A Study of Aerosol Effects on Warm Ice Clouds

这项提议的主要目标是研究气溶胶对温暖的冰云的影响。这些是混合相云，既包含冰粒，也包含过冷液滴，可能发生在0摄氏度到零下40摄氏度之间。云是由冰还是液体组成的，对于确定它将多少来自太阳的传入辐射反射回太空至关重要，因此对气候预测也是至关重要的。PI感兴趣的是，生物质燃烧或作为冰核的其他人为气溶胶产生的尘埃、气溶胶和烟雾如何影响这些云的微物理和辐射特性，以及降水形成过程被改变的程度。为了实现这一目标，国家大气研究中心(NCAR)的大气环流模式(GCM)和社区大气模式(CAM)耦合了一个气溶胶模式。作为PI目前研究的一部分，她在NCAR CAM中实施了冰晶混合比和数字浓度预报方程，以研究气溶胶-卷云-气候效应，其基础是沙尘、烟尘和硫气溶胶对这些冷云的影响的新的参数化。这项研究将把这一参数化扩展到处理温暖冰云(T-40C)中的沉积成核和接触成核。在即将到来的云中冰实验(ICE)期间开发的数据将被用来指导参数化的发展。一个具有尺寸分辨微物理的云团模式将被用来模拟冰暴过程中的条件和发展冰核的参数化。然后，该参数化将被包括在CAM模型中的冰相微物理过程中。与IMPACT气溶胶模型相结合的凸轮模型将用于模拟当今和工业化前的气候，以评估人为气溶胶的影响。PI还将检查观察到的尘埃浓度趋势的可能性及其对冰云和气候的影响。来自卫星和激光雷达观测的可用数据将被用来评估她的结果。除了上面概述的项目，PI计划继续她在欧洲的量化项目中的合作。量化是第六框架方案下的一个由欧洲资助的项目，有40个伙伴和8个单独的工作包。量化的主要目标是量化全球和欧洲运输系统对当前局势和未来发展的几种情景的气候影响。PI在量化方面的主要工作将是将她的气溶胶/气候耦合模型(与NCAR CAM模型耦合的影响模型)与冰微物理模型的预测与丹麦气象研究所的云解析模型的预测进行比较。该项目的学术价值在于它有助于理解尘埃和人为冰核在间接影响气候方面可能发挥的作用。该项目更广泛的价值在于它对科学的贡献，这对政策决策是有用的。此外，研究生将参与研究，因此该项目将有助于研究生培养。此外，在2007年3月期间，彭纳将在密歇根教授“云与降水”课程。计划在这一时间框架内进行的ICE实验的实时数据将用于一个期末项目，以使学生熟悉野外实验在理解冰核现象中的作用。

The main objective of this proposal is to study aerosol effects on warm ice clouds. These are mixed-phase clouds that contain both ice particles and supercooled liquid droplets, and can occur between 0C and -40C. Whether a cloud is composed of ice or liquid is crucial for determining how much of the incoming radiation from the sun it reflects back to space and therefore crucial for climate prediction. The PI is interested in how dust aerosols and smoke from biomass burning or other anthropogenic aerosols acting as ice nuclei influence the microphysical and radiative properties of these clouds as well as the extent to which precipitation formation processes are altered. To achieve this goal an aerosol model has been coupled with the National Center for Atmospheric Research (NCAR) General Circulation Model (GCM), Community Atmospheric Model (CAM). As part of the PI's present research, she has implemented ice crystal mixing ratio and number concentration prognostic equations in the NCAR CAM in order to study aerosol-cirrus-climate effects, based on a new parameterization for the effects of dust, soot, and sulfur aerosols on these cold clouds. This study will extend this parameterization to treat deposition nucleation and contact nucleation in warm ice clouds (T -40C). Data developed during the forthcoming Ice in Clouds Experiments (ICE) will be used to guide the development of the parameterization. A cloud parcel model with size-resolved microphysics will be used to both simulate conditions during ICE and to develop the ice nucleation parameterization. This parameterization will then be included in the ice phase microphysical processes in the CAM model. CAM coupled to the IMPACT aerosol model will be used for simulations for the present-day and pre-industrial climate to assess the effects of anthropogenic aerosols. The PI will also examine the possibility of trends observed in dust concentration and their effect on ice clouds and climate. Available data from satellite and lidar observations will be used to evaluate her results.In addition to the project outlined above, the PI plans to continue her collaboration in the European-based Quantify Project. Quantify is a European-funded project under the Sixth Framework Programme with 40 partners and 8 separate work packages. The main goal of QUANTIFY is to quantify the climate impact of global and European transport systems for the present situation and for several scenarios of future development. The PI's main effort in Quantify will be to compare the predictions of her coupled aerosol/climate model (the IMPACT model coupled to the NCAR CAM model) with ice microphysics to the predictions of a cloud-resolving model from the Danish Meteorological Institute. The intellectual merit of this project lays in its contribution to an understanding of the possible role of both dust and anthropogenic ice nuclei in indirect effects on climate. The broader merits of the project lie in its contribution to the science that is useful for policy decisions. Moreover, graduate students will participate in the research, so that this project will contribute to graduate training. Additionally, during March 2007, Penner will be teaching the "clouds and precipitation" course at Michigan. Real time data from the ICE experiments planned for this time frame will be used in an end-of-term project to acquaint students with the role of field experiments in understanding ice nucleation phenomena.