5:15 PM - 7:15 PM
[AAS02-P05] Upper-Level Structures of Typhoon Nanmadol (2022) Revealed by Aircraft Flight Data
Keywords:Typhoon, Aircraft obsevation
In direct aircraft observations of typhoons, dropsondes and airborne radar are commonly employed to investigate the thermodynamic and kinematic fields surrounding the storm, including its inner-core region. The data obtained from these equipment play a vital role in illuminating typhoon structures and data assimilation. Although aircraft routinely record flight-level parameters such as temperature and wind speed for safe navigation, these data are generally regarded as merely one among many observational resources, and only limited research has leveraged onboard flight-level data. Even when such data are utilized, their application is restricted—for example, to correct dropsonde measurements. Therefore, this study aims to elucidate the horizontal structure near the cruising altitude of approximately 13,000 m by employing flight-level data acquired during direct typhoon observations.
Focusing on Typhoon Nanmadol (2022), which was directly observed in the T-PARCII project, we analyzed data obtained on September 16 (developing stage) and 17 (mature stage). In this mission, the aircraft conducted an eyewall penetration flight, entering the typhoon’s eye on both days. From cockpit video footage showing onboard radar imagery, we confirmed that the eye radius was about 20 km on September 16 and approximately 15 km on September 17. The flight data included air temperature, wind direction and speed, pressure, as well as aircraft position and acceleration, recorded at frequencies ranging from about 5 to 100 Hz. In this study, the data were averaged to 1-second intervals, creating a 1 Hz log dataset. At the cruising altitude, the aircraft flew at around 405 knots, so each data point corresponds to roughly 200 m along the flight path. To represent the flight data in a typhoon-centered polar coordinate system, we estimated the storm center using 30-second orbital observations from Himawari-8 (Band 13, infrared), then performed linear interpolation at 1-second intervals to obtain the center coordinates.
Our study revealed marked horizontal variations. With respect to temperature, both days showed positive temperature anomalies from the eyewall region into the eye. On September 16 (developing stage), the anomaly was about 6°C, while on September 17 (mature stage), it reached approximately 10°C, indicating the presence and intensification of a warm-core structure. Regarding the tangential wind, a maximum wind speed peak appeared about 40 km from the typhoon center on September 17. On September 16, when wind speeds were around 30 m/s, no distinct peak was observed.
These flight data, which recorded temperature, wind fields, and pressure at high frequency, demonstrate that they can be leveraged to elucidate typhoon structures. On the other hand, significant noise was found in each dataset. On the other hand, each dataset contained noise, with temperature likely affected by sensor icing and wind fields highly influenced by changes in the aircraft’s heading. Identifying the tendencies of these anomalies will be a key focus for future research. Addressing these anomaly tendencies will be a key focus of future research.
Focusing on Typhoon Nanmadol (2022), which was directly observed in the T-PARCII project, we analyzed data obtained on September 16 (developing stage) and 17 (mature stage). In this mission, the aircraft conducted an eyewall penetration flight, entering the typhoon’s eye on both days. From cockpit video footage showing onboard radar imagery, we confirmed that the eye radius was about 20 km on September 16 and approximately 15 km on September 17. The flight data included air temperature, wind direction and speed, pressure, as well as aircraft position and acceleration, recorded at frequencies ranging from about 5 to 100 Hz. In this study, the data were averaged to 1-second intervals, creating a 1 Hz log dataset. At the cruising altitude, the aircraft flew at around 405 knots, so each data point corresponds to roughly 200 m along the flight path. To represent the flight data in a typhoon-centered polar coordinate system, we estimated the storm center using 30-second orbital observations from Himawari-8 (Band 13, infrared), then performed linear interpolation at 1-second intervals to obtain the center coordinates.
Our study revealed marked horizontal variations. With respect to temperature, both days showed positive temperature anomalies from the eyewall region into the eye. On September 16 (developing stage), the anomaly was about 6°C, while on September 17 (mature stage), it reached approximately 10°C, indicating the presence and intensification of a warm-core structure. Regarding the tangential wind, a maximum wind speed peak appeared about 40 km from the typhoon center on September 17. On September 16, when wind speeds were around 30 m/s, no distinct peak was observed.
These flight data, which recorded temperature, wind fields, and pressure at high frequency, demonstrate that they can be leveraged to elucidate typhoon structures. On the other hand, significant noise was found in each dataset. On the other hand, each dataset contained noise, with temperature likely affected by sensor icing and wind fields highly influenced by changes in the aircraft’s heading. Identifying the tendencies of these anomalies will be a key focus for future research. Addressing these anomaly tendencies will be a key focus of future research.