Investigation of Severe Turbulence Over China During 2018–2025 From In Situ EDR Data

ABSTRACT The nation‐scale airborne turbulence features remain unclear in China. We investigated the characteristics of turbulence for the period 2018–2025 over China based on in situ eddy dissipation rate (EDR) observations of turbulence from Xiamen Airlines, in combination with pilot reports (PIREPs). Using different EDR thresholds, we quantitatively analyzed the seasonal variation characteristics of severe turbulence and its spatial distribution across different flight phases and examined the characteristics of various potentially hazardous persistent severe turbulence event. The National Centers for Environmental Prediction reanalysis data, along with precipitation observations from automatic weather stations, were used to summarize the weather factors that trigger turbulence through synoptic analysis. Results showed that the frequency of turbulence occurrence decreases with increasing altitude, and turbulence intensity in the upper troposphere is systematically weaker than PIREPs. The seasonal variation in the proportion of turbulence occurrence at different altitudes becomes more pronounced for stronger turbulence. Severe turbulence is rare below 3 km, but peaks at 3–8 km in summer (60%–70%) and above 8 km in winter. Diurnal variation in turbulence is confined mainly to low altitudes, where the frequency and intensity of turbulence increase simultaneously only in the afternoon. Those flight routes prone to more severe or greater turbulence (EDR ≥ 0.45 m 2/3 s −1 ) are mainly the north–south routes over eastern China. In the vicinity of airports, severe turbulence is frequently observed at altitudes of < 400 m and 2–3 km. Persistent severe turbulence events occur mostly in winter and spring, although turbulence intensity peaks in autumn and winter. They are characterized by either brief high‐frequency bursts or prolonged persistence and are triggered primarily by upper‐level jets, typhoons, trough/shear‐line passages, and cold air outbreaks. Our findings advance the understanding of in situ EDR and offer a practical reference for its quantitative application in turbulence monitoring over China.