Obstruction Influence on Low-Speed, In-Situ Stratospheric Turbulence Measurements

2021 ◽  
Author(s):  
Joseph L. Pointer ◽  
Kenneth E. Jansen ◽  
Brian M. Argrow ◽  
Dale A. Lawrence
Keyword(s):  
Turbulence Measurements ◽  
Low Speed

scholarly journals Evaluation of wake influence on high-resolution balloon-sonde measurements

2019 ◽  
Vol 12 (8) ◽  
pp. 4191-4210 ◽  
Author(s):  
Jens Söder ◽  
Michael Gerding ◽  
Andreas Schneider ◽  
Andreas Dörnbrack ◽  
Henrike Wilms ◽  
...  
Keyword(s):  
High Resolution ◽  
Uncertainty Analysis ◽  
Atmospheric Turbulence ◽  
Evaluation Tool ◽  
Turbulence Measurements ◽  
Wake Effects ◽  
Humidity Measurements ◽  
Average Probability ◽  
Vertical Winds

Abstract. Balloons are used for various in situ measurements in the atmosphere. On turbulence measurements from rising balloons there is a potential for misinterpreting wake-created fluctuations in the trail of the balloon for atmospheric turbulence. These wake effects have an influence on temperature and humidity measurements from radiosondes as well. The primary aim of this study is to assess the likelihood for wake encounter on the payload below a rising balloon. Therefore, we present a tool for calculating this probability based on radiosonde wind data. This includes a retrieval of vertical winds from the radiosonde and an uncertainty analysis of the wake assessment. Our wake evaluation tool may be used for any balloon–gondola distance and provides a significant refinement compared to existing assessments. We have analysed wake effects for various balloon–gondola distances applying atmospheric background conditions from a set of 30 radiosondes. For a standard radiosonde we find an average probability for wake encounter of 28 %, pointing out the importance of estimating wake effects on sounding balloons. Furthermore, we find that even millimetre-sized objects in the payload can have significant effects on high-resolution turbulence measurements, if they are located upstream of the turbulence sensor.

scholarly journals Small-scale structures in neutrals and charged aerosol particles as observed during the ECOMA/MASS rocket campaign

2009 ◽  
Vol 27 (4) ◽  
pp. 1449-1456 ◽  
Author(s):  
B. Strelnikov ◽  
M. Rapp ◽  
I. Strelnikova ◽  
N. Engler ◽  
R. Latteck
Keyword(s):  
Doppler Radar ◽  
Companion Paper ◽  
Density Fluctuations ◽  
Lapse Rate ◽  
Small Scale ◽  
Turbulence Energy ◽  
Turbulence Measurements ◽  
Charged Aerosols ◽  
Schmidt Numbers

Abstract. We present results of in situ measurements of neutral temperature during the ECOMA/MASS rocket campaign. We present and compare results of turbulence measurements conducted simultaneously by both in situ and doppler radar techniques. We show that the derived values of the turbulence energy dissipation rates are similar on average. We also find a region with a near adiabatic lapse rate with turbulence detected at the upper and lower edge. We note that it is consistent with expectation for a Kelvin-Helmholtz instability. We also present an estimate of the Schmidt numbers, Sc, for the charged aerosols that utilizes in situ measured small-scale density fluctuations of charged aerosols and both in situ and radar turbulence measurements. The derived Schmidt numbers fall within the range between 100 and 4500. This result agrees with previous estimates based on multi-frequency observations of PMSE (Rapp et al., 2008) and also with estimates of microphysical parameters presented in the companion paper by Rapp et al. (2009).

In-situ turbulence measurements over a desert basin using a kite/tethered-blimp platform

1999 ◽  
Author(s):  
Frank D. Eaton ◽  
Ben B. Balsley ◽  
Kenneth P. Bishop ◽  
Rod G. Frehlich ◽  
Ronald J. Hugo ◽  
...  
Keyword(s):  
Turbulence Measurements

scholarly journals Evaluation of wake influence on high-resolution balloon-sonde measurements

2019 ◽  
Author(s):  
Jens Söder ◽  
Michael Gerding ◽  
Andreas Schneider ◽  
Andreas Dörnbrack ◽  
Henrike Wilms ◽  
...  
Keyword(s):  
High Resolution ◽  
Uncertainty Analysis ◽  
Atmospheric Turbulence ◽  
Evaluation Tool ◽  
Turbulence Measurements ◽  
Wake Effects ◽  
Humidity Measurements ◽  
Average Probability ◽  
Vertical Winds

Abstract. Balloons are used for various in-situ measurements in the atmosphere. On turbulence measurements from rising balloons there is a potential for misinterpreting wake-created fluctuations in the trail of the balloon for atmospheric turbulence. These wake effects have an influence on temperature and humidity measurements from radiosondes as well. The primary aim of this study is to assess the likelihood for wake encounter on the payload below a rising balloon. Therefore, we present a tool for calculating this probability based on radiosonde wind data. This includes a retrieval of vertical winds from the radiosonde and an uncertainty analysis of the wake assessment. Our wake evaluation tool may be used for any balloon-gondola distance and provides a significant refinement compared to existing assessments. We have analysed wake effects for various balloon-gondola distances applying atmospheric background conditions from a set of 30 radiosondes. For a standard radiosonde we find an average probability for wake encounter of 28 %, pointing out the importance of estimating wake effects on sounding balloons. Furthermore, we find that even millimetre sized objects in the payload can have significant effects on high-resolution turbulence measurements, if they are located upstream of the turbulence sensor.

scholarly journals Development of $${\rm N}_2{\rm O}$$ N 2 O -MTV for low-speed flow and in-situ deployment to an integral effect test facility

2017 ◽  
Vol 59 (1) ◽  
Author(s):  
Matthieu A. André ◽  
Ross A. Burns ◽  
Paul M. Danehy ◽  
Seth R. Cadell ◽  
Brian G. Woods ◽  
...  
Keyword(s):  
Test Facility ◽  
Low Speed ◽  
Speed Flow ◽  
Integral Effect ◽  
Effect Test

Geometric Design of Low-Speed Urban Streets

2000 ◽  
Vol 1701 (1) ◽  
pp. 95-103 ◽  
Author(s):  
Joseph P. Tarris ◽  
John M. Mason ◽  
Nicholas D. Antonucci
Keyword(s):  
Traffic Engineering ◽  
Research Effort ◽  
Operating Speed ◽  
Low Speed ◽  
Urban Streets ◽  
Geometric Conditions ◽  
Speed Prediction ◽  
Design Speed ◽  
Geometric Elements

A research effort is progressing to develop a rational process for designing roadway geometric elements on low-speed urban streets and using a “target”operating speed as the preselected design speed. The goal is to provide geometric street designs that reflect the in situ operating environment (form to follow function). Such an approach produces geometric conditions that result in operating speeds that are consistent with driver expectations and commensurate with the function and purpose of the roadway. The data collection methodology being used to develop a speed-prediction model between operating speed and roadway geometry, roadside features, land use, and traffic engineering considerations is also described. A comparison of design speed and operating speed for one study site is provided as an example of anticipated results.

scholarly journals Low-Speed DSMC Simulations of Hotwire Anemometers at High-Altitude Conditions

Fluids ◽  
2021 ◽  
Vol 6 (1) ◽  
pp. 20
Author(s):  
Christopher A. Roseman ◽  
Brian M. Argrow
Keyword(s):  
Reynolds Number ◽  
High Altitude ◽  
Knudsen Number ◽  
Slip Flow ◽  
Molecular Flow ◽  
Fast Time ◽  
Transition Regime ◽  
Dsmc Method ◽  
Low Speed

Numerical simulations of hotwire anemometers in low-speed, high-altitude conditions have been carried out using the direct simulation Monte Carlo (DSMC) method. Hotwire instruments are commonly used for in-situ turbulence measurements because of their ability to obtain high spatial and temporal resolution data. Fast time responses are achieved by the wires having small diameters (1–5 μm). Hotwire instruments are currently being used to make in-situ measurements of high-altitude turbulence (20–40 km). At these altitudes, hotwires experience Knudsen number values that lie in the transition-regime between slip-flow and free-molecular flow. This article expands the current knowledge of hotwire anemometers by investigating their behavior in the transition-regime. Challenges involved with simulating hotwires at high Knudsen number and low Reynolds number conditions are discussed. The ability of the DSMC method to simulate hotwires from the free-molecular to slip-flow regimes is demonstrated. Dependence of heat transfer on surface accommodation coefficient is explored and discussed. Simulation results of Nusselt number dependence on Reynolds number show good agreement with experimental data. Magnitude discrepancies are attributed to differences between simulation and experimental conditions, while discrepancies in trend are attributed to finite simulation domain size.

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