Standardization of Gustiness Values from Aircraft

MacCready, Paul B.

doi:10.1175/1520-0450(1964)003<0439:sogvfa>2.0.co;2

Cited by 81 publications

(43 citation statements)

References 4 publications

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“…The eddy dissipation rate is a natural measure for quantifying the strength of turbulence. For a given aircraft type, aircraft weight, airspeed, and altitude, the rootmean-square vertical acceleration of the aircraft in turbulence is proportional to the cube-root of the eddy dissipation rate (MacCready, 1964). For a large commercial aircraft, cube-rooted eddy dissipation rates of 0.0-0.1 m 2/3 s −1 generate null turbulence, 0.1-0.2 m 2/3 s −1 generate light turbulence, 0.2-0.3 m 2/3 s −1 generate lightto-moderate turbulence, 0.3-0.4 m 2/3 s −1 generate moderate turbulence, 0.4-0.5 m 2/3 s −1 generate moderate-to-severe turbulence, 0.5-0.6 m 2/3 s −1 generate severe turbulence, 0.6-0.7 m 2/3 s −1 generate severe-to-extreme turbulence, and values greater than 0.7 m 2/3 s −1 generate extreme turbulence Williams, 2014;Sharman et al, 2014).…”

Section: 2)mentioning

confidence: 99%

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

Williams

2017

Adv. Atmos. Sci.

102

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Anthropogenic climate change is expected to strengthen the vertical wind shears at aircraft cruising altitudes within the atmospheric jet streams. Such a strengthening would increase the prevalence of the shear instabilities that generate clear-air turbulence. Climate modelling studies have indicated that the amount of moderate-or-greater clear-air turbulence on transatlantic flight routes in winter will increase significantly in future as the climate changes. However, the individual responses of light, moderate, and severe clear-air turbulence have not previously been studied, despite their importance for aircraft operations. Here, we use climate model simulations to analyse the transatlantic wintertime clear-air turbulence response to climate change in five aviation-relevant turbulence strength categories. We find that the probability distributions for an ensemble of 21 clear-air turbulence diagnostics generally gain probability in their right-hand tails when the atmospheric carbon dioxide concentration is doubled. By converting the diagnostics into eddy dissipation rates, we find that the ensembleaverage airspace volume containing light clear-air turbulence increases by 59% (with an intra-ensemble range of 43%-68%), light-to-moderate by 75% (39%-96%), moderate by 94% (37%-118%), moderate-to-severe by 127% (30%-170%), and severe by 149% (36%-188%). These results suggest that the prevalence of transatlantic wintertime clear-air turbulence will increase significantly in all aviation-relevant strength categories as the climate changes.

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Section: 2)mentioning

confidence: 99%

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

Williams

2017

Adv. Atmos. Sci.

102

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“…The noise is not an artifact of the measurements but is attributed to the real atmospheric conditions, primarily enhanced turbulence in the vicinity of the sharp MBL height drop and large wind shear. The eddy dissipation rate (EDR) is a measure of turbulence using the method developed by MacCready (1964) with higher values corresponding to more turbulence. There is a spike in turbulence as the aircraft crosses the temperature inversion and encounters large changes in wind speed and direction.…”

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confidence: 99%

Coastal Jet Adjustment near Point Conception, California, with Opposing Wind in the Bight

Rahn

Parish

Leon

2014

Monthly Weather Review

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Typical spring and summer conditions offshore of California consist of strong northerly low-level wind contained within the cool, well-mixed marine boundary layer (MBL) that is separated from the warm and dry free troposphere by a sharp temperature inversion. This system is often represented by two layers constrained by a lateral boundary. Aircraft measurements near Point Conception, California, on 3 June 2012 during the Precision Atmospheric MBL Experiment (PreAMBLE) captured small-scale features associated with northerly flow approaching the point with the added complexity of encountering opposing wind in the Santa Barbara Channel. An extremely sharp cloud edge extends south-southwest of Point Conception and the flight strategy consisted of a spoke pattern to map the features across the cloud edge. Lidar and in situ measurements reveal a nearly vertical jump in the MBL from 500 to 100 m close to the coast and a sharp edge at least 70 km away from the coast. In this case, it is hypothesized that it is not solely hydraulic features responsible for the jump, but the opposing flow in the Santa Barbara Channel is a major factor modifying the flow. Just southeast of Point Conception are three distinct layers: a shallow, cold layer near the surface with northwesterly winds associated with an abrupt decrease in MBL height from the north that thins eastward into the Santa Barbara Channel; a cool middle layer with easterly wind whose top slopes upward to the east; and the warm and dry free troposphere above.

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“…The terms light, moderate, severe, and extreme are in common use and have operational definitions in aviation (see Table 1). There is also some history of relating these descriptions to numerical turbulence values (MacCready 1964), but these are not universally accepted. Note that the operational definitions are aircraft and pilot based-a given turbulent state of the atmosphere has a greater effect on a small, light aircraft than a larger one.…”

Section: Turbulence Alert Model Develop-mentmentioning

confidence: 99%

The Juneau Terrain-Induced Turbulence Alert System

Politovich

Goodrich

Morse

et al. 2011

Bulletin of the American Meteorological Society

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The Juneau, Alaska, airport vicinity experiences frequent episodes of moderate and severe turbulence, which affect arriving and departing air traffic. The Federal Aviation Administration funded the National Center for Atmospheric Research to develop a warning system, consisting of carefully placed anemometers and wind profilers, along with data communications, an algorithm, and display, to warn pilots of potentially hazardous situations. The system uses regressions based on comparisons of research aircraft data with measurements from the ground-based sensors to estimate the turbulence intensity along selected flight paths. This paper describes the development of the turbulence warning system, from meteorological characteristics through sensor placement, algorithm construction and evaluation, and display design. The discussion includes how best estimates of winds were made in adverse meteorological and topographic conditions, how turbulence was calculated from aircraft conducting various flight maneuvers, how bad data were identified and removed from the system, how the regressors were selected, and the skill of the system.

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Standardization of Gustiness Values from Aircraft

Cited by 81 publications

References 4 publications

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

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

Coastal Jet Adjustment near Point Conception, California, with Opposing Wind in the Bight

The Juneau Terrain-Induced Turbulence Alert System

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