Diurnal dynamics of the Umov kinetic energy density vector in the atmospheric boundary layer from minisodar measurements

The diurnal hourly dynamics of the kinetic energy flux density vector, called the Umov vector, and the mean and turbulent components of the kinetic energy are estimated from minisodar measurements of wind vector components and their variances in the lower 200 m layer of the atmosphere. During a 24 h period of continuous minisodar observations, it was established that the mean kinetic energy density dominated in the surface atmospheric layer at altitudes below ~50 m. At altitudes from 50 to 100 m, the relative contributions of the mean and turbulent wind kinetic energy densities depended on the time of the day and the sounding altitude. At altitudes below 100 m, the contribution of the turbulent kinetic energy component is small, and the ratio of the turbulent to mean wind kinetic energy components was in the range 0.01–10. At altitudes above 100 m, the turbulent kinetic energy density sharply increased, and the ratio reached its maximum equal to 100–1000 at altitudes of 150–200 m. A particular importance of the direction and magnitude of the wind effect, that is, of the direction and magnitude of the Umov vector at different altitudes was established. The diurnal behavior of the Umov vector depended both on the time of the day and the sounding altitude. Three layers were clearly distinguished: a near-surface layer at altitudes of 5–15 m, an intermediate layer at altitudes from 15 m to 150 m, and the layer of enhanced turbulence above. The feasibility is illustrated of detecting times and altitudes of maximal and minimal wing kinetic energy flux densities, that is, time periods and altitude ranges most and least favorable for flights of unmanned aerial vehicles. The proposed novel method of determining the spatiotemporal dynamics of the Umov vector from minisodar measurements can also be used to estimate the effect of wind on high-rise buildings and the energy potential of wind turbines

Dynamics of turbulence kinetic energy from minisodar measurements

In the report, spatiotemporal dynamics of the turbulent kinetic energy (TKE) retrieved from minisodar measurements o

Spatiotemporal dynamics of the kinetic energy in the atmospheric boundary layer from minisodar measurements

Spatiotemporal dynamics of the atmospheric kinetic energy and its components caused by the ordered and turbulent motions of air masses are estimated from minisodar measurements of three velocity vector components and their variances within the lowest 5–200 m layer of the atmosphere, with a particular emphasis on the turbulent kinetic energy. The layered structure of the total atmospheric kinetic energy has been established. From the diurnal hourly dynamics of the altitude profiles of the turbulent kinetic energy (TKE) retrieved from minisodar data, four layers are established by the character of the altitude TKE dependence, namely, the near-ground layer, the surface layer, the layer with a linear TKE increase, and the transitive layer above. In the first layer, the most significant changes of the TKE were observed in the evening hours. In the second layer, no significant changes in the TKE values were observed. A linear increase in the TKE values with altitude was observed in the third layer. In the fourth layer, the TKE slightly increased with altitude and exhibited variations during the entire observation period. The altitudes of the upper boundaries of these layers depended on the time of day. The MKE values were much less than the corresponding TKE values, they did not exceed 50 m2/s2. From two to four MKE layers were distinguished based on the character of its altitude dependence. The two-layer structures were observed in the evening and at night (under conditions of the stable atmospheric boundary layer). In the morning and daytime, the four-layer MKE structures with intermediate layers of linear increase and subsequent decrease in the MKE values were observed. Our estimates demonstrated that the TKE contribution to the total atmospheric kinetic energy considerably (by a factor of 2.5–3) exceeded the corresponding MKE contribution

Influence of the outer scales of temperature and dynamic turbulence on the characteristics of transmitted acoustic radiation

In the present work, the problem of propagation of monochromatic acoustic radiation in the lower 500-meter layer of the plain stratified moving turbulent atmosphere is solved by the Monte Carlo method. The influence of the parameters of models of the outer scales of temperature and dynamic turbulence on the intensity of transmitted acoustic radiation intensity is investigate

Spatiotemporal dynamics of the wind velocity variance from the data of acoustic sounding of the atmospheric boundary layer

In the report spatiotemporal dynamics of the variance of three components of the wind velocity in the atmospheric boundary layer retrieved from measurements with a Doppler mini-sodar is analyzed. During measurements, the variances of the x- and y-components of the wind velocity were in the range 0.001 ≤ Dx, Dy ≤ 10 m2/s2; for the z-component 0.001 ≤ Dz ≤ 1.2 m2/s2. Their increase in the morning hours (at about 11:00, local time) and in the evening hours (from 18:00 till 22:00, local time) was noticed. This was explained by warming and subsequent cooling of the Earth surface accompanied by strengthening of motion of air masses. At night (from 00:00 till 5:00, local time), 0.01 ≤ Dz ≤ 0.56 m2/s2, which is in good agreement with the literature data. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only

Experimental and theoretical investigations of the near-ground propagation of acoustic radiation in the atmosphere

Near-ground propagation of monochromatic acoustic radiation at frequencies of 300, 1000, 2000, and 3150 Hz along atmospheric paths up to 100 m long is investigated experimentally and theoretically depending on altitudes of the acoustic source and receiver. The experiment was carried out at the experimental site of the Institute of Monitoring of Climatic and Ecological Systems (IMCES) using a specially developed setup. The dependence of the recorded sound pressure level on the propagation path length and initial signal power is analyzed. The theoretical analysis is performed by the Monte Carlo method using the local estimation algorithm developed by the authors. The comparison of the experimental and theoretical results shows their satisfactory agreement, which indicates the effectiveness of the proposed algorithm and its applicability to predicting the near-ground sound propagation

Robust nonparametric generators of random variables

A method of constructing consistent and effective algorithms for robust nonparametric generators of random variables is considered for statistical simulation problems and bootstrap procedures. Semiparametric and semi-nonparametric algorithms of generators have been synthesized for inhomogeneous experimental data. It is shown that standard parametric and nonparametric generators of random variables are inconsistent under conditions of inhomogeneous samples, and their use can significantly and unpredictably distort simulation results and decision-making procedures. In the presence of outliers, the efficiency of the robust semiparametric and semi-nonparametric generators can considerably exceed that of standard generators of random variables, especially in situations with asymmetric outlier

Robust parametric estimates of heterogeneous experimental data

In the present work, a weighted maximum likelihood method (WMLM) is proposed to obtain robust estimates of experimental data containing outliers. The method allows asymptotically effective robust unbiased estimates to be obtained in the presence of not only external, but also internal asymmetric and symmetric outliers. Algorithms for obtaining robust WMLM estimates are considered at the parametric level of aprioristic uncertainty. It is demonstrated that these estimates converge to the maximum likelihood estimates of a heterogeneous data sample for each distribution within the Tukey supermodel

Diurnal dynamics of the kinetic energy in the atmospheric boundary layer retrieved from minisodar measurements

Based on the results of postprocessing of minisodar measurements of three wind velocity components and their variances in the lower 200-meter layer of the atmosphere, the diurnal hourly dynamics of the kinetic energy of the atmosphere reduced to unit air mass and its component ETKE (caused by turbulent pulsations of the wind velocity) and EMKE (caused by the mean wind velocity) are analyzed focusing on the turbulent kinetic energy. It is shown that during 24 hour continuous minisodar observations, ETKE was low up to 50 m, increased from 50 to 100 m, and fast increased at higher altitudes. A significant influence of the time of day on the observation results was noted. Thus, at night the kinetic energy did not exceed 20 J/kg and then increased with time from 20 to 50 J/kg. It reached a maximum in the morning. After sunrise, the turbulent kinetic energy quickly decreased, and the system underlying surface – near-surface air layer went into equilibrium. As a consequence, the spread of turbulent kinetic energy values decreased. The most significant changes were observed at altitudes of 100–200 m.Tthe time of day had no significant influence at altitudes of 50–100 m, and the ETKE values were low and remained practically unchanged with time. Irrespective of the time of day, the maximum turbulent kinetic energy was observed at altitudes of 100–200 m, which poses the greatest danger to unmanned aerial vehicles. The corresponding numerical estimations are presented

Spatiotemporal dynamics of the average and turbulent components of the kinetic wind energy in the lower atmosphere from minisodar data

Based on post-processing of diurnal hourly measurements of three wind velocity components and their variances with an AV4000 minisodar in the lower 200-meter layer of the atmosphere, statistical analysis of the turbulent, ЕТКЕ, and average, ЕМКЕ, kinetic wind energy components has been performed. It was shown that for the diurnal period of continuous minisodar observations, the turbulent kinetic energy component in the groundatmospheric layer to altitudes of ~50 m was low. At altitudes in the range from 50 to 100 m, the turbulent kinetic energy ЕТКЕ increased, at altitudes exceeding 100 m, its growth rate intensified, and the maximum ЕТКЕ values were observed at altitudes of 150–200 m. It was established that the results of observations influenced significantly by time of the day. However, at any time, the maximum turbulent energy was localized at altitudes of ~100–200 m, which posed the greatest danger to light small-sized unmanned vehicles. The approach to revealing times and altitudes of maximum and minimum kinetic wind energy values from the minisodar data, that is, the most and least favorable time and altitude range for flights of light small-sized unmanned aerial vehicles has been proposed, and its efficiency has been illustrated