Satellite scatterometers play a crucial role in monitoring ocean surface winds, with their accuracy directly impacting weather forecasting and climate research. However, rainfall has consistently challenged precise wind measurements, as Ku-band radar signals are much affected by rain clouds.

A recent collaborative study involving researchers from the China Meteorological Administration, the Chinese Academy of Sciences, and the Royal Netherlands Meteorological Institute has led to the development of an innovative rain conceptual model using dual-frequency measurements from the WindRAD instrument aboard China’s FengYun-3E (FY-3E) satellite to quantify and correct rain-induced errors in wind measurements. This breakthrough is detailed in their publication “A rain effect elimination approach using FengYun-3E WindRAD dual-frequency measurements” in Atmospheric and Oceanic Science Letters.

The method demonstrates remarkable effectiveness under moderate rainfall conditions. After correction, discrepancies between Ku-band and C-band wind measurements show significant improvement: the wind speed root-mean-square errors decrease by approximately 0.2 m s^-1, while wind direction errors reduce by about 1.6°. Notably, the average wind speed bias was nearly eliminated at rain rates below 10 mm h^-1.

“Our method improves the agreement between Ku-band and C-band wind retrievals during rain events,” notes corresponding author Dr. Xu Na. “Although further refinements are needed for complex conditions like heavy rainfall and low wind speeds, this work establishes a viable path toward more reliable scatterometer data in rainy conditions globally.”

Schematic of the assumed Ku-band measured NRCS bias distribution with rain rates and wind-induced NRCS.

This advancement not only enhances the data quality from FY-3E’s WindRAD but also offers an adaptable framework for other international Ku-band scatterometers, representing a significant step forward in global ocean wind monitoring capabilities.

Citation: Ke Zhao, Ad Stoffelen, Jeroen Verspeek, Anton Verhoef, Zhen Li, Na Xu, Lin Chen, Xiaochun Zhai, Fangli Dou, Yunkai Zhang, Peng Zhang, Tie Dai, 2025. A rain effect elimination approach using FengYun-3E WindRAD dual-frequency measurements. Atmospheric and Oceanic Science Letters, 100725. https://doi.org/10.1016/j.aosl.2025.100725.