用条件WGAN提升加拿大风场降尺度精度,实现10天预报的高分辨率拓展。
Enhancing operational wind downscaling capabilities over Canada: Application of a Conditional Wasserstein GAN methodology
- 基于UNet的条件WGAN模型,融合地形等高分辨率静态变量
- 在加拿大全域实现15公里到2.5公里分辨率的风场提升,RMSE与LSD显著下降
- 适合气象预报、气候建模及可再生能源领域应用
风场降尺度对提升天气预报空间分辨率至关重要,尤其在数值天气预报(NWP)中。本研究在Annau等人提出的DownGAN框架基础上,扩展至加拿大全域的全球确定性预报系统(GDPS,15 km,10天预报)和高分辨率确定性预报系统(HRDPS,2.5 km,48小时预报)数据。通过引入高分辨率地形等静态协变量,并采用带有梯度惩罚的条件Wasserstein生成对抗网络(Conditional WGAN-GP),结合源自计算机视觉的频率分离技术,构建基于UNet的生成器。在加拿大区域进行稳健训练与推理,验证了该方法在业务化场景下的可扩展性。统计评估显示,相较于原始DownGAN,模型在根均方误差(RMSE)和对数谱距离(LSD)上均有显著降低。高分辨率协变量与频率分离策略对性能提升起关键作用。本工作展示了将高分辨率风场预测从48小时拓展至10天低分辨率预报窗口的可行性,弥合了二者之间的差距。
原文摘要 · Abstract (English)
Wind downscaling is essential for improving the spatial resolution of weather forecasts, particularly in operational Numerical Weather Prediction (NWP). This study advances wind downscaling by extending the DownGAN framework introduced by Annau et al.,to operational datasets from the Global Deterministic Prediction System (GDPS) and High-Resolution Deterministic Prediction System (HRDPS), covering the entire Canadian domain. We enhance the model by incorporating high-resolution static covariates, such as HRDPS-derived topography, into a Conditional Wasserstein Generative Adversarial Network with Gradient Penalty, implemented using a UNET-based generator. Following the DownGAN framework, our methodology integrates low-resolution GDPS forecasts (15 km, 10-day horizon) and high-resolution HRDPS forecasts (2.5 km, 48-hour horizon) with Frequency Separation techniques adapted from computer vision. Through robust training and inference over the Canadian region, we demonstrate the operational scalability of our approach, achieving significant improvements in wind downscaling accuracy. Statistical validation highlights reductions in root mean square error (RMSE) and log spectral distance (LSD) metrics compared to the original DownGAN. High-resolution conditioning covariates and Frequency Separation strategies prove instrumental in enhancing model performance. This work underscores the potential for extending high-resolution wind forecasts beyond the 48-hour horizon, bridging the gap to the 10-day low resolution global forecast window.
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