北太平洋地区冬季气溶胶和云的相互作用研究

Current understanding of the aerosol indirect effect remains highly uncertain,constituting the greatest uncertainty to global climate forcing. The wintertime north Pacific is highly vulnerable to the aerosol-cloud interaction due to favorable cloud dynamical and microphysical conditions, providing a good experimental region for investigation of aerosol-cloud interactions. This research project is aimed at assessing impacts of aerosols from Asian pollution outflows on clouds and precipitation over the north Pacific, using observational and modeling procedures. Our studies include the following activities: (1) analysis of satellite measurements of cloudiness and aerosols from the Moderate Resolution Imaging Spectroradiometer (MODIS) and precipitation from Tropical Rainfall Measuring Mission (TRMM) to establish their variability and correlation over the north Pacific, (2) simulations of storms over the north Pacific in the winter using a cloud-resolving Weather Research and Forecasting model with chemistry (CR-WRF-CHEM) with a domain spanning much of the north Pacific and a seasonal time scale to assess the effect of aerosols on cloud properties and precipitation, and compare with satellite observations, (3) simulations of several cyclone activities over the north-west Pacific to verify the contributions of aerosols from Asian pollution outflows to the sudden development of cyclones. The analyses and modeling proposed in this project seek to improve understanding of the changes and variability of aerosol and cloud properties and precipitation over the north Pacific. The project will provide research opportunities for graduate students who will be involved in the data analysis and modeling。

目前对于气溶胶通过间接效应对天气和气候的影响的评估仍然存在着高度的不确定性。北太平洋中纬度地区的动力，热力和水汽条件都很有利于气溶胶和云的相互作用，为研究气溶胶和云的相互作用提供了理想的研究场所。本项目运用卫星观测的气溶胶、云和降水资料，结合模式模拟，认识在北太平洋地区气溶胶、云和降水的空间分布和时间变化规律，研究气溶胶与云和降水的关系；定量确定在北太平洋地区从亚洲输送的气溶胶对云的光学厚度、云滴浓度、云滴大小、云水的柱含量、云量、云顶气压及温度的影响以及对大气辐射的作用；确定从亚洲输送的气溶胶对北太平洋地区降水及极端降水的贡献；评估亚洲输送的气溶胶对西北太平洋地区气旋的爆发性增长的影响，为气溶胶对天气及气候的研究提供重要的参考。

大气气溶胶既可以通过散射和吸收太阳辐射直接地影响气候，也可以作为云凝结核和冰凝结核改变云的光学性质和生命史而间接地影响气候。目前对于气溶胶间接效应的研究仍存在高度的不确定性，并且该效应已经成为全球气候强迫评估和预测中不确定性最大的因子。北太平洋中纬度地区的动力、热力和水汽条件都很有利于气溶胶和云的相互作用，为研究气溶胶和云的相互作用提供了理想的研究场所。本课题以数值模式模拟为主要手段，并结合卫星观测的气溶胶、云和降水的资料，认识冬季北太平洋地区气溶胶、云和降水的空间分布和时间变化规律，研究气溶胶与云和降水的关系；定量分析从亚洲输送的气溶胶对北太平洋地区云特性的影响以及对大气辐射的作用；确定从亚洲输送的气溶胶对北太平洋地区降水与极端降水的贡献；评估从亚洲输送的气溶胶对西北太平洋地区气旋的爆发性增长的影响，为进一步评估气溶胶对气候变化的贡献提供重要的参考。