Collaborative Research: Enabling Cloud-Permitting and Coupled Climate Modeling via Nonhydrostatic Extensions of the CESM Spectral Element Dynamical Core

地球系统模型（ESM）的运行计算量非常大，其组成部分涵盖大气、海洋、陆地、生物圈和冰。这些模型通常运行在分辨率太粗糙，无法明确表示雷暴复合体，热带气旋和地形强迫降水等天气系统。然而，计算能力现在足以允许使用几公里的网格间距在全球范围内对这些系统进行显式模拟，尽管模拟时间为几周到几个月，而不是在较低分辨率下可能的几十年到几个世纪。在该项目中，研究小组将增强由NSF国家大气研究中心（NCAR）领导的社区地球系统模型（CESM），使其能够作为全球风暴解析模型（GSRM）运行。CESM的GSRM版本作为天气-气候界面研究工具具有巨大潜力，特别是因为CESM拥有全球开发人员和用户社区，并且是美国学术研究界使用的主要模型。作为该项目的一部分，多名学生和早期职业科学家将在大气科学和高性能计算的交叉领域接受培训，增强科学进步所急需的劳动力。该项目的主要目标是为CESM的模拟奠定基础，CESM由包括社区大气模型，其版本7（CAM 7）目前正在开发中，将于2024年发布。 CAM 7的动力学核心使用谱元（SE）方法在流体静力学近似下求解流体运动方程，其中在垂直动量方程中忽略了加速度项。 该项目将把为美国能源部（DOE）的能源亿级地球系统模式（E3 SM）开发的非静力学SE动力核心移植到CESM/CAM 7中。 第二个，更多的实验版本的SE动态核心意味着运行在先进的计算架构也将被移植。 然后，研究人员将运行CAM 7来测试再现小规模现象的能力。 具体而言，该项目将：·将Port DOE的非流体静力学、基于Fortran的SE动力学核心纳入CESM框架。利用NSF资助的EarthWorks项目中支持GPU的物理包，将SE核心的实验性C++版本集成到CESM中。·该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Earth System Models (ESMs) are very computationally intensive to run, with components spanning the atmosphere, ocean, land, biosphere, and ice. These models are typically run at resolutions which are too coarse to explicitly represent weather systems like thunderstorm complexes, tropical cyclones, and terrain-forced precipitation. However, computing power is now sufficient to allow explicit simulation of these systems on a global domain using grid spacings of a few kilometers, albeit for simulations of weeks to months rather than the decades to centuries possible at lower resolutions. In this project, the research team will enhance the Community Earth System Model (CESM), led by the NSF National Center for Atmospheric Research (NCAR), with the capability to run as a Global Storm Resolving Model (GSRM). The GSRM version of CESM has tremendous potential as a tool for research on the weather-climate interface, particularly as CESM has a worldwide community of developers and users and is the primary model used by the US academic research community. As part of the project, multiple students and early career scientists would be trained at the intersection of atmospheric science and high-performance computing, enhancing a workforce that is crucially needed for scientific advancement.The main objective of the project is to lay the groundwork for simulations with CESM, which is comprised of individual models including the Community Atmosphere Model, for which version 7 (CAM7) is currently under development for release in 2024. CAM7's dynamical core uses the Spectral Element (SE) method to solve the equations of fluid motion under the hydrostatic approximation, in which the acceleration term is neglected in the vertical momentum equation. This project will port the nonhydrostatic SE dynamical core developed for the Department of Energy’s (DOE’s) Energy Exascale Earth System Model (E3SM) into CESM/CAM7. A second, more experimental version of the SE dynamical core meant to run on advanced computing architectures will also be ported. The researchers will then run CAM7 to test the ability to reproduce smaller-scale phenomena. Specifically, the project will: • Port DOE’s nonhydrostatic, Fortran-based, SE dynamical core into the CESM framework.• Integrate an experimental C++ version of the SE core into CESM with a GPU-enabled physics package from the NSF-funded EarthWorks project.• Test and demonstrate the capabilities of the new CESM configuration using mesoscale convective systems and tropical cyclones as exemplars.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.