Climatology of the Estimated Eddy Dissipation Rate (EDR) Using the 1-Hz Wind Observations from In Situ Flight Data

Aircraft Turbulence is defined as a sudden jolt of cruising aircraft due to unexpected turbulent motions in atmosphere. It often induces in-flight injuries, structural damage, and flight delays. To objectively report turbulence intensity, the International Civil Aviation Organization /World Meteorological Organization (ICAO/WMO) has been used the cube root of Energy Dissipation Rate (EDR) as a standard for reporting aircraft turbulence. The purpose of this study is to construct climatology of the EDR using the 1-Hz sampling rate of wind observations from the archived in-situ flight data.

The data includes three different types of aircraft (B737-800, B777-200, and B777-300) from the Korean-based national air carrier in 2012. After applying the Fast Fourier Transform (FFT) to the quality-controlled 1-Hz wind data, total of 622,225 individual spectra over 1-min time segment are obtained for u, v, and w wind components separately. Here, w wind component is derived using the 1-Hz data of avionic parameters like true airspeed, roll and pitch angles, angles of attack, and inertial vertical velocity. Finally, two different estimates of the EDR are computed by fitting either the Kolmogorov scale (k^-5/3) slope or prescribed von Kármán spectrum model on the individual spectrum within the inertial subrange. Eventually climatology of various EDR estimates (two methods for u, v, and w wind components from three aircraft types) are constructed, which follows well a lognormal distribution. Mean and standard deviation of the log-scale EDR from the different EDR estimates are comparable with those results from the previous study (Sharman and Pearson 2017) using higher sampling rate (10-Hz) of in situ flight data. This suggests that the estimated EDR using relatively low sampling rate (1-Hz) of flight data like the Automatic Dependence Surveillance – Broadcast (ADS-B) is also useful for turbulence reporting, which eventually contributes to more widespread database of turbulence observation in the world.