scholarly journals Results analysis of the tests and certification of near-airfield meteorological radar complex

2020 ◽  
Vol 23 (1) ◽  
pp. 28-40
Author(s):  
K. I. Galaeva
Keyword(s):  
Velocity Field ◽  
Meteorological Data ◽  
A Priori ◽  
Radar Data ◽  
Sources Of Information ◽  
Movement Vector ◽  
Vector Velocity ◽  
Meteorological Radar ◽  
Characteristic Features ◽  
Vector Velocity Field

The article presents the tasks, characteristic features, tactical and technical characteristics, the possible location and scope of the near-airfield meteorological radar complex. The analysis is made of the comparison of meteorological radar data from the near-airfield meteorological radar complex with reliable sources of meteorological information obtained during preliminary, acceptance, certification tests. The features of carrying out during the validation tests of meteorological radar data of the near-airfield meteorological radar complex are described, namely: dangerous meteorological phenomena (showers of different intensities, thunderstorms with a probability of 30-70%, 71-90%, > 90%, hail of varying degrees of intensity, squall of different intensities), velocity and direction of movement of cloud formations, vector velocity field. Examples of comparing the data of the near-airfield meteorological radar complex with data from a priori reliable sources of information are shown in the form of maps, graphs and tables. It is shown that the data of the near-airfield meteorological radar complex were obtained during testing and certification covering the warm and cold periods of the year, the sample size is statistically significant (except for the sample to assess the vector velocity field from data of aircraft and radar due to the spatial-temporal features comparing data from the two indicated information sources). It was established that the near-airfield meteorological radar complex provides acceptable in accordance with the requirements the construction quality of meteorological phenomena maps, the vector velocity field and the estimation of the cloud formations movement vector. The article illustrates the results of the statistical analysis of the data of the near-airfield meteorological radar complex, obtained personally by the author of the article. Analysis of meteorological data of the near-airfield meteorological radar complex was carried out with the aim of further exploitation of the near-airfield meteorological radar complex.

Operational evaluation of volcanic source terms (volcanic ash and SO2) from inverse modelling for aviation

2020 ◽  
Author(s):  
Mariëlle Mulder ◽  
Delia Arnold ◽  
Christian Maurer ◽  
Marcus Hirtl
Keyword(s):  
Source Term ◽  
Dispersion Model ◽  
Meteorological Data ◽  
A Priori ◽  
Radar Data ◽  
Particle Dispersion ◽  
Volcanic Emissions ◽  
Volcanic Source ◽  
Computational Resources ◽  
Different Sources

<p>An operational framework is developed to provide timely and frequent source term updates for volcanic emissions (ash and SO<sub>2</sub>). The procedure includes running the Lagrangian particle dispersion model FLEXPART with an initial (a priori) source term, and combining the output with observations (from satellite, ground-based, etc. sources) to obtain an a posteriori source term. This work was part of the EUNADICS-AV (eunadics-av.eu), which is a continuation of the work developed in the VAST project (vast.nilu.no). The aim is to ensuring that at certain time intervals when new observational and meteorological data is available during an event, an updated source term is provided to analysis and forecasting groups. The system is tested with the Grimsvötn eruption of 2011. Based on a source term sensitivity test, one can find the optimum between a sufficiently detailed source term and computational resources. Because satellite and radar data from different sources is available at different times, the source term is generated with the data that is available the earliest after the eruption started and data that is available later is used for evaluation.</p>

scholarly journals Wave mixing in a system of moving coaxial cylinders

2019 ◽  
Vol 486 (1) ◽  
pp. 30-33
Author(s):  
R. F. Ganiev ◽  
D. L. Reviznikov ◽  
T. Yu. Sukharev ◽  
L. E. Ukrainskii
Keyword(s):  
Computer Simulation ◽  
Velocity Field ◽  
Flow Field ◽  
Singular Points ◽  
Wave Mixing ◽  
Coaxial Cylinders ◽  
Laboratory Bench ◽  
Vector Velocity ◽  
Vector Velocity Field

The results of computer simulation of mixing in a system of moving coaxial cylinders are presented. Detailed spatial-temporal pictures of the processes occurring were obtained and the main structures in the flow field were determined. Based on the analysis of the singular points of the vector velocity field of the liquid, a method for profiling the rotor is proposed. Introduced dimensionless quantities, the use of which allows the transition from laboratory bench installations to real production devices.

scholarly journals Blow-up criterion for the density dependent inviscid Boussinesq equations

2020 ◽  
Vol 2020 (1) ◽  
Author(s):  
Li Li ◽  
Yanping Zhou
Keyword(s):  
Velocity Field ◽  
Energy Method ◽  
Blow Up ◽  
A Priori Estimates ◽  
A Priori ◽  
Boussinesq Equations ◽  
Smooth Solutions ◽  
Density Dependent ◽  
Priori Estimates ◽  
Blow Up Criterion

Abstract In this work, we consider the density-dependent incompressible inviscid Boussinesq equations in $\mathbb{R}^{N}\ (N\geq 2)$ R N ( N ≥ 2 ) . By using the basic energy method, we first give the a priori estimates of smooth solutions and then get a blow-up criterion. This shows that the maximum norm of the gradient velocity field controls the breakdown of smooth solutions of the density-dependent inviscid Boussinesq equations. Our result extends the known blow-up criteria.

scholarly journals Adaptive regridding in 3D reflection tomography

1997 ◽  
Vol 40 (1) ◽  
Author(s):  
G. Böhm ◽  
G. Rossi ◽  
A. Vesnaver
Keyword(s):  
Velocity Field ◽  
A Priori ◽  
A Priori Information ◽  
Complex Velocity ◽  
Variable Resolution ◽  
Fitting Procedure ◽  
Voronoi Polygons ◽  
Fully Automatic ◽  
Priori Information ◽  
Reflection Tomography

3D reflection tomography allows the macro-model of complex geological structures to be reconstructed. In the usual approach, the spatial distribution of the velocity field is discretized by regular grids. This choice simplifies the development of the related software, but introduces two serious drawbacks: various domains of the model may be poorly covered, and a relevant mismatch between the grid and a complex velocity field may occur. So the tomographic inversion becomes unstable, unreliable and necessarily blurred. In this paper we introduce an algorithm to adapt the grid to the available ray paths and to the velocity field in sequence: so we get irregular grids with a locally variable resolution. We can guide the grid fitting procedure interactively, if we are going to introduce some geological a priori information; otherwise, we define a fully automatic approach, which exploits the Delauny triangles and Voronoi polygons.

scholarly journals Comparison analysis of numerically calculated slip surfaces with measured S-wave velocity field for Just-Tęgoborze landslide in Carpathian flysch

2019 ◽  
Vol 133 ◽  
pp. 01003
Author(s):  
Krzysztof Krawiec ◽  
Paulina Harba
Keyword(s):  
Velocity Field ◽  
Wave Velocity ◽  
Strength Criterion ◽  
Deformation Field ◽  
Comparison Analysis ◽  
S Wave ◽  
Velocity Models ◽  
Characteristic Features ◽  
Analysis Of Dispersion ◽  
Comparison Of The Results

The article presents the comparison analysis between deformation field from numerical model and shear wave (S-wave) velocity field obtained from seismic interferometry (SI). Tests were conducted on active Just-Tęgoborze landslide. Geologically, the study area lies in Magura Nappe in the Outer Carpathians. The landslide’s flysch bedrock is covered by Quaternary colluvium built of clays and weathered clayey-rock deposits. During geotechnical investigation, properties of landslide body were established and failure surfaces were distinguished. In order to obtain S-wave velocity models, one-hour of ambient seismic noise was recorded by 12 broadband seismometers. As a result of data processing with SI method, Rayleigh surface wave propagation was reconstructed. The analysis of dispersion curves allowed to estimate a two dimensional S-wave velocity field. The deformation field were calculated assuming an elastic-plastic Coulomb-Mohr strength criterion. Images of shear strain increment, and values of factor of safety of the slope were obtained as a result of calculation. The comparison of the results indicates the similar characteristic features in the S-wave velocity field and the field of deformation calculated numerically.

scholarly journals Application and evaluation of the dendroclimatic process-based model MAIDEN during the last century in Canada and Europe

2020 ◽  
Vol 16 (3) ◽  
pp. 1043-1059
Author(s):  
Jeanne Rezsöhazy ◽  
Hugues Goosse ◽  
Joël Guiot ◽  
Fabio Gennaretti ◽  
Etienne Boucher ◽  
...  
Keyword(s):  
Tree Ring ◽  
Tree Growth ◽  
Meteorological Data ◽  
Ring Width ◽  
Complex Model ◽  
Added Value ◽  
Model Parameters ◽  
Sources Of Information ◽  
Calibration And Validation

Abstract. Tree-ring archives are one of the main sources of information to reconstruct climate variations over the last millennium with annual resolution. The links between tree-ring proxies and climate have usually been estimated using statistical approaches, assuming linear and stationary relationships. Both assumptions may be inadequate, but this issue can be overcome by ecophysiological modelling based on mechanistic understanding. In this respect, the model MAIDEN (Modeling and Analysis In DENdroecology) simulating tree-ring growth from daily temperature and precipitation, considering carbon assimilation and allocation in forest stands, may constitute a valuable tool. However, the lack of local meteorological data and the limited characterization of tree species traits can complicate the calibration and validation of such a complex model, which may hamper palaeoclimate applications. The goal of this study is to test the applicability of the MAIDEN model in a palaeoclimate context using as a test case tree-ring observations covering the 20th century from 21 Eastern Canadian taiga sites and 3 European sites. More specifically, we investigate the model sensitivity to parameter calibration and to the quality of climatic inputs, and we evaluate the model performance using a validation procedure. We also examine the added value of using MAIDEN in palaeoclimate applications compared to a simpler tree-growth model, i.e. VS-Lite. A Bayesian calibration of the most sensitive model parameters provides good results at most of the selected sites with high correlations between simulated and observed tree growth. Although MAIDEN is found to be sensitive to the quality of the climatic inputs, simple bias correction and downscaling techniques of these data improve significantly the performance of the model. The split-sample validation of MAIDEN gives encouraging results but requires long tree ring and meteorological series to give robust results. We also highlight a risk of overfitting in the calibration of model parameters that increases with short series. Finally, MAIDEN has shown higher calibration and validation correlations in most cases compared to VS-Lite. Nevertheless, this latter model turns out to be more stable over calibration and validation periods. Our results provide a protocol for the application of MAIDEN to potentially any site with tree-ring width data in the extratropical region.

scholarly journals High-Resolution Coherency Functionals for Improving the Velocity Analysis of Ground-Penetrating Radar Data

2020 ◽  
Vol 12 (13) ◽  
pp. 2146
Author(s):  
Eusebio Stucchi ◽  
Adriano Ribolini ◽  
Andrea Tognarelli
Keyword(s):  
High Resolution ◽  
Velocity Field ◽  
Ground Penetrating Radar ◽  
Energy Content ◽  
Signal To Noise Ratio ◽  
Synthetic Data ◽  
Radar Data ◽  
Position Type ◽  
Reliable Interpretation ◽  
Ground Penetrating

We aim at verifying whether the use of high-resolution coherency functionals could improve the signal-to-noise ratio (S/N) of Ground-Penetrating Radar data by introducing a variable and precisely picked velocity field in the migration process. After carrying out tests on synthetic data to schematically simulate the problem, assessing the types of functionals most suitable for GPR data analysis, we estimated a varying velocity field relative to a real dataset. This dataset was acquired in an archaeological area where an excavation after a GPR survey made it possible to define the position, type, and composition of the detected targets. Two functionals, the Complex Matched Coherency Measure and the Complex Matched Analysis, turned out to be effective in computing coherency maps characterized by high-resolution and strong noise rejection, where velocity picking can be done with high precision. By using the 2D velocity field thus obtained, migration algorithms performed better than in the case of constant or 1D velocity field, with satisfactory collapsing of the diffracted events and moving of the reflected energy in the correct position. The varying velocity field was estimated on different lines and used to migrate all the GPR profiles composing the survey covering the entire archaeological area. The time slices built with the migrated profiles resulted in a higher S/N than those obtained from non-migrated or migrated at constant velocity GPR profiles. The improvements are inherent to the resolution, continuity, and energy content of linear reflective areas. On the basis of our experience, we can state that the use of high-resolution coherency functionals leads to migrated GPR profiles with a high-grade of hyperbolas focusing. These profiles favor better imaging of the targets of interest, thereby allowing for a more reliable interpretation.

Classification Of Dual-polarisation Meteorological Radar Data

2005 ◽  
Author(s):  
L. Alparone ◽  
G. Benelli ◽  
A. Freni ◽  
D. Giuli ◽  
S. Minuti
Keyword(s):  
Radar Data ◽  
Meteorological Radar
Sign in / Sign up

Export Citation Format

Share Document