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FY-3E/WindRAD双频散射计海面风场反演和验证研究

Ocean surface wind field retrieval and validation from FY-3E/WindRAD dual-frequency scatterometer

  • 摘要: 2021年7月发射的FY-3E星是世界首颗民用晨昏轨道气象卫星,其搭载的WindRAD双频测风雷达具有全球海面风场探测能力。本文首先基于FY-3E/WindRAD L1级观测资料,研究了雷达海面后向散射和风场非线性关系,分别建立了适用于C和Ku波段VV/HH极化的地球物理模式函数(GMF)。随后,结合最大似然估计法(MLE对WindRAD散射计探测资料进行风场反演。 利用海洋浮标、中法海洋卫星散射计(CSCAT)和美国国家环境预报中心(NCEP)模式风场资料对WindRAD反演风场进行验证。结果显示:WindRAD反演风速与浮标风速偏差约为0.2 m/s,均方根误差(RMSE)在1.13~1.44 m/s之间,优于2m/s的业务化应用的风速精度要求;两者风向偏差在1.4 ~ 3.0°之间,RMSE在25.3 ~ 30.0°之间。WindRAD和CSCAT风场具有较好的一致性,风速RMSE在1.37~1.6m/s之间,风向RMSE在22.9° ~ 25.9 °之间 。WindRAD和NCEP模式风速RMSE在1.87~2.12m/s之间,风向RMSE 在22.3°~27.1°之间。研究表明WindRAD散射计C和Ku波段VV/HH极化反演风场均具有较高的精度,充分显示了WindRAD载荷在全球海面风场探测方面的应用潜力和价值。

     

    Abstract: The FY-3E satellite launched in July 2021, which is the world"s first civilian twilight orbit meteorological satellite. The WindRAD dual-frequency scatterometer it carries has the ability to detect global ocean surface wind fields. This paper first studies the nonlinear relationship between sea surface backscatter and wind field based on FY-3E/WindRAD L1 level observation data, and then establishes geophysical model functions (GMFs) for C- and Ku-band VV/HH polarization wind field retrieval respectively. Based on the maximum likelihood estimation (MLE) method, ocean surface wind field were retrieve from WindRAD scatterometer data. The wind field is validated using ocean buoy, CSCAT and NCEP wind field data. The results show that the wind speed bias between the WindRAD and buoy is about 0.2m/s, and the root-mean-square error (RMSE) is range from 1.20 to 1.44 m/s, which better than 2m/s for operational applications. The wind direction bias and RMSE are range from 1.4 ~ 3.0° and 25.3 ~ 30.0°, respectively. WindRAD and HSCAT wind fields have good consistency, with the RMSE of wind speed between 1.37~1.6m/s and the RMSE of wind direction between 22.9°~25.9°. The RMSE between WindRAD and NCEP wind speed is 1.87~2.12m/s, and the RMSE of wind direction is between 22.3°~27.1°. These results indicate that sea surface wind fields retrieved from WindRAD dual-frequency scatterometer have high accuracy, fully demonstrating the application potential and value of WindRAD payload in global sea surface wind field detection.

     

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