Simulation of Rotating System Microwave Scatterometer Performance and Observation of Tropical Cyclone

The observation of high speed wind fields, especially tropical cyclone wind fields, has long been an important research subject in scatterometer remote sensing. In this study, we analyzed the backscattering coefficient measurement accuracies and wind retrieval performances of the two scatterometer systems that have been operational in China: the rotating fan-beam system and the rotating pencil-beam system by simulation methods. Simulations at varying wind speed wind fields and tropical cyclone wind fields observations are conducted for both systems. Simulation results obtained with reference to the parameters of existing operational scatterometers show that the rotating fan-beam system demonstrates superior sampling capacity compared to the rotating pencil-beam system, with the vast majority of its observation views gaining a greater number of independent observation samples than 1000, whereas the rotating pencil-beam system has mainly 100～400 independent observation samples for each observation view only. This sampling advantage enables the rotating fan-beam system to achieve better performance in backscattering coefficient measurement and wind field retrieval in the simulations for wind fields with high wind speeds above 20 m·s^–1. At the same time, the normalized SNR of each observation view is higher for the rotating pencil-beam system, which is about 300～600 per observation view, compared to 6～14 for the rotating fan-beam system. This SNR superiority enables the rotating pencil-beam system to maintain a more precise observation for wind fields with low and medium wind speeds below 20 m·s^–1 in the simulation. This study reveals the performance characteristics of backscattering coefficient measurement and wind field retrieval of different scatterometer systems under various wind speed conditions, which is of reference significance for high speed wind fields retrieval and tropical cyclone wind fields observation. Meanwhile, the conclusions of this study also lay a foundation for subsequent research on the improvement of scatterometer wind field observation accuracy and optimization of signal processing algorithms for different scatterometer systems.