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

本项目的目的是利用与两个不同气候模式耦合的综合大规模平行大气化学输送（IMPACT）气溶胶模式来研究气溶胶变化、云变化和气候变化之间的关系，并评价在两个版本的耦合IMPACT/气候模式中气溶胶处理和云处理的适当性。具体而言，研究人员将（i）将气溶胶模型与地球物理流体动力学实验室（GFDL）大气环流模型（AGCM）和国家大气研究中心（NCAR）社区大气模型（CAM）模型耦合，这些模型将用于政府间气候变化专门委员会第五次评估报告（AR 5）模拟，（ii）比较模式中的不同参数化以及基本模式动力学如何帮助确定云场、气溶胶场以及气溶胶的直接和间接强迫;（iii）研究气候变化和气溶胶变化对云的相对变化。 该项目将有助于确定哪种气溶胶的输送、化学转化和清除气候模型最能再现气溶胶光学厚度、消光比随波长的变化、后向散射剖面和气溶胶有效半径的卫星数据。它还可能有助于减少气候模型对温室气体增加的敏感性。该项目的更广泛影响涉及其政策影响和科学人员的培训。所处理的问题对于确定气候变化及其预测至关重要。使用提交给下一次IPCC AR 5报告的模型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，一名研究生和一名博士后将接受培训，该项目的结果通常用于更新由一名调查人员教授的降水和云课程。

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.