Evolution of Shapes, Sizes and Impurity Contents of Ice Particles in Cirrus Clouds

Baker/摘要9704156 PI计划使用与J.Nelson博士合作开发的单晶演化模型来研究现实大气中单个冰晶的蒸汽生长和升华。这个模型产生了稳定的生长形状，并预测了晶体是中空的条件。该模型将在颗粒环境中与二氧化硫和水蒸气一起运行，以研究两种气体的同时吸收。随后粒子的化学成分将作为假设的冰核含量以及环境气体浓度、温度和压力的函数进行检查。单一研究完成后，结果将用于现实大气中冰粒种群演化特征(大小和化学成分分布)的拉格朗日小块研究。这项工作将与Nelson博士(亚利桑那州大学)、位于美因茨的MPI毛皮化学公司的T.Peter博士和他的同事在实验室研究二氧化硫在单晶上的吸收情况以及来自斯德哥尔摩大学的Noone博士和他的合作者合作进行，他们将收集卷云中微物理演变的现场数据。这些研究将有助于提供卷云粒子的自洽图像，并将为目前使用的模型增加物理真实感，这些模型主要基于球形粒子类似物，没有纳入关于晶体/蒸汽界面的现代概念。研究的最后阶段将是将新模式与GCM中使用的参数进行比较，以评估参数的有用性。

Baker/Abstract 9704156 The PI plans to use a single crystal evolution model developed in collaboration with Dr. J. Nelson to investigate the vapor growth and sublimation of individual ice crystals in realistic atmospheres. This model produces steady state growth shapes and predicts the conditions under which the crystals are hollow. The model will be run with SO2 as well as water vapor in the particle environment to study the simultaneous takeup of the two gases. The chemical composition of the ensuing particles will be examined as a function of assumed ice nucleus content as well as environmental gas concentrations, temperature and pressure. After the single study is completed, the results will be used in a Lagrangian parcel study of the evolving characteristics (size and chemical composition distributions) of ice particle populations in realistic atmospheres This work will be carried out in informal collaboration with Dr. Nelson (U. Arizona), with Dr. T. Peter and his colleagues at the MPI fur Chemie in Mainz, who are studying takeup of SO2 on single crystals in the laboratory, and with Dr. Noone and his collaborators rom Stockholm University, who will be collecting in situ data on microphysical evolution in cirrus clouds. These studies will be useful in providing a self-consistent picture of cirrus particles, and will add physical realism to the models now used, which are based largely on spherical particle analogues and do not incorporate modern ideas on the crystal/vapor interface. The final stage of the study will be the comparison of the new models with the parameterizations used in GCM's to assess the usefulness of the parameterizations.