，对南美洲赤道西部和安第斯山脉西部上新世三个关键时期的上新世植被变化进行孢粉学记录。我们的目标是在气候和陆地水文的南美洲西北部的早期转移的ITCZ之间的4.7和4.2和3.6和1.7 Ma之间的步行者流通的加强的时间有关的变化的记录。第一年，我们接近上新世早期。我们可以证明，ITCZ南移的数据证实了其南移的假设，在CAS关闭。