Retrieving Tropical Cyclone Radius of Maximum Wind From Geostationary Satellite Infrared Imagery With SAR Observations as Ground Truth

The radius of maximum wind (RMW) is a critical parameter for characterizing the tropical cyclone (TC) inner core structure, wind field distribution, and potential hazard extent. While spaceborne cross-polarized synthetic aperture radar (SAR) enables high-precision wind field measurements, its high operational cost and low temporal resolution restrict widespread application. To address this challenge, this study develops an RMW retrieval algorithm leveraging geostationary satellite infrared imagery, with SAR-derived wind products serving as ground truth. Focusing on TCs over Western North Pacific during 2016–2024, a dataset comprising 110 eyed and 121 noneye TC samples was curated from quality-controlled SAR observations. The proposed algorithm extends the eye-radius-based RMW estimation method, which was originally designed for clear-eyed TC, to unclear-eyed scenarios. Simultaneously, it introduces a novel proxy based on the radius of strongest convection for retrieving RMW in noneye TCs. Rigorous evaluation through independent validation, cross-validation, and comparative analysis confirms that the algorithm achieves superior accuracy relative to the Joint Typhoon Warning Center best-track records. Ablation experiments and sensitivity tests examining satellite data sources, temporal asynchrony, eyewall replacement cycles, and center positioning accuracy, further substantiate the robustness and stability of the proposed algorithm. This work establishes an operationally feasible and scalable framework for high-accuracy, high-frequency monitoring of TC inner core dynamics, with direct implications for advancing forecasting and hazard assessment capabilities.