Collaborative Research: High-Resolution, Low-Latitude Paleoclimatology From Newly Acquired Sediment Drill Cores From Lake Bosumtwi, Ghana

博苏姆特维湖位于西非加纳热带森林低地的一个百万年前的陨石撞击坑内。该湖在水文上是封闭的，众所周知，它对降水/蒸发平衡和西非季风的强度非常敏感。博苏姆特维湖包含热带地区为数不多的、每年长时间的层状沉积记录之一，并且拥有迄今为止赤道西非最长、分辨率最高的古气候记录。这项工作洞察了热带地区在触发、加剧和传播气候变化以及应对全球和高纬度变化方面的作用。这项工作将产生关于西非气候和气溶胶在多个冰川周期中变化的第一个连续的准确的陆地记录，并对一个关键的甲烷来源区提供水文约束，并利用每年分层的沉积物来审查有关多个冰川终止的确切时间和变化模式的全球重大问题(例如，低纬地区对冰川消融事件的反应是什么，我们能否评估大冰盖融化和导致间冰期条件的速度？在以前的终止中，气候逆转的性质是什么？MIS11持续了多长时间，它是如何在热带地区表现出来的，它与轨道强迫，特别是最后的轨道强迫有什么真正的联系？在温暖的气候中，干旱变化的全部范围是什么？)

Lake Bosumtwi lies in a million-year-old meteorite impact crater located in the tropical forest lowlands of Ghana, in West Africa. The lake is hydrologically closed and known to be very sensitive to the precipitation/evaporation balance and the strength of the West African Monsoon. Lake Bosumtwi contains one of a very few, long annually laminated sediment records in the tropics, and has by far the longest, highest-resolution paleoclimate record in equatorial West Africa.Intellectual Merit: This grant studies interannual to millennial-scale West African monsoon dynamics over the last ~430 kyr (i.e., back through Marine Isotopic Stage [MIS] 11). This work provides insight into the role of the tropics in triggering, intensifying and propagating climate changes, as well as in responding to global and highlatitude changes. This work will produce the first continuous well-dated terrestrial record of West African climate & aerosol variability over multiple glacial cycles, and provide hydrologic constraints on a key methane source region, and use the annually-laminated sediments to examine globally significant questions regarding the exact timing and patterns of change over multiple glacial terminations (e.g., What is the low-latitude response to deglaciation events, and can we assess how fast large ice sheets melt and lead to interglacial conditions? What is the nature of climatic reversals on previous terminations? How long was MIS11, how was it manifested in the tropics, and how does it really relate to orbital forcing, particularly at the end? What is the full range of drought variability during warm climates?)