Historical February / September sea-ice concentration and annual sea-ice cover estimation at the location of core MD88-787 in the Southeast Indian Ocean

Variations in microfossil records in sediments over time are used as proxies for changes in the ocean. One important record determined from microfossils is sea-ice cover which influences, and is influenced by, wind and ocean circulation, atmospheric conditions, and heat balance. Increasing emphasis is being placed on the predictive capabilities diatoms may bear in estimating Antarctic sea-ice, one of the important modulators of Southern Hemisphere climate. The purpose of this study was to estimate past sea-ice concentration and annual coverage at the site of core MD88-787 in the Southeast Indian Ocean. The accumulation of diatom microplankton assemblages in sediments being the proxy for these records of climatic change. A new method for sea-ice concentration and cover estimation from CABFAC derived factor analysis was developed during this project. Previous estimations of sea-ice have relied on other avenues of deriving limits to the maximum sea-ice edge, while the model developed here made use of modern sea-ice satellite observations combined with diatom distributions that are considered more closely linked to the sea-ice cover.Three models were proposed which estimated sea-ice concentration in February and September, and annual sea-ice cover.

沉积物（sediments）中微体化石（microfossil）记录的时间序列变化，可作为海洋环境变迁的代用指标。通过微体化石可重建的一项关键环境记录为海冰覆盖（sea-ice cover）状况：海冰覆盖既会影响风力、海洋环流、大气条件与热平衡，同时也受这些因素调控。当前学界愈发重视硅藻（diatoms）在估算南极海冰（Antarctic sea-ice）方面的预测潜力——南极海冰是南半球（Southern Hemisphere）气候的重要调控因子之一。本研究旨在重建东南印度洋（Southeast Indian Ocean）MD88-787岩心（core MD88-787）位点的过去海冰浓度与年覆盖范围。本研究以沉积物中硅藻微浮游生物组合（diatom microplankton assemblages）的堆积特征作为此类气候变化记录的代用指标。本研究开发了一种基于CABFAC因子分析的海冰浓度与覆盖范围估算新方法。以往海冰估算多通过其他途径限定最大海冰边缘范围，而本研究构建的模型则结合了现代海冰卫星观测数据，以及与海冰覆盖联系更为紧密的硅藻分布数据。本研究共构建了三类模型，分别用于估算2月与9月的海冰浓度，以及年海冰覆盖范围。