[A-AS01] Evolution of Global Environmental Research based on Atmospheric Vertical Motions

[AAS01-04] Clear Air Turbulence Resolved by Numerical Weather Prediction Model Validated by Onboard and Virtual Flight Data

*Ryoichi Yoshimura¹, Junshi Ito², Patrick Antonio Schittenhelm³, Kento Suzuki⁴, Aiko Yakeno⁵, Shigeru Obayashi⁵ (1.ISEE, Nagoya University, Japan, 2.Graduate School of Science, Tohoku University, Japan, 3.University of Stuttgart, Stuttgart, Germany, 4.Osaka Regional Headquarters, Meteorological Agency, Osaka, Japan, 5.Institute of Fluid Science, Tohoku University, Japan)

Keywords:Turbulence, Large Eddy Simulation, Aircraft, Flight Data

Turbulence, a sudden shift in air, poses a serious threat to flying airplanes. While most turbulence can be avoided by visually monitoring factors such as clouds or nearby aircraft, Clear Air Turbulence (CAT) remains a challenge due to its invisible nature.

To study CAT generation, high-resolution numerical simulations, offer insights into the intricate processes involved. However, accurately reproducing turbulent eddies in simulations and assessing their danger to aircraft remains uncertain.

In our investigation, we investigate a CAT event affecting aircraft at lower altitudes by enhancing the resolution of a regional weather forecasting model. Through simulations conducted on Fugaku, validated against flight data, we reveal the role of Kelvin-Helmholtz instability waves in generating hazardous turbulence over Tokyo.

Using flight data from encounters with CAT on Dec 30, 2020, we validate simulated results through virtual flight simulations. Our findings suggest that while the 35-m LES captures turbulence shaking aircraft at their natural frequencies, finer grid spacing enhances fidelity to flight data.