Research on Spatial Range of GNSS-R Detection of Evaporation Duct in the Coastal Waters of China

Objectives: The evaporation duct has a significant impact on shore based radar, shipborne radar, and 5G communication due to its refractive effect. GNSS-R has the application potential of detecting evaporation duct due to the characteristics of all-weather, passive reception and high spatial and temporal resolution. However, spatial range of GNSSR detection of evaporation duct is closely related to the evaporation duct height, and whether it has practical value in the complex evaporation duct environment near the coast of China still needs to be studied. Methods: Thus, meteorological data measured from coastal meteorological observation stations and sea surface temperature released by ECMWF were used to obtain the spatiotemporal distribution pattern of the spatial range of GNSS-R detection of evaporation duct, which the evaporation duct model and GNSS-R evaporation duct detection range model are adopted. Results: The results indicate that the spatial range of GNSS-R detection of evaporation duct based on Chinese coastal meteorological data first increases and then decreases during the day, reaches maximum from 5:00 to 7:00 UTC, and gradually decreases and stabilizes at night. In terms of seasonal changes, the highest is reached in summer and autumn, and the lowest is in winter. The detection range of the Bohai Sea and Yellow Sea are greatly affected by seasons, while the detection range of the East China Sea and South China Sea is large and remains relatively stable throughout the year, especially in the South China Sea, it can maintain a detection range of about 130km throughout the year. Further analysis found that during the high incidence period and the quiet period of the evaporation duct, the average spatial range of GNSS-R detection of the evaporation duct is 145km and 103km, respectively. In addition, regional differences have an influence on the detection range, for example, the average spatial range of GNSS-R detection of evaporation duct on the western side of Liaodong Peninsula and Hainan Island is greater than that on the eastern side, and the Taiwan Strait, as a high incidence area for evaporation ducts, has a larger spatial range for GNSS-R detection of evaporation ducts than the surrounding waters. Conclusions: The analysis results can expand the application areas of meteorological data, improve radar detection efficiency in relevant areas, and provide the warning information for communication.