Use Of Doppler Radar Research Articles

Wind-Induced Displacement Analysis for a Traffic Light Structure Based on a Low-Cost Doppler Radar Array

This study is concerned with the analysis of the displacement measurements simultaneously retrieved from multiple Doppler radars placed at different positions of a traffic light's mast. Currently, the structural health monitoring (SHM) works based on portable Doppler radars consider primarily methods for the extraction of displacement measurements. However, other measurements in the form of instantaneous natural frequencies and mode shapes can also be calculated with the use of Doppler radars arranged as an array. In this article, the wind-induced vibration displacement analysis based on a low-cost Doppler radar array is proposed. The sensitivity of the proposed array to changes in the instantaneous natural frequencies is evaluated. In addition, the structural modal analysis based on a Doppler radar array operating in the passive backscattering mode is demonstrated. The accuracy of the measurements obtained from the radars' demodulated data is compared with the accelerometer-based measurements. The ability of the proposed array to provide instantaneous natural frequency measurements and structural modal analysis is validated by the experimental results.

Activity Recognition in Smart Homes using UWB Radars

Abstract In the last decade, smart homes have transitioned from a potential solution for aging-in-place to a real set of technologies being deployed in the real-world. This technological transfer has been mostly supported by simple, commercially available sensors such as passive infrared and electromagnetic contacts. On the other hand, many teams of research claim that the sensing capabilities are still too low to offer accurate, robust health-related monitoring and services. In this paper, we investigate the possibility of using Ultra-wideband (UWB) Doppler radars for the purpose of recognizing the ongoing ADLs in smart homes. Our team found out that with simple configuration and classical features engineering, a small set of UWB radars could reasonably be used to recognize ADLs in a realistic home environment. A dataset was built from 10 persons performing 15 different ADLs in a 40 square meters apartment with movement on the other side of the wall. Random Forest was able to attain 80% accuracy with an F1-Score of 79%, and a Kappa of 77%. Those results indicate the use of Doppler radars can be a good research avenue for smart homes.

Identifying Plume Mode via WSR-88D Observations of Wildland Fire Convective Plumes and Proposed Tactical Decision Support Applications

To date, the use of Doppler radar (WSR-88D) in wildland fire operations has been limited, with tactical applications focused on analyzing ambient atmospheric features. This paper presents geographically diverse analysis of radar-observed wildland fire convective plumes to determine indicators of plume mode for tactical decision support. Through the visualization of buoyancy via thermal bubbles and vertical plumes, plume mode is revealed via WSR-88D interrogation of three Southern Great Plains grass/shrub fires and two timber fires in Texas and California. Analogous to thunderstorm convective modes, past research has identified two distinct plume modes of wildland fire: multicell and intense convective plume. Multicell plume mode is characterized by a series of shallow discrete cells that move away from the fire’s main buoyancy source, with successive cells rising, expanding, and replacing cells from the updraft source. This process, known as the thermal bubble concept, occurs most notably in strong vertical wind profile environments with a strong advection component. These cells or thermal bubbles are observed via WSR-88D data for three Southern Great Plains cases. Intense convective plumes are observed to be vertical with the low-level reflectivity maximum and maximum echo top juxtaposed and occurrence is confined to weak wind environments; these plume structures are identified in the two timber fire cases. An important WSR-88D signature, the back-sheared convective plume (hereafter BSCP), is identified in terms of transverse vortices and vortex rings, which may imply enhanced combustion rates due to increased turbulent mixing. Determination of plume convective mode via radar offers meteorologists the ability to detect changes in plume mode and to provide important tactical decision support information about fire behavior.

An algorithm of matched pursuit with compensation for the analysis of multicomponent Doppler signals

The problem of decomposition of multicomponent Doppler signals in order to increase the operation efficiency of systems based on the use of Doppler radars for a wide range of applications is considered. To study the structure of these signals, a matched pursuit algorithm and its modification—matched pursuit with compensation, which have been developed for the analysis of signals represented by functions of time and their spectrograms, respectively, are used. Obtained and analyzed the Results of decomposition of a simulated three-component signal against the background of noise for a signal-to-noise ratio of 20 dB as well as actual Doppler signals by these algorithmsare obtained and analyzed.

On the Use of Doppler Radar–Derived Wind Fields to Diagnose the Secondary Circulations of Tornadoes

Abstract A number of studies in recent years have used wind fields derived from portable Doppler radars in combination with the ground-based velocity track display (GBVTD) technique to diagnose the primary (tangential) and secondary (radial and vertical) circulations in tornadoes. These analyses indicate very strong vertical motions in the vortex core, in some cases with updrafts and downdrafts exceeding 100 m s−1. In addition, many of the analyses indicate strong radial outflow at low levels and in the vicinity of the low-level tangential wind maximum. This paper shows that strong outward motion at this location cannot be consistent with a tornado circulation that lasts more than a few minutes. In addition, using data from numerical simulations as truth, it is shown that using observed radial velocities to diagnose vertical velocities greatly overestimates the intensity of downward motion in the core for two reasons: neglect of the mass flux into the core through the swirling boundary layer, and the likely positive bias in low-level radial velocities due to the centrifuging of debris. Possible methods for accounting for these errors are briefly discussed.

The use of doppler radars for studying the turbulence of air masses in clouds

A method for estimating the turbulent pulsations of the velocity of air masses in clouds has been proposed. This method is based on the spectra of scattered signals and makes use of the moment characteristics of the scattered signal spectrum and deviations of the characteristics from trend changes for estimating the shear characteristics of the air stream in terms of both the average speed and its spread.

Use of Doppler radar to assess ice cloud particle fall velocity‐size relations for remote sensing and climate studies

Knowledge of ice crystal terminal velocities, both for individual crystals and for size distributions, is important for an adequate representation of ice particle sedimentation in climate models. While the terminal velocities (υt) of individual crystals of simple shapes have been measured, theoretical relations of the form υt = ADB (where D is the maximum particle dimension), obtained using expressions for the aerodynamic drag force, are often more useful because they can be applied to a wide range of particle sizes and heights and temperatures in the atmosphere. For high tropospheric ice clouds the coefficient A has been found to vary over 1 order of magnitude; the exponent B is generally within the range 0.7–1.4. Aerodynamic drag force calculations show that A and B are related. A and B can also be used to characterize terminal‐velocity‐particle characteristic size relations for size distributions. In this study we use collocated, vertically pointing measurements of ice cloud radar reflectivity, Doppler velocity, and IR brightness temperatures to estimate the vertical profiles of cloud particle characteristic size, cloud ice water content, and vertically averaged value of the coefficient A, emphasizing cirrus clouds. We analyze variations in terminal‐velocity‐size relations for individual particles and corresponding variations for ensembles of particles: for example, in relations between the reflectivity‐weighted terminal velocity and the median volume size and between the mass‐weighted terminal velocity and the median volume size. The retrievals indicate that A ranges from ∼250 to almost 4000 (cgs units), similar to the range found from the theoretical calculations. The coefficient A tends to decrease as a characteristic particle size (e.g., median size) increases. As a simplification for climate modeling efforts, we present an empirical relation between median size and A, although there is a fair amount of variability about this relation. Using the Doppler measurements and retrieval data, we also derive relations between the mass‐weighted terminal velocity and cloud ice water content. Such relations are useful for representing fallout of ice particles in climate and cloud‐resolving models.

Tropical cyclone hazards and warning and disaster mitigation systems in India

The main features of a cyclone that cause death and destruction are: (1) Storm surge, a rapid increase in sea level along the coast, primarily caused by the strong surface wind field of the cyclone as it approaches the coast, (2) the violent sustained wind and wind gusts and cyclone-spawned tornadoes, and (3) the heavy rain and consequent flooding. The paper describes the structure of a tropical cyclone of hurricane intensity and its damage potential, cyclone detection, tracking, forecasting and warning systems. It concludes that with over a hundred years of research and operational experience on cyclones available with the meteorological community and with theinsat and cyclone detection radar network, India has now an efficient cyclone warning system. This system would however benefit from further sophistication notably the use of Doppler Radars for cyclone wind field monitoring and an aircraft reconnaissance facility for probing cyclones. Research is needed to develop techniques for better forecasting of the tracks of cyclones more than a day ahead and also their intensity changes. Cyclone disaster mitigation arrangements were organised in the maritime states of India only during the last 25 years. This relatively young field requires more developmental work, particularly in coastal area planning to reduce property losses, and exploration of alternative approaches to large-scale evacuation of the coastal population threatened by cyclones to distant temporary shelters.

A review of multiparameter radar observations of precipitation

From the earliest years of radar meteorology, efforts have been devoted to multiparameter observations: the measurement of one or more signal properties, ordinarily in addition to the signal intensity, to give added information about the precipitation. Studies employing variable polarization or Doppler frequency measurement were among the first such techniques and over the years have proved fruitful in terms of the information provided. During the past decade there has been such an increase in the use of Doppler radar in meteorological research that radar‐measured wind fields are becoming nearly as routine as reflectivity fields. Research has continued in variable polarization techniques, which appear to provide a means of distinguishing remotely between various precipitation types. Investigations of the correlation between the copolarized and cross‐polarized components of the received signal have given new insight into the falling behavior of precipitation particles. A great deal of new information will evidently be made available by combining coherent signal processing techniques with variable polarization measurements.

Use of Doppler radar for the measurement of atmospheric turbulence parameters from the intensity of clear‐air echoes

Doppler radars measure the refractivity turbulence structure constant Cn2 in a straightforward manner. In this paper we explore the relationship between Cn2 and the intensity of atmospheric turbulence as parameterized by the eddy dissipation rate ε. We develop some tentative relations between mean Cn2 and mean ε within the framework of inertial range turbulence theory, taking into account the intermittent nature of atmospheric turbulence. These relations permit the estimation of mean ε from radar observations alone. The analysis is applied to the determination from Sunset radar data of vertical profiles and time‐height contours of mean ε.

A Radar Study of Turbulent Diffusion in the Lower Atmosphere

Abstract A new technique for the experimental study of atmospheric turbulent diffusion is presented and applied to the study of diffusion in the lower 3 km of a cloudless summer atmosphere. This new technique makes use of Doppler radar and of radar reflecting chaff. The design and operation of a new chaff releasing device is presented. This device makes possible the creation of vertical columns of chaff through several kilometers of the atmosphere. The chaff is used to model atmospheric contaminants in diffusion measurements and as an air motion tracer in Doppler studies of turbulent air motions. The shear is observed to have a strong effect on horizontal turbulent diffusion, with the diffusion rates frequently being an order of magnitude greater in the direction of the shear than across it. The strong shear enhancement of horizontal diffusion is interpreted to imply shear-generated eddies which are oriented by the shear. Empirical equations are presented which relate the apparent eddy diffusivity, the po...

Radar Meteorology in the Soviet Union-1970

Abstract On the basis of a review of the abstracts of articles published in the last 5 years or so a summary has been prepared of Soviet research activity in the field of radar meteorology. A wide spectrum of topics has been getting some study, but in recent years, Soviet scientists have been giving particular attention to the following areas of research: calculations of the scattering and attenuation cross sections of various hydrometeors; the use of Doppler radar to study the turbulent properties of the atmosphere; the development of procedures by which the characteristics of radar echoes can be used to identify cloud and hydrometeor types, with particular emphasis on the discrimination of severe thunderstorms from other precipitating cloud systems; the detection and measurement of hail; and the measurement of precipitation.

The use of Doppler radar in meteorological research

A 3-cm pulsed Doppler radar constructed at the Royal Radar Establishment is described and the use of this equipment to increase knowledge of atmospheric precipitation processes is explained. With the aerial pointing vertically in widespread rain it is possible to deduce the drop size distribution in the free atmosphere and to study its variation with height. In showers it is possible to derive height-time sections of both vertical air motion and maximum particle velocity; examples of these sections are shown and discussed. A new mobile Doppler radar designed for investigation of thunderstorms is briefly mentioned. Finally, the application of Doppler radar operating at low angles of elevation to the measurement of horizontal convergence and vertical velocity of the air during widespread rain is described and initial results shown.

Discussion on “The use of Doppler radar in meteorological research”

Discussion on “The use of Doppler radar in meteorological research”

Airborne Doppler Radar Navigation of Jet Transport Aircraft

Trans World Airlines will pioneer use of Doppler radar as a primary means of transport aircraft navigation over the North Atlantic. This paper summarizes flight test results using dual Doppler radar sensors and dual Doppler navigation computers on Boeing 707 long range aircraft. Test flights have been flown over TWA's North Atlantic routes for almost two years to "prove-in" the Doppler system.