Development of Parameterizations of Aerosol/Cloud Interactions and Assessment of Their Potential Climatic Impacts

这是一项基于模型的云和气溶胶相互作用的研究，以及这些相互作用对云动力学、降水和辐射传输的影响。它是最近对云边界层研究的扩展，基于所谓的假设概率密度函数(PDF)方法。在云模式的每个计算网格盒中，假定垂直速度、位势温度和液态水含量的联合概率满足参数形式，如多元高斯。大涡模拟(LES)提供了关于这些量的小尺度变化的信息，从而能够估计分布的参数。云模式预测网格箱中的量的平均值在时间上的发展，而PDF模式描述次网格尺度的变异性。在这个项目中，以前的工作将扩展到包括降水过程以及不同浓度的云凝结核和结冰核对云的微物理、动力学和辐射性质的影响的估计。将研究将该技术应用于大型积雨云(深对流)的可行性。敏感性研究将确定气溶胶特性的变化对云层和区域气候的影响程度。

This is a modeling-based investigation of the interactions of clouds and aerosols and the effects of these interactions on cloud dynamics, precipitation, and radiative transfer. It is an extension of a recent study of the cloudy boundary layer, based on what is called the assumed probability density function (PDF) method. Within every computational grid box of the cloud model, it is assumed that the joint probability of vertical velocity, potential temperature, and liquid water content satisfies a parametric form such as the multivariate Gaussian. Large-eddy simulation (LES) provides information on the small-scale variability of these quantities, enabling the estimation of the parameters of the distribution. The cloud model predicts the development in time of the mean values of the quantities in the grid boxes and the PDF model characterizes the subgrid-scale variability. In this project, the previous work will be extended to include precipitation processes and the estimation of the effects of variable concentrations of cloud condensation nuclei and ice forming nuclei on the microphysical, dynamic, and radiative properties of clouds. The feasibility of applying the technique to large cumulonimbus clouds (deep convection) will be investigated. Sensitivity studies will determine the extent to which changes in aerosol characteristics can affect the clouds and influence regional climate.