Investigating sources of error in balloon-borne optical turbulence measurements

Jumper, George Y.; Beland, Robert R.; Tracy, Paul

doi:10.2514/6.1999-3618

Cited by 5 publications

(8 citation statements)

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“…While we treat the in situ thermosonde measurements as our reference, these data are also subject to error and can deviate from the true atmospheric parameters. Jumper et al [1999] investigated possible error sources in thermosonde measurements, including pendular motion, strong thermal gradients, and regions of non‐Kolmogorov turbulence. They estimated that the integrated circuit used to compute the output signal may exaggerate the turbulence by 20–30%.…”

Section: Instrumentation and Data Processingmentioning

confidence: 99%

Comparison of radar and in situ measurements of atmospheric turbulence

Zink¹

2004

J. Geophys. Res.

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[1] We compare measurements of refractive index structure constant C n 2 and energy dissipation rate by VHF radar with in situ observations by high-resolution thermosondes during a campaign near Adelaide, Australia, in August 1998. A total of 17 thermosonde soundings was performed within a distance of 120 km to the radar site. The variance between estimates of hC n 2 i from backscattered radar power and in situ thermosonde observations is found to be comparable to the observed variance of the radar estimates due to temporal and spatial variations of the turbulent parameters (angle brackets denote average over the radar range resolution of 1 km). The high-resolution thermosonde observations allow us to test the applicability of the turbulent volume fraction model to the estimation of hi from hC n 2 i. The data indicate that the turbulent volume fraction should not be modeled as the fraction of unstable layers with gradient Richardson number R i < 0.25.

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Section: Instrumentation and Data Processingmentioning

confidence: 99%

Comparison of radar and in situ measurements of atmospheric turbulence

Zink¹

2004

J. Geophys. Res.

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“…Both are reduced by averaging over a number of profiles. Numerical simulations of the RMS chip averaging by Jumper et al [1999] using typical distributions of simulated turbulence showed random error factors of 10-20%. Jumper et al [1999] also observed a dual time constant behavior which may contribute to a 20 -30% increase in the turbulence.…”

Section: Thermosonde Measurementsmentioning

confidence: 99%

“…Numerical simulations of the RMS chip averaging by Jumper et al [1999] using typical distributions of simulated turbulence showed random error factors of 10-20%. Jumper et al [1999] also observed a dual time constant behavior which may contribute to a 20 -30% increase in the turbulence. Representative error bars of 20% have been included on day C n 2 profiles in Figures 1, 2, and 3 for comparison with measured layer values, along with a vertical profile of the approximate noise floor.…”

Section: Thermosonde Measurementsmentioning

confidence: 99%

A preliminary comparison of daylit and night C_n² profiles measured by thermosonde

Roadcap¹,

Tracy²

2009

Radio Science

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The refractive index structure constant Cn2 is needed to characterize optical wave propagation in a refractive turbulent scattering medium. A limited number of in situ measurements of Cn2 made during day and night conditions from the surface to 10 km above sea level are compared in three different atmospheric boundary layer environments: dry convective, moist convective, and marine inversion. Cn2 on average appears to be higher through the convective boundary layer depth during the day compared to night for the same air mass type and location but is generally lower than night values within the stable marine inversion layer. Calculations of path scintillation effects for slant paths in the lower atmosphere at near‐infrared wavelengths are also compared for day and night conditions associated with the different air mass types.

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“…In order to understand the response of the thermosonde, an engineering model was assembled and analyzed in a computer simulation. The basis of the engineering model are two AFGL technical reports 1,6 , the NASA technical note by the thermosonde developer, Jack Bufton 7 , and recent inhouse engineering work 8 . The simulation model uses the software package, Advanced Continuous Simulation Language (ACSL) 9 .…”

Section: Description Of the Instrumentmentioning

confidence: 99%

THERMOSONDE 2007: In-Situ Measurement of Optical Turbulence

Murphy¹,

Tracy²,

Beland³

et al. 2007

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This report updates Ihe 1982 Thennosonde technical report, by docwnenting the current configuration. The wires in the thennosonde are arranged as two legs of a Wheatstone bridge, wh ich generales a voltage proportional to the resistance difference. The telemetry signal now consists of digital signal "counts," rather than analog freq uency changes, the multiple segment calibration relationship has ben replace by a single straight line, and a new, lower signal calibration input point has been added to the calibration source. Synchronous detection of the telemetry signal has allowed the overall gain to be increased to approximately 600,000. Calibration voltages are read within ImV for a range ofvollages from the minimum, which is the noise floor of about 10 mV (equivalent to about 0.0005K up to a maximum output of2.0 V. For a modesl CT2 value ofO.0002K2M-213, the uncertainty in Cn2 is down to 1.5 percent. For a stronger CT2 of 0.001 , overall Cn2 uncertainty is below 0.5% at low altitudes and starts to noticeably increase al20 km, reaching a 4% uncertainty at 30 km due to pressure uncertainties. 1S. SUBJECT TERMS Temperature structure constant Thennosonde Refractive index structure constant 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF a .

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Investigating sources of error in balloon-borne optical turbulence measurements

Cited by 5 publications

References 0 publications

Comparison of radar and in situ measurements of atmospheric turbulence

Comparison of radar and in situ measurements of atmospheric turbulence

A preliminary comparison of daylit and night C_n² profiles measured by thermosonde

THERMOSONDE 2007: In-Situ Measurement of Optical Turbulence

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Investigating sources of error in balloon-borne optical turbulence measurements

Cited by 5 publications

References 0 publications

Comparison of radar and in situ measurements of atmospheric turbulence

Comparison of radar and in situ measurements of atmospheric turbulence

A preliminary comparison of daylit and night Cn2 profiles measured by thermosonde

THERMOSONDE 2007: In-Situ Measurement of Optical Turbulence

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A preliminary comparison of daylit and night C_n² profiles measured by thermosonde