Assimilation of Ocean Surface Wind Data by the HY-2B Satellite in GRAPES: Impacts on Analyses and Forecasts

• Published in: Advances in atmospheric sciences 2023, Vol.40 (1), p.44-61
• Main Authors: Wang, Jincheng, Jiang, Xingwei, Shen, Xueshun, Zhang, Youguang, Wan, Xiaomin, Han, Wei, Wang, Dan
• Format: Article
• Language: English
• Subjects: Atmospheric Sciences; Boundary layers; Data analysis; Data assimilation; Data collection; Dynamic height; Earth and Environmental Science; Earth Sciences; Fruits; Geophysics/Geodesy; Geopotential; Geopotential height; Grapes; Height; Mathematical models; Meteorology; Middle troposphere; Numerical models; Ocean models; Ocean surface; Oceans; Original Paper; Prediction models; Scatterometers; Skills; Southern Hemisphere; Surface wind; Temperature; Tropical environments; Troposphere; Weather forecasting; Wind; Wind data; Wind fields
• ISSN: 0256-1530; 1861-9533
• DOI: 10.1007/s00376-022-1349-2

The ocean surface wind (OSW) data retrieved from microwave scatterometers have high spatial accuracy and represent the only wind data assimilated by global numerical models on the ocean surface, thus playing an important role in improving the forecast skills of global medium-range weather prediction models. To improve the forecast skills of the Global/Regional Assimilation and Prediction System Global Forecast System (GRAPES_GFS), the HY-2B OSW data is assimilated into the GRAPES_GFS four-dimensional variational assimilation (4DVAR) system. Then, the impacts of the HY-2B OSW data assimilation on the analyses and forecasts of GRAPES_GFS are analyzed based on one-month assimilation cycle experiments. The results show that after assimilating the HY-2B OSW data, the analysis errors of the wind fields in the lower-middle troposphere (1000–600 hPa) of the tropics and the southern hemisphere (SH) are significantly reduced by an average rate of about 5%. The impacts of the HY-2B OSW data assimilation on the analysis fields of wind, geopotential height, and temperature are not solely limited to the boundary layer but also extend throughout the entire troposphere after about two days of cycling assimilation. Furthermore, assimilating the HY-2B OSW data can significantly improve the forecast skill of wind, geopotential height, and temperature in the troposphere of the tropics and SH.