Towards a Better Representation of Cloud-Aerosol Interactions in the Community Earth System Model: With Applications to Heterogeneous Nucleation of Cirrus, and Aerosol-Cloud Intera

云和气溶胶在地球的辐射预算和水文循环中发挥着重要作用。在地球气候系统的全球模式中真实地表示/模拟云和云-气溶胶相互作用是一个具有挑战性的问题，因为它们非常复杂，而且通常比目前全球模式中典型的几十公里大小的网格单元小得多。为了限制计算成本，目前的共同体地球系统模型(CESM)是美国领先的全球模型之一，它通过只计算云的平均颗粒大小和凝结水质量来使用云的最小表示法。这些简化导致了大量调整参数的扩展，这些参数的值没有很好地定义。因此，目前的CESM云模式预测的液态云粒子大小与卫星观测的大小有很大不同。这项工作用一个完全跟踪云中粒子大小范围的模型取代了CESM液态云模型。在充分了解粒子大小的情况下，模型中将实现更完整和更真实的云物理，并将减少可调、定义不佳的参数的数量。新模型还将用于改进物理机构的参数化。这项工作的另一个目标是将气溶胶与冰云模式联系起来，并应用冰云模式来确定新的冰粒形成在控制云特性方面的作用，特别是涉及有机气溶胶的作用。通过利用尺寸分辨的液体和冰模式，该研究将评估气溶胶-云气候强迫，这是气候模拟中最不确定的因素之一。云特性和气溶胶-云相互作用是气候模拟中最不确定的因素之一。通过改进用于模拟云层及其与气溶胶的相互作用的物理，可能会减少不确定性。该项目将改进CESM中对冰云和液态云的表示，主要根据来自卫星的数据来测试这些变化，并将这些模型应用于涉及云-气溶胶相互作用的定义明确、可测试的项目。该项目将通过促进发现和理解，同时促进教学、培训和学习，将研究和教育结合起来；通过让女研究生参与，扩大未被充分代表的群体对自然科学的参与；通过进一步发展CESM模式，加强国家研究和教育基础设施；以及，通过减少由于更好地反映云和气溶胶之间的相互作用而产生的气溶胶辐射气候强迫的不确定性，以及通过改进解决这些问题的国家工具，使社会受益。

Clouds and aerosols play a major role in the Earth's radiative budgets and in the hydrological cycle. It is a challenge problem to realistically represent/simulate clouds and cloud-aerosol interactions in global models of the Earth's climate system because they are very complex and usually much smaller than the typical tens of kilometer sized grid cells in current global models. In order to limit computing costs, the present Community Earth System Model (CESM), which is one of the nation's leading global models, uses a minimalist representation of clouds by computing only their mean particle size and their condensed water mass. These simplifications lead to a vast expansion of tuning parameters whose values are not well defined. As a result, the current CESM cloud model predicts liquid cloud particle sizes that differ greatly from those observed by satellite. The work replaces the CESM liquid cloud model with one that fully tracks the range of particles sizes in the clouds. With full knowledge of the particle sizes much more complete and realistic cloud physics will be implemented in the model, and the number of tunable, poorly defined parameters will be reduced. The new model will also be used to improve the parameterization of physical mechanisms. Another goal of the work is to link aerosols to the ice cloud model, and apply the ice cloud model to determine the role of new ice particle formation, particularly involving organic aerosols, in controlling cloud properties. By utilizing the size resolved liquid and ice models, the study will evaluate the aerosol-cloud climate forcing, one of the most uncertain factors in climate modeling.Cloud properties and aerosol-cloud interactions are among the greatest uncertainties in climate modeling. By improving the physics used to simulate clouds and their interactions with aerosols the uncertainties may be reduced. This project will improve representations of both ice and liquid clouds in CESM, test these changes against data mainly from satellites, and apply the models to well-defined, testable projects involving cloud-aerosol interactions. This project will integrate research and education by advancing discovery and understanding while promoting teaching, training, and learning; broaden participation of underrepresented groups in the Physical Sciences by involving female graduate students; enhance the national infrastructure for research and education by further developing the CESM model; and, provide benefits to society by reducing uncertainty in aerosol radiative climate forcing resulting from a better representation of interactions between clouds and aerosols as well as by improving national tools to address such issues.