High Wind Speed Correction of HY-2 Satellite Microwave Scatterometer Based on Broad Learning System
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摘要: 针对国产微波散射计高风速订正需求, 以2021—2022年9个台风的HY-2系列微波散射计观测资料为数据源, 以机载步频微波辐射计(Stepped Frequency Microwave Radiometer, SFMR)风速为参考真值, 通过时空匹配构建建模数据集, 并将其以7︰3随机划分为训练集与测试集; 基于轻量化的宽度学习系统(Broad Learning System, BLS)开展回归分析, 构建高风速订正模型. 模型测试结果表明: 订正后HY-2风速的均方根误差(Root Mean Squared Error, RMSE)为4.47 m·s–1, 比订正前提升了35%; 风速大于25 m·s–1时, 订正后风速的RMSE为6.76 m·s–1, 相比订正前的13.27 m·s–1有了明显改善. 此外, 以2021年台风灿都为例进行对比分析, 结果显示订正后HY-2C最大风速从22.09 m·s–1提高至32.73 m·s–1, 并且风速廓线的对比进一步证实了本文模型的有效性.Abstract: Accurate observation of sea surface wind fields is essential for tropical cyclone forecasting and meteorological hazard mitigation. The HY-2 series microwave scatterometer continuously measures Ku-band ocean surface winds. However, its current wind speed retrieval algorithm struggles in high wind conditions and systematically underestimates speeds during extreme events such as typhoons. To address this bias, this study utilized the HY-2 wind speed data of nine tropical cyclones between 2021 and 2022 as the data source. The Stepped Frequency Microwave Radiometer (SFMR) wind speed measurements served as the ground truth. A modeling dataset was constructed by resampling the SFMR reference data to match the 25 km spatial resolution of the HY-2 scatterometer, followed by spatiotemporal matching within a two-hour time window. The matched dataset was then randomly divided into a training set and a testing set at a 7︰3 ratio. Subsequently, the Broad Learning System (BLS) was employed to conduct the regression analysis and develop a high-wind-speed correction model. BLS employs a shallow, flat architecture in which input features are expanded into “enhanced nodes,” avoiding the deep stacks typical of conventional neural networks. This structure reduces computational cost and accelerates convergence while maintaining predictive performance. Validation results demonstrate that the corrected HY-2 wind speeds achieved a Root Mean Square Error (RMSE) of 4.47 m·s–1, representing a 35% improvement compared to the uncorrected data. For wind speeds exceeding 25 m·s–1, the corrected RMSE reached 6.76 m·s–1, marking significant enhancements over the original values of 13.27 m·s–1. Additionally, a comparative analysis using Typhoon Chanthu (in 2021) as a case study revealed that the corrected HY-2C maximum wind speed increased from 22.09 m·s–1 to 32.73 m·s–1, closely matching wind fields retrieved by Synthetic Aperture Radar (SAR). Further validation through wind speed profile comparisons confirmed the effectiveness of the proposed model. These results demonstrate that our correction framework markedly improves extreme-wind retrieval accuracy, yielding bias-corrected HY-2 products that are more reliable for applications, such as storm surge simulation and typhoon track forecasting.
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图 2 不同SFMR分辨率下的HY-2B微波散射计风速与SFMR的时空匹配散点密度. (a) SFMR分辨率1 km, (b) SFMR分辨率10 km, (c) SFMR分辨率25 km
Figure 2. Spatiotemporal matching point density distribution of wind speed between HY-2B microwave scatterometer and SFMR at various SFMR resolutions. (a) SFMR resolution is 1 km, (b) SFMR resolution is 10 km, (c) SFMR resolution is 25 km
图 4 HY-2与SFMR风速的散点分布及二者风速差值变化趋势. (a) SFMR与HY-2时空匹配数据风速分布散点图, (b)不同风速区间HY-2与SFMR风速差值分布
Figure 4. Scatter plot of wind speeds between HY-2 and SFMR, and the vatiation trend of the wind speed difference between them. (a) Scatter plot of wind speed distribution for SFMR and HY-2 spatiotemporal matching data, (b) distribution of wind speed difference between HY-2 and SFMR in different wind speed ranges
图 7 2021年9月8日HY-2C微波散射计和台风灿都的风速. (a) HY-2C微波散射计全球风速, (b)台风灿都08:36-08:39 UTC风速, (c) 模型订正后HY-2微波散射计风速, (d) 09:17 UTC SAR反演风速
Figure 7. Wind speed of HY-2C microwave scatterometer and Typhoon Chanthu on 8 September 2021. (a) Global wind speed of HY-2C microwave scatterometer, (b) wind speed of Typhoon Chanthu at 08:36-08:39 UTC, (c) corrected HY-2 wind speed from microwave scatterometer, (d) SAR-derived wind speed at 09:17 UTC
表 1 HY-2系列微波散射计主要信息
Table 1. Main information of HY-2 series microwave scatterometer
卫星 散射计 在轨时间 波段 标称风速范围 /(m·s–1) 轨道重访周期 / d HY-2B HSCAT-B 2018-10至今 Ku 2~24 14 HY-2C HSCAT-C 2020-09至今 Ku 2~24 10 HY-2 D HSCAT-D 2021-05至今 Ku 2~24 10 表 2 飓风案例及对应的SFMR与HY-2卫星观测数据
Table 2. Hurricane cases and corresponding SFMR and HY-2 satellite observation data
台风名称 日期 HY-2数据源 HY-2观测时间(UTC) SFMR观测时间段(UTC) 道格拉斯 (Douglas) 2020-07-25 HY-2B 2020-07-25 03:20:00 2020-07-25
02:15:34-05:20:59道格拉斯 (Douglas) 2020-07-26 HY-2B 2020-07-26 16:34:00 2020-07-26
16:04:10-18:34:59萨利 (Sally) 2020-09-17 HY-2B 2020-09-17 21:45:00 2020-09-17
20:30:27-23:35:58贝塔 (Beta) 2020-09-20 HY-2B 2020-09-20 00:16:00 2020-09-20
00:00:00-02:16:59泰迪 (Teddy) 2020-09-21 HY-2B 2020-09-21 09:57:00 2020-09-21
07:57:01-11:57:59泰迪 (Teddy) 2020-09-21 HY-2B 2020-09-21 21:33:00 2020-09-21
19:33:00-23:33:59德尔塔 (Delta) 2020-10-08 HY-2B 2020-10-08 00:00:00 2020-10-08
00:00:00-02:00:59德尔塔 (Delta) 2020-10-08 HY-2B 2020-10-08 12:49:00 2020-10-08
10:49:00-14:49:59拉里 (Larry) 2021-09-07 HY-2C 2021-09-07 20:30:00 2021-09-07
18:30:00-22:30:59山姆 (Sam) 2021-09-27 HY-2C 2021-09-27 15:52:00 2021-09-27
15:22:22-17:52:59表 3 模型订正前后各风速区间指标统计结果
Table 3. Statistical results of metrics for each wind speed interval before and after model correction
风速区间/(m·s–1) RMSE /(m·s–1) CC SD/(m·s–1) 订正前 0~10 2.03 –0.07 1.98 10~25 3.76 0.77 2.44 > 25 13.27 0.24 5.25 订正后 0~10 2.67 –0.06 1.95 10~25 3.84 0.76 3.70 > 25 6.76 0.25 6.07 -
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苏月 女, 2002年9月出生于山东省聊城市, 现为中国科学院空天信息创新研究院硕士研究生, 主要研究方向为海面风场反演. E-mail:
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