A Comparison Study of EDR Estimates from the NLR and NCAR Algorithms

Jeffrey Chi Wai Lee,Mang Hin Kok,Pak Wai Chan,Christy Yan Yu Leung

doi:10.3390/atmos13010132

Jeffrey Chi Wai Lee, Mang Hin Kok + Show 2 more

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https://doi.org/10.3390/atmos13010132

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Journal: Atmosphere	Publication Date: Jan 14, 2022
Citations: 2	License type: CC BY 4.0

Affiliation: Hong Kong Observatory

Abstract

A comparison was made of two eddy dissipation rate (EDR) estimates based on flight data recorded by commercial flights. The EDR estimates from real-time data using the National Center for Atmospheric Research (NCAR) Algorithm were compared with the EDR estimates derived using the Netherlands Aerospace Centre (NLR) Algorithm using quick assess recorder (QAR) data. The estimates were found to be in good agreement in general, although subtle differences were found. The agreement between the two algorithms was better when the flight was above 10,000 ft. The EDR estimates from the two algorithms were also compared with the vertical acceleration experienced by the aircraft. Both EDR estimates showed good correlation with the vertical acceleration and would effectively capture the turbulence subjectively experienced by pilots.

Highlights

Turbulence is a hazardous weather phenomenon and is the main cause of weatherrelated reported aircraft incidents and accidents [1]
Because pilots report the severity of turbulence based on their subjective feeling of the degree of shaking during a flight, we examined the vertical acceleration recorded by the quick assess recorder (QAR) to see how well it correlates with the eddy dissipation rate (EDR) estimates
The National Center for Atmospheric Research (NCAR) Algorithm has been implemented on the B777 fleets of Cathay Pacific since early 2020 [17], and we had access to all EDR estimates from the NCAR Algorithm from Cathay Pacific B777 flights in real time

Summary

Introduction

Turbulence is a hazardous weather phenomenon and is the main cause of weatherrelated reported aircraft incidents and accidents [1]. There are a wide range of eddy sizes in the atmosphere, aircraft mainly respond to eddies having sizes in the order of tens to hundreds of meters Eddies of this size can be created by an energy cascade [2], i.e., a larger eddy in the atmosphere breaks up and forms a smaller eddy, which eventually dissipates as heat. Because the scale of interest for turbulence forecasting is in the order of hundreds of meters, which is outside the current scope of state-of-the-art operational NWP, these turbulence forecasts are often still diagnostic based, i.e., forecasting the weather quantities that are prone to create an eddy of the right size to result in an impact with an aircraft [5]. Parameters in these forecast techniques often need to be “calibrated” using turbulence observations

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