PAESCAL, or Physical, Accurate, and Efficient Atmosphere and Surface Coupling Across Scales, is a new project funded by the fifth instantiation of DOE’s SciDAC (Scientific Discovery Through Advanced Computing) program. The project combines deep understanding of atmospheric physics with advanced computational methods to improve the numerical process coupling in E3SM. This includes both the coupling among atmospheric phenomena and the coupling between the atmosphere and the Earth’s surface. The presentation will explain the motivation and provide a high-level overview of the planned work.