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人工智能垂直混合参数化方案在海洋模式中的应用和评估

Application and Evaluation of An Artificial Intelligence Vertical Mixing Parameterization in An Ocean Model

  • 摘要: 垂直混合参数化是海洋环流模拟中的主要不确定性来源。近年来,深度学习因其刻画复杂非线性过程的能力,逐渐用于改进传统参数化方案。本文基于Fang et al.(2025)提出的深度学习垂直混合参数化方案(DLVMP),借助Python与Fortran混合编程技术,将其嵌入大气物理研究所发展的气候系统海洋模式(LICOM),设计了参照试验CNTR,采用Canuto et al.(2001)混合参数化方案、K-Profile-Parameterization(KPP)混合参数化方案试验与DLVMP敏感性试验并开展长期气候模拟。结果表明,DLVMP方案整体继承了KPP的偏差特征,但因引入赤道观测数据,对赤道次表层海温气候态模拟有所改进;与Canuto et al.(2001)方案相比,DLVMP与KPP普遍低估表层混合强度、高估次表层混合强度,致使三组试验在海温、盐度、混合层深度、大西洋经圈翻转流(AMOC)和副热带环流(Subtropical Cell, STC)等方面存在显著差异;表层混合强度的低估削弱了中纬度通风过程,导致DLVMP试验中STC结构上移,强度增强,并在温跃层附近引起显著的海温冷偏差。本研究揭示了深度学习参数化方案在实际应用中面临训练集规模和质量的双重挑战,为后续改进提供了关键方向。

     

    Abstract: Vertical mixing parameterization is a major source of uncertainty in ocean circulation models. Recently, deep learning has been used to improve traditional parameterization schemes as it can effectively capture complex nonlinear processes. This study employs hybrid programming technology to integrate the DLVMP (deep learning-based vertical mixing parameterization) proposed by Fang et al. (2025) into the LASG/IAP Climate System Ocean Model (LICOM) developed by the Institute of Atmospheric Physics. Three long-term climate simulations were conducted: A control experiment CNTR, using Canuto et al. (2001) scheme, a K-Profile Parameterization (KPP) experiment, and a DLVMP sensitivity experiment. The results show that DLVMP shares some biases with KPP but improves the simulation of equatorial subsurface temperatures by using observations from that region. Compared with the Canuto et al. (2001) scheme, both DLVMP and KPP underestimated surface mixing and overestimated subsurface mixing in the equatorial Pacific, resulting in significant differences in temperature, salinity, mixed-layer depth, Atlantic Meridional Overturning Circulation (AMOC), and the STC (subtropical cell) among the experiments. Additionally, the underestimated surface vertical mixing weakens the mid-latitude ventilation process, resulting in an upward shift and intensification of the STC in the DLVMP experiment, accompanied by a significant cold temperature bias near the thermocline. This study highlights the challenges of considering the appropriate size and quality of the training dataset for deep learning-based parameterizations, providing key insights for future improvements.

     

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