Journal articles on the topic 'Atmospheric turbulence'
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1
Wang, Fazhi, Wenhe Du, Qi Yuan, Daosen Liu, and Shuang Feng. "A Survey of Structure of Atmospheric Turbulence in Atmosphere and Related Turbulent Effects." Atmosphere 12, no. 12 (December 2, 2021): 1608. http://dx.doi.org/10.3390/atmos12121608.
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The Earth’s atmosphere is the living environment in which we live and cannot escape. Atmospheric turbulence is a typical random inhomogeneous medium, which causes random fluctuations of both the amplitude and phase of optical wave propagating through it. Currently, it is widely accepted that there exists two kinds of turbulence in the aerosphere: one is Kolmogorov turbulence, and the other is non-Kolmogorov turbulence, which have been confirmed by both increasing experimental evidence and theoretical investigations. The results of atmospheric measurements have shown that the structure of atmospheric turbulence in the Earth’s atmosphere is composed of Kolmogorov turbulence at lower levels and non-Kolmogorov turbulence at higher levels. Since the time of Newton, people began to study optical wave propagation in atmospheric turbulence. In the early stage, optical wave propagation in Kolmogorov atmospheric turbulence was mainly studied and then optical wave propagation in non-Kolmogorov atmospheric turbulence was also studied. After more than half a century of efforts, the study of optical wave propagation in atmospheric turbulence has made great progress, and the theoretical results are also used to guide practical applications. On this basis, we summarize the development status and latest progress of propagation theory in atmospheric turbulence, mainly including propagation theory in conventional Kolmogorov turbulence and one in non-Kolmogorov atmospheric turbulence. In addition, the combined influence of Kolmogorov and non-Kolmogorov turbulence in Earth’s atmosphere on optical wave propagation is also summarized. This timely summary is very necessary and is of great significance for various applications and development in the aerospace field, where the Earth’s atmosphere is one part of many links.
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Xu, Manman, Shiyong Shao, Ningquan Weng, Liangping Zhou, Qing Liu, and Yuefeng Zhao. "Atmospheric Optical Turbulence Characteristics over the Ocean Relevant to Astronomy and Atmospheric Physics." Applied Sciences 11, no. 22 (November 9, 2021): 10548. http://dx.doi.org/10.3390/app112210548.
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Due to the space and time constraints of turbulence measurement equipment and the experiment scene, it is difficult to obtain the atmosphere refractive index structure constant over the ocean. In this paper, the characteristics of atmospheric optical turbulence in offshore and open ocean conditions are summarized by analyzing the meteorological data obtained from two ocean atmospheric optical parameter field experiments. Because of the influence of land undersurface, the turbulence strength in offshore conditions is roughly the same as that on land and presents different characteristics in open ocean. Compared with the offshore area, the turbulence strength over the open ocean near-surface decreases during the day and increases at night, and the diurnal variation characteristics weaken. The turbulence strength profiles over the offshore area show different characteristics at different times, where the turbulence strength in the morning is higher than that in the evening. By retrieving the meteorological factors affecting the turbulence, it is found that the temperature gradient and wind shear are in good agreement with turbulence strength in both offshore and open ocean areas. Furthermore, the integrated parameters for astronomy and optical telecommunication are derived from profiles over the offshore and open ocean areas. It is of great significance to research the turbulent characteristics of ocean atmosphere for optical transmission and astronomical observations.
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Seitz, Joseph, Shiyuan Zhong, Joseph J. Charney, Warren E. Heilman, Kenneth L. Clark, Xindi Bian, Nicholas S. Skowronski, et al. "Atmospheric turbulence observed during a fuel-bed-scale low-intensity surface fire." Atmospheric Chemistry and Physics 24, no. 2 (January 26, 2024): 1119–42. http://dx.doi.org/10.5194/acp-24-1119-2024.
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Abstract. The ambient atmospheric environment affects the growth and spread of wildland fires, whereas heat and moisture released from the fires and the reduction of the surface drag in the burned areas can significantly alter local atmospheric conditions. Observational studies on fire–atmosphere interactions have used instrumented towers to collect data during prescribed fires, but a few towers in an operational-scale burn plot (usually > 103 m2) have made it extremely challenging to capture the myriad of factors controlling fire–atmosphere interactions, many of which exhibit strong spatial variability. Here, we present analyses of atmospheric turbulence data collected using a 4 × 4 array of fast-response sonic anemometers during a fire experiment on a 10 m × 10 m burn plot. In addition to confirming some of the previous findings on atmospheric turbulence associated with low-intensity surface fires, our results revealed substantial heterogeneity in turbulent intensity and heat and momentum fluxes just above the combustion zone. Despite the small plot (100 m2), fire-induced atmospheric turbulence exhibited strong dependence on the downwind distance from the initial line fire and the relative position specific to the fire front as the surface fire spread through the burn plot. This result highlights the necessity for coupled atmosphere–fire behavior models to have 1–2 m grid spacing to resolve heterogeneities in fire–atmosphere interactions that operate on spatiotemporal scales relevant to atmospheric turbulence. The findings here have important implications for modeling smoke dispersion, as atmospheric dispersion characteristics in the vicinity of a wildland fire are directly affected by fire-induced turbulence.
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Liu, Xianlong, Fei Wang, Minghui Zhang, and Yangjian Cai. "Effects of Atmospheric Turbulence on Lensless Ghost Imaging with Partially Coherent Light." Applied Sciences 8, no. 9 (August 28, 2018): 1479. http://dx.doi.org/10.3390/app8091479.
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Ghost imaging with partially coherent light through two kinds of atmospheric turbulences: monostatic turbulence and bistatic turbulence, is studied, both theoretically and experimentally. Based on the optical coherence theory and the extended Huygens–Fresnel integral, the analytical imaging formulae in two kinds of turbulence have been derived with the help of a tensor method. The visibility and quality of the ghost image in two different atmospheric turbulences are discussed in detail. Our results reveal that in bistatic turbulence, the visibility and quality of the image decrease with the increase of the turbulence strength, while in monostatic turbulence, the image quality remains invariant when turbulence strength changes in a certain range, only the visibility decreases with the increase of the strength of turbulence. Furthermore, we carry out experimental demonstration of lensless ghost imaging through monostatic and bistatic turbulences in the laboratory, respectively. The experiment results agree well with the theoretical predictions. Our results solve the controversy about the influence of atmospheric turbulence on ghost imaging.
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Mokhov, I. I., O. G. Chkhetiani, and I. A. Repina. "Turbulence, Atmosphere and Climate Dynamics." IOP Conference Series: Earth and Environmental Science 1040, no. 1 (June 1, 2022): 011001. http://dx.doi.org/10.1088/1755-1315/1040/1/011001.
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Abstract The conference "Turbulence, Atmosphere and Climate Dynamics" dedicated to the memory of the Alexander M. Obukhov was held in Moscow from November 10 to 12, 2020. The topics of the conference covered the following scientific areas: turbulence; geophysical hydrodynamics; atmospheric and climate system dynamics; physics and composition of the atmosphere; air-sea interaction; wave propagation. The conference showed a high scientific level of almost all the presentations. Studies of turbulent, climatic and atmospheric processes are traditionally conducted in our country at the highest level, as evidenced by the publication in high-ranking scientific journals and the active participation of Russian scientists in international programs. List of Program committee, Organizing committee are avilable in this pdf.
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Klyuev, Dmitriy S., Andrey N. Volobuev, Sergei V. Krasnov, Kaira A. Adyshirin-Zade, Tatyana A. Antipova, and Natalia N. Aleksandrova. "Occurrence of fluctuations in the amplitude and phase of the radio signal in a turbulent atmosphere." Physics of Wave Processes and Radio Systems 26, no. 1 (March 30, 2023): 28–37. http://dx.doi.org/10.18469/1810-3189.2023.26.1.28-37.
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Abstract Interaction of an electromagnetic wave, as the determined wave process spreading in an atmosphere and atmospheric turbulence, as stationary stochastic wave process is considered. The differential equation for eikonal fluctuations of an electromagnetic wave is received. On basis of this equation the occurrence of amplitude and a phase fluctuations of an electromagnetic wave at distribution of a radio signal into a turbulent atmosphere is investigated. In particular the differential equations for fluctuations of amplitude and a phase of the electromagnetic wave caused by turbulent pulsations of a parameter of an atmosphere refraction are received and solved. Fourier-spectra of two-point correlations of a parameter of an atmosphere refraction, amplitude and a phase of an electromagnetic wave are considered. Are received also by a method of introduction of Greens function the differential equations for these correlations are solved. On basis of the analysis of various wave ranges of an atmospheric power spectrum of turbulence the dependences of amplitude and a phase Fourier-spectra of a radio signal on parameters of an electromagnetic wave and turbulence of an atmosphere are found.
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Avsarkisov, Victor, Erich Becker, and Toralf Renkwitz. "Turbulent Parameters in the Middle Atmosphere: Theoretical Estimates Deduced from a Gravity Wave–Resolving General Circulation Model." Journal of the Atmospheric Sciences 79, no. 4 (April 2022): 933–52. http://dx.doi.org/10.1175/jas-d-21-0005.1.
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Abstract We present a scaling analysis for the stratified turbulent and small-scale turbulent regimes of atmospheric flow with emphasis on the mesosphere. We distinguish rotating-stratified macroturbulence turbulence (SMT), stratified turbulence (ST), and small-scale isotropic Kolmogorov turbulence (KT), and we specify the length and time scales and the characteristic velocities for these regimes. It is shown that the buoyancy scale (Lb) and the Ozmidov scale (Lo) are the main parameters that describe the transition from SMT to KT. We employ the buoyancy Reynolds number and horizontal Froude number to characterize ST and KT in the mesosphere. This theory is applied to simulation results from a high-resolution general circulation model with a Smagorinsky-type turbulent diffusion scheme for the subgrid-scale parameterization. The model allows us to derive the turbulent root-mean-square (rms) velocity in the KT regime. It is found that the turbulent RMS velocity has a single maximum in summer and a double maximum in winter months. The secondary maximum in the winter MLT we associate with a secondary gravity wave–breaking phenomenon. The turbulent rms velocity results from the model agree well with full correlation analyses based on MF-radar measurements. A new scaling for the mesoscale horizontal velocity based on the idea of direct energy cascade in mesoscales is proposed. The latter findings for mesoscale and small-scale characteristic velocities support the idea proposed in this research that mesoscale and small-scale dynamics in the mesosphere are governed by SMT, ST, and KT in the statistical average. Significance Statement Mesoscale dynamics in the middle atmosphere, which consists of atmospheric turbulence and gravity waves, remains a complex problem for atmospheric physics and climate studies. Due to its high nonlinearity, the mesoscale dynamics together with the small-scale turbulence is the primary source of uncertainties and biases in high-altitude general circulation models (GCM) in the middle atmosphere. We use the stratified turbulence theory and the gravity wave–resolving GCM to characterize different scaling regimes and to define various length, time, and velocity scales, that are relevant for the mesoscale and small-scale dynamical regimes. Our results highlight the importance of stratified turbulence in the mesosphere and lower-thermosphere region.
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Kovadlo, P. G., A. Yu Shikhovtsev, E. A. Kopylov, A. V. Kiselev, and I. V. Russkikh. "The study of the optical atmospheric distortions uning the wavefront sensor data." Izvestiya vysshikh uchebnykh zavedenii. Fizika, no. 11 (2020): 109–14. http://dx.doi.org/10.17223/00213411/63/11/109.
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The paper is aimed to the study of the optical turbulence structure at the site of the Large solar vacuum telescope site. Results concerning observed wavefront distortions are given for expanding the data archive. The possibilities to reveal the optical turbulence layers in the atmosphere are discussed. The estimations of the heights of the atmospheric turbulent layers in the boundary layer are performed.
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Bursik, Marcus, Qingyuan Yang, Adele Bear-Crozier, Michael Pavolonis, and Andrew Tupper. "The Development of Volcanic Ash Cloud Layers over Hours to Days Due to Atmospheric Turbulence Layering." Atmosphere 12, no. 2 (February 23, 2021): 285. http://dx.doi.org/10.3390/atmos12020285.
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Volcanic ash clouds often become multilayered and thin with distance from the vent. We explore one mechanism for the development of this layered structure. We review data on the characteristics of turbulence layering in the free atmosphere, as well as examples of observations of layered clouds both near-vent and distally. We then explore dispersion models that explicitly use the observed layered structure of atmospheric turbulence. The results suggest that the alternation of turbulent and quiescent atmospheric layers provides one mechanism for the development of multilayered ash clouds by modulating vertical particle motion. The largest particles, generally μ>100 μm, are little affected by turbulence. For particles in which both settling and turbulent diffusion are important to vertical motion, mostly in the range of 10–100 μμm, the greater turbulence intensity and more rapid turbulent diffusion in some layers causes these particles to spend greater time in the more turbulent layers, leading to a layering of concentration. The results may have important implications for ash cloud forecasting and aviation safety.
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Guan, Bing, Haiyang Yu, Wei Song, and Jaeho Choi. "Wave Structure Function and Long-Exposure MTF for Gaussian-Beam Waves Propagating in Anisotropic Maritime Atmospheric Turbulence." Applied Sciences 10, no. 16 (August 7, 2020): 5484. http://dx.doi.org/10.3390/app10165484.
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The expressions of wave structure function (WSF) and long-exposure modulation transfer function (MTF) for laser beam propagation through non-Kolmogorov turbulence were derived in our previous work. In this paper, based on anisotropic maritime atmospheric non-Kolmogorov spectrum, the new analytic expression of WSF for Gaussian-beam waves propagation through turbulent atmosphere in a horizontal path is derived. Moreover, using this newly derived expression, long-exposure MTF for Gaussian-beam waves is obtained for analyzing the degrading effects in an imaging system. Using the new expressions, WSF and MTF for Gaussian-beam waves propagating in terrestrial and maritime atmospheric turbulence are evaluated. The simulation results show that Gaussian-beam waves propagation through maritime turbulence obtain more degrading effects than terrestrial turbulence due to the humidity and temperature fluctuations. Additionally, the degrading effects under anisotropic turbulence get less loss than that of isotropic turbulence.
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Lu, Yuqing, Jiandong Mao, Yingnan Zhang, Hu Zhao, Chunyan Zhou, Xin Gong, Qiang Wang, and Yi Zhang. "Simulation and Analysis of Mie-Scattering Lidar-Measuring Atmospheric Turbulence Profile." Sensors 22, no. 6 (March 17, 2022): 2333. http://dx.doi.org/10.3390/s22062333.
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Based on the residual turbulent scintillation theory, the Mie-scattering lidar can measure the intensity of atmospheric turbulence by detecting the light intensity scintillation index of the laser return signal. In order to evaluate and optimize the reliability of the Mie-scattering lidar system for detecting atmospheric turbulence, the appropriate parameters of the Mie-scattering lidar system are selected and optimized using the residual turbulent scintillation theory. Then, the Fourier transform method is employed to perform the numerical simulation of the phase screen of the laser light intensity transformation on the vertical transmission path of atmospheric turbulence. The phase screen simulation, low-frequency optimization, and scintillation index calculation methods are provided in detail, respectively. Based on the phase distribution of the laser beam, the scintillation index is obtained. Through the relationship between the scintillation index and the atmospheric turbulent refractive index structure constant, the atmospheric turbulence profile is inverted. The simulation results show that the atmospheric refractive index structure constant profile obtained by the iterative method is consistent with the input HV5/7 model below 6500 m, which has great guiding significance to carry out actual experiments to measure atmospheric turbulence using the Mie lidar.
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Wyngaard, J. C. "Atmospheric Turbulence." Annual Review of Fluid Mechanics 24, no. 1 (January 1992): 205–34. http://dx.doi.org/10.1146/annurev.fl.24.010192.001225.
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Wilson, R. "Turbulent diffusivity in the free atmosphere inferred from MST radar measurements: a review." Annales Geophysicae 22, no. 11 (November 29, 2004): 3869–87. http://dx.doi.org/10.5194/angeo-22-3869-2004.
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Abstract. The actual impact on vertical transport of small-scale turbulence in the free atmosphere is still a debated issue. Numerous estimates of an eddy diffusivity exist, clearly showing a lack of consensus. MST radars were, and continue to be, very useful for studying atmospheric turbulence, as radar measurements allow one to estimate the dissipation rates of energy (kinetic and potential) associated with turbulent events. The two commonly used methods for estimating the dissipation rates, from the backscattered power and from the Doppler width, are discussed. The inference methods of a local diffusivity (local meaning here "within" the turbulent patch) by using the dissipation rates are reviewed, with some of the uncertainty causes being stressed. Climatological results of turbulence diffusivity inferred from radar measurements are reviewed and compared. As revealed by high resolution MST radar measurements, atmospheric turbulence is intermittent in space and time. Recent theoretical works suggest that the effective diffusivity of such a patchy turbulence is related to statistical parameters describing the morphology of turbulent events: filling factor, lifetime and height of the patches. It thus appears that a statistical description of the turbulent patches' characteristics is required in order to evaluate and parameterize the actual impact of small-scale turbulence on transport of energy and materials. Clearly, MST radars could be an essential tool in that matter.
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Klyuev, Dmitriy S., Andrey N. Volobuev, Sergei V. Krasnov, Kaira A. Adyshirin-Zade, Tatyana A. Antipova, and Natalia N. Aleksandrova. "Flickering of a radio-signal due to an atmospheric turbulence." Physics of Wave Processes and Radio Systems 26, no. 3 (September 25, 2023): 11–19. http://dx.doi.org/10.18469/1810-3189.2023.26.3.11-19.
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Background. Turbulent fluctuations of the refractive index in the atmosphere lead to distortions during the passage of the radio signal. This can lead to distortion of the transmitted information due to the resulting fluctuations of the amplitude, phase and intensity of the electromagnetic wave that transmits the radio signal. Fluctuations in the intensity of the radio signal lead to flickering of the radio signal on the receiving antenna due to turbulent phenomena in the atmosphere, which are a complex multifunctional physical phenomenon. Aim. The problem of fluctuation of the intensity of the radio signal at the receiving antenna due to atmospheric turbulence is considered the flicker of the radio signal. This problem is currently extremely actual, because there is a tendency of active, negative interference in the process of high-quality transmission of the radio signal on the background of naturally caused turbulent fluctuations. Methods. A theoretical analysis of the passage of a radio signal through a turbulent atmosphere is carried out. The spatial correlation function of fluctuations in the intensity of the received radio signal due to atmospheric turbulence is investigated. Results. The concept of the radio signal flicker characteristic is introduced as the average value of a random variable over the cross section of the receiving antenna the dispersion of the logarithm of the radio signal power. A model of the occurrence of fluctuations in the case of two regions in the cross section of the receiving antenna with different levels of radio signal intensity is calculated. The correlation function for this model is found. Conclusion. Based on the Fourier-spectrum expansion of the two-point spatial correlation function of turbulent fluctuations of the refractive index, the dependence of the flicker characteristic of the radio signal on the wave number of turbulent fluctuations of the atmosphere is found. It is shown that the turbulence of the atmosphere has the greatest effect on the radio signal when the length of the electromagnetic wave is comparable to the scale of turbulent fluctuations.
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Allouche, Mohammad, Elie Bou-Zeid, Cedrick Ansorge, Gabriel G. Katul, Marcelo Chamecki, Otavio Acevedo, Sham Thanekar, and Jose D. Fuentes. "The Detection, Genesis, and Modeling of Turbulence Intermittency in the Stable Atmospheric Surface Layer." Journal of the Atmospheric Sciences 79, no. 4 (April 2022): 1171–90. http://dx.doi.org/10.1175/jas-d-21-0053.1.
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Abstract Intermittent transitions between turbulent and nonturbulent states are ubiquitous in the stable atmospheric surface layer (ASL). Data from two field experiments in Utqiaġvik, Alaska, and from direct numerical simulations are used to probe these state transitions so as to (i) identify statistical metrics for the detection of intermittency, (ii) probe the physical origin of turbulent bursts, and (iii) quantify intermittency effects on overall fluxes and their representation in closure models. The analyses reveal three turbulence regimes, two of which correspond to weakly turbulent periods accompanied by intermittent behavior (regime 1: intermittent; regime 2: transitional), while the third is associated with a fully turbulent flow. Based on time series of the turbulence kinetic energy (TKE), two nondimensional parameters are proposed to diagnostically categorize the ASL state into these regimes; the first characterizes the weakest turbulence state, while the second describes the range of turbulence variability. The origins of intermittent turbulence activity are then investigated based on the TKE budget over the identified bursts. While the quantitative results depend on the height, the analyses indicate that these bursts are predominantly advected by the mean flow, produced locally by mechanical shear, or lofted from lower levels by turbulent ejections. Finally, a new flux model is proposed using the vertical velocity variance in combination with different mixing length scales. The model provides improved representation (correlation coefficients with observations of 0.61 for sensible heat and 0.94 for momentum) compared to Monin–Obukhov similarity (correlation coefficients of 0.0047 for sensible heat and 0.49 for momentum), thus opening new pathways for improved parameterizations in coarse atmospheric models. Significance Statement Airflow in the lowest layer of the atmosphere is often modulated by a strong gradient of temperature when the surface is much cooler than the air. Such a regime results in weak turbulence and mixing, and is ubiquitous during nighttime and in polar regions. Understanding and modeling atmospheric flow and turbulence under such conditions are further complicated by “turbulence intermittency,” which manifests as periods of strong turbulent activity interspersed in a more quiescent airflow. The turbulent periods dominate the air–surface exchanges even when they occur over a small fraction of the time. This paper develops approaches to detect and classify such intermittent regimes, examines how the turbulent bursts are generated and advected, and offers guidance on representing such regimes in geophysical models. The findings have the potential to advance weather forecasting and climate modeling, particularly in the all-important polar regions.
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Paugam, R., R. Paoli, and D. Cariolle. "Influence of vortex dynamics and atmospheric turbulence on the early evolution of a contrail." Atmospheric Chemistry and Physics 10, no. 8 (April 27, 2010): 3933–52. http://dx.doi.org/10.5194/acp-10-3933-2010.
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Abstract. This study describes three-dimensional numerical simulations of the evolution of an aircraft contrail during the first 30 min following the emission of exhausts. The wake is modeled as a vortex pair descending in a stratified atmosphere where turbulent fluctuations are sustained in the late dissipation regime. The focus of the study is laid on the interactions between vortex dynamics, atmospheric turbulence and contrail microphysics, and their role in determining the growth and the distribution of ice crystals. The atmospheric turbulence is synthesized using a methodology developed to force anisotropic turbulent fluctuations. The results show the feasibility of three-dimensional simulations of the early development of a contrail in supersaturated conditions before its transition into a contrail-cirrus. %(when radiative heating and sedimentation are no more negligible). It is shown that in case of strongly supersaturated and shear-free atmosphere the optical depth is maintained as the contrail spreads by turbulent diffusion in the late dissipation regime.
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Laurent, Kasey M., Bob Fogg, Tobias Ginsburg, Casey Halverson, Michael J. Lanzone, Tricia A. Miller, David W. Winkler, and Gregory P. Bewley. "Turbulence explains the accelerations of an eagle in natural flight." Proceedings of the National Academy of Sciences 118, no. 23 (June 1, 2021): e2102588118. http://dx.doi.org/10.1073/pnas.2102588118.
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Turbulent winds and gusts fluctuate on a wide range of timescales from milliseconds to minutes and longer, a range that overlaps the timescales of avian flight behavior, yet the importance of turbulence to avian behavior is unclear. By combining wind speed data with the measured accelerations of a golden eagle (Aquila chrysaetos) flying in the wild, we find evidence in favor of a linear relationship between the eagle’s accelerations and atmospheric turbulence for timescales between about 1/2 and 10 s. These timescales are comparable to those of typical eagle behaviors, corresponding to between about 1 and 25 wingbeats, and to those of turbulent gusts both larger than the eagle’s wingspan and smaller than large-scale atmospheric phenomena such as convection cells. The eagle’s accelerations exhibit power spectra and intermittent activity characteristic of turbulence and increase in proportion to the turbulence intensity. Intermittency results in accelerations that are occasionally several times stronger than gravity, which the eagle works against to stay aloft. These imprints of turbulence on the bird’s movements need to be further explored to understand the energetics of birds and other volant life-forms, to improve our own methods of flying through ceaselessly turbulent environments, and to engage airborne wildlife as distributed probes of the changing conditions in the atmosphere.
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Liu, Wenyao, Xuehen Chen, Miao Liu, and Yanqing Hong. "Bidirectional Atmospheric Channel Reciprocity-Based Adaptive Power Transmission." Photonics 10, no. 10 (September 22, 2023): 1067. http://dx.doi.org/10.3390/photonics10101067.
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In atmosphere free-space optical communication (FSO) systems, the scintillation effect produced by turbulence effects increases the bit error rate (BER) of the communication system and reduces the system’s performance. However, a high correlation of turbulent noise occurs in the two transmission channels when a signal transmitted in the bidirectional atmospheric channel with channel reciprocity. The performance of the FSO system can be increased by extracting channel state information (CSI) in forward transmission and using adaptive power technology to reduce turbulence in inverse transmission. In this research, we propose a bidirectional atmospheric channel reciprocity-based adaptive power transmission (CR-APT) technique that lowers the bit error rate of the transmitted signal by using the CSI of the relevant channel. To verify the effectiveness of the technique, a bidirectional atmospheric channel with various turbulence intensities is built in the simulation program, along with various background sounds to vary the channel reciprocity, and the impact of reciprocity on signal transmission is examined. The simulation findings demonstrate that adaptive power transmission with high reciprocity is excellent under the weak turbulence condition, and its future development is promising.
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GRAJEWSKI, Krzysztof, Grzegorz KOWALECZKO, and Mariusz PIETRASZEK. "Effect of Atmospheric Turbulence on the Striking Accuracy of Guided Bombs." Problems of Mechatronics Armament Aviation Safety Engineering 11, no. 1 (March 31, 2020): 31–48. http://dx.doi.org/10.5604/01.3001.0014.0284.
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This paper presents the test results of a simulation of an air-to-surface guided bomb drop in a turbulent atmosphere. The guided bomb was developed from a practice bomb built and upgraded by the Air Force Institute of Technology. The paper presents the test results of a numerical simulation of an air-to-surface guided bomb drop ran in a proprietary software environment. The numerical simulation inputs included aerodynamic characteristics calculated with PRODAS software and verified by wind tunnel tests. The stochastic components of atmospheric turbulence were simulated with a stochastic process model proposed by Shinozuki. Examples of the guided bomb drop simulation results are given in the paper. The effect of atmospheric turbulence parameters, i.e. standard deviation, σ and turbulence scale, Lw on the striking accuracy and ground impact scatter, are also shown.
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Zeng, Xiping, Yansen Wang, and Benjamin T. MacCall. "A k–ε Turbulence Model for the Stable Atmosphere." Journal of the Atmospheric Sciences 77, no. 1 (December 16, 2019): 167–84. http://dx.doi.org/10.1175/jas-d-19-0085.1.
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Abstract A realizable k–ε turbulence model of incompressible fluid is extended for the stable atmosphere after taking account of the buoyancy damping of gravity waves. The new model is consistent with the Monin–Obukhov similarity theory on the stable atmospheric boundary layer (ABL) over a horizontally uniform surface. The model is incorporated into an ABL model to simulate mean flow against observations. Its ABL-model output is compared with the Leipzig dataset, showing the turbulence model works well for a stable ABL. Specifically, the ABL model properly replicates 1) the mixing length, turbulent viscosity, and mean wind; 2) a significant decrease of the mixing length with height in the upper ABL and thus a reasonable altitude of the ABL top; and 3) a sensitivity of the mixing length and turbulent viscosity to atmospheric stability.
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Vargas, Arley Cardona, Hernando Alexander Yepes Tumay, and Andrés Amell. "Experimental study of the correlation for turbulent burning velocity at subatmospheric pressure." EUREKA: Physics and Engineering, no. 4 (July 30, 2022): 25–35. http://dx.doi.org/10.21303/2461-4262.2022.002414.
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Turbulent burning velocity is one of the most relevant parameters to characterize the premixed turbulent flames. Different correlation has been proposed to estimate this parameter. However, most of them have been obtained using experimental data at atmospheric pressure or higher. The present study is focused on obtaining a correlation for the turbulent burning velocity using data at sub-atmospheric pressure. The turbulent burning velocity was experimentally calculated using the burner method, where turbulent premix flames are generated in a Bunsen burner. Stoichiometric and lean conditions were evaluated at a pressure of 0.85 atm and 0.98 atm, whereas the turbulence intensity was varied for each condition. Perforated plates and a hot-wire anemometer were used to generate and measure the turbulence intensity. Schlieren images were used to obtain the average angle of the flame and calculate the turbulent burning velocity. Experiments and theory show that the turbulent deflagration rate decrease as pressure decrease. The turbulent deflagration speed decreased by up to 16 % at 0.85 atm concerning atmospheric conditions for the same turbulence intensity, discharge velocity, and ambient temperature, according to the experimental results. The comparison among the experimental results at sub-atmospheric conditions and the correlations reported in the literature exposes prediction issues because most of them are fitted using data at atmospheric conditions. A general correlation is raised between turbulent burning velocity (ST), laminar burning velocity (SL) and turbulence intensity (u’) proposed from the experimental data. This correlation has the form For sub-atmospheric and atmospheric conditions, the coefficients were determined
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Khetselius, O. Y., A. V. Gkuskov, S. M. Stepanenko, and A. A. Svinarenko. "New theoretical approach to dynamics of heat-mass-transfer, thermal turbulence and air ventilation in atmosphere of an industrial city II. Spectrum of thermal turbulence." Physics of Aerodisperse Systems, no. 61 (December 9, 2023): 165–75. http://dx.doi.org/10.18524/0367-1631.2023.61.291656.
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In this paper we go on a development of consistent theoretical approach to modelling the turbulent regime in the atmosphere of the industrial cities and present the analytical foundations of a new model of thermal turbulence spectrum for atmosphere of an industrial city. Special attention is paid to general analytical aspects for accounting of the phenomenon of wave or vortex diffusion, which is usually ignored in most works on atmospheric ventilation modelling. Redistribution of energy over the spectrum of eddy sizes is usually called a spectral transformation, the study of which is possible only under the condition of real introduction of nonlinearity into the equation of turbulent motion. The approach presented is implemented into the general theory of heat-mass-transfer, thermal turbulence and air ventilation in atmosphere of an industrial city, including an improved theory of atmospheric circulation in combination with the hydrodynamic modelling, method of a complex geophysical plane field and the Arakawa-Schubert approach to a quantitative description of convective instability in the city’s atmosphere.
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Farrell, Brian F., and Petros J. Ioannou. "A Theory of Baroclinic Turbulence." Journal of the Atmospheric Sciences 66, no. 8 (August 1, 2009): 2444–54. http://dx.doi.org/10.1175/2009jas2989.1.
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Abstract Understanding the physical mechanism maintaining fluid turbulence remains a fundamental theoretical problem. The two-layer model is an analytically and computationally simple system in which the dynamics of turbulence can be conveniently studied; in this work, a maximally simplified model of the statistically steady turbulent state in this system is constructed to isolate and identify the essential mechanism of turbulence. In this minimally complex turbulence model the effects of nonlinearity are parameterized using an energetically consistent stochastic process that is white in both space and time, turbulent fluxes are obtained using a stochastic turbulence model (STM), and statistically steady turbulent states are identified using stochastic structural stability theory (SSST). These turbulent states are the fixed-point equilibria of the nonlinear SSST system. For parameter values typical of the midlatitude atmosphere, these equilibria predict the emergence of marginally stable eddy-driven baroclinic jets. The eddy variances and fluxes associated with these jets and the power-law scaling of eddy variances and fluxes are consistent with observations and simulations of baroclinic turbulence. This optimally simple model isolates the essential physics of baroclinic turbulence: maintenance of variance by transient perturbation growth, replenishment of the transiently growing subspace by nonlinear energetically conservative eddy–eddy scattering, and equilibration to a statistically steady state of marginal stability by a combination of nonlinear eddy-induced mean jet modification and eddy dissipation. These statistical equilibrium states provide a theory for the general circulation of baroclinically turbulent planetary atmospheres.
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Bresciani, Andrea P. C., Julien Maillard, and Leandro D. de Santana. "Physics-based scintillations for outdoor sound auralization." Journal of the Acoustical Society of America 154, no. 2 (August 1, 2023): 1179–90. http://dx.doi.org/10.1121/10.0020666.
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The sound propagating in a turbulent atmosphere fluctuates in amplitude and phase. This phenomenon, known as acoustic scintillation, is caused by random fluctuations in the acoustic refractive index of the air induced by atmospheric turbulence. Auralization techniques should consider this phenomenon to increase the realism of the synthetic sound. This paper proposes a physics-based formulation to model sequences of log-amplitude and phase fluctuations of a sound propagating in a turbulent atmosphere. This method applies to slanted and vertical propagation of the sound, which is useful for simulating elevated noise sources such as aircraft, drones, and wind turbines. The theoretical framework is based on the spatial correlation functions for the log-amplitude and phase fluctuations for spherical waves, the von Kármán spectrum, and similarity theories to model atmospheric turbulence. Two applications with audio files are presented to demonstrate the applicability of this method to tonal and broadband noise.
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Zhu, Kaicheng, Xiaolei Ma, Chang Gao, Dengjuan Ren, and Jie Zhu. "Propagation Properties of an Astigmatic Cos-Gaussian Beam through Turbulent Atmosphere." E3S Web of Conferences 299 (2021): 02003. http://dx.doi.org/10.1051/e3sconf/202129902003.
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We use the extended Huygens-Fresnel integral to investigate the propagation properties of a cos-Gaussian beam (cosGB) with astigmatism in atmospheric turbulence. The intensity distribution behaviour along the propagation distance for an astigmatic cosGB in atmospheric turbulence are analytically and numerically demonstrated. Some novel phenomena are presented graphically, indicating that the intensity distribution and the on-axial intensity closely depend on the astigmatic parameter and the turbulent structure constant of the cosGBs in the atmospheric turbulence.
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Sun, Jielun, and Jeffrey R. French. "Air–Sea Interactions in Light of New Understanding of Air–Land Interactions." Journal of the Atmospheric Sciences 73, no. 10 (September 21, 2016): 3931–49. http://dx.doi.org/10.1175/jas-d-15-0354.1.
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Abstract Air–sea interactions are investigated using the data from the Coupled Boundary Layers Air–Sea Transfer experiment under low wind (CBLAST-Low) and the Surface Wave Dynamics Experiment (SWADE) over sea and compared with measurements from the 1999 Cooperative Atmosphere–Surface Exchange Study (CASES-99) over land. Based on the concept of the hockey-stick transition (HOST) hypothesis, which emphasizes contributions of large coherent eddies in atmospheric turbulent mixing that are not fully captured by Monin–Obukhov similarity theory, relationships between the atmospheric momentum transfer and the sea surface roughness, and the role of the sea surface temperature (SST) and oceanic waves in the turbulent transfer of atmospheric momentum, heat, and moisture, and variations of drag coefficient Cd(z) over sea and land with wind speed V are studied. In general, the atmospheric turbulence transfers over sea and land are similar except under weak winds and near the sea surface when wave-induced winds and oceanic currents are relevant to wind shear in generating atmospheric turbulence. The transition of the atmospheric momentum transfer between the stable and the near-neutral regimes is different over land and sea owing to the different strength and formation of atmospheric stable stratification. The relationship between the air–sea temperature difference and the turbulent heat transfer over sea is dominated by large air temperature variations compared to the slowly varying SST. Physically, Cd(z) consists of the surface skin drag and the turbulence drag between z and the surface; the increase of the latter with decreasing V leads to the minimum Cd(z), which is observed, but not limited to, over sea.
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Dordov ́a, Lucie, and Otakar Wilfert. "Laser Beam Attenuation Determined by the Method of Available Optical Power in Turbulent Atmosphere." Journal of Telecommunications and Information Technology, no. 2 (June 26, 2023): 53–57. http://dx.doi.org/10.26636/jtit.2009.2.927.
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This work is focused on the atmospheric turbulence effect and a new method for determining optical signal attenuation caused by turbulence is presented here. A new method of power budget of optical links comes from optical intensity distribution in a laser beam after the beam passed through turbulent atmosphere. Results given by this method are compared with Rytov approximation which is nowadays the most frequently used method for determining turbulent attenuation. Results for communication wavelength of 850 nm and 1550 nm are presented as well as the results for a wavelength of 633 nm.
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Cheng, Mingjian, Kangjun Dong, Chenge Shi, Al-Ahsab Hassan Thabet Mohammed, Lixin Guo, Xiang Yi, Ping Wang, and Juan Li. "Enhancing Performance of Air–Ground OAM Communication System Utilizing Vector Vortex Beams in the Atmosphere." Photonics 10, no. 1 (December 30, 2022): 41. http://dx.doi.org/10.3390/photonics10010041.
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The modified uplink and downlink atmospheric turbulence channel models were established and employed to assess the system performance of air–ground orbital angular momentum (OAM) communication. The advantage of the vector vortex beam taking the place of the scalar one in the OAM communication system operated in the atmospheric turbulence was verified, that vector vortex beam can guarantee the more homogeneous energy in the circular hollow beam profile and the less phase distortion on signal OAM in the turbulence, which can reduce OAM crosstalk and improve OAM communication performance, especially small topological charge in strong turbulent regime. With the increase in turbulence strength, the vortex beam with a larger topological charge suffered more OAM mode crosstalk, and the average BER of the OAM communication system increased. Bessel–Gaussian (BG) beams with larger beam shape parameters had the strong capability of turbulence disturbance rejection in short-distance atmospheric applications, conversely, Laguerre–Gaussian (LG) beams with suitable parameter selection were preferred for long-distance atmospheric applications. Additionally, compared to the downlink channel, the transmission of OAM mode and the related communication system in the uplink channel are dramatically deteriorated due to atmospheric turbulent effects.
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Golbraikh, E., H. Branover, N. S. Kopeika, and A. Zilberman. "Non-Kolmogorov atmospheric turbulence and optical signal propagation." Nonlinear Processes in Geophysics 13, no. 3 (July 17, 2006): 297–301. http://dx.doi.org/10.5194/npg-13-297-2006.
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Abstract. In the present review, we make an attempt to attract attention to the effect of non-Kolmogorov behavior of turbulence in various scales on the characteristics of electromagnetic waves propagation through a turbulent atmosphere on the example of certain atmospheric experiments. We discuss the interpretation of experimental data based on the model of spectral behavior of a passive scalar field within a broad range of scales, which has been developed recently.
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Angelou, Nikolas, Jakob Mann, and Ebba Dellwik. "Wind lidars reveal turbulence transport mechanism in the wake of a tree." Atmospheric Chemistry and Physics 22, no. 4 (February 18, 2022): 2255–68. http://dx.doi.org/10.5194/acp-22-2255-2022.
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Abstract. Solitary trees are natural land surface elements found in almost all climates, yet their influence on the surrounding airflow is poorly known. Here we use state-of-the-art, laser-based, remote sensing instruments to study the turbulent wind field in the near-wake region of a mature, open-grown oak tree. Our measurements provide for the first time a full picture of the mixing layer of high turbulence that surrounds the mean wind speed deficit. In this layer, we investigate the validity of a two-dimensional vectorial relation derived from the eddy-viscosity hypothesis, a hypothesis commonly used in modelling the turbulence transport of momentum and scalars in the atmosphere. We find that the momentum fluxes of the streamwise wind component can be adequately predicted by the transverse gradient of the mean flow. Using the mixing-length hypothesis we find that for this tree the corresponding turbulence length scale in the mixing layer can be approximated by one height-independent value. Further, the laser-based scanning technology used here was able to accurately reveal three-dimensional turbulent and spatially varying atmospheric flows over a large plane without seeding or intruding the atmospheric flow. This capability points to a new and more exact way of exploring the complex earth–atmosphere interactions.
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Tjernström, Michael, Ben B. Balsley, Gunilla Svensson, and Carmen J. Nappo. "The Effects of Critical Layers on Residual Layer Turbulence." Journal of the Atmospheric Sciences 66, no. 2 (February 1, 2009): 468–80. http://dx.doi.org/10.1175/2008jas2729.1.
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Abstract The authors report results of a study of finescale turbulence structure in the portion of the nocturnal boundary layer known as the residual layer (RL). The study covers two nights during the Cooperative Atmosphere–Surface Exchange Study 1999 (CASES-99) field experiment that exhibit significant differences in turbulence, as indicated by the observed turbulence dissipation rates in the RL. The RL turbulence sometimes reaches intensities comparable to those in the underlying stable boundary layer. The commonly accepted concept of turbulence generation below critical values of the gradient Richardson number (Rig) is scale dependent: Ri values typically decrease with decreasing vertical scale size, so that critical Rig values (≈0.25) occur at vertical scales of only a few tens of meters. The very small scale for the occurrence of subcritical Ri poses problems for incorporating experimentally determined Rig -based methods in model closures in models with poor resolution. There appear to be two distinct turbulence “regimes” in the RL: a very weak but ever-present background turbulence level with minimal temporal and spatial structure and a more intense intermittent regime during which turbulent intensity can approach near-surface nighttime turbulent intensities. It is hypothesized that the locally produced RL turbulence can be related to upward-propagating atmospheric gravity waves generated by flow over the low-relief terrain. The presence of critical layers in the RL, caused by wind turning with height, results in the generation of intermittent turbulence.
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Cazacu, Ana, Ilie Bodale, and Alin Iulian Roșu. "Employing Atmospheric Sensors and Turbulent Energy Cascade Theory to Quantify Hazardous Airborne Transmissibility." BULETINUL INSTITUTULUI POLITEHNIC DIN IAȘI. Secția Matematica. Mecanică Teoretică. Fizică 67, no. 3 (September 1, 2021): 9–19. http://dx.doi.org/10.2478/bipmf-2021-0012.
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Abstract Airborne viruses, bacteria, or toxins are dangerous because of the nature of the human transmission pathway through breathing. However, every airborne component must conform to the laws of physics governing atmospheric propagation. Given the fact that most atmospheric flows, at both ground level and throughout the atmosphere, are highly turbulent, the mechanisms of turbulence can be employed to understand the propagation of such components. In this paper, the problem of harmful airborne pathogen transmission is considered in the context of atmospheric turbulence and wall-bounded flow theory. Two approaches are considered: one of them relies on singular measurements of building boundary distances and morphology, and the other relies on constant temperature measurement. The theoretical and practical potential of these approaches is then discussed and explained in a larger urban context.
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STEFANESCU, Irina-Beatrice, Andreea-Irina AFLOARE, and Achim IONITA. "Validation of a helicopter turbulence model on PUMA 330 dynamics." INCAS BULLETIN 11, no. 1 (March 5, 2019): 179–87. http://dx.doi.org/10.13111/2066-8201.2019.11.1.14.
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Aircraft and algorithms used in automated flight control are always designed for calm atmospheric conditions; therefore, testing their behaviour in realistic atmospheric conditions implies the necessity for efficient turbulence models. The present paper tests the behaviour of a helicopter in turbulent atmospheric conditions, using two different, complex models and a mathematically derived CETI-type turbulence model, specific to the PUMA 330 helicopter.
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V. Belgaonkar, Vijayashri, and Sundaraguru Ramakrishnan. "Free space optical communication system in the presence of atmospheric losses." Indonesian Journal of Electrical Engineering and Computer Science 33, no. 1 (January 1, 2024): 159. http://dx.doi.org/10.11591/ijeecs.v33.i1.pp159-166.
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<span>Free space optical communication is gaining importance in the field of optical communication due to its high speed and high bandwidth applications. Free space optical communication system (FSOCS) provides many benefits as compared to traditional wireless communication system and fiber optic cables. This makes this technology the reasonable extension of metropolitan area network and also provides the quick recovery during natural disaster. This system performance is limited due to the atmospheric turbulence effect and various atmospheric losses such as rain, and fog. Gamma gamma atmospheric turbulent model is used to analyze the system performance in the presence of moderate to strong atmospheric turbulence. We have designed the FSO gamma <span>gamma turbulent model with non-return to zero (NRZ) modulation format employing wavelength division multiplexing (WDM), spatial diversity multiple input multiple output (MIMO) (8×8) at various atmospheric turbulence levels and attenuation loss of 10 dB/km at the distance of 2-4 km. Using the proposed model, the link distance is enhanced up to 4km in the presence of turbulence and atmospheric losses with minimum laser transmitted power.</span></span>
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Xian, Jinhong, Chao Lu, Xiaoling Lin, Honglong Yang, Ning Zhang, and Li Zhang. "Directly measuring the power-law exponent and kinetic energy of atmospheric turbulence using coherent Doppler wind lidar." Atmospheric Measurement Techniques 17, no. 6 (April 2, 2024): 1837–50. http://dx.doi.org/10.5194/amt-17-1837-2024.
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Abstract. Atmospheric turbulence parameters, such as turbulent kinetic energy and dissipation rate, are of great significance in weather prediction, meteorological disasters, and forecasting. Due to the lack of ideal direct detection methods, traditional structure function methods are mainly based on Kolmogorov's assumption of local isotropic turbulence and the well-known -5/3 power law within the inertial subrange, which limits their application. Here, we propose a method for directly measuring atmospheric turbulence parameters using coherent Doppler wind lidar, which can directly obtain atmospheric turbulence parameters and vertical structural features, breaking the limitations of traditional methods. The first published spatiotemporal distribution map of the power-law exponent of the inertial subrange is provided in this study, which indicates the heterogeneity of atmospheric turbulence at different altitudes and also indicates that the power-law exponent at high altitudes does not fully comply with the -5/3 power law, proving the superiority of our method. We analyze the results under different weather conditions, indicating that the method still holds. The turbulent kinetic energy and power-law index obtained by this method are continuously compared with the results obtained with an ultrasonic anemometer for a month-long period. The results of the two have high consistency and correlation, verifying the accuracy and applicability of the proposed method. The proposed method has great significance in studying the vertical structural characteristics of atmospheric turbulence.
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Xiao, X., H. C. Zuo, Q. D. Yang, S. J. Wang, L. J. Wang, J. W. Chen, B. L. Chen, and B. D. Zhang. "On the factors influencing surface-layer energy closure and their seasonal variability over the semi-arid Loess Plateau of Northwest China." Hydrology and Earth System Sciences 16, no. 3 (March 20, 2012): 893–910. http://dx.doi.org/10.5194/hess-16-893-2012.
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Abstract. The energy observed in the surface layer, when using eddy-covariance techniques to measure turbulent fluxes, is not balanced. Important progress has been made in recent years in identifying potential reasons for this lack of closure in the energy balance, but the problem is not yet resolved. In this paper, long-term data that include output of tower, radiation, surface turbulence flux and soil measurement collected from September 2006 to August 2010 in the Semi-Arid Climate Change and Environment Observatory, Lanzhou University, in the semi-arid Loess Plateau of Northwest China, were analysed, focusing on the seasonal characteristics of the surface energy and the factors that have impact on the energy balance closure (EBC). The analysis shows that (1) the long-term observations are successful; the interaction between the land and the atmosphere in semi-arid climates can be represented by the turbulent transport of energy. In addition, even though the residual is obvious, this suggests that the factors that impact the EBC are stable, and their seasonal variations are identical. The analysis also shows that (2) four factors have obvious impact on the EBC: the diverse schemes for surface soil heat flux, the flux contribution from the target source area, the low-frequency part of the turbulence spectra, and the strength of atmospheric turbulence motion. The impact of these four factors on the EBC are similar in all seasons. Lastly, the results indicate that (3) atmospheric turbulence intensity is a very important factor in terms of its impact on the EBC. The relative turbulence intensity, RIw, characterises the strength of atmospheric turbulence motion, and is found to exert a noticeable impact on the EBC; in all seasons, the EBC is increased when the relative turbulence intensity is enlarged.
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Mao, Jiandong, Yingnan Zhang, Juan Li, Xin Gong, Hu Zhao, and Zhimin Rao. "Novel Detection of Atmospheric Turbulence Profile Using Mie-Scattering Lidar Based on Non-Kolmogorov Turbulence Theory." Entropy 25, no. 3 (March 9, 2023): 477. http://dx.doi.org/10.3390/e25030477.
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Turbulence can cause effects such as light intensity fluctuations and phase fluctuations when a laser is transmitted in the atmosphere, which has serious impacts on a number of optical engineering application effects and on climate improvement. Therefore, accurately obtaining real-time turbulence intensity information using lidar-active remote sensing technology is of great significance. In this paper, based on residual turbulent scintillation theory, a Mie-scattering lidar method was developed to detect atmospheric turbulence intensity. By extracting light intensity fluctuation information from a Mie-scattering lidar return signal, the atmospheric refractive index structure constant, Cn2, representing the atmospheric turbulence intensity, could be obtained. Specifically, the scintillation effect on the detection path was analyzed, and the probability density distribution of the light intensity of the Mie-scattering lidar return signal was studied. It was verified that the probability density of logarithmic light intensity basically follows a normal distribution under weak fluctuation conditions. The Cn2 profile based on Kolmogorov turbulence theory was retrieved using a layered, iterative method through the scintillation index. The method for detecting Kolmogorov turbulence intensity was applied to the detection of the non-Kolmogorov turbulence intensity. Through detection using the scintillation index, the corresponding C˜n2 profile could be calculated. The detection of the C˜n2 and Cn2 profiles were compared with the Hufnagel–Valley (HV) night model in the Yinchuan area. The results show that the detection results are consistent with the overall change trend of the model. In general, it is feasible to detect a non-Kolmogorov turbulence profile using Mie-scattering lidar.
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Nosov, V. V., P. G. Kovadlo, V. P. Lukin, and A. V. Torgaev. "Atmospheric coherent turbulence." Atmospheric and Oceanic Optics 26, no. 3 (May 2013): 201–6. http://dx.doi.org/10.1134/s1024856013030123.
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Shikhovtsev, Artem, Aleksandr Kiselev, Pavel Kovadlo, Dmitriy Kolobov, Ivan Russkikh, and Vitaliy Tomin. "Turbulent parameters at different heights in the atmosphere. Shack–Hartmann wavefront sensor data." Solar-Terrestrial Physics 8, no. 2 (June 30, 2022): 20–25. http://dx.doi.org/10.12737/stp-82202203.
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The paper presents the results of studies of wavefront distortions at different heights in the atmosphere. We have used measurement wavefront data to determine optical turbulence parameters along the line of sight of the Large Solar Vacuum Telescope. Through cross-correlation analysis of differential motions of sunspots at spaced wavefront sensor subapertures, we determined turbulent parameters at different heights at the Large Solar Vacuum Telescope site. The differential motions of sunspots characterize the small-scale structure of turbulent phase distortions in the atmosphere. Synchronous temporal changes in the amplitude of these distortions at certain regions of the telescope aperture are conditioned by turbulent layers at different heights. We have estimated the contribution of optical turbulence to integral distortions at the telescope aperture for layers 0–0.6, 0.6–1.1, 1.1–1.7 km. The contribution of optical turbulence concentrated in a 1.7 km atmospheric layer to the wavefront distortions at the aperture telescope is shown to be ~43 %.
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Shikhovtsev, Artem, Aleksandr Kiselev, Pavel Kovadlo, Dmitriy Kolobov, Ivan Russkikh, and Vitaliy Tomin. "Turbulent parameters at different heights in the atmosphere. Shack–Hartmann wavefront sensor data." Solnechno-Zemnaya Fizika 8, no. 2 (June 30, 2022): 23–28. http://dx.doi.org/10.12737/szf-82202203.
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The paper presents the results of studies of wavefront distortions at different heights in the atmosphere. We have used measurement wavefront data to determine optical turbulence parameters along the line of sight of the Large Solar Vacuum Telescope. Through cross-correlation analysis of differential motions of sunspots at spaced wavefront sensor subapertures, we determined turbulent parameters at different heights at the Large Solar Vacuum Telescope site. The differential motions of sunspots characterize the small-scale structure of turbulent phase distortions in the atmosphere. Synchronous temporal changes in the amplitude of these distortions at certain regions of the telescope aperture are conditioned by turbulent layers at different heights. We have estimated the contribution of optical turbulence to integral distortions at the telescope aperture for layers 0–0.6, 0.6–1.1, 1.1–1.7 km. The contribution of optical turbulence concentrated in a 1.7 km atmospheric layer to the wavefront distortions at the aperture telescope is shown to be ~43 %.
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Wang, Fazhi, Wenhe Du, Qi Yuan, Daosen Liu, and Shuang Feng. "Wander of a Gaussian-Beam Wave Propagating through Kolmogorov and Non-Kolmogorov Turbulence along Laser-Satellite Communication Uplink." Atmosphere 13, no. 2 (January 20, 2022): 162. http://dx.doi.org/10.3390/atmos13020162.
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It is accepted that there exists two kinds of atmospheric turbulence in the Earth’s aerosphere—Kolmogorov and non-Kolmogorov turbulence; therefore, it is important to research their combined impacts on laser-satellite communications. In this paper, the exponential power spectra of refractive-index fluctuations for non-Kolmogorov turbulence in the free troposphere and stratosphere are proposed, respectively. Based on these two spectra, using the Markov approximation, beam wander displacement variances of a Gaussian-beam wave are derived, respectively, which are valid under weak turbulent fluctuations condition. On this basis, using a three-layer altitude-dependent turbulent spectrum model for vertical/slant path, the combined influence of a three-layer atmospheric turbulence on wander of a Gaussian-beam wave as the carrier wave in laser-satellite communication is studied. This three-layer spectrum is more accurate than a two-layer model. Moreover, the variations of beam wander displacement with beam radius, zenith angles, and nominal value of the refractive-index structure parameter on the ground are estimated. The theory of optical wave propagation through non-Kolmogorov atmospheric turbulence is further enriched and a theoretical model of a three-layer atmospheric turbulence beam wander for a satellite-ground laser communication uplink is established.
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Roșu, Iulian Alin, Marius Mihai Cazacu, and Maricel Agop. "Multifractal Model of Atmospheric Turbulence Applied to Elastic Lidar Data." Atmosphere 12, no. 2 (February 6, 2021): 226. http://dx.doi.org/10.3390/atmos12020226.
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This paper shall present a multifractal interpretation of turbulent atmospheric entities, considering them a complex system whose dynamics are manifested on continuous yet non-differentiable multifractal curves. By bringing forth theoretical considerations regarding multifractal structures through non-differentiable functions in the form of an adaptation of scale relativity theory, the minimal vortex of an instance of turbulent flow is considered. In this manner, the spontaneous breaking of scale invariance becomes a mechanism for atmospheric turbulence generation. This then leads to a general equation for the non-differentiable vortex itself, with its component velocity fields, and to a vortex turbulent energy dissipation—all of which are plotted and studied. Once the structure of the non-differentiable multifractal structure is mathematically described, an improved phenomenological turbulence model and relations between turbulent energy dissipation and the minimal vortex are employed together, exemplifying the codependency of such models. Using turbulent medium wave propagation theory, certain relations are then extrapolated which allow the obtaining of the inner and outer length scales of the turbulent flow using lidar data. Finally, these altitude profiles are compiled and assembled into timeseries to exemplify the theory and to compare the results with known literature. This model is a generalization of our recent results published under the title “On a Multifractal Approach of Turbulent Atmosphere Dynamics”.
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Hong, J., J. Kim, H. Ishikawa, and Y. Ma. "Surface layer similarity in the nocturnal boundary layer: the application of Hilbert-Huang transform." Biogeosciences Discussions 6, no. 5 (October 8, 2009): 9677–99. http://dx.doi.org/10.5194/bgd-6-9677-2009.
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Abstract. Turbulence statistics such as flux-variance relationship is critical information in measuring and modeling carbon, water, energy, and momentum exchanges at the biosphere-atmosphere interface. Using a recently proposed mathematical technique, the Hilbert-Huang transform (HHT), this study highlights its possibility to quantify impacts of non-turbulent flows on turbulence statistics in the stable surface layer. The HHT is suitable for the analysis of non-stationary and intermittent data and thus very useful for better understanding of the interplay of the surface layer similarity with complex nocturnal environment. Our analysis showed that the HHT can successfully sift non-turbulent components and be used as a tool to estimate the relationships between turbulence statistics and atmospheric stability in complex environment such as nocturnal stable boundary layer.
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Hong, J., J. Kim, H. Ishikawa, and Y. Ma. "Surface layer similarity in the nocturnal boundary layer: the application of Hilbert-Huang transform." Biogeosciences 7, no. 4 (April 19, 2010): 1271–78. http://dx.doi.org/10.5194/bg-7-1271-2010.
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Abstract. Turbulence statistics such as flux-variance relationship are critical information in measuring and modeling ecosystem exchanges of carbon, water, energy, and momentum at the biosphere-atmosphere interface. Using a recently proposed mathematical technique, the Hilbert-Huang transform (HHT), this study highlights its possibility to quantify impacts of non-turbulent flows on turbulence statistics in the stable surface layer. The HHT is suitable for the analysis of non-stationary and intermittent data and thus very useful for better understanding the interplay of the surface layer similarity with complex nocturnal environment. Our analysis showed that the HHT can successfully sift non-turbulent components and be used as a tool to estimate the relationships between turbulence statistics and atmospheric stability in complex environments such as nocturnal stable boundary layer.
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Shelekhov, Alexander, Alexey Afanasiev, Evgeniya Shelekhova, Alexey Kobzev, Alexey Tel’minov, Alexander Molchunov, and Olga Poplevina. "High-Resolution Profiling of Atmospheric Turbulence Using UAV Autopilot Data." Drones 7, no. 7 (June 22, 2023): 412. http://dx.doi.org/10.3390/drones7070412.
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The capabilities of hovering unmanned aerial vehicles (UAVs) in low-altitude sensing of atmospheric turbulence with high spatial resolution are studied experimentally. The vertical profile of atmospheric turbulence was measured at the Basic Experimental Observatory (Tomsk, Russian Federation) with three quadcopters hovering at altitudes of 4, 10, and 27 m in close proximity (~5 m) to anemometers installed on weather towers. The behavior of the longitudinal and lateral wind velocity components in the 0–10 Hz frequency band is analyzed. In addition, the obtained wind velocity components were smoothed over 1 min by the moving average method to describe long turbulent wind gusts. The discrepancy between the UAV and anemometer data is examined. It is found that after smoothing, the discrepancy does not exceed 0.5 m/s in 95% of cases. This accuracy is generally sufficient for measurements of the horizontal wind in the atmosphere. The spectral and correlation analysis of the UAV and anemometer measurements is carried out. The profiles of the longitudinal and lateral scales of turbulence determined from turbulence spectra and autocorrelation functions are studied based on the UAV and anemometer data.
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Pastore, Douglas M., Ryan T. Yamaguchi, Qing Wang, and Erin E. Hackett. "On the Variability of In Situ Surface Layer Refractivity Measurements." Atmosphere 14, no. 7 (June 28, 2023): 1085. http://dx.doi.org/10.3390/atmos14071085.
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Direct measurements of profiles of atmospheric properties near the ocean surface and within the marine atmospheric surface layer often contain a large degree of variability. The variability observed can be explained by numerous technical and natural reasons such as the temporal variability over the time span a profile is measured (unsteadiness in the mean), spatial variations (inhomogeneity), turbulent fluctuations, and measurement uncertainty. In this study, we explored the observed variability in vertical distributions of refractive index measured with a tethered-balloon-based marine atmospheric profiling system (MAPS). MAPS profiled the atmosphere from approximately 0.5 to 50 m, with instantaneous (order 1 s) measurements performed at each profiled altitude. To explore whether the observed scatter could be largely explained by (inertial-scale) turbulent fluctuations, we simulated refractive index fluctuations with a spectral-based turbulent refractive index fluctuation (TRIF) model. TRIF was optimized based on the MAPS measurements to determine a vertical length scale of the turbulence. The scales computed in the optimization were reasonable based on other estimates in the literature under similar conditions. However, finer-scale trends of the length scale with atmospheric stability did not match expectations, and thus the estimated length scales may be considered more as an order-of-magnitude estimate rather than an exact measurement of this scale. The ability to match the observed variability in the MAPS data using a turbulence model with a reasonable choice of vertical length scale suggests that the MAPS variability is dominated by physical processes such as turbulence rather than being primarily driven by measurement uncertainty.
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Li, Lin, Ning Ji, Zhiyong Wu, and Jiabin Wu. "Design and Experimental Demonstration of an Atmospheric Turbulence Simulation System for Free-Space Optical Communication." Photonics 11, no. 4 (April 3, 2024): 334. http://dx.doi.org/10.3390/photonics11040334.
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In this paper, the design of an atmospheric turbulence simulation system for free-space optical (FSO) communication is proposed. The system can accurately simulate repeatable atmospheric turbulent fading channels. It has a dynamic execution range of 30 dB with an execution rate of 1 MHz. The execution accuracy of the system is higher than 0.1 dB. In addition, the reliable TCP/IP protocol is used for communication, which ensures the convenience and versatility of the system. Experiments are carried out to investigate the performance of the system, and the results prove its superiority. Hence, the atmospheric turbulence simulation system can effectively simulate the influence of atmospheric turbulence channels on FSO communication systems.
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Kaloshin, Gennady, and Igor Lukin. "Laser Interferometry of Turbulent Atmosphere." Journal of Atmospheric and Oceanic Technology 29, no. 3 (March 1, 2012): 323–27. http://dx.doi.org/10.1175/jtech-d-11-00190.1.
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Abstract The paper introduces a new laser interferometry–based method for diagnosis of random media by means of high-accuracy angle measurements and describes the results of its development and testing. Theoretical calculations of the dependence of the range of the laser interferometer on laser beam parameters, device geometry, and atmospheric turbulence characteristics are reported. It is demonstrated that at moderate turbulence intensities corresponding to those observed most frequently in turbulent atmosphere at moderate latitudes and with low interference contrast values, the performance range of the laser interferometer–based device exceeds 5 km.
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Chen, J., Y. Hu, Y. Yu, and S. Lü. "Ergodicity test of the eddy-covariance technique." Atmospheric Chemistry and Physics 15, no. 17 (September 4, 2015): 9929–44. http://dx.doi.org/10.5194/acp-15-9929-2015.
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Abstract. The ergodic hypothesis is a basic hypothesis typically invoked in atmospheric surface layer (ASL) experiments. The ergodic theorem of stationary random processes is introduced to analyse and verify the ergodicity of atmospheric turbulence measured using the eddy-covariance technique with two sets of field observational data. The results show that the ergodicity of atmospheric turbulence in atmospheric boundary layer (ABL) is relative not only to the atmospheric stratification but also to the eddy scale of atmospheric turbulence. The eddies of atmospheric turbulence, of which the scale is smaller than the scale of the ABL (i.e. the spatial scale is less than 1000 m and temporal scale is shorter than 10 min), effectively satisfy the ergodic theorems. Under these restrictions, a finite time average can be used as a substitute for the ensemble average of atmospheric turbulence, whereas eddies that are larger than ABL scale dissatisfy the mean ergodic theorem. Consequently, when a finite time average is used to substitute for the ensemble average, the eddy-covariance technique incurs large errors due to the loss of low-frequency information associated with larger eddies. A multi-station observation is compared with a single-station observation, and then the scope that satisfies the ergodic theorem is extended from scales smaller than the ABL, approximately 1000 m to scales greater than about 2000 m. Therefore, substituting the finite time average for the ensemble average of atmospheric turbulence is more faithfully approximate the actual values. Regardless of vertical velocity or temperature, the variance of eddies at different scales follows Monin–Obukhov similarity theory (MOST) better if the ergodic theorem can be satisfied; if not it deviates from MOST. The exploration of ergodicity in atmospheric turbulence is doubtlessly helpful in understanding the issues in atmospheric turbulent observations and provides a theoretical basis for overcoming related difficulties.
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Shen, Hong, Longkun Yu, Xu Jing, and Fengfu Tan. "Method for Measuring the Second-Order Moment of Atmospheric Turbulence." Atmosphere 12, no. 5 (April 28, 2021): 564. http://dx.doi.org/10.3390/atmos12050564.
Full textAbstract:
The turbulence moment of order m (μm) is defined as the refractive index structure constant Cn2 integrated over the whole path z with path-weighting function zm. Optical effects of atmospheric turbulence are directly related to turbulence moments. To evaluate the optical effects of atmospheric turbulence, it is necessary to measure the turbulence moment. It is well known that zero-order moments of turbulence (μ0) and five-thirds-order moments of turbulence (μ5/3), which correspond to the seeing and the isoplanatic angles, respectively, have been monitored as routine parameters in astronomical site testing. However, the direct measurement of second-order moments of turbulence (μ2) of the whole layer atmosphere has not been reported. Using a star as the light source, it has been found that μ2 can be measured through the covariance of the irradiance in two receiver apertures with suitable aperture size and aperture separation. Numerical results show that the theoretical error of this novel method is negligible in all the typical turbulence models. This method enabled us to monitor μ2 as a routine parameter in astronomical site testing, which is helpful to understand the characteristics of atmospheric turbulence better combined with μ0 and μ5/3.