气溶胶对中国东部冬季低云微物理特性及云辐射效应的影响研究

The heavy aerosols over Eastern China not only cause serious environmental concerns, but also affect low-level cloud micro-physical properties. Low-level cloud processes are one of key aspects that determines low tropospheric climate and there is crucial scientific importance to conduct in-depth studies about aerosol effects on low-level cloud processes. However, there are few of relevant studies conducted over Eastern China, especially in wintertime. In this proposal, we will first investigate relationships between aerosol optical features and low-level cloud micro-physical properties, such as cloud effect radius and water content, and analyses possible relationship between aerosol and long-term variation of cloud radiative effects. Secondly, based on observational results, we will partly improve the newest climate model (FGOALS), developed by Institute of Atmospheric Physics in Chinese Academy of Sciences; Thirdly, FGOALS will be used to design reasonable numerical experiments and verify relationships obtained in above observational analysis; next, further simulation will examine how aerosols influence low-level cloud micro-physical properties and cloud radiative effects and reveal detailed impact mechanisms; the changed variation of cloud radaitive effects due to increased aerosol in last decades will also be compared to warming effects due to greenhouse gases. This study is expected to strengthen the understanding of aerosol and low-level cloud climate processes over Eastern China; moreover, our work will help to provide valuable references for applications of satellite datasets in domestic climate models and climate change studies in wintertime.

中国东部高含量的气溶胶不仅引起严重的环境问题（如雾霾），还会影响大气低层的云微物理特性；深入理解气溶胶对低云物理过程的影响具有重要科学价值，但目前针对中国东部冬季相关问题的研究非常缺乏。为此，本项目首先通过分析卫星反演与典型站点观测资料，研究中国东部冬季气溶胶光学特性与低云微物理特性（如云粒子有效半径和云水含量）的关系，考察气溶胶与云辐射效应长期变化的联系。其后，基于观测改进中科院大气物理研究所最新气候模式FGOALS的气溶胶和云物理过程，并设计合理的数值试验，验证观测分析所得的统计关系，揭示气溶胶影响中国东部冬季低云微物理特性及云辐射效应的主要机理。最后，通过数值模拟进一步研究过去数十年气溶胶增加对区域云辐射效应的影响，同时与温室气体的暖化效应相比较。本项目预期为中国东部气溶胶和低云物理过程研究提供新的科学认识，也为国内气候模式中卫星资料的应用以及特定季节的气候变化研究提供有效参考。

中国东部高含量的气溶胶不仅是严重的大气环境和公众健康问题，还会强烈影响区域云辐射特性（特别是低云微物理特性）。低云物理过程是当前气候模拟和预估中的关键问题之一，而中国东部冬季分布有大量的低云。因此，深入理解气溶胶对中国东部冬季低云影响具有重要科学价值。本项目利用卫星反演资料和大气模式FGOALS-F，分析中国东部气溶胶光学特性、低云微物理特性及云辐射效应，揭示气溶胶对中国东部冬季低云微物理特性及云辐射效应的影响。主要研究成果如下：（1）收集整理项目急需的云辐射卫星反演资料，特别是日和月平均的云辐射效应和三维云量数据，为后续分析及大气模式验证提供了关键数据支撑。（2）基于卫星资料，系统分析了中国东部云辐射效应的季节特征及与云量的关系；冬春季节中国东部高含量的气溶胶有助于减少云粒子有效半径，从而增强区域云反照率和云辐射冷却效应。（3）系统评估了当前再分析资料及大气模式FAMIL-F对中国东部云辐射效应的描述能力，表明年平均和冬季的总云量、云短波辐射效应和净云辐射效应被系统性低估。（4）利用改进后的大气模式开展了气溶胶影响云辐射效应的模拟试验，表明该区域冬季云短波辐射效应的强度对气溶胶光学厚度非常敏感，增强后者之后，通过云粒径和云光学厚度的传递影响，可明显减少模拟偏差。通过上述资料分析与数值模拟，加速了对我国东部冬季气溶胶-云物理过程的认识，并为大气模式云辐射过程改进提供了有价值的线索。