用机器学习替代传统辐射计算,提速八倍且精度相当。
Machine learning based radiative parameterization scheme and its performance in operational reforecast experiments
- 用残差卷积网络拟合辐射模型,离线训练在线耦合。
- 实测运行加速8倍,十天预报稳定且精度接近物理模型。
- 适合需要高速气象预报的业务系统部署。
辐射过程是数值模式中最耗时的物理过程之一。本文从业务应用角度出发,研究将深度神经网络嵌入数值预报模型所面临的两大核心瓶颈:耦合兼容性与长期积分稳定性。采用残差卷积神经网络,在中国气象局全球业务系统中近似替代快速辐射传输模型(RRTMG)。通过模型模拟生成包含有云和无云大气柱的综合数据集,并引入经验回放增强数据稳定性,同时施加基于物理意义的输出约束。采用基于LibTorch的耦合方法,更适配实时业务计算。该混合模型可实现十天积分预报。两个月的业务重预报实验表明,机器学习代理模型在精度上达到传统物理方案水平,计算速度提升约八倍。
原文摘要 · Abstract (English)
Radiation is typically the most time-consuming physical process in numerical models. One solution is to use machine learning methods to simulate the radiation process to improve computational efficiency. From an operational standpoint, this study investigates critical limitations inherent to hybrid forecasting frameworks that embed deep neural networks into numerical prediction models, with a specific focus on two fundamental bottlenecks: coupling compatibility and long-term integration stability. A residual convolutional neural network is employed to approximate the Rapid Radiative Transfer Model for General Circulation Models (RRTMG) within the global operational system of China Meteorological Administration. We adopted an offline training and online coupling approach. First, a comprehensive dataset is generated through model simulations, encompassing all atmospheric columns both with and without cloud cover. To ensure the stability of the hybrid model, the dataset is enhanced via experience replay, and additional output constraints based on physical significance are imposed. Meanwhile, a LibTorch-based coupling method is utilized, which is more suitable for real-time operational computations. The hybrid model is capable of performing ten-day integrated forecasts as required. A two-month operational reforecast experiment demonstrates that the machine learning emulator achieves accuracy comparable to that of the traditional physical scheme, while accelerating the computation speed by approximately eightfold.
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