Climatology of Anomalous Propagation Radar Echoes in a Coastal Area

Abstract Anomalous propagation (AP) of ground-based radar beam results in the detection of ground echoes beyond the horizon. One year of data gathered with an S-band meteorological radar located on the coast in southwest France is used to analyze the spatial distribution of AP ground echoes (APE). The APE distributions of duration and reflectivity in the radar-observed area are found to be strongly related to the main feature of the regional orography and topography up to the farthest distance (250 km) observed by the radar, notably the nature of the surface, the topographic orientation with respect to the radar beam direction, and the altitude. The distribution of APE in the studied area is found to be strongly anisotropic around the radar, with wide differences between land and sea. Rain accumulation equivalent to the APE is, in certain places, of the same order or higher than the real rain depth. The distribution of the ground surfaces, as calculated from a ground numerical model, compares qualitatively well with the APE radar reflectivity distribution.

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Identification and Removal of Ground Echoes and Anomalous Propagation Using the Characteristics of Radar Echoes

Journal of Atmospheric and Oceanic Technology ◽

10.1175/jtech1913.1 ◽

2006 ◽

Vol 23 (9) ◽

pp. 1206-1222 ◽

Cited By ~ 68

Author(s):

Yo-Han Cho ◽

Gyu Won Lee ◽

Kyung-Eak Kim ◽

Isztar Zawadzki

Keyword(s):

Fuzzy Logic ◽

Membership Functions ◽

Echo Intensity ◽

Radar Echoes ◽

Lower Elevation ◽

Fuzzy Logic Approach ◽

Logic Approach ◽

Overall Performance ◽

Anomalous Propagation ◽

Ground Echoes

Abstract This paper explores the removal of normal ground echoes (GREs) and anomalous propagation (AP) in ground-based radars using a fuzzy logic approach. Membership functions and their weights are derived from the characteristics of radar echoes as a function of radar reflectivity. The dependence on echo intensity is shown to significantly improve the proper identification of GRE/AP. In addition, the proposed method has a better performance at lower elevation angles. The overall performance is comparable with that from a polarimetric approach and can thus be easily implemented in operational radars.

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Improved fuzzy logic method to distinguish between meteorological and non-meteorological echoes using C-band polarimetric radar data

Atmospheric Measurement Techniques ◽

10.5194/amt-13-537-2020 ◽

2020 ◽

Vol 13 (2) ◽

pp. 537-551

Author(s):

Shuai Zhang ◽

Xingyou Huang ◽

Jinzhong Min ◽

Zhigang Chu ◽

Xiaoran Zhuang ◽

...

Keyword(s):

Fuzzy Logic ◽

Radar Data ◽

Weak Signal ◽

Post Processing ◽

Algorithm Performance ◽

Radar Echoes ◽

Fuzzy Logic Method ◽

Anomalous Propagation ◽

Logic Method

Abstract. To obtain better performance of meteorological applications, it is necessary to distinguish radar echoes from meteorological and non-meteorological targets. After a comprehensive analysis of the computational efficiency and radar system characteristics, we propose a fuzzy logic method that is similar to the MetSignal algorithm; the performance of this method is improved significantly in weak-signal regions where polarimetric variables are severely affected by noise. In addition, post-processing is adjusted to prevent anomalous propagation at a far range from being misclassified as meteorological echo. Moreover, an additional fuzzy logic echo classifier is incorporated into post-processing to suppress misclassification in the melting layer. An independent test set is selected to evaluate algorithm performance, and the statistical results show an improvement in the algorithm performance, especially with respect to the classification of meteorological echoes in weak-signal regions.

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Modelling of weather radar echoes from anomalous propagation using a hybrid parabolic equation method and NWP model data

Natural Hazards and Earth System Science ◽

10.5194/nhess-7-391-2007 ◽

2007 ◽

Vol 7 (3) ◽

pp. 391-398 ◽

Cited By ~ 7

Author(s):

D. Bebbington ◽

S. Rae ◽

J. Bech ◽

B. Codina ◽

M. Picanyol

Keyword(s):

Parabolic Equation ◽

Weather Prediction ◽

Weather Radar ◽

Equation Method ◽

Index Structure ◽

Entire Area ◽

Parabolic Equation Method ◽

Radar Echoes ◽

Anomalous Propagation ◽

Nwp Model

Abstract. Contamination of weather radar echoes by anomalous propagation (anaprop) mechanisms remains a serious issue in quality control of radar precipitation estimates. Although significant progress has been made identifying clutter due to anaprop there is no unique method that solves the question of data reliability without removing genuine data. The work described here relates to the development of a software application that uses a numerical weather prediction (NWP) model to obtain the temperature, humidity and pressure fields to calculate the three dimensional structure of the atmospheric refractive index structure, from which a physically based prediction of the incidence of clutter can be made. This technique can be used in conjunction with existing methods for clutter removal by modifying parameters of detectors or filters according to the physical evidence for anomalous propagation conditions. The parabolic equation method (PEM) is a well established technique for solving the equations for beam propagation in a non-uniformly stratified atmosphere, but although intrinsically very efficient, is not sufficiently fast to be practicable for near real-time modelling of clutter over the entire area observed by a typical weather radar. We demonstrate a fast hybrid PEM technique that is capable of providing acceptable results in conjunction with a high-resolution terrain elevation model, using a standard desktop personal computer. We discuss the performance of the method and approaches for the improvement of the model profiles in the lowest levels of the troposphere.

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On the influence of the spatial distribution of fine content in the hydraulic conductivity of sand-clay mixtures

Earth Sciences Research Journal ◽

10.15446/esrj.v22n4.69332 ◽

2018 ◽

Vol 22 (4) ◽

pp. 239-249 ◽

Cited By ~ 1

Author(s):

William Mario Fuentes ◽

Carolina Hurtado ◽

Carlos Lascarro

Keyword(s):

Spatial Distribution ◽

Hydraulic Conductivity ◽

Numerical Model ◽

Soil Sample ◽

Gaussian Distribution ◽

Geotechnical Engineering ◽

Empirical Relation ◽

Fine Content ◽

The Mean

Sand-clay mixtures are one of the most usual types of soils in geotechnical engineering. These soils present a hydraulic conductivity which highly depends on the fine content. In this work, it will be shown, that not only the mean fine content of a soil sample affects its hydraulic conductivity, but also its spatial distribution within the sample. For this purpose, a set of hydraulic conductivity tests with sand-clay mixtures have been conducted to propose an empirical relation of the hydraulic conductivity depending on the fine content. Then, a numerical model of a large scaled hydraulic conductivity test is constructed. In this model, the heterogeneity of the fine content is simulated following a Gaussian distribution. The equivalent hydraulic conductivity resulting of the whole model is then computed and the influence of the spatial distribution of the fine content is evaluated. The results indicate that the hydraulic conductivity is not only related to the mean fine content, but also on its heterogeneity.

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EXPERIMENTAL, NUMERICAL AND ANALYTICAL INVESTIGATIONS OF WIND-INDUCED NET PRESSURES FOR INDUSTRIAL BUILDINGS WITH ENVELOPE POROSITIES

Acta Polytechnica CTU Proceedings ◽

10.14311/app.2017.7.0058 ◽

2016 ◽

Vol 7 ◽

pp. 58

Author(s):

Vanessa Saubke ◽

Rüdiger Höffer

Keyword(s):

Spatial Distribution ◽

Numerical Model ◽

Wind Tunnel ◽

External Pressure ◽

Navier Stokes ◽

Industrial Building ◽

Wind Tunnel Experiments ◽

Industrial Buildings ◽

External Pressures

The magnitude and the spatial distribution of wind-induced net pressures (external and internal) on buildings are frequently discussed among research communities and construction industries. This paper deals with this topic based on a case study about an industrial building in Denmark, which was damaged due to the wind impact during a storm when a large part of the roof covering was blown off. In order to detect the reason for the damage the wind-induced loads were studied by i) wind tunnel experiments on the external pressures due to different wind directions, ii) analytical investigations of internal pressure due to envelope porosities and planned openings and iii) numerical analyses for the internal and the external pressure. The Reynolds averaged Navier-Stokes (RANS) method is employed to build a numerical model. The experimental, analytical and numerical results are compared with the indicated characteristic loads from the Eurocode.

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Numerical model of the catchments of the oziąbel and wołczyński strumień rivers – Wołczyn municipality

Studia Geotechnica et Mechanica ◽

10.2478/sgm021207 ◽

2012 ◽

Vol 34 (2) ◽

pp. 73-89

Author(s):

Tomasz Olichwer ◽

Marek Wcisło ◽

Stanisław Staśko ◽

Sebastian Buczyński ◽

Magdalena Modelska ◽

...

Keyword(s):

Numerical Model ◽

Water Balance ◽

Water Table ◽

Cross Sections ◽

Visual Modflow ◽

Step Size ◽

Hydrogeological Mapping ◽

One Year ◽

Discretization Grid ◽

Hydrogeological System

Abstract The article presents a numerical model designed for determining groundwater dynamics and water balance of the catchments of the Oziąbel (Czarna Woda) river and the Wołczyński Strumień river in Wołczyn region. Hydrogeological mapping and modelling research covered the area of 238.9 km2. As a result of measurements performed in 2008-2009, flows were determined in major rivers and water table positions were measured at 26 points. In the major part of the area described, the water table, lying at the depth of 1.5-18.7 m, has unconfined character, and the aquifer is built of Neogene (Quaternary) sands and gravels. In the area under study, groundwaters are drawn from 6 wells with total withdrawal of 6133 m3/d. The numerical modelling was performed with the use of Visual Modflow 3.1.0 software. The area was partitioned by a discretization grid with a step size l = 250 m. The conceptual model of the hydrogeological system is based on hydrological data gathered over a period of one year, data from HYDRO bank database, cross-sections and maps. The boundaries of the modelled hydrogeological system were established on the watersheds of the Wołczyński Strumień river and the Oziąbel river, apart from the areas where they run together. The modelled area was extended (271.5 km2) around the Wołczyński Strumień river catchment to achieve a more effective mapping of the anthropogenic impact on its balance and the hydrodynamic system of the catchment area. The structure is characterised by the occurrence of one or rarely two aquifers separated by a pack of Quaternary clays. The investigation produced a detailed water balance and its components.

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Parallel Control to Fragments of a Cylindrical Structure Driven by Explosive inside

Mathematical Problems in Engineering ◽

10.1155/2015/723463 ◽

2015 ◽

Vol 2015 ◽

pp. 1-13

Author(s):

Wenkai Chen ◽

Xiangyu Li ◽

Fangyun Lu ◽

Zhenduo Li ◽

Zhenyu Zhang

Keyword(s):

Spatial Distribution ◽

Numerical Model ◽

Design Method ◽

Shell Shape ◽

Curvature Radius ◽

Simulation Data ◽

End Effects ◽

Cylindrical Structure ◽

Theoretical Design ◽

Parallel Control

By analyzing the fragmentation distributions of a cylindrical structure and a specific structure, the necessity of parallel control to the fragments is presented. The shell shape of structures has an influence on the fragment spatial distribution. A new design method for the shell shape is proposed. To facilitate the establishment of the numerical model and the machining for relative experiments, the mathematical description of the theoretical calculated generatrix of the shell is simplified. The fragment spraying processes of the designed structures are simulated, and end effects are analyzed. Based on the theoretical design and plentiful simulation data, the relationships between the size of the parallel fragmentation structure and the optimized curvature radius of the shell are expressed by an equation. The equation is validated by numerical means and can be a reliable reference to the design of the parallel fragmentation structure.

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PATTERN OF TICK SPATIAL DISTRIBUTION OF A FRAGMENT OF FOREST IN AN URBAN AREA, THROUGH A SURVEY BY CO2 TRAP

Arquivos do Instituto Biológico ◽

10.1590/1808-1657v76p4612009 ◽

2009 ◽

Vol 76 (3) ◽

pp. 461-464

Author(s):

A.F.S.F. Rodrigues ◽

C.M.O. Monteiro ◽

L.S. Rosa ◽

L. Dabés

Keyword(s):

Spatial Distribution ◽

Urban Area ◽

Spotted Fever ◽

Amblyomma Cajennense ◽

Aggregate Distribution ◽

Brazilian Spotted Fever ◽

One Year ◽

Wild Hosts

ABSTRACT The study of the ixodofauna in fragments of woods in an urban area is important to the knowledge of species of tick and the dynamic among wild and domestic hosts, allowing to subsidize proposals for the conservation of the fauna and the control of zoonoses such as Brazilian spotted fever. To accomplish the survey, CO2 traps were built up in six different sites of the forest, during a oneyear period, totalizing 12 collections. The ixodids were collected by monitoring the traps and the adjacent vegetation during two hours and put in ethanol 70° GL. At the laboratory they were identified under the stereoscopic optics. At the end of a one-year period of study 2.122 ixodids were colleted, being 793 larvae (37,3%) and 1.277 nymphs (57,8%) of the genus Amblyomma and 102 were adults (4,9%) of the Amblyomma species. The most constant species was Amblyomma cajennense, present in 83,33% of the collections (71 specimen) followed by Amblyomma dubitatum, present in 50% (30 specimen), and Amblyomma calcaratum, 8,33% (one specimen). The observations showed that in the observed environment the populations of Ixodidae have an aggregate distribution, possibly because of the aggregate distribution of the resource, in the case wild hosts.

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Temporal-spatial Analysis of Contributors’ Mapping Behavior for Building Data in OpenStreetMap

Proceedings of the ICA ◽

10.5194/ica-proc-2-149-2019 ◽

2019 ◽

Vol 2 ◽

pp. 1-10

Author(s):

Jin Xu ◽

Qi Zhou

Keyword(s):

Spatial Distribution ◽

Spatial Analysis ◽

Spatial Patterns ◽

Volunteered Geographic Information ◽

Geographic Information ◽

Developing Regions ◽

Temporal And Spatial Patterns ◽

Temporal And Spatial ◽

One Year ◽

Beijing China

<p><strong>Abstract.</strong> Volunteered Geographic Information (VGI) crowdsourced from volunteering posts, is closely related to contributors’ mapping behavior. As the most noticeable VGI source, OpenStreetMap (OSM) is one of the most studied objectives in VGI and data contributors. In this paper, temporal-spatial analysis is applied in seeking the temporal and spatial patterns of the number of buildings and contributors in Beijing, China. Temporal changes of the number of updated buildings, and the population of total, new and quitted contributors, were interpreted, as well as the spatial distribution of updated buildings, participated contributors, and frequency of updates. The result suggests that the number of updated buildings, participated contributors, new and quitted contributors are growing. Buildings are mostly updated by a small number of contributors, the majority of which did not participated in mapping in the previous year. Most contributors update buildings for one year without succeeding till the next. Contributors are interested in updating a large amount of buildings frequently around landmarks, commercial districts, universities, and transit hubs. They update buildings at an expanding range and an increasing density, but their attentions do not necessarily bring large quantity of building updates. In general, OSM buildings in developing regions with less complete database are updated under similar patterns as developed regions where data are much more complete.</p>

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