论文标题

来自全球风暴模型的机器学习气候模型校正

Machine-learned climate model corrections from a global storm-resolving model

论文作者

Kwa, Anna, Clark, Spencer K., Henn, Brian, Brenowitz, Noah D., McGibbon, Jeremy, Perkins, W. Andre, Watt-Meyer, Oliver, Harris, Lucas, Bretherton, Christopher S.

论文摘要

由于计算限制,运行全球气候模型(GCM)多年需要较低的空间网格分辨率($ {\ gtrsim} 50 $ km),而不是用于准确解决重要物理过程的最佳选择。此类过程通过亚网格参数化在GCM中近似,这对GCM预测的不确定性产生了显着贡献。提高粗网格全球气候模型准确性的一种方法是在每个仿真时间段上添加机器学习的状态依赖性校正,以便气候模型更像是高分辨率的全球风暴解决模型(GSRM)。我们训练神经网络,以了解将200 km的粗网格气候模型推动到3〜km细网格GSRM的演变所需的状态依赖温度,湿度和辐射通量校正。当这些矫正ML模型与长达一年的粗网格气候模拟耦合时,对于NO-ML基线模拟,土地表面温度的时间均值空间模式误差将减少6-25%,土地表面降水量为9-25%。经ML校正的模拟在气候和循环中产生了其他偏见,与基线模拟不同,但具有可比的幅度。

Due to computational constraints, running global climate models (GCMs) for many years requires a lower spatial grid resolution (${\gtrsim}50$ km) than is optimal for accurately resolving important physical processes. Such processes are approximated in GCMs via subgrid parameterizations, which contribute significantly to the uncertainty in GCM predictions. One approach to improving the accuracy of a coarse-grid global climate model is to add machine-learned state-dependent corrections at each simulation timestep, such that the climate model evolves more like a high-resolution global storm-resolving model (GSRM). We train neural networks to learn the state-dependent temperature, humidity, and radiative flux corrections needed to nudge a 200 km coarse-grid climate model to the evolution of a 3~km fine-grid GSRM. When these corrective ML models are coupled to a year-long coarse-grid climate simulation, the time-mean spatial pattern errors are reduced by 6-25% for land surface temperature and 9-25% for land surface precipitation with respect to a no-ML baseline simulation. The ML-corrected simulations develop other biases in climate and circulation that differ from, but have comparable amplitude to, the baseline simulation.

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