Using observational data from Korean Air Lines (KAL) Boeing (B) 737-800, B777-200 and B777-300 flights from January to December 2012, the derived equivalent vertical gust velocity (DEVG) was calculated as a turbulence indicator. Based on 1 min flight segments using the calculated DEVG, the highest frequency of moderate-or-greater (MOG) turbulence occurred in the Northern Hemisphere winter, whereas the lowest frequency occurred in the Northern Hemisphere summer. Spatially, the KAL turbulence encounters (KAL-DEVG) covered five regions, Asia, Oceania, Western Europe, North America and South America, following major flight routes. The number of observed turbulence events is normalized by flight density and navigation times. As a result, 1 MOG turbulence is observed per flight and per 10 h of navigation. Over East Asia, the observed MOG KAL-DEVG mainly appeared to follow the jet stream and most turbulence events were related to shear instability and inertial instability. KAL-DEVG was used to evaluate the operational Korean Aviation Turbulence Guidance (KTG) system developed using a combination of the Regional Data Assimilation and Prediction System (RDAPS) of the Korea Meteorological Administration and pilot reports over East Asia. The forecasting performance evaluated by the skill score (defined as the area under the curve based on the probability of detection statistics) on the operational-KTG system against KAL-DEVG and RDAPS analysis data was found to be 0.815, with 95% confidence levels ranging from 0.812 to 0.821. Using the RDAPS 6 and 12 h forecast data, the skill score was slightly less than 0.8 in comparison to KAL-DEVG.
All Science Journal Classification (ASJC) codes
- Atmospheric Science