A Preliminary Report on Doppler Radar Observation of Turbulence in a Thunderstorm PDF Download
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Author: Ralph J. Donaldson
Publisher:
ISBN:
Category : Atmospheric turbulence
Languages : en
Pages : 26
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Book Description
Vertical-incidence observations by Doppler radar of velocities in a thunderstorm reveal some regions in which the spread of velocities is unusually broad. The widths of the vertical velocity spectra are generally greatest along the edges of a major updraft, where the maximum shear in updraft speed also occurs. The observations indicate that turbulence is an important cause of the abnormally wide velocity spectra, and suggest the utility of Doppler radar measurements of the vertical velocity spectrum as an indicator of severe cloudy-air turbulence. Furthermore, vertical velocity spectra in the more convective regions of thunderstorms, where they may be seriously affected by turbulence and wind shear, probably give an exaggerated picture of the particle size distribution. (Author)
Author: Ralph J. Donaldson
Publisher:
ISBN:
Category : Atmospheric turbulence
Languages : en
Pages : 26
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Book Description
Vertical-incidence observations by Doppler radar of velocities in a thunderstorm reveal some regions in which the spread of velocities is unusually broad. The widths of the vertical velocity spectra are generally greatest along the edges of a major updraft, where the maximum shear in updraft speed also occurs. The observations indicate that turbulence is an important cause of the abnormally wide velocity spectra, and suggest the utility of Doppler radar measurements of the vertical velocity spectrum as an indicator of severe cloudy-air turbulence. Furthermore, vertical velocity spectra in the more convective regions of thunderstorms, where they may be seriously affected by turbulence and wind shear, probably give an exaggerated picture of the particle size distribution. (Author)
Author: Ralph J. Donaldson
Publisher:
ISBN:
Category : Doppler radar
Languages : en
Pages : 0
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Book Description
Vertical-incidence observations by Doppler radar of velocities in a thunderstorm reveal some regions in which the spread of velocities is unusually broad. The widths of the vertical velocity spectra are generally greatest along the edges of a major updraft, where the maximum shear in updraft speed also occurs. The observations indicate that turbulence is an important cause of the abnormally wide velocity spectra, and suggest the utility of Doppler radar measurements of the vertical velocity spectrum as an indicator of severe cloudy-air turbulence. Furthermore, vertical velocity spectra in the more convective regions of thunderstorms, where they may be seriously affected by turbulence and wind shear, probably give an exaggerated picture of the particle size distribution. (Author)
Author: Ralph J Donaldson (Jr)
Publisher:
ISBN:
Category :
Languages : en
Pages : 24
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Book Description
Vertical-incidence observations by Doppler radar of velocities in a thunderstorm reveal some regions in which the spread of velocities is unusually broad. The widths of the vertical velocity spectra are generally greatest along the edges of a major updraft, where the maximum shear in updraft speed also occurs. The observations indicate that turbulence is an important cause of the abnormally wide velocity spectra, and suggest the utility of Doppler radar measurements of the vertical velocity spectrum as an indicator of severe cloudy-air turbulence. Furthermore, vertical velocity spectra in the more convective regions of thunderstorms, where they may be seriously affected by turbulence and wind shear, probably give an exaggerated picture of the particle size distribution.
Author: Richard J. Doviak
Publisher: Academic Press
ISBN: 148329482X
Category : Technology & Engineering
Languages : en
Pages : 591
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Book Description
This book reviews the principles of Doppler radar and emphasizes the quantitative measurement of meteorological parameters. It illustrates the relation of Doppler radar data and images to atmospherix phenomena such as tornados, microbursts, waves, turbulence, density currents, hurricanes, and lightning. Radar images and photographs of these weather phenomena are included. Polarimetric measurements and data processing An updated section on RASS Wind profilers Observations with the WSR-88D An updated treatment of lightning Turbulence in the planetary boundary layer A short history of radar Chapter problem sets
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 28
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Book Description
A thunderstorm turbulence detection test bed was developed at the Federal Aviation Administration (FAA) Technical Center by the Massachusetts Institute of Technology, Lincoln Laboratory. This consists of a system to measure and process Doppler radar parameters, and an FAA aircraft instrumented to measure turbulence concurrently with the radar observations. The test bed is being used to investigate the relationship between radar-and aircraft-measured turbulence. Radar measurements of the Doppler spectrum width and aircraft measurements of airspeed fluctuations and center-of-gravity normal accelerations were converted to the cube root of epsilon (cube root of the turbulence dissipation factor) for comparison. Several data collections were made during the summer of 1980. Results of data analysis showed that the major turbulence sequences experienced by the aircraft were essentially reflected by the radar. However, Linear correlation coefficients between radar and aircraft the the cube root of epsilon were only about 0.5. The low correlations are considered to be due to differences in response to turbulence by the two measuring systems, deficiencies in the radar processing, and radar data interpolation errors between the 80-second radar scans. In a more practical analysis, radar-measured turbulence, classified into ranges of light, moderate, and severe turbulence, showed a potentially useful relationship to aircraft turbulence. The predictive value was enhanced by consideration of radar reflectivity factor as a screening variable.
Author: Alan R. Bohne
Publisher:
ISBN:
Category : Atmospheric turbulence
Languages : en
Pages : 68
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Book Description
Theoretical investigations are undertaken to relate intensity of turbulent air motion to Doppler radar spectrum mean and variance in precipitation environments. Examples of theoretical radar derived turbulence power density spectra and total precipitation motion variance show that effects due to imperfect particle response are significant for turbulence scale lengths less than 250 m. Doppler spectrum variance and estimated eddy dissipation rate (epsilon) are found strongly dependent upon precipitation environment for ranges less than about 20 km, and for cases where the turbulence outer scale length (lambda) is less than 0.5 km. They are also found to be essentially independent of lambda when the maximum pulse volume dimension is less than 1/2 lambda, and independent of range but strongly dependent on lambda at ranges where the maximum pulse volume dimension is greater than lambda. Estimation of epsilon by radar is shown to be unreliable until a method of remotely determining lambda is found. Nevertheless, classification of turbulence severity (index = cube root of epsilon is possible with only a reasonable guess of lambda. Analyses of aircraft/gust velocity data indicate that thunderstorm turbulence is localized into discrete patches, and that such localization must be accounted for when aircraft gust velocity data undergo power spectrum analysis.
Author:
Publisher:
ISBN:
Category : Thunderstorms
Languages : en
Pages : 334
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Book Description
Author:
Publisher:
ISBN:
Category : Hail
Languages : en
Pages : 340
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Book Description
Author: J. T. Lee
Publisher:
ISBN:
Category : Doppler radar
Languages : en
Pages : 52
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Book Description
Analysis of thunderstorm turbulence hazardous to aircraft operation and coordinated Doppler radar observations indicate a high potential for Doppler radar utilization particularly the mean velocity spectrum breadth observations in defining severe turbulence areas. The mean Velocity Processor (MVP, the first real-time display of Doppler radar data) and the Multi-moment Ling Display (MMD), both developed at NSSL, are utilized with the radars to study vortex motion, turbulence, and wind shear areas. In addition, the Plan Shear Indicator (PSI) developed by the Air Force Cambridge Research Laboratory (AFCRL) was also employed. A number of severe convective storms were penetrated by an instrumented aircraft directed into areas which analysis inferred to be turbulent. Aircraft recorded turbulence and concurrent Doppler data are compared. Utilization of the spectrum breadth calculated from the mean velocity data as a turbulence signature is discussed. Vortex motion signature is also defined. (Author).
Author: Air Force Cambridge Research Laboratories (U.S.)
Publisher:
ISBN:
Category : Geophysics
Languages : en
Pages : 384
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Book Description
