末次盛冰期沙尘和海盐气溶胶气候效应及其对东亚气候影响

A state-of-the-art climate model, which is coupled with atmospheric chemistry and aerosol model, and an equilibrium vegetation model are used here to study global climate changes and climatic responses of East Asia to the shortwave and longwave radiative effects of mineral dust and sea salt aerosols at the last glacial maximum..In this project, we plan to employ systematic numerical experiments and related model-data comparison to investigate the global climatic effects of mineral dust and sea salt aerosols at the last glacial maximum, estimate their contribution to global and East Asian climate, surface energy balance and hydrological cycle, and assess the improvement of the numerical model for last glacial maximum simulation after considering the mineral dust and sea salt aerosols. Up to now, there are very few studies related to the climatic effects of the mineral dust and sea salt aerosols at the last glacial maximum. Therefore, this project is expected to further reveal the mechanism of a typical glacial climate change. At the same time, it helps us to understand the climatic effects of mineral dust and sea salt aerosols and their impacts on East Asian climate, and provides a scientific reference for the uncertainty of the natural aerosol-related research in the field of atmospheric chemistry.

利用大气环流-气态化学-气溶胶化学-混合层海洋和海冰模式-植被平衡模式，模拟末次盛冰期气候变化特征，着重研究沙尘和海盐气溶胶的气候效应以及它们对东亚气候变化的影响。.本项目拟通过系统的数值模拟试验，以及它们与相关地质重建记录的比较分析，深入研究末次盛冰期沙尘和海盐气溶胶的气候效应，检验上述两种气溶胶对冰期全球和东亚气候、地表能量和水循环变化产生何种程度的影响，评估这两种气溶胶的加入在多大程度上改变了模式对冰期气候特征的模拟效能。目前，国际上鲜有末次盛冰期沙尘和海盐气溶胶气候效应数值模拟工作的报道，本项目的及时开展有望进一步揭示典型冰期气候变化机制；同时，有助于认识沙尘和海盐气溶胶气候效应及其对东亚气候变化的影响，以及为评估自然释放气溶胶气候效应的不确定性提供科学依据。

该项目利用美国新一代地球系统模式CESM的大气模块（CAM5）模拟研究了末次盛冰期（LGM）气候变化特征及沙尘、海盐气溶胶的分布特征和气候效应。研究结果显示，在未加入沙尘和海盐气溶胶时，CAM5模拟的LGM全球年平均地表气温与现代相比降低4.94ºC，年平均降水减少10.6%。只加入沙尘气溶胶后，CAM5模拟的全球全年起沙总量为4042 Tg yr-1，是现代的1.14倍。相应地，全球年平均地表气温与现代相比降低4.81 ºC，降温幅度减小；年平均降水较现代减少14.0%。只加入海盐气溶胶后，CAM5模拟的LGM全球全年海盐排放总量为4102 Tg yr-1，少于现代排放总量。相应地，全球年平均地表气温与现代相比降低4.50 ºC，降温幅度明显减小；年平均降水减少9.75%。同时考虑两种气溶胶之后，CAM5模拟的全球年平均地表气温降低4.84 ºC，降水较现代减少11.29%。综上，沙尘和海盐气溶胶具有显著的负辐射强迫，但是考虑了两种气溶胶之后，CAM5缩小了LGM时期的年平均气温降温幅度；而年平均降水与现代相比进一步减少，气候干旱加剧。这一结果有助于我们深入认识和理解沙尘和海盐气溶胶在冰期的分布特征及气候效应。