题目: Aerosol Effects on Clouds, Precipitation and Stratospheric Water Vapor

报告人:  Dr. Hui Su, Research Scientist, Jet Propulsion Laboratory, California Institute of Technology

时 间：2010年7月14日 上午 10点30 分
地 点：LAPC多功能会议厅

报告摘要: Aerosol-cloud interaction has been a challenging problem in climate research and contributes the largest uncertainty in climate predictions. Observational studies of aerosol effects on clouds have been hindered by the difficulty of measuring aerosols in the presence of clouds in remote sensing. In our study, we capitalize on the carbon monoxide (CO) measurements from Aura Microwave Limb Sounder (MLS) and use CO as a proxy for aerosols to study the relationships among pollution, clouds, precipitation and water vapor. We have analyzed collocated CO, cloud ice (IWC), water vapor from Aura MLS, cloud particle effective radii (re) and aerosol optical thickness (AOT) from Aqua-MODIS, as well as precipitation from TRMM. We define “polluted” and “clean” ice clouds according to the collocated CO loadings and compare cloud properties and precipitation for the two groups of clouds. The validity of CO as a proxy of aerosols was examined for various regions and seasons. Three categories of CO and AOT relation were classified. In regions/seasons of “high” or “moderate” CO to AOT sensitivity, we find polluted clouds have smaller ice particle size and weaker precipitation than clean clouds. In regions that Asian pollution prevails, we also find that polluted clouds have higher temperature and water vapor near the tropopause, causing enhanced water vapor transport to the stratosphere. The physical mechanisms for these aerosol, clouds, water vapor and precipitation relations are being investigated using NCAR CAM coupled with an aerosol model and WRF-Chem.