2:45 PM - 3:00 PM
[ACG45-05] Twin Experiment on Dropsonde Observation of Typhoon Nanmadol
Keywords:Typhoon, Data Assimilation, OSSE, Dropsonde
Extremely strong typhoons classified as "intense typhoons" by the Japan Meteorological Agency are likely to increase in intensity in a future warming climate and reach Japan while maintaining their "intense typhoon" status. Such typhoons are known to undergo a rapid development process in which the central pressure drops by 42 hPa or more in a single day. However, the rapid development process is difficult to predict using numerical weather models, and this leads to uncertainty in forecasting the path and intensity of typhoons.
T-PARCII, a group led by Nagoya University, has been conducting observation surveys of typhoon interiors using aircraft and drop observation equipment called drop sondes. The purpose of this study is to elucidate the mechanisms controlling typhoon intensity, such as the rapid development process and developed wall clouds, through the investigation of the acquired three-dimensional observation data of typhoons, and to improve the accuracy of forecasting the path and intensity of future strong typhoons.
In this study, we conduct a data assimilation experiment using aircraft observations of Typhoon Nanmadol (2022) to investigate the impact of aircraft observations on typhoon intensity prediction. We use the framework of identical-twin experiment for the impact of observation in which we perform 2 simulations of Nanmadol: "true" and "forecast" and both are performed by CReSS non-hydrostatic model with different computational settings. Pseudo dropsonde observation data for data assimilation is generated by a dropsonde simulation that extract variables (wind, pressure, humidity and temperature) from the "true" simulation along with trajectories of falling dropsonde. 3D-VAR data assimilation method is used for data assimilation. The results from the experiments suggest that temperature observation close to the eye of the typhoon is important for improving intensity forecasts, the temperature of the warm core being close to the "true" simulation.
T-PARCII, a group led by Nagoya University, has been conducting observation surveys of typhoon interiors using aircraft and drop observation equipment called drop sondes. The purpose of this study is to elucidate the mechanisms controlling typhoon intensity, such as the rapid development process and developed wall clouds, through the investigation of the acquired three-dimensional observation data of typhoons, and to improve the accuracy of forecasting the path and intensity of future strong typhoons.
In this study, we conduct a data assimilation experiment using aircraft observations of Typhoon Nanmadol (2022) to investigate the impact of aircraft observations on typhoon intensity prediction. We use the framework of identical-twin experiment for the impact of observation in which we perform 2 simulations of Nanmadol: "true" and "forecast" and both are performed by CReSS non-hydrostatic model with different computational settings. Pseudo dropsonde observation data for data assimilation is generated by a dropsonde simulation that extract variables (wind, pressure, humidity and temperature) from the "true" simulation along with trajectories of falling dropsonde. 3D-VAR data assimilation method is used for data assimilation. The results from the experiments suggest that temperature observation close to the eye of the typhoon is important for improving intensity forecasts, the temperature of the warm core being close to the "true" simulation.