Ice Nucleation in Cirrus Clouds: Anthropogenic Climate Forcing and Uncertainties

GSTDTAP

项目编号	1540954
	Ice Nucleation in Cirrus Clouds: Anthropogenic Climate Forcing and Uncertainties
	Joyce Penner
主持机构	University of Michigan Ann Arbor
项目开始年	2015
	2015-09-01
项目结束日期	2018-08-31
资助机构	US-NSF
项目类别	Standard Grant
项目经费	572578(USD)
国家	美国
语种	英语
英文摘要	This research focuses on the use of a global chemistry/climate model to improve the modeling of ice formation in cirrus clouds. This research will better inform climate modelers about the causes of differences in model predictions of the effects of small particles (aerosol) in cirrus clouds. It will also provide a representation of aerosol and ice formation that is based on physical and chemical processes and broadly consistent with the field observations used to evaluate the model. The researchers hypothesize that a substantial fraction of ice formation in cirrus clouds is associated with secondary organic aerosols (SOA) and/or solid ammonium sulfate (NH4)2SO4 and that changes in these aerosols over time result in a significant climate forcing. The hypothesis will be tested using the Community Atmosphere Model (CAM5) climate model coupled to the IMPACT aerosol model. The IMPACT model ties the formation of SOA to the photochemical oxidation of volatile organic compounds (VOCs) based on a recently extended oxidation scheme. The researchers are in the process of extending the SOA formation framework to allow it to consider how the formation mechanism alters the size distribution of both primary organics and other aerosol species associated with SOA. In this research, they will explore several ways of parameterizing SOA nucleation. They will compare the changes in SOA formation and forcing in cirrus clouds using varying amounts of dust, sulfate, glassy organic aerosols (depending on the glass transition temperature of each SOA), and solid (NH4)2SO4. The model simulations will be compared with observations from recent measurement campaigns to identify which treatments of SOA formation, ice cloud nucleation, and updraft velocities are best able to reproduce the observations. This research will better inform the climate community of the causes of differences in model predictions of aerosol effects in cirrus clouds. The results of this research will aid in quantifying climate forcing by aerosols and help to inform policy makers of the possible role of aerosols in either heating or cooling climate through their action in nucleating ice crystals.
来源学科分类	Geosciences - Atmospheric and Geospace Sciences
文献类型	项目
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/68740
专题	环境与发展全球科技态势
推荐引用方式 GB/T 7714	Joyce Penner.Ice Nucleation in Cirrus Clouds: Anthropogenic Climate Forcing and Uncertainties.2015.