Coupled Aerosol and Climate Models: An Intercomparison of the GFDL Model and the NCAR Model

该项目的目的是利用与两个不同气候模式相耦合的综合大规模并行大气化学输送(IMPACT)气溶胶模式，研究气溶胶变化、云变化和气候变化之间的关系，并评估两个版本的IMPACT/气候模式中气溶胶处理和云处理的充分性。具体地说，研究人员将(1)将气溶胶模式与将用于政府间气候变化专门委员会第五次评估报告(AR5)模拟的地球物理流体动力学实验室(GFDL)大气环流模式(AGCM)和国家大气研究中心(NCAR)社区大气模式(CAM)模式耦合，(2)比较模式中的不同参数化以及基本模式动力学如何有助于确定云场、气溶胶场以及气溶胶的直接和间接强迫，(3)研究气候变化和气溶胶对云的相对变化。该项目将有助于确定哪种气候模式的气溶胶输送、化学转化和去除最能再现气溶胶光学厚度、消光比随波长、后向散射分布和气溶胶有效半径的变化的卫星数据。它还可能有助于降低气候模型对温室气体增加的敏感度。该项目的更广泛影响涉及其政策影响和对科学人员的培训。正在解决的问题在确定气候变化及其预测方面至关重要。正在提交给下一份IPCC AR5报告的模型的使用将有助于理解和比较该政策相关报告中使用的两个主要美国模型。此外，还将对一名研究生和一名博士后进行培训，该项目的成果通常用于更新其中一名研究人员教授的降水和云层课程。

This project aims to examine the relationships between aerosol changes, cloud changes and climate change using the Integrated Massively Parallel Atmospheric Chemical Transport (IMPACT) aerosol model coupled to two different climate models and to evaluate the adequacy of the aerosol treatment and cloud treatments within the two versions of the coupled IMPACT/climate models. Specifically, the investigators will (i) couple the aerosol model to the Geophysical Fluid Dynamics Laboratory (GFDL) atmospheric general circulation model (AGCM) and the National Center for Atmospheric Research (NCAR) Community Atmosphere Model (CAM) models that will be used in the Intergovernmental Panel on Climate Change 5th assessment report (AR5) simulations, (ii) compare how different parameterizations in the models as well as basic model dynamics help determine the cloud fields, aerosol fields, and direct and indirect forcing by aerosols, and (iii) study the relative changes to clouds from changes in climate and from aerosols. This project will help to determine which climate model transport, chemical transformation, and removal for aerosols is best able to reproduce satellite data for aerosol optical depth, ratio of extinction as a function of wavelength, backscattering profiles, and the effective radius of aerosols. It may also help to reduce the range of sensitivity of climate models to increases in greenhouse gases. Broader impacts of this project concern both its policy implications and the training of scientific personnel. The issues being addressed are of prime importance in the determination of climate change and its prediction. The use of models that are being submitted to the next IPCC AR5 report will help the understanding and comparison two primary U.S. models used in that policy-relevant report. In addition, a graduate student as well as a post-doctoral will be trained and results from this project are routinely used to update the Precipitation and Clouds course taught by one of the investigators.