Earth's global temperature responds to changes in the balance between incoming solar radiation and outgoing longwave radiation. The largest uncertainty in quantifying the radiative impacts of human emissions on the present and historical climate is caused by the interaction of aerosols with clouds. From a computational modeling standpoint, the main challenge is the multi-scale nature of the problem. Conventional global climate models rely heavily on suboptimal parameterization of cloud-scale processes. On the other hand, global simulations that resolve cloud-scale processes are still prohibitively expensive.
In this XRAC proposal, we address this problem by combining the strengths of a multi-scale model and machine learning techniques to better advance our understanding of aerosol-cloud interactions. We will run the multi-scale Ultra-Parameterized Community Atmosphere Model (UPCAM) that embeds large-eddy resolution cloud resolving models within larger domain climate model columns and train a neural network with the model output to leverage machine learning techniques to estimate the impact of aerosols on cloud radiative properties. First, we will catalogue present-day aerosol-cloud relationships using UPCAM simulations. Second, we will compare simulations with present-day and pre-industrial emissions of aerosols to quantify the impact of anthropogenic aerosol emissions on cloud properties. Third, a neural network will be trained on the output from the UPCAM simulations to test the viability of the neural network predicting the effect of anthropogenic aerosol emissions on cloud properties.