Comparison of Turbulence Indicators Obtained from In Situ Flight Data

Abstract

Two indicators of turbulence—the eddy dissipation rate (EDR) and derived equivalent vertical gust velocity (DEVG)—are calculated using aircraft observations from Hong Kong–based airlines, whose aircraft included Boeing and Airbus models, for 39 months from February 2011 to April 2014. Characteristics of the two turbulence indicators that were calculated at 1-min intervals from the flight data are investigated. For Boeing and Airbus aircraft, there are large seasonal variations in the 90th and 99th percentiles of EDR and DEVG, whereas there are relatively small seasonal variations in the medians of EDR and DEVG. For the turbulence encounters estimated from EDR and DEVG, the authors compute their correlations for each level of turbulence and each type of aircraft. Strong correlations (larger than 0.7) occurred for all levels of turbulence encounters for Boeing aircraft, whereas relatively weak correlations (less than 0.5) occurred for Airbus aircraft. This difference is due to the different characteristics of recorded Boeing and Airbus aircraft data (the number of decimals and data sampling frequency). Based on correlation analyses, the authors construct the best-fit curves using mean EDR values for each DEVG bin and mean DEVG values for each EDR bin and obtain relationships between EDR and DEVG for Boeing and Airbus aircraft. The EDR and DEVG-derived EDR for moderate-or-greater-level turbulence are generally similar for Boeing aircraft.

Retrieval of Eddy Dissipation Rate from Derived Equivalent Vertical Gust included in Aircraft Meteorological Data Relay (AMDAR)

“…The primary peak falls within relatively small DEVG values (less than 8 m s -1 ), and the secondary peak falls within relatively large DEVG values (greater than 8 m s -1 ). This bimodal distribution, 25 which is more prominent in the NH (blue curve) than in the SH (red curve), is highly suspicious considering that Kim et al (2017) showed that the PDFs of the DEVG have a unimodal distribution following a lognormal distribution.…”

“…Stickland (1998) conducted a direct comparison between a vertical acceleration-based EDR and DEVG time series of Qantas Airways Boeing 747 data over a 3-month period (from October to December 1997) and showed that the two turbulence metrics are roughly correlated; however, this study considered a limited data period and only one aircraft type. Kim et al (2017) compared the EDR from some aircraft of Hong Kong-based airline (Haverdings and Chan, 2010) and the DEVG from the same aircraft using a relatively long period (39 months from February 2011 to April 2014) data. Kim et al (2017) developed 20 the best-fit curves between the EDR and DEVG for Airbus and Boeing aircraft data, separately.…”

“…Kim et al (2017) compared the EDR from some aircraft of Hong Kong-based airline (Haverdings and Chan, 2010) and the DEVG from the same aircraft using a relatively long period (39 months from February 2011 to April 2014) data. Kim et al (2017) developed 20 the best-fit curves between the EDR and DEVG for Airbus and Boeing aircraft data, separately. Although it was not directly used for the conversion of the DEVG to the EDR, Sharman and Pearson (2017) suggested a methodology to convert various turbulence diagnostics to the EDR by assuming that the turbulence diagnostics follow a lognormal distribution at upper levels.…”

“…For homogenized global aviation turbulence observations, in the current study, we convert the DEVG to the EDR 25 using two conversion methods, one based on Sharman and Pearson (2017) and the other based on Kim et al (2017), using historical DEVG records in the AMDAR National Oceanic and Atmospheric Administration (NOAA)-archives (hereafter, DEVG) dataset for 36 months (October 2015-September 2018. This paper is organized as follows.…”

Aviation Turbulence: Dynamics, Forecasting, and Response to Climate Change

“…The DEVG (Tenenbaum 1991;Gill 2014Gill , 2016Kim et al 2017) is calculated following Truscott (2000) using:…”