On 21 May 2024, Singapore Airlines Flight SQ321 encountered severe turbulence over Myanmar. Aviation turbulence can be separated into two common categories: convectively-induced turbulence (CIT), which emerges as a result of convective storms, or clear-air turbulence (CAT), which is characterized by strong shear. In the case of SQ321, a recent study used GPS Radio Occultation (GPS-RO) to analyze the convective conditions that could have contributed to the turbulence event. However, usage of GPS-RO for deriving convective potential metrics is dubious which, in combination with an exclusive focus on CIT, may have limited a complete evaluation of the meteorologic conditions. This therefore prompts further clarification regarding the processes responsible for severe turbulence by providing additional analysis on CAT diagnostics. Using ECMWF's ERA5 reanalysis database, the atmospheric environment of SQ321 at the time of turbulence was investigated via mapping and creating vertical profiles of meteorologic parameters which measured stability and convective potential. Findings show that the convective energy necessary for convective storms, which exceeded 2200 J/kg, was present within the range of the flight altitude. Atmospheric stability parameters revealed low shear and weak stratification in the surrounding area, resulting in a Richardson number of 23.35, far above the critical instability threshold of 0.25. Convectively-induced turbulence diagnostics suggest that SQ321 was flying within an environment conducive to convective processes, triggering its severe turbulence event. This study examines both convective and clear-air metrics in order to provide a comprehensive evaluation into atmospheric conditions capable of causing severe turbulence. In the face of climate change, it's essential to understand these mechanisms as they relate to the future of commercial aviation.
Acknowledgements: My advisor, Osamu Miyawaki