Mid Miocene Indian Monsoon Dynamics

20多亿人的生计依赖于亚洲季风雨，即使使用最先进的海洋-大气耦合大气环流模式，也仍然难以预测。对于这些模型来说，详细了解季风在不同边界条件下的行为是至关重要的，例如，世界变暖，大陆冰盖减少。我们还需要知道季风系统第一次增强的方式和时间，它后来是如何发展的，以及它如何因应各种潜在的影响而发生变化，这些影响包括全球气候变化、造山以及海洋航道的开放和关闭。现代东亚和印度季风系统加强的时间存在争议，一些记录(如阿拉伯海上升流)表明最初的加强发生在约700-800万年前，而另一些记录(如黄土形成)表明它最早发生在约2200万年前，甚至更早。模拟研究表明，季风的加强与西藏的隆升直接相关，直接将全球气候和构造联系在一起。在这里，我们建议使用新的高质量的中新世沉积岩心，来自孟加拉湾(Exp.353)重建印度季风在中新世(2300万至560万年前)的演化。我们将在轨道时间尺度上研究该地区大陆风化与全球气候的耦合。利用季风风引起的垂直表层海洋混合、季风雨引起的盐度变化和痕量金属向海洋的风化通量的高分辨率替代记录，这一研究结果将显著提高我们对亚洲季风发展的理解，并将有助于更准确地模拟季风系统。

The livelihoods of more than 2 billion people depend on the Asian monsoon rains, which are still difficult to predict even with the most advanced coupled ocean-atmosphere general circulation models. A detailed understanding how the monsoon behaves under different boundary conditions such as a warmer world with less continental ice cover is vital for these models. We also need to know how and when the monsoon system first intensified, how it subsequently developed and how it has varied in response to various potential influences including global climate changes, mountain building and opening and closing of oceanic gateways. The timing of the intensification of the modern East Asian and Indian monsoon systems is controversial, with some records (e.g. Arabian Sea upwelling) indicating initial intensification occurred ~7–8 million years ago, whereas others (e.g. Loess formation) suggest it was as early as ~22 million years ago, or even earlier. Modeling studies have suggested that the intensification of the monsoon was directly related to the uplift of Tibet, directly linking global climate and tectonics. Here we propose to use new high quality Miocene sediment cores from the Bay of Bengal (Exp. 353) to reconstruct the evolution of the Indian monsoon through the Miocene period (23 to 5.6 million years ago). We will investigate the coupling of continental weathering in the region with global climate on orbital time scales. Using high resolution proxy records of vertical surface ocean mixing by monsoon winds, salinity changes caused by monsoon rains and the weathering flux of trace metals to the ocean, the results of this study will significantly improve our understanding of the development of the Asian monsoon and will contribute to a more accurate modeling of the monsoon system.