Collaborative Research into Indo-Asian Monsoon Variability: Data and Model Assessment of Northern- and Southern-Hemisphere Mechanisms

根据该奖项，PI将生成和分析亚洲季风系统在500万至200万年前的代理记录，并运行一组核心的8个GCM实验，这些实验将测试导致印度和亚洲季风增强和演变的关键气候过程的三个假设：1）北方夏季的时间-季风对来自南半球的潜热输出比对亚洲地区的直接感热输出更敏感。2）大尺度季风的产生和发展，北方半球的规模冰量加强了冬季风，减弱了夏季风，是观测到的相对于轨道强迫的非定常相位响应的根本原因（即最强的夏季季风漂移相对于太阳辐射强迫的时间）。3）冬季和夏季的强度-季风环流与北方半球的冰川演变是动态耦合和联系的。 使用地质记录测试这些假设将通过分析和比较季风响应期间迅速演变，高冰量间隔从3.2马到现在和温暖，相对稳定，最小的冰间隔5至3.2马。在地球历史的两个间隔期间，具有非常不同的大尺度边界条件的分析季风变化的组合数据/模型策略将能够区分在轨道时间尺度上负责季节性季风变化的内部（气候反馈）和外部（日射）机制。

Under this award the PIs will generate and analyze proxy records of the Asian monsoon system over the interval from 5 to 2 million years before present and to run a core set of eight GCM experiments which will test three hypotheses regarding key climate processes that lead to intensification and evolution of the Indian and Asian monsoons:1) The timing of strong Northern Hemisphere summer-monsoons is more sensitive to the export of latent heat from the Southern Hemisphere than to direct sensible heating over Asia.2) The initiation and development of large-scale ice volume in the Northern Hemisphere strengthens the winter monsoon, weakens the summer monsoon and is the root cause of the observed non-stationary phase response relative to orbital forcing (i.e. the timing of the strongest summer-monsoon drifts relative to insolation forcing).3) The intensity of winter- and summer-monsoon circulation is dynamically coupled and linked to glacial evolution in the Northern Hemisphere. Testing these hypotheses using the geological record will be accomplished by analyzing and comparing the monsoon response during the rapidly evolving, high ice-volume interval from 3.2 Ma to present and the warm, relatively stable, minimal ice interval 5 to 3.2 Ma. The combined data/model strategy of analyzing monsoon variability during two intervals of Earth history with very different large-scale boundary conditions will enable differentiation of internal (climate feedback) and external (insolation) mechanisms responsible for seasonal monsoon variability at orbital time scales.