研究影响南海北部沉积物输移的气候与人为强迫因素：旨在重新评估并更深入理解改变东南亚台风发生频率与强度的过程。

本研究项目旨在通过分析高平海底峡谷中的沉积物堆积，重建过去数千年中影响台湾南部的台风历史。将利用地球化学技术评估台风强度和频率的变化，并将这些变化与气候过程及环境变化联系起来。

Job description: Project description: Approximately 80 tropical storms form each year at tropical and subtropical latitudes of the ocean. Tropical cyclones, referred to as typhoons in the western North Pacific regions, are the most intense tropical storms, accounting for more than 50% of the yearly events (Emanuel, 2003). Tropical cyclones have a significant impact on societies and human activities, causing considerable human and economic losses each year (Zhang et al., 2009; Smith, 2020). In the region of Taiwan, the rainfall associated with the 3-4 typhoons that occur per year leads to destructive processes on land, such as landslide and floods which cause considerable damage and casualties. Strong typhoons like Morakot (2009) can produce rainfall and sediment loads sufficient to trigger deep-sea hyperpycnal flows and damage human submarine infrastructures like telecommunication cables to the south of Taiwan (Gavey et al., 2017). It is therefore essential to reconstruct the dynamics of typhoons (recurrence and intensity) and the causes of their evolution through time in order to improve their predictability in the context of global warming. A large effort has been done during the last decade in order to constrain mineralogical and geochemical compositions of the present-day sediments supplied by the rivers feeding the northern South China Sea (e.g., Liu et al., 2016) and collected by mooring systems (e.g., Zhang et al., 2018). Results allow to better constrain the sources of the sediment to the northern South China Sea (Liu et al., 2016) as well as to establish the present-day dynamic of sediments transport to the deep basins of the South China Sea in link with the climatic changes such as monsoon rainfall or extreme events (typhoons, mesoscale eddies…) (Zhang et al., 2018). The northern South China Sea can be considered as a natural “sedimentological laboratory’’ permitting, for the first time in detail, to constrain the relationships existing between past climate changes and sediment dynamic processes by using a robust ‘’source to sink’’ approach. Notably, it is possible to reconstruct extreme events, such as typhoons, affecting southern Taiwan over the last few millennia from sediments deposits along the submarine canyon of Gaoping. This original and innovative approach allows us to constrain the anthropogenic and climatic processes that have modified the recurrence and intensity of typhoons affecting southern Taiwan over time. The HYDROSED cruise, aboard the Marion Dufresne, have permit to recovery long cores from the levee of the Gaoping submarine canyon. The thesis work will permit to reconstruct the evolution of levee of the submarine canton since the last glacial periods and to constrain the dynamics of sedimentary processes linked to sediment transfers input from the Gaoping River (South Taiwan) to the northern margin of the South China Sea. More particularly, we propose to (i) identify sources and characterize turbidite deposits ; (ii) to analyse the relationship between sea level variations, rainfall (Southeast Asian monsoon and typhoons) and paleo-environmental changes on land, and the recurrence of turbidite deposits over time ; (iii) reconstruct the history of typhoon recurrence and intensity since the last glacial period ; and (iv) establish and constrain the climatic mechanisms responsible for changes in typhoon frequency over time in order to improve the predictability of future climate scenarios.

所需个人背景与技能要求： 申请者需具备地球化学与地质学方面的知识。对古气候学和/或海洋沉积地质学技能亦备受重视。申请者将在多个分析平台上开展研究，并运用各种尖端技术取得研究成果。此外，申请者需进行文献研究，撰写摘要与文章，且具备较高的英语水平。 所需法语水平：基础级。如果您与交流对象能够轻声清晰地交谈，您就能理解日常基本场景中的语言内容。您能够理解并使用简单的表达方式。