论文标题

数据驱动的超级参数使用深度学习:使用多尺度Lorenz 96系统和转移学习实验

Data-driven super-parameterization using deep learning: Experimentation with multi-scale Lorenz 96 systems and transfer-learning

论文作者

Chattopadhyay, Ashesh, Subel, Adam, Hassanzadeh, Pedram

论文摘要

为了使天气/气候建模的计算负担得起,通常使用基于物理或半经验参数化方案的大规模,明确分辨的过程来表示小规模的过程。在计算上要求更高但通常更准确的另一种方法是超级参数(SP),它涉及将小规模过程的方程式集成到嵌入大型过程低分辨率网格中的高分辨率网格上。最近,研究已使用机器学习(ML)来开发数据驱动的参数化(DD-P)方案。在这里,我们提出了一种新方法,即数据驱动的SP(DD-SP),其中小规模过程的方程是使用ML方法(例如复发神经网络)集成了数据驱动的。我们使用多尺度的Lorenz 96系统作为测试床,我们比较了参数化低分辨率(LR),SP,DD-P和DD-SP模型的成本和准确性(就短期预测和长期统计数据而言)。我们表明,凭借相同的计算成本,DD-SP基本上要优于LR,并且比DD-P更好,尤其是在缺乏比例分离的情况下。 DD-SP比SP便宜得多,但其准确性在复制长期统计数据中是相同的,并且通常在短期预测中相当。我们还研究了概括,发现当对一个系统的数据进行训练的模型应用于具有不同强迫的系统(例如,更混乱)时,模型通常不会概括,尤其是在检查短期预测准确性时。但是我们表明,转移学习涉及通过新系统中的少量数据重新训练数据驱动模型,从而显着提高了概括。讨论了DD-SP和转移学习在气候/天气建模中的潜在应用以及预期的挑战。

To make weather/climate modeling computationally affordable, small-scale processes are usually represented in terms of the large-scale, explicitly-resolved processes using physics-based or semi-empirical parameterization schemes. Another approach, computationally more demanding but often more accurate, is super-parameterization (SP), which involves integrating the equations of small-scale processes on high-resolution grids embedded within the low-resolution grids of large-scale processes. Recently, studies have used machine learning (ML) to develop data-driven parameterization (DD-P) schemes. Here, we propose a new approach, data-driven SP (DD-SP), in which the equations of the small-scale processes are integrated data-drivenly using ML methods such as recurrent neural networks. Employing multi-scale Lorenz 96 systems as testbed, we compare the cost and accuracy (in terms of both short-term prediction and long-term statistics) of parameterized low-resolution (LR), SP, DD-P, and DD-SP models. We show that with the same computational cost, DD-SP substantially outperforms LR, and is better than DD-P, particularly when scale separation is lacking. DD-SP is much cheaper than SP, yet its accuracy is the same in reproducing long-term statistics and often comparable in short-term forecasting. We also investigate generalization, finding that when models trained on data from one system are applied to a system with different forcing (e.g., more chaotic), the models often do not generalize, particularly when the short-term prediction accuracy is examined. But we show that transfer-learning, which involves re-training the data-driven model with a small amount of data from the new system, significantly improves generalization. Potential applications of DD-SP and transfer-learning in climate/weather modeling and the expected challenges are discussed.

扫码加入交流群

加入微信交流群

微信交流群二维码

扫码加入学术交流群,获取更多资源