Application of radiosonde ascent rate variations to detect atmospheric turbulence affecting aircraft

Abstract. In the present communication a novel method is presented to derive the altitude profile of Brunt-Väisälä period from the ascent rate profile of sounding balloons. The basic premise of the present method is that the oscillations in the ascent rate of the balloon will have the signature of Brunt-Väisälä frequency, which can be retrieved by using sophisticated spectral tools. We employ wavelet transforms to arrive at the Brunt-Väisälä period profile. Comparison of retrieved Brunt-Väisälä periods with the values derived from the temperature data available from the same radiosonde ascent shows good agreement. Retrieving the atmospheric temperature from the height profile of Brunt-Väisälä period is also discussed in the present communication. We have shown that it is possible to estimate the Brunt-Väisälä period and temperature profiles from the rawinsonde ascent rate data alone where temperature sounding is not available.

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On the estimation of vertical air velocity and detection of atmospheric turbulence from the ascent rate of balloon soundings

Atmospheric Measurement Techniques ◽

10.5194/amt-13-1989-2020 ◽

2020 ◽

Vol 13 (4) ◽

pp. 1989-1999

Author(s):

Hubert Luce ◽

Hiroyuki Hashiguchi

Keyword(s):

Atmospheric Turbulence ◽

Large Scale ◽

Radar Data ◽

Air Velocity ◽

Convective Boundary ◽

Ascent Rate ◽

Mu Radar ◽

Turbulence Effects ◽

Aerial Vehicle ◽

The Cost

Abstract. Vertical ascent rate VB of meteorological balloons is sometimes used for retrieving vertical air velocity W, an important parameter for meteorological applications, but at the cost of crude hypotheses on atmospheric turbulence and without the possibility of formally validating the models from concurrent measurements. From simultaneous radar and unmanned aerial vehicle (UAV) measurements of turbulent kinetic energy dissipation rates ε, we show that VB can be strongly affected by turbulence, even above the convective boundary layer. For “weak” turbulence (here ε≲10−4 m2 s−3), the fluctuations of VB were found to be fully consistent with W fluctuations measured by middle and upper atmosphere (MU) radar, indicating that an estimate of W can indeed be retrieved from VB if the free balloon lift is determined. In contrast, stronger turbulence intensity systematically implies an increase in VB, not associated with an increase in W according to radar data, very likely due to the decrease in the turbulence drag coefficient of the balloon. From the statistical analysis of data gathered from 376 balloons launched every 3 h at Bengkulu (Indonesia), positive VB disturbances, mainly observed in the troposphere, were found to be clearly associated with Ri≲0.25, usually indicative of turbulence, confirming the case studies. The analysis also revealed the superimposition of additional positive and negative disturbances for Ri≲0.25 likely due to Kelvin–Helmholtz waves and large-scale billows. From this experimental evidence, we conclude that the ascent rate of meteorological balloons, with the current performance of radiosondes in terms of altitude accuracy, can potentially be used for the detection of turbulence. The presence of turbulence complicates the estimation of W, and misinterpretations of VB fluctuations can be made if localized turbulence effects are ignored.

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On the estimation of vertical air velocity and detection of atmospheric turbulence from the ascent rate of balloon soundings

10.5194/amt-2019-357 ◽

2019 ◽

Author(s):

Hubert Luce ◽

Hiroyuki Hashiguchi

Keyword(s):

Unmanned Aerial Vehicles ◽

Atmospheric Turbulence ◽

Radar Data ◽

Weak Turbulence ◽

Air Velocity ◽

Convective Boundary ◽

Ascent Rate ◽

Mu Radar ◽

Turbulence Effects ◽

The Cost

Abstract. Vertical ascent rate VB of meteorological balloons is sometimes used for retrieving vertical air velocity W, an important parameter for meteorological applications, but at the cost of crude hypotheses on atmospheric turbulence and without the possibility of formally validating the models from concurrent measurements. From simultaneous radar and Unmanned Aerial Vehicles (UAV) measurements of turbulent kinetic energy dissipation rates &varepsilon;, we show that VB can be strongly affected by turbulence, even above the convective boundary layer. For “weak” turbulence (here &varepsilon; ≲ 10−4 m2 s-3), the fluctuations of VB were found to be fully consistent with W fluctuations measured from MU radar, indicating that an estimate of W can indeed be retrieved from VB if the free balloon lift is determined. In contrast, stronger turbulence intensity systematically implies an increase of VB, not associated with an increase of W according to radar data, very likely due to the decrease of the turbulence drag coefficient of the balloon. From the statistical analysis of data gathered from 376 balloons launched every 3 hours at Bengkulu (Indonesia), positive VB disturbances, mainly observed in the troposphere, were found to be clearly associated with Ri &lesssim; 0.25, usually indicative of turbulence, confirming the case studies. The analysis also revealed the superimposition of additional positive and negative disturbances for Ri ≲ 0.25 likely due to Kelvin-Helmholtz waves in the vicinity of the turbulent layers. From these experimental evidences, we conclude that the ascent rate of meteorological balloons, with the current performance of radiosondes in terms of altitude accuracy, can potentially be used for the detection of turbulence. The presence of turbulence makes impossible the estimation of W and misinterpretations of VB fluctuations can be made if localized turbulence effects are ignored.

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Prediction of Atmospheric Turbulence Characteristics for Surface Boundary Layer using Empirical Spectral Methods

Revista Brasileira de Meteorologia ◽

10.1590/0102-77863540083 ◽

2020 ◽

Author(s):

Yagya Dutta Dwivedi ◽

Vasishta Bhargava Nukala ◽

Satya Prasad Maddula ◽

Kiran Nair

Keyword(s):

Boundary Layer ◽

Time Series ◽

Surface Roughness ◽

Wind Speed ◽

Atmospheric Turbulence ◽

Surface Boundary ◽

Low Frequencies ◽

Surface Boundary Layer ◽

Power Spectral ◽

Mean Wind Speed

Abstract Atmospheric turbulence is an unsteady phenomenon found in nature and plays significance role in predicting natural events and life prediction of structures. In this work, turbulence in surface boundary layer has been studied through empirical methods. Computer simulation of Von Karman, Kaimal methods were evaluated for different surface roughness and for low (1%), medium (10%) and high (50%) turbulence intensities. Instantaneous values of one minute time series for longitudinal turbulent wind at mean wind speed of 12 m/s using both spectra showed strong correlation in validation trends. Influence of integral length scales on turbulence kinetic energy production at different heights is illustrated. Time series for mean wind speed of 12 m/s with surface roughness value of 0.05 m have shown that variance for longitudinal, lateral and vertical velocity components were different and found to be anisotropic. Wind speed power spectral density from Davenport and Simiu profiles have also been calculated at surface roughness of 0.05 m and compared with k−1 and k−3 slopes for Kolmogorov k−5/3 law in inertial sub-range and k−7 in viscous dissipation range. At high frequencies, logarithmic slope of Kolmogorov −5/3rd law agreed well with Davenport, Harris, Simiu and Solari spectra than at low frequencies.

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Estimating Atmospheric Turbulence Parameters from the Envelopes of Radio Acoustic Signals

Telecommunications and Radio Engineering ◽

10.1615/telecomradeng.v55.i8.30 ◽

2001 ◽

Vol 55 (8) ◽

pp. 5

Author(s):

V. M. Kartashov ◽

V. A. Petrov ◽

Ye. G. Proshkin ◽

G. I. Sidorov

Keyword(s):

Atmospheric Turbulence ◽

Acoustic Signals ◽

Turbulence Parameters

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Numerical study of wake vortex decay and descent in homogeneous atmospheric turbulence

AIAA Journal ◽

10.2514/3.14456 ◽

2000 ◽

Vol 38 ◽

pp. 643-656 ◽

Cited By ~ 1

Author(s):

Jongil Han ◽

Yuh-Lang Lin ◽

S. P. Arya ◽

Fred H. Proctor

Keyword(s):

Atmospheric Turbulence ◽

Numerical Study ◽

Wake Vortex

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A striped pattern of snowfall and snow cover

Annals of Glaciology ◽

10.3189/s0260305500011216 ◽

1993 ◽

Vol 18 ◽

pp. 27-32

Author(s):

Yasuaki Nohguchi ◽

Takashi Ikarashi ◽

Osamu Abe ◽

Atsushi Sato

Keyword(s):

Snow Cover ◽

Atmospheric Turbulence ◽

Layered Structure ◽

Time Variation ◽

Vertical Wall ◽

Striped Pattern

A striped pattern can be seen by spraying ink on a vertical wall of a snow pit to observe the layered structure of a snow cover. This pattern is caused by variations of snowfall in time, particularly pauses in snowfall, and its structure is related to a kind of fractal. In this paper, we consider snowfall and snow cover from a viewpoint of fractals and show that the layered structure of snow cover is a record of fractals on atmospheric-turbulence phenomena through the time variation of snowfall.

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