scholarly journals Robust Nonparametric Methods of Statistical Analysis of Wind Velocity Components in Acoustic Sounding of the Lower Layer of the Atmosphere

Symmetry ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 961 ◽  
Author(s):  
Krasnenko ◽  
Simakhin ◽  
Shamanaeva ◽  
Cherepanov
Keyword(s):  
Statistical Analysis ◽  
Wind Velocity ◽  
Numerical Experiments ◽  
Lower Layer ◽  
Statistical Characteristics ◽  
Nonparametric Method ◽  
Vertical Profiles ◽  
Acoustic Sounding ◽  
Sodar Data ◽  
First Four Moments

Statistical analysis of the results of minisodar measurements of vertical profiles of wind velocity components in a 5–200 m layer of the atmosphere shows that this problem belongs to the class of robust nonparametric problems of mathematical statistics. In this work, a new consecutive nonparametric method of adaptive pendular truncation is suggested for outlier detection and selection in sodar data. The method is implemented in a censoring algorithm. The efficiency of the suggested algorithm is tested in numerical experiments. The algorithm has been used to calculate statistical characteristics of wind velocity components, including vertical profiles of the first four moments, the correlation coefficient, and the autocorrelation and structure functions of wind velocity components. The results obtained are compared with classical sample estimates.

STATISTICAL ANALYSIS OF LIGHTNING ACTIVITY IN THE NORTH CAUCASUS

2021 ◽  
pp. 112-115
Author(s):  
M. V. Zharashuev ◽  
Keyword(s):  
Statistical Analysis ◽  
Lightning Activity ◽  
Statistical Characteristics ◽  
North Caucasus ◽  
The North

Statistical analysis of lightning activity in the North Caucasus and Stavropol Territory depending on orography is carried out. The statistical characteristics of lightning for the period 2009-2018 on the territory of 173056 km2 were analyzed.

scholarly journals A Combined Quantitative Evaluation Model for the Capability of Hyperspectral Imagery for Mineral Mapping

Sensors ◽  
2019 ◽  
Vol 19 (2) ◽  
pp. 328 ◽  
Author(s):  
Na Li ◽  
Xinchen Huang ◽  
Huijie Zhao ◽  
Xianfei Qiu ◽  
Kewang Deng ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Statistical Analysis ◽  
Imaging System ◽  
Evaluation Model ◽  
Spectral Response ◽  
Influence Factors ◽  
Hyperspectral Data ◽  
Statistical Characteristics ◽  
Mineral Mapping ◽  
Proposed Model

To analyze the influence factors of hyperspectral remote sensing data processing, and quantitatively evaluate the application capability of hyperspectral data, a combined evaluation model based on the physical process of imaging and statistical analysis was proposed. The normalized average distance between different classes of ground cover is selected as the evaluation index. The proposed model considers the influence factors of the full radiation transmission process and processing algorithms. First- and second-order statistical characteristics (mean and covariance) were applied to calculate the changes for the imaging process based on the radiation energy transfer. The statistical analysis was combined with the remote sensing process and the application performance, which consists of the imaging system parameters and imaging conditions, by building the imaging system and processing models. The season (solar zenith angle), sensor parameters (ground sampling distance, modulation transfer function, spectral resolution, spectral response function, and signal to noise ratio), and number of features were considered in order to analyze the influence factors of the application capability level. Simulated and real data collected by Hymap in the Dongtianshan area (Xinjiang Province, China), were used to estimate the proposed model’s performance in the application of mineral mapping. The predicted application capability of the proposed model is consistent with the theoretical analysis.

scholarly journals Estimates of boundary layer parameters in the atmospheres of the terrestrial planets

1971 ◽  
Vol 40 ◽  
pp. 297-303
Author(s):  
G. S. Golitsyn
Keyword(s):  
Boundary Layers ◽  
Wind Velocity ◽  
Lower Layer ◽  
Similarity Theory ◽  
Potential Temperature ◽  
Terrestrial Planets ◽  
Turbulent Heat ◽  
Low Density ◽  
Free Atmosphere ◽  
Night Time

The similarity theory of atmospheric boundary layers is applied to an estimate of the form of vertical profiles of average wind velocity and potential temperature in the atmospheres of the terrestrial planets in day- and night-time conditions.It is then considered, as in the case of the earth, that the magnitude of the turbulent heat flux qT during the day is about 0.1 of q(1 – A), where q is the solar constant for the planet and A is its albedo; at night, qT is several times smaller still. The friction velocity u* is taken equal to 2–5% (depending upon the stratification) of the mean wind velocity in the free atmosphere, which was adopted from previous calculations (Golitsyn, 1968).The boundary layers in the atmospheres of Mars and Venus and in the hypothetical atmosphere of Mercury are examined in detail. Sharp temperature drops are characteristic of Mars within a few tens of meters from the surface, attaining a magnitude of several tens of degrees, especially during the day. Large changes of the wind velocity also take place in this thin lower layer. This effect results from the low density of the Martian atmosphere.For Venus, owing to the very high density of the atmosphere, the stratification is close to neutral, i.e., the temperature profile is close to the adiabatic one and the wind profile is of a logarithmic shape.Owing to high winds, the stratification on Mercury must also be close to neutral with respect to the wind (the profile being close to the logarithmic), but because of the expected low density, the temperature changes near the ground may still be very great.

Statistical Characteristics of Thermal Convection Structures based on Acoustic Sounding Data

2020 ◽  
Author(s):  
Natalia Vazaeva ◽  
Otto Chkhetiani ◽  
Michael Kurgansky ◽  
Margarita Kallistratova ◽  
Vasily Lyulyukin ◽  
...  
Keyword(s):  
Velocity Field ◽  
Wind Velocity ◽  
Vertical Velocity ◽  
Thermal Convection ◽  
Rayleigh Distribution ◽  
Arid Zones ◽  
Grey Zone ◽  
Time Step ◽  
Limit Values ◽  
Acoustic Sounding

<p>The thermal convection structures (TCS) and their characteristics manifestations in the atmospheric boundary layer were investigated using the data from acoustic Doppler sodar LATAN-3M. A longwave LATAN-3M sodar with a vertical resolution of 20 m in 2007 and 10 m in 2016, 2018, 2019, a pulse emission interval of 5 s in 2007 and 3 s in 2016, 2018, 2019, an altitude range of 400–600 m in 2007 and 350 m in 2016, 2018, 2019, and a basic carrier frequency of 2 kHz in 2007 and 3 kHz in 2016, 2018, 2019 had measured the profiles of the wind velocity components which were used for calculating the scale of TCS. Experimental data were being obtained during the field campaigns organized by the A.M. Obukhov Institute of Atmospheric Physics RAS in Rostov region and over semi-arid zones of the Caspian lowland in the eastern part of Kalmykia Republic, Russia.</p><p>The wind was weak and the convection was well-developed in the case studies over July of years 2007, 2016, 2018, 2019. A moving rectangular filter was used for averaging the original data of the horizontal and vertical wind-velocity components. The averaging interval had been empirically chosen and, in this case, amounted to 10 min. At such values, the spatiotemporal velocity-field structure was adequately reproduced.</p><p>The original method of acoustic sounding data treatment for extracting TCS has been developed and put to an evaluation test. The episodes of the vertical velocities above limit values at which TCS aroused hypothetically were considered. As the threshold, a few alternatives were used: 0.3 m/s, 0.6 m/s and 1.2 m/s. The duration of vertical velocity excess over the threshold, the maximum velocity within this interval and the horizontal scale were calculated. It is assumed that TCS move forward with some averaged velocity during any relatively small time step. In this case, the spatial distribution of velocity field and its time variations have been reproduced suitably.</p><p>The statistical distribution was close to Rayleigh distribution:</p><p><em>p</em>(<em>U</em>) = (2<em>U</em>/<em>U<sub>0</sub></em><sup>2</sup>)*<em>exp </em>((<em>U<sub>m</sub></em><sup>2</sup>-<em>U </em><sup>2</sup>)/<em>U<sub>0</sub></em><sup>2</sup>),</p><p>where <em>U<sub>0</sub></em><sup>2 </sup>= (<<em>U </em><sup>2</sup>>-<em>U<sub>m</sub></em><sup>2</sup>), <<em>U </em><sup>2</sup>> is the root-mean-square vertical velocity of TCS, and <em>U<sub>m</sub></em> – the threshold for vertical velocity. This closeness can facilitate the understanding of the processes in the so-called “grey-zone” of numerical simulation and be implemented in the parameterization, forecast of TCS. Note that Rayleigh distribution is applied to the statistics of the intense moist convective vortices and also of the height of the ocean waves.</p><p>This work was supported by Russian Foundation for Basic Research (projects No.19-05-50110, No.19-05-01008, No.17-05-41121), and by fundamental research program of Russian Academy of Science (program No.1).</p>

scholarly journals Characteristics of the catalogue according to the KNET network (Northern Tian Shan)

2021 ◽  
Vol 254 ◽  
pp. 02005
Author(s):  
Naylya Sycheva ◽  
Vladimir Sychev
Keyword(s):  
Distribution Function ◽  
Spatial Distribution ◽  
Statistical Analysis ◽  
Energy Distribution ◽  
Representative Sample ◽  
B Value ◽  
Statistical Characteristics ◽  
S Waves ◽  
Localization Errors ◽  
Minimum Number

Various characteristics of the catalogue obtained from the data of the KNET network, containing the parameters of more than 10,000 earthquakes that occurred from 1994 to 2020, are considered. A statistical analysis of the number of P- and S-waves registered by each station of the network is carried out. The activity of the stations during the localization of earthquakes has been determined. The most active station is AAK. The minimum number of P- and S-waves is recorded at the ULHL station. Statistical analysis of localization errors has been performed. The boundaries of the territory for which the minimum values of errors are observed are determined. The statistical characteristics of earthquakes in terms of magnitude, time, depth are presented. The distribution of the number of earthquakes by different energy classes in time and the spatial distribution of earthquakes by depths: 0-5 km, 5-10 km, 10-15 km and more than 15 km are constructed. The Gutenberg Richter law was used to describe the energy distribution function of earthquakes. A representative sample of the catalogue was determined, which includes events with M ≥ 1.8. The b-value for the directory is 0.88.

scholarly journals Stratification effects on shoaling Internal Solitary Waves

2021 ◽  
Author(s):  
Sam Hartharn-Evans ◽  
Magda Carr ◽  
Marek Stastna ◽  
Peter Davies
Keyword(s):  
Density Gradient ◽  
Solitary Waves ◽  
Numerical Experiments ◽  
Lower Layer ◽  
Internal Solitary Waves ◽  
Topographic Slope ◽  
Numerical Studies ◽  
The World ◽  
Upper Boundary ◽  
Mixing And Transport

<p>Shoaling is a key mechanism by which Internal Solitary Waves (ISWs) dissipate energy, induce mixing, and transport sediment. Past studies of shoaling ISWs in a three-layer stratification (with homogeneous upper and lower layers separated by a thin pycnocline layer) have identified a classification system where waves over the shallowest slopes undergo fission, whilst over steeper slopes, the breaking type changes from surging, through collapsing to plunging as a function of increasing internal Irribaren number (Ir) defined with the topographic slope, s, and the incident wave’s amplitude and wavelength, A<sub>w</sub> and L<sub>w </sub>respectively, as <img src="https://contentmanager.copernicus.org/fileStorageProxy.php?f=gnp.9fb46536f70067154311161/sdaolpUECMynit/12UGE&app=m&a=0&c=d84eaf790c6586a46ed8fca09040fcd7&ct=x&pn=gnp.elif&d=1" alt="" width="117" height="24">. Here, a combined numerical and laboratory study extends this prior work into new stratifications, representing the diversity of ocean structures across the world. Numerical results were able to successfully reproduce past studies in the three-layer stratification, and those in the two-layer stratification in the laboratory. Where a linear stratified layer overlays a homogeneous lower layer (two-layer stratification), it is found that plunging dynamics are inhibited by the density gradient throughout the upper layer, instead forming collapsing-type breakers. In numerical experiments, where the density gradient is continuous throughout the full water column (linear stratification), not only are the plunging dynamics inhibited, but the density gradient at the bottom boundary also prevents the formation of collapsing dynamics, instead all waves in this stratification either fission, or form surging breakers. Where the wave steepness is particularly high in the linear stratification, the upslope bolus formed by surging was unstable, and Kelvin-Helmholtz instabilities were observed on the upper boundary of the bolus, dynamics not previously observed in the literature. These results indicate the importance of using representative stratifications in laboratory and numerical studies of ISW behaviours.</p>

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