基于交互式全球大集合预报系统TIGGE的ECMWF、JMA和UKMO集合预报数据,运用概率统计中的贝叶斯模型平均对东北地区24小时累积降水量的预报技术进行后处理.已有研究发现,BMA预报对弱降水事件是准确的,但对中等、强降水事件的能力有限.因此...基于交互式全球大集合预报系统TIGGE的ECMWF、JMA和UKMO集合预报数据,运用概率统计中的贝叶斯模型平均对东北地区24小时累积降水量的预报技术进行后处理.已有研究发现,BMA预报对弱降水事件是准确的,但对中等、强降水事件的能力有限.因此,提出基于模糊C均值聚类的分类贝叶斯模型平均(Categorized Bayesian Model Averaging,CBMA).结果表明,CBMA基于FCM算法,考虑BMA在不同量级降水的参数不确定性,提高BMA在中等、强降水的适用性,具有较好的预报效果.展开更多
The challenges of applying deep learning(DL) to correct deterministic numerical weather prediction(NWP) biases with non-Gaussian distributions are discussed in this paper.It is known that the DL UNet model is incapabl...The challenges of applying deep learning(DL) to correct deterministic numerical weather prediction(NWP) biases with non-Gaussian distributions are discussed in this paper.It is known that the DL UNet model is incapable of correcting the bias of strong winds with the traditional loss functions such as the MSE(mean square error),MAE(mean absolute error),and WMAE(weighted mean absolute error).To solve this,a new loss function embedded with a physical constraint called MAE_MR(miss ratio) is proposed.The performance of the UNet model with MAE_MR is compared to UNet traditional loss functions,and statistical post-processing methods like Kalman filter(KF) and the machine learning methods like random forest(RF) in correcting wind speed biases in gridded forecasts from the ECMWF high-resolution model(HRES) in East China for lead times of 1–7 days.In addition to MAE for full wind speed,wind force scales based on the Beaufort scale are derived and evaluated.Compared to raw HRES winds,the MAE of winds corrected by UNet(MAE_MR) improves by 22.8% on average at 24–168 h,while UNet(MAE),UNet(WMAE),UNet(MSE),RF,and KF improve by 18.9%,18.9%,17.9%,13.8%,and 4.3%,respectively.UNet with MSE,MAE,and WMAE shows good correction for wind forces 1–3 and 4,but negative correction for 6 or higher.UNet(MAE_MR) overcomes this,improving accuracy for forces 1–3,4,5,and 6 or higher by 11.7%,16.9%,11.6%,and 6.4% over HRES.A case study of a strong wind event further shows UNet(MAE_MR) outperforms traditional post-processing in correcting strong wind biases.展开更多
文摘基于交互式全球大集合预报系统TIGGE的ECMWF、JMA和UKMO集合预报数据,运用概率统计中的贝叶斯模型平均对东北地区24小时累积降水量的预报技术进行后处理.已有研究发现,BMA预报对弱降水事件是准确的,但对中等、强降水事件的能力有限.因此,提出基于模糊C均值聚类的分类贝叶斯模型平均(Categorized Bayesian Model Averaging,CBMA).结果表明,CBMA基于FCM算法,考虑BMA在不同量级降水的参数不确定性,提高BMA在中等、强降水的适用性,具有较好的预报效果.
基金Supported by the National Key Research and Development Program of China (2021YFC3000905)Key Innovation Team Fund of China Meteorological Administration (CMA2022ZD04)。
文摘The challenges of applying deep learning(DL) to correct deterministic numerical weather prediction(NWP) biases with non-Gaussian distributions are discussed in this paper.It is known that the DL UNet model is incapable of correcting the bias of strong winds with the traditional loss functions such as the MSE(mean square error),MAE(mean absolute error),and WMAE(weighted mean absolute error).To solve this,a new loss function embedded with a physical constraint called MAE_MR(miss ratio) is proposed.The performance of the UNet model with MAE_MR is compared to UNet traditional loss functions,and statistical post-processing methods like Kalman filter(KF) and the machine learning methods like random forest(RF) in correcting wind speed biases in gridded forecasts from the ECMWF high-resolution model(HRES) in East China for lead times of 1–7 days.In addition to MAE for full wind speed,wind force scales based on the Beaufort scale are derived and evaluated.Compared to raw HRES winds,the MAE of winds corrected by UNet(MAE_MR) improves by 22.8% on average at 24–168 h,while UNet(MAE),UNet(WMAE),UNet(MSE),RF,and KF improve by 18.9%,18.9%,17.9%,13.8%,and 4.3%,respectively.UNet with MSE,MAE,and WMAE shows good correction for wind forces 1–3 and 4,but negative correction for 6 or higher.UNet(MAE_MR) overcomes this,improving accuracy for forces 1–3,4,5,and 6 or higher by 11.7%,16.9%,11.6%,and 6.4% over HRES.A case study of a strong wind event further shows UNet(MAE_MR) outperforms traditional post-processing in correcting strong wind biases.
