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arXiv 1806.04731physics.ao-phcs.LGstat.ML
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深度学习在气候模式中表示次网格过程

Deep learning to represent sub-grid processes in climate models

Ludwig-Maximilian-University(慕尼黑大学);Columbia University(哥伦比亚大学);University of California, Irvine(加州大学欧文分校)

Stephan Rasp, Michael S. Pritchard, Pierre Gentine

摘要:

非线性次网格过程的表示,特别是云,几十年来一直是气候模式不确定性的主要来源。云解析模型更好地代表了许多这些过程,现在可以在全球范围内运行,但由于计算限制,只能进行最多几年的短期模拟。在这里,我们证明了深度学习可以用于以计算成本的一小部分捕获云解析建模的许多优点。我们训练一个深度神经网络,通过从显式处理对流的多尺度模型中学习,来表示气候模式中的所有大气次网格过程。训练的神经网络,然后取代传统的子网格参数化的全球大气环流模式,在该模式中,它自由地与解决的动力学和表面通量方案相互作用。预测多年模拟是稳定的,不仅准确地再现了云解析模拟的平均气候,而且还再现了变异的关键方面,包括极端降水和赤道波谱。此外,神经网络近似地保存能量,尽管没有被明确指示。最后,我们表明神经网络参数化可以推广到新的表面强迫模式,但很难应对远远超出其训练流形的温度。我们的研究结果表明了使用深度学习进行气候模式参数化的可行性。在更广泛的背景下,我们预计,数据驱动的地球系统模型的开发可以在未来十年减少气候预测的不确定性方面发挥关键作用。

英文摘要:

The representation of nonlinear sub-grid processes, especially clouds, has been a major source of uncertainty in climate models for decades. Cloud-resolving models better represent many of these processes and can now be run globally but only for short-term simulations of at most a few years because of computational limitations. Here we demonstrate that deep learning can be used to capture many advantages of cloud-resolving modeling at a fraction of the computational cost. We train a deep neural network to represent all atmospheric sub-grid processes in a climate model by learning from a multi-scale model in which convection is treated explicitly. The trained neural network then replaces the traditional sub-grid parameterizations in a global general circulation model in which it freely interacts with the resolved dynamics and the surface-flux scheme. The prognostic multi-year simulations are stable and closely reproduce not only the mean climate of the cloud-resolving simulation but also key aspects of variability, including precipitation extremes and the equatorial wave spectrum. Furthermore, the neural network approximately conserves energy despite not being explicitly instructed to. Finally, we show that the neural network parameterization generalizes to new surface forcing patterns but struggles to cope with temperatures far outside its training manifold. Our results show the feasibility of using deep learning for climate model parameterization. In a broader context, we anticipate that data-driven Earth System Model development could play a key role in reducing climate prediction uncertainty in the coming decade.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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