Aviation turbulence encounters detected from aircraft observations: spatiotemporal characteristics and application to Korean Aviation Turbulence Guidance

Abstract

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.

Improvements in Nonconvective Aviation Turbulence Prediction for the World Area Forecast System

“…This is much smaller than the grid spacing of the current (and near-future version of) global NWP models. However, because the energy of the large-scale disturbances cascades down to smaller scales (e.g., Cho and Lindborg 2001), aircraft-scale turbulence can be logically predicted using NWP model-based turbulence diagnostics formulated based on the aforementioned turbulence generation mechanisms (e.g., Gill 2014;Kim et al 2011Kim et al , 2015Kim and Chun 2016;Sharman et al 2006;Sharman and Pearson 2017).…”

Increased light, moderate, and severe clear-air turbulence in response to climate change

“…Any two independent constraints on the cumulative distribution function of the log-normal distribution will uniquely define the values of these two parameters. Here, we require that the probability of light-or-greater turbulence (with a cube-rooted eddy dissipation rate greater than 0.1 m 2/3 s −1 ) is 3.0% (Watkins and Browning, 1973;Kim and Chun, 2016) and that the probability of moderate-orgreater turbulence (with a cube-rooted eddy dissipation rate greater than 0.3 m 2/3 s −1 ) is 0.4% (Sharman et al, 2006;Kim and Chun, 2016). This definition of moderate-or-greater turbulence is slightly different from the one used by Williams and Joshi (2013).…”

Influence of meteorological phenomena on worldwide aircraft accidents, 1967–2010

“…They found that the intermittent gust, which created a severe crosswind over the runaways, was associated with undulations in a train of lee waves in the mid‐troposphere in a stable layer above the airport, creating descending strong winds towards the surface. Kim and Chun () used observational data recorded by some flights of Korean Air Lines to obtain the derived equivalent vertical gust velocity as a turbulence indicator. They found an average of one turbulence per flight and per 10 h of navigation, mainly following the jet stream.…”