Collaborative Research: Demonstration of a New Framework for Studying Aerosol Indirect Effects

这些研究人员将使用一种新的耦合模型来研究气溶胶如何影响云的特性。因此，这项研究解决了气候模拟中的一个主要不确定性，即气溶胶对云的辐射特性的影响所产生的“气溶胶的间接效应”。预计粒子浓度越高，云滴就越多，云也就越亮，云的寿命也就越长，产生降水的可能性也就越小，但事实证明，很难根据这种预期作出定量预测。在这项研究中，研究人员将试图隔离预计影响突出的情况，然后使用他们的模型将气溶胶对这些云的影响与其他影响相同云特性的因素分开。这项工作需要几个模型的耦合，以代表现实的云场，云元素，云滴大小，化学和气溶胶传输。这个耦合模型将被应用到休斯顿，得克萨斯州，那里有显着的城市污染，预计会影响云的性质，形成下风向的城市。这项研究的预期结果将是如何城市污染或其他来源的气溶胶影响云的特性，如反射率，形成降水的概率，和寿命的评估。这项研究的成果将适用于积云，因此最终需要扩展到其他类型的云，这些云也会影响全球辐射平衡。气候科学家需要这些信息，以便预测大气中不断增加的气溶胶含量将如何影响地球的辐射平衡和降水分布。

These investigators will use a new coupled model to study how aerosols influence the properties of clouds. This study thus addresses one of the major uncertainties in climate simulations, the "indirect effect of aerosols" that arising from their influence on the radiative properties of clouds. It is expected that higher concentrations of particles lead to more cloud droplets and so to brighter clouds as well as clouds with longer lifetime and reduced probability of producing precipitation, but it has proven difficult to formulate a quantitative prediction based on this expectation. In this study, the investigators will attempt to isolate cases where the influence is expected to be prominent and will then use their model to separate the influence of aerosols on those clouds from other factors that also affect the same cloud properties. The effort requires coupling of several models in order to represent realistic cloud fields, cloud elements, cloud-droplet sizes, and chemical and aerosol transport. This coupled model will then be applied to conditions appropriate for Houston, Texas, where there is significant urban pollution expected to affect the properties of clouds that form downwind of the city.The expected result of this research will be an assessment of how urban pollution or other sources of aerosols affects cloud properties like reflectivity, probability of forming precipitation, and lifetime. The product of this research will apply to Cumulus clouds, and so will need eventual extension to other cloud types that also influence the global radiation balance. This information is needed by climate scientists who seek to predict how the increasing aerosol content of the atmosphere will affect the radiative balance and the precipitation distribution of the Earth.