Opportunities for Advancing the Understanding and Prediction of Typhoons in the South China Sea with Multi-aircraft Missions: Super Typhoon Ragasa (2025)

A summary is provided of aircraft missions into Super Typhoon Ragasa (2025), the most intense typhoon of the 2025 season that impacted the Philippines and south China coast. The aircraft missions occurred as Ragasa was approaching Hong Kong, with the Challenger aircraft from the Hong Kong Observatory and the King Air aircraft from the Asia-Pacific Typhoon Collaborative Research Center conducting joint missions into the typhoon, marking only the second time that such two-plane missions have occurred in the South China Sea. Unique measurements from these aircraft, including deep-layer dropsondes within the moat region between Ragasa’s primary and outer eyewalls and between the outer eyewall and spiral rainband, are described. Additionally, surface wind radii as measured by the dropsondes, and how they compare with satellite measurements provided ∼12 h after the aircraft missions, are presented. The temporal separation between the aircraft and satellite measurements provides the ability to monitor the evolution of the surface wind as the typhoon approaches land, a valuable observation for forecasters and storm surge modelers. An evaluation of the Shanghai Typhoon Model wind field based on a comparison with dropsonde observations is also performed, identifying potential sources of biases in the model and pointing toward ways to improve the model. Using these missions as a guide, suggestions for more fully exploiting the complementary capabilities of each aircraft are provided. These suggestions include optimizing the coordinated sampling to provide simultaneous measurements of surface winds in various quadrants and radii and providing dropsonde profiles of temperature, moisture, and pressure in the vicinity of in situ measurements of microphysics properties from the King Air. The use of composite datasets of dropsondes and Stepped Frequency Microwave Radiometer is also discussed as a way to obtain robust, quantifiable characterizations of tropical cyclone structure and how it relates to intensity change and associated hazards such as storm surge and rainfall, providing a way to advance the understanding and prediction of hazards and impacts from landfalling tropical cyclones.