Fusion Correction Method for Numerical Weather Forecast Based on LGU-Net
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摘要: 数值天气预报是现代天气预报的主流技术方法,近年来一直在向精细化方向发展,但预报误差仍无法完全避免。本研究提出了基于LSTM-GAM-UNet(LGU-Net)的数值预报偏差订正模型,该模型在CU-Net的基础上引入了长短期记忆网络(Long Short-Term Memory, LSTM)结构和全局注意力机制(Global Attention Mechanism, GAM),进一步融合多种气象要素、“吉林一号”卫星获取的地形特征以及卫星云图,构建多要素融合订正模型,并专门针对气象预报领域进行了优化设计。在中国东北地区进行实验,对美国国家环境预报中心的全球预报系统(Global Forecast System, GFS)数值预报模式中2 m温度(T2)、2 m露点温度(D2)、10 m的风速(U10、V10)和降水量进行订正,并进行了不同模型的偏差订正实验和对比分析。通过与GFS数值预报模式原始预报结果、模式距离积分订正预报法(Anomaly Numerical-correction with Observation, ANO)订正结果以及CU-Net方法订正结果进行对比,结果表明LGU-Net模型能有效改进数值预报订正效果。此外,云图数据的加入对降水量订正有着明显的正向增益效果,其均方根误差(RMSE)和平均绝对误差(MAE)相对于GFS分别提升了80.76%和76.04%。本研究为高精度气象要素预报提供了新的技术支持。Abstract: Numerical weather forecast is the mainstream technique in modern weather forecasting, which has been developing towards higher resolution in recent years, while forecast errors remain unavoidable. This paper proposes a numerical forecast bias correction model, termed LSTM-GAM-UNet (LGU-Net), which introduces the Long Short-Term Memory (LSTM) structure and Global Attention Mechanism (GAM) based on the CU-Net model. The model further integrates various meteorological elements, terrain features derived from"Jilin-1"satellite data, and satellite cloud images, thereby constructing a multielement fusion correction model. This model is also specifically optimized for meteorological forecasting. An experiment was conducted in northeastern China to correct the biases of the Global Forecast System (GFS) for the 2 m temperature (T2), 2 m dew point temperature (D2), 10 m wind components (U10, V10), and precipitation. Different models were compared and analyzed for bias correction experiments. By comparing with the original GFS forecasts, as well as the correction results from Anomaly Numericalcorrection with Observation (ANO) method and the CU-Net method, it was shown that the LGU-Net model effectively improved the bias correction performance. In addition, the addition of cloud imagery data has a significant positive impact on precipitation correction, with an 80.76% and 76.04% improvement in RMSE and MAE compared to GFS, respectively. This paper provides new technical support for highprecision meteorological element forecasts.
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Key words:
- numerical weather prediction /
- deep learning /
- LGU-Net /
- bias correction
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表 1 T2订正结果误差评价
评价指标 ANO CU-Net LGU-Net(单) LGU-Net(多) GFS RMSE/℃ 3.658 2.423 1.832 1.011 4.738 MAE/℃ 2.254 1.539 1.214 0.823 3.124 表 2 D2订正结果误差评价
评价指标 ANO CU-Net LGU-Net(单) LGU-Net(多) GFS RMSE/m 3.435 2.950 1.965 1.124 5.245 MAE/m 2.171 1.586 1.277 0.923 3.715 表 3 U10订正结果误差评价
阈值 评价指标 ANO CU-Net LGU-Net(单) LGU-Net(多) GFS / RMSE/(m·s-1) 2.658 1.744 1.436 0.850 3.412 MAE/(m·s-1) 1.957 1.330 1.023 0.650 1.825 0.2 m·s-1 POD/(m·s-1) 0.72 0.77 0.79 0.88 0.67 FAR/(m·s-1) 0.70 0.65 0.58 0.51 0.72 CSI/(m·s-1) 0.36 0.39 0.44 0.48 0.34 10 m·s-1 POD/(m·s-1) 0.19 0.32 0.35 0.40 0.14 FAR/(m·s-1) 0.68 0.56 0.46 0.34 0.78 CSI/(m·s-1) 0.22 0.25 0.29 0.30 0.17 表 4 V10订正结果误差评价
阈值 评价指标 ANO CU-Net LGU-Net(单) LGU-Net(多) GFS / RMSE/(m·s-1) 2.374 1.678 1.396 0.894 3.737 MAE/(m·s-1) 1.850 1.265 0.987 0.671 1.730 0.2 m·s-1 POD/(m·s-1) 0.73 0.76 0.81 0.89 0.69 FAR/(m·s-1) 0.65 0.61 0.58 0.49 0.70 CSI/(m·s-1) 0.34 0.39 0.47 0.51 0.32 10 m·s-1 POD/(m·s-1) 0.20 0.34 0.33 0.41 0.15 FAR/(m·s-1) 0.63 0.54 0.46 0.33 0.77 CSI/(m·s-1) 0.23 0.27 0.31 0.37 0.19 表 5 降水量订正结果误差评价
阈值 评价指标 ANO CU-Net LGU-Net(无云图) LGU-Net(云图) GFS / RMSE/(mm·h-1) 3.374 3.005 1.367 0.912 4.741 MAE/(mm·h-1) 2.150 2.074 1.170 0.633 2.642 0.1 mm·h-1 POD/(mm·h-1) 0.79 0.85 0.89 0.91 0.70 FAR/(mm·h-1) 0.68 0.64 0.59 0.48 0.72 CSI/(mm·h-1) 0.28 0.31 0.39 0.50 0.24 7.0 mm·h-1 POD/(mm·h-1) 0.19 0.25 0.30 0.42 0.15 FAR/(mm·h-1) 0.64 0.50 0.43 0.32 0.73 CSI/(mm·h-1) 0.20 0.29 0.34 0.39 0.15 表 6 消融实验评价结果
评价指标 阈值 模型 3h 6h 9h 12h 15h 18h 21 h 24 h 平均 RMSE/(mm·h-1) / U-Net 2.500 2.645 2.801 2.953 3.102 3.251 3.398 3.549 2.977 LU-Net 2.187 2.195 2.203 2.212 2.220 2.228 2.236 2.244 2.263 GU-Net 0.902 1.501 1.799 2.050 2.301 2.450 2.600 2.751 1.914 LGU-Net 0.903 0.911 0.904 0.908 0.912 0.905 0.910 0.906 0.912 MAE/(mm·h-1) / U-Net 1.452 1.583 1.754 1.923 2.134 2.345 2.568 2.788 2.067 LU-Net 1.309 1.321 1.333 1.345 1.357 1.369 1.381 1.393 1.362 GU-Net 0.612 0.724 0.856 1.012 1.165 1.321 1.489 1.654 1.147 LGU-Net 0.638 0.645 0.634 0.631 0.637 0.642 0.639 0.635 0.633 POD/(mm·h-1) 0.1 U-Net 0.76 0.75 0.74 0.70 0.70 0.66 0.65 0.64 0.70 LU-Net 0.76 0.77 0.79 0.76 0.77 0.78 0.76 0.76 0.77 GU-Net 0.90 0.88 0.85 0.82 0.79 0.76 0.74 0.72 0.82 LGU-Net 0.92 0.91 0.90 0.91 0.92 0.90 0.91 0.92 0.91 FAR/(mm·h-1) 0.1 U-Net 0.61 0.61 0.64 0.65 0.69 0.69 0.73 0.74 0.66 LU-Net 0.60 0.61 0.60 0.62 0.58 0.60 0.61 0.60 0.60 GU-Net 0.48 0.51 0.51 0.53 0.57 0.58 0.59 0.63 0.57 LGU-Net 0.48 0.47 0.46 0.48 0.47 0.48 0.46 0.47 0.48 CSI/(mm·h-1) 0.1 U-Net 0.37 0.35 0.34 0.33 0.32 0.31 0.30 0.28 0.33 LU-Net 0.36 0.37 0.38 0.37 0.36 0.37 0.38 0.37 0.37 GU-Net 0.48 0.46 0.45 0.43 0.42 0.41 0.41 0.39 0.43 LGU-Net 0.48 0.51 0.50 0.49 0.50 0.51 0.50 0.49 0.50 -
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