用AI模拟大气从地表到电离层的耦合变化,速度快且稳定。
A Geometry-Aware AI Emulator for the Coupled Whole Atmosphere from Earth Surface to the Ionosphere and Thermosphere
- 基于球面傅里叶神经算子,融合几何感知机制建模大气全层耦合
- 在未参与训练的模拟中保持电离层形态稳定,多日自回归推演不发散
- 适合开展快速集合实验与不确定性分析,助力大尺度大气研究
全大气模型如WACCM-X可解析从地表到中间层-低热层(MLT)及电离层-热层(IT)系统的耦合过程,但计算成本高昂。本文提出CAM-NET,一种基于球面傅里叶神经算子(SFNO)的轻量级代理模型,用于模拟从地表至IT区域的WACCM-X变化。该模型以3小时间隔的WACCM-X模拟数据训练,预测中性风、温度、压强坐标垂直速度、电子密度及纬向离子漂移。框架结合了新型轻量化模块,将冻结大气表示扩展至等离子体变量。在保留外推模拟的主导IT结构的同时,模型在多日自回归滚动中保持稳定。球谐诊断显示,模型保留低阶变率,同时抑制高波数中层结构,尤其在90 km高度附近重力波破碎区域。CAM-NET旨在作为计算高效的WACCM-X代理,而非业务预报系统。结果表明其适用于快速集合实验、不确定性量化及大规模耦合大气变异的敏感性研究。
原文摘要 · Abstract (English)
Whole-atmosphere models such as WACCM-X resolve coupling from the Earth surface to the Mesosphere-Lower-Thermosphere (MLT), and Ionosphere-Thermosphere (IT) systems with expensive computational costs. Here we introduce CAM-NET, a geometry-aware Spherical Fourier Neural Operator (SFNO) surrogate for emulating WACCM-X variability from Earth surface to IT region. CAM-NET is trained on 3-hourly WACCM-X simulations and predicts neutral winds, temperature, pressure-coordinate vertical velocity, electron density, and zonal ion drift. The framework combines a Spherical Fourier Neural Operator (SFNO) backbone with a newly developed lightweight module that extends the frozen atmospheric representation to plasma variables. For the held-out simulation, CAM-NET preserves the dominant IT morphology and remains stable during multi-day autoregressive rollouts. Spherical-harmonic diagnostics show that the model retains low-degree variability while damping high-wavenumber mesospheric structures, especially near 90 km where gravity wave breaks. CAM-NET is intended as a computationally efficient emulator of WACCM-X, rather than an operational forecasting system. These results demonstrate its potential for rapid ensemble experiments, uncertainty quantification, and sensitivity studies of large-scale coupled whole atmospheric variability.
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