Doppler Radar

shown in many aspects. The target tracking in MIMO radars is one of these aspects that has not been considered thoroughly yet. These radars consist of many transmitters and receivers located far from each other. In this scenario, the MIMO radar is able to observe different aspects of the target. One of the advantages of these radars is exploitation of Doppler frequencies from different transmitter-target-receiver paths. The extracted Doppler frequencies can be used for estimation of target velocity vector so that, the radar can be able to track the targets by use of its velocity vector with reasonable accuracy. In this paper, the pulse Doppler processing in MIMO radars is considered. The measurement of the velocity vector of the target and its counterpart errors is taken in to account. The extended Kalman target tracking by using its velocity vector is considered too. Besides, its performance is compared with those of MIMO target tracking without using the velocity vector and conventional radars. The simulation results show that the MIMO radars using velocity vector have superior performance over conventional radars in fast maneuvering target tracking.

shown in many aspects. The target tracking in MIMO radars is one of these aspects that has not been considered thoroughly yet. These radars consist of many transmitters and receivers located far from each other. In this scenario, the MIMO radar is able to observe different aspects of the target. One of the advantages of these radars is exploitation of Doppler frequencies from different transmitter-target-receiver paths. The extracted Doppler frequencies can be used for estimation of target velocity vector so that, the radar can be able to track the targets by use of its velocity vector with reasonable accuracy. In this paper, the pulse Doppler processing in MIMO radars is considered. The measurement of the velocity vector of the target and its counterpart errors is taken in to account. The extended Kalman target tracking by using its velocity vector is considered too. Besides, its performance is compared with those of MIMO target tracking without using the velocity vector and conventional radars. The simulation results show that the MIMO radars using velocity vector have superior performance over conventional radars in fast maneuvering target tracking.

The spatiotemporal variability of precipitation in regions of complex mountainous terrains constitutes one of the most challenging research topics of geosciences. This paper explores hourly precipitation data from a set of 25 stations spanning the period 1998 to 2005 within northwestern Colombia, in the Aburrá Valley and the neighboring San Nicolás plateau (75.16W-6N and 75.66W-6.6N) which accounts for a land area of approximately 4000 km2. Our aim is to identify the main features of the diurnal cycle of precipitation over this complex terrain. We found that the average diurnal cycle of rainfall in the study region is bimodal at regional scale although it results from the superposition of two unimodal diurnal cycles shifting its phase throughout the seasons of the year. From October to April, average diurnal rainfall peaks in the afternoon hours (13:00-16:00 LST) but from May to September, the phase of the diurnal cycle changes to midnight hours (22:00-02:00 LST). Three low-leve...

Background: Knee osteoarthritis (KOA) pain is often misattributed to cartilage structural degeneration. Yet cartilage is aneural, avascular, and alymphatic-incapable of generating pain. Doppler ultrasound enables biologic phenotyping, distinguishing synovitis, iliotibial band syndrome (ITBS), and subchondral insufficiency fracture (SCIF). "KOA is not a picture-it's a phenotype." 1

A UHF clear-air Doppler radar wind profiler was purchased by the Naval Postgraduate School and began operation in late-March of 1990. The identification of numerous meteorological phenomena utilizing UHF Doppler radar wind profilers has been successfully documented; however, published work to-date has concentrated on interpretation of hourly-consensus data. But with the onset of improved technology, it is now possible to retrieve reliable data within the hourly period. This study examines the quality of the six-minute data through statistical analysis and determines the overall accuracy of the School's profiler. Specifically, the performance of the profiler is compared with rawinsonde data, other profiler comparison studies, as well as the contract specifications. The study also looks at overall performance of UHF Doppler radar profiler in an environment characterized by a strong marine inversion. Finally the study presents evidence that meteorological phenomena which exhibit time scales on the order of minutes can be observed using the six-minute profiler data.

Purpose -The purpose of this paper is to propose multisensory integration for train positioning application, to support recent automatic train control systems and also moving block signaling systems. Design/methodology/approach -Reducing the cost and at the same time improving the reliability and accuracy of the overall positioning system, are primary goals of the researches going on in this field. Findings -This paper designs and evaluates two different algorithms of Kalman filtering (KF) and particle filtering (PF), on a set of low cost positioning systems, as tachometers, Doppler radar and balises. Originality/value -This paper's research outcomes introduce considerable improvements upon the results when compared to the current utilization of the stand-alone tachometer and Doppler radar sensors, and slight improvements in comparison with the KF algorithm, and also upon results in recent publications on the subject

A variational method is formulated with theoretical considerations for analyzing vortex flows in Doppler radar-scanned tornadic mesocyclones. The method has the following features. (i) The vortex center axis (estimated as a continuous function of time and height in the four-dimensional space) is used as the vertical coordinate, so the coordinate system used for the analysis is slantwise curvilinear and nonorthogonal in general. (ii) The vortex flow (VF), defined by the three-dimensional vector wind minus the horizontal moving velocity of vortex center axis, is expressed in terms of the covariant basis vectors (tangent to the coordinate curves), so its axisymmetric part can be properly defined in that slantwisecurvilinear coordinate system. (iii) To satisfy the mass continuity automatically, the axisymmetric part is expressed by the scalar fields of azimuthally averaged tangential velocity and cylindrical streamfunction and the remaining asymmetric part is expressed by the scalar fields of streamfunction and vertically integrated velocity potential. (iv) VF-dependent covariance functions are formulated for these scalar variables and then deconvoluted to construct the square root of background error covariance matrix analytically with the latter used to transform the control vector to precondition the cost function. (v) The deconvoluted covariance functions and their transformed control variables satisfy two required boundary conditions (i.e., zero vertical velocity at the lower rigid boundary and zero cross-axis velocity along the vortex center axis), so the analyzed VF satisfies not only the mass continuity but also the two boundary conditions automatically.

Radar was associated with military industries in earlier centuries. This day's several industries, like automobile, mining, medical, etc., are also using radars. It is becoming very popular for contact less bio-medical investigation on human body, because of its less microwave energy radiation over short distance. Continuous monitoring of cardio respiratory activity, breast tumor diagnostics, imaging of blood circulation are few immerging areas of research in bio-medical applications. Continuous wave, frequency modulated, ultra-wideband, these are few popular radars which researcher start implementing in bio-medical application. Now recent radar topologies, mainly advance antenna technologies, like MIMO, array and Phased MIMO radar are also becoming very popular in medical applications because of effective performance ability in low signal-to-noise ratio environment. On the other hand, advance computational techniques like soft computing is also becoming part of the modern radar which can improve noise performance Doppler tolerance in bio-medical application.

Incredible phenomena will occur. Such is the final descriptor in the list of catastrophic effects of an EF5 Tornado, the most severe category on the Enhanced Fujita Scale used to measure these weather events. It might also describe the profound and unexpected results of bringing artists and scientists together over shared concerns for the current climate crisis. Although these disciplines consider similar issues, they do so from different perspectives, each asking questions that mutually complicate their respective areas of investigation. Scientists and engineers are often credited with engaging in research that aims to solve the problems that humanity has created, while artists cast a critical eye on their progress. The resulting pragmatic, social, and kinship-based perspectives lead to a deeper and more nuanced understanding of global environmental issues and help to initiate conversations about how we might move towards the betterment of the planet.

This study examines the effectiveness of an ensemble Kalman filter based on the weather research and forecasting model to assimilate Doppler-radar radial-velocity observations for convection-permitting prediction of convection evolution in a high-impact heavy-rainfall event over coastal areas of South China during the pre-summer rainy season. An ensemble of 40 deterministic forecast experiments (40 DADF) with data assimilation (DA) is conducted, in which the DA starts at the same time but lasts for different time spans (up to 2 h) and with different time intervals of 6, 12, 24, and 30 min. The reference experiment is conducted without DA (NODA).To show more clearly the impact of radar DA on mesoscale convective system (MCS) forecasts, two sets of 60-member ensemble experiments (NODA EF and exp37 EF) are performed using the same 60-member perturbed-ensemble initial fields but with the radar DA being conducted every 6 min in the exp37 EF experiments from 0200 to 0400 BST. It is found that the DA experiments generally improve the convection prediction. The 40 DADF experiments can forecast a heavy-rain-producing MCS over land and an MCS over the ocean with high probability, despite slight displacement errors. The exp37 EF improves the probability forecast of inland and offshore MCSs more than does NODA EF. Compared with the experiments using the longer DA time intervals, assimilating the radial-velocity observations at 6-min intervals tends to produce better forecasts. The experiment with the longest DA time span and shortest time interval shows the best performance. However, a shorter DA time interval (e.g., 12 min) or a longer DA time span does not always help. The experiment with the shortest DA time interval and maximum DA window shows the best performance, as it corrects errors in the simulated convection evolution over both the inland and offshore areas. An improved representation of the initial state leads to dynamic and thermodynamic conditions that are more conducive to earlier initiation of the inland MCS and longer maintenance of the offshore MCS.

O Pantanal é um dos mais importantes ecossistemas do planeta, representando a maior área continental úmida, com aproximadamente 140 mil km2 em território brasileiro. Nele habitam milhares de espécies vegetais e animais, incluindo uma variedade de aves, tanto nativas como provenientes de outras áreas das Américas. Seu território ocupa uma imensa planície cortada pelo Rio Paraguai e afluentes, como o Taquari e o Miranda, que na época das chuvas, início das cheias, fica parcialmente inundada, principalmente nas baías e lagoas que margeiam esses rios. O INPE, juntamente com a UFMS, vem desenvolvendo um experimento micrometeorológico no Pantanal, o IPE- Experimento Integrado do Pantanal, cujo objetivo é investigar e compreender a estrutura da Camada Limite Atmosférica (CLA), de forma a caracterizar o tempo e o clima da região. Para isto, são efetuados medidas meteorológicas em torre e na superficie, sondagens verticais, monitoramentos com sodar e desenvolvimentos de simulação numérica. A...

The 3 CAT-2 nanosatellite aims at demonstrating global navigation satellite system reflectometry (GNSS-R) techniques for spaceborne applications in the small form of a six-unit CubeSat. There are many challenges involved from a size, processing, and power perspectives. The proposed solution for the payload uses a software-defined radio (SDR) connected to a nadir looking array of dual-band and dual-frequency and dual-polarization antennas to capture the reflected GNSS signals and to a zenith looking patch antenna to capture the direct ones. The SDR is controlled by the payload computer, which retrieves the binary samples and processes the raw data to obtain delay-doppler maps (DDMs) via various techniques. DDMs are then compressed using the fully adaptive prediction error coder algorithm, producing an output more suitable for the limited downlink capabilities of these small platforms.

Observations inside a tornado, integrated with fine-resolution rapid-scan Doppler on Wheels data, and real-time observations of damage, reveal for the first time the three-dimensional structure of a tornado near the ground and help evaluate the enhanced Fujita scale.

In an experimental set‐up in and around Helsinki, Finland (60°N, 25°E), we have detected pest insect immigration using weather radars and insect traps in the field. This study was part of a project to develop a system to give warning of a possible arrival of long‐range migrant insect pests. Bird‐cherry aphid, Rhopalosiphum padi, and diamondback moth, Plutella xylostella, were found on the ground following migrations in warm airstreams at the end of May 2007. This migration episode was successfully forecast by the meteorologists in the project team. For the summer 2008, we developed a pest insect immigration alarm system based on SILAM, a Finnish Meteorological Institute atmospheric dispersion model. The first important pest insect immigration occurred in late June, bringing bird‐cherry aphids. Our alarm system correctly produced a warning of this immigration. We studied the migration path in the observed events in 2007 and 2008 with the help of the atmospheric dispersion model. Weat...

Les panaches volcaniques de tephras constituent un des aleas volcaniques majeurs. Pour prevoir leur dispersion et les zones d'impacts de leurs retombees, des modeles numeriques sont utilises en operationnel et bases sur des parametres eruptifs, regroupes sous la notion de terme source, caracterisant l'emission des panaches. L'ensemble du terme source est cependant difficile a mesurer en temps reel. C'est pourquoi les modeles de dispersion sont souvent bases sur des scenarios d'eruptions passees et utilisent des lois empiriques reliant la hauteur des panaches avec les flux massiques a la source. Cependant, les resultats qui decoulent de ces modeles sont peu contraints, moyennes sur la duree des eruptions, et souffrent de larges incertitudes. Dans cette optique, les radars Doppler, capables de sonder l'interieur des colonnes eruptives avec des echelles spatio-temporelles fines, peuvent fournir des contraintes cruciales sur le terme source des panaches en temps ...

Explosive basaltic eruptions eject a great amount of pyroclastic material into the atmosphere, forming columns rising to several kilometers above the eruptive vent and causing significant disruption to both proximal and distal communities. Here, we analyze data, collected by an X-band polarimetric weather radar and an L-band Doppler fixed-pointing radar, as well as by a thermal infrared (TIR) camera, in relation to lava fountain-fed tephra plumes at the Etna volcano in Italy. We clearly identify a jet, mainly composed of lapilli and bombs mixed with hot gas in the first portion of these volcanic plumes and here called the incandescent jet region (IJR). At Etna and due to the TIR camera configuration, the IJR typically corresponds to the region that saturates thermal images. We find that the IJR is correlated to a unique signature in polarimetric radar data as it represents a zone with a relatively high reflectivity and a low copolar correlation coefficient. Analyzing five recent Etn...

Real-time estimation of eruptive source parameters during explosive volcanic eruptions is a major challenge in terms of hazard evaluation and risk assessment as these inputs are essential for tephra dispersal models to forecast the impact of ash plumes and tephra deposits. In this aim, taking advantage of the 23.5 cm wavelength Doppler radar (VOLDORAD 2B) monitoring Etna volcano, we analyzed 47 paroxysms produced between 2011 and 2015, characterized by lava fountains generating tephra plumes that reached up to 15 km a.s.l. Range gating of the radar beam allows the identification of the active summit craters in real-time, no matter the meteorological conditions. The radar echoes help to mark (i) the onset of the paroxysm when unstable lava fountains, taking over Strombolian activity, continuously supply the developing tephra plume, then (ii) the transition to stable fountains (climax), and (iii) the end of the climax, therefore providing paroxysm durations. We developed a new methodology to retrieve in real-time a Mass Eruption Rate (MER) proxy from the radar echo power and maximum Doppler velocity measured near the emission source. The increase in MER proxies is found to precede by several minutes the time variations of plume heights inferred from visible and X-Band radar imagery. A calibration of the MER proxy against ascent models based on observed plume heights leads to radar-derived climax MER from 2.96 × 10 4 to 3.26 × 10 6 kg s -1 . The Total Erupted Mass (TEM) of tephra was computed by integrating over beam volumes and paroxysm duration, allowing quantitative comparisons of the relative amounts of emitted tephra among the different paroxysms. When the climactic phase can be identified, it is found to frequently release 76% of the TEM. Calibrated TEMs are found to be larger than those retrieved by satellite and X-band radar observations, deposit analyses, ground-based infrared imagery, or dispersion modeling. Our methodology, potentially applicable to every Doppler radar, provides mass load parameters that represent a powerful all-weather tool for the quantitative monitoring and real-time hazard assessment of tephra plumes at Etna or any other volcano with radar monitoring.

Real-time estimation of eruptive source parameters during explosive volcanic eruptions is a major challenge in terms of hazard evaluation and risk assessment as these inputs are essential for tephra dispersal models to forecast the impact of ash plumes and tephra deposits. In this aim, taking advantage of the 23.5 cm wavelength Doppler radar (VOLDORAD 2B) monitoring Etna volcano, we analyzed 47 paroxysms produced between 2011 and 2015, characterized by lava fountains generating tephra plumes that reached up to 15 km a.s.l. Range gating of the radar beam allows the identification of the active summit craters in real-time, no matter the meteorological conditions. The radar echoes help to mark (i) the onset of the paroxysm when unstable lava fountains, taking over Strombolian activity, continuously supply the developing tephra plume, then (ii) the transition to stable fountains (climax), and (iii) the end of the climax, therefore providing paroxysm durations. We developed a new methodology to retrieve in real-time a Mass Eruption Rate (MER) proxy from the radar echo power and maximum Doppler velocity measured near the emission source. The increase in MER proxies is found to precede by several minutes the time variations of plume heights inferred from visible and X-Band radar imagery. A calibration of the MER proxy against ascent models based on observed plume heights leads to radar-derived climax MER from 2.96 × 10 4 to 3.26 × 10 6 kg s -1 . The Total Erupted Mass (TEM) of tephra was computed by integrating over beam volumes and paroxysm duration, allowing quantitative comparisons of the relative amounts of emitted tephra among the different paroxysms. When the climactic phase can be identified, it is found to frequently release 76% of the TEM. Calibrated TEMs are found to be larger than those retrieved by satellite and X-band radar observations, deposit analyses, ground-based infrared imagery, or dispersion modeling. Our methodology, potentially applicable to every Doppler radar, provides mass load parameters that represent a powerful all-weather tool for the quantitative monitoring and real-time hazard assessment of tephra plumes at Etna or any other volcano with radar monitoring.

For automotive radar sensors the Doppler resolution is a key parameter, since it is used to separate targets which are in the same radial distance. For future applications the Doppler signature of targets can be exploited for classification purpose, e.g. discrimination among road users like pedestrians or bicyclists. In this paper, a signal processing scheme based on the chirp-sequence modulation principle is proposed to enhance the Doppler domain resolution. Simulations and measurement results are shown to prove the signal processing leading to an enhanced separability of close targets.

This article proposes a method for estimating the Doppler power spectrum (DPS) of a weather radar via minimum mean square error (MMSE). In order to detect severe weather phenomena that mostly occur within the lowest few kilometers of the atmosphere, weather radars have to direct their beams at low elevation angles, and the received signals from such observations usually contain reflections from the ground and buildings, so-called ground clutter. The MMSE estimator, which is an adaptive spectral estimator, allows weather radar DPSs to be obtained with excellently reduced ground clutter contaminations. The MMSE estimator was examined by numerical simulations, which supposed various precipitation and ground clutter scenarios and DPS estimation parameter values. The MMSE estimator provided DPSs almost as accurate as those from the traditional Fourier and windowed Fourier estimators in simulations with no ground clutter and much better DPSs than those estimators in the presence of ground...

Applied Weather Associates, LLC and Metstat, Inc have teamed to develop a rainfall analysis procedure for analyzing rainfall associated with extreme storms. The Storm Precipitation Analysis System (SPAS) applies the same basic approach used by the Weather Bureau and the Corps of Engineers, thereby achieving a level of consistency between the newly analyzed storms and the historic storms previously analyzed. The SPAS algorithm is a suite of UNIX-based programs that utilize the Geographic Resources Analysis Support System (GRASS) GIS engine to evaluate the spatial, temporal and depth-area characteristics of precipitation events. (1) SPAS uses a spatial approach for allocating precipitation at the daily reporting stations into hourly rainfall values, thus creating high resolution precipitation maps for each hour of the rainfall event. SPAS has been rigorously tested, both with a theoretical storm where the rainfall rates and spatial distribution are known exactly and with historic stor...

The Norwegian Geotechnical Institute (NGI) has been running full-scale avalanche experiments at the Ryggfonn test-site in western Norway for close to 40 years. Data from this period involve observations from about 32 artificial avalanche releases and 158 natural ones. In this paper, we do an attempt to correlate avalanche observations and obtained measurements from the Ryggfonn path with snow and weather conditions at the time. In this way, we hope to obtain an improved data set useful for model calibration and to obtain information on avalanche release probability. The final aim is to contribute to the further improvement of the quality of hazard zoning.

Wildfire management in the eastern U.S. is more complex than in the west because of higher population density, increased closeness of housing and people with wildlands, and large spatial and temporal variability of topography, climate, ecosystems, and development patterns. The diversity requires a large group of data sets from heterogeneous sources, such as fuel property and fire characteristics data from in situ or remote sensing observations, weather data from observations and model prediction, topography data over long temporal scales but high spatial resolution, socio-economic data, etc. Those data sets are different in spatial and temporal resolutions, data types (data models) and data formats, and are in different distributed sites, accessible in a variety of ways. An integrated data access is needed to support decision making process. Current existing technology in earth science community for data interoperability, and in particular, Grid technology will be valuable for building such an integrated data access system. In this paper, we will identify the data needs and describe a scalable Grid-enabled data framework for wildfire decision support. We will also give overall system architecture and outline the major components.

To obtain accurate radar-measured wind measurements in tornadoes, differences between air and Doppler velocities must be corrected. These differences can cause large errors in radar estimates of maximum tangential wind speeds, and large errors in single-Doppler retrievals of radial and vertical velocities. Since larger scatterers (e.g., debris) exhibit larger differences from air velocities compared to small scatterers (e.g., raindrops), the dominant scatterer type affecting radar measurements is examined. In this study, radar variables are simulated for common weather radar frequencies using debris and raindrop trajectories computed with a large-eddy simulation model and two electromagnetic scattering models. These simulations include a large range of raindrop and wood board sizes and concentrations, and reveal the significant frequency dependence of the equivalent reflectivity factor and Doppler velocity. At S band, dominant scatterers are wood boards, except when wood board conce...

Mobile radar platforms designed for observation of severe local storms have consistently pushed the boundaries of spatial and temporal resolution in order to allow for detailed analysis of storm structure and evolution. Digital beamforming, or radar imaging, is a technique that is similar in nature to a photograwphic camera, where data samples from different spaces at the same range are collected simultaneously. This allows for rapid volumetric update rates compared to radars that scan with a single narrow beam. The Atmospheric Imaging Radar (AIR) is a mobile X-band (3.14-cm wavelength) imaging weather radar that transmits a vertical, 20° fan beam and uses a 36-element receive array to form instantaneous range–height indicators (RHIs) with a native beamwidth of 1° × 1°. Rotation in azimuth allows for 20° × 90° volumetric updates in under 6 s, while advanced pulse compression techniques achieve 37.5-m range resolution. The AIR has been operational since 2012 and has collected data on...

When a light beam with a transverse spatially varying phase is considered for optical remote sensing, in addition to the usual longitudinal Doppler frequency shift of the returned signal induced by the motion of the scatter along the beam axis, a new transversal Doppler shift appears associated to the motion of the scatterer in the plane perpendicular to the beam axis. We discuss here how this new effect can be used to enhance the current capabilities of optical measurement systems, adding the capacity to detect more complex movements of scatters.

Single Doppler analysis techniques known as velocity azimuth display (VAD) and volume velocity processing (VVP) are used to analyze kinematics of mesoscale flow such as horizontal wind and divergence using X-band Doppler weather radar observations, for selected cases of convective, stratiform, and shallow cloud systems near tropical Indian sites Pune (18.58°N, 73.92°E, above sea level (asl) 560 m) and Mandhardev (18.51°N, 73.85°E, asl 1297 m). The vertical profiles of horizontal wind estimated from radar VVP/VAD methods agree well with GPS radiosonde profiles, with the low-level jet at about 1.5 km during monsoon season well depicted in both. The vertical structure and temporal variability of divergence and reflectivity profiles are indicative of the dynamical and microphysical characteristics of shallow convective, deep convective, and stratiform cloud systems. In shallow convective systems, vertical development of reflectivity profiles is limited below 5 km. In deep convective systems, reflectivity values as large as 55 dBZ were observed above freezing level. The stratiform system shows the presence of a reflectivity bright band (~35 dBZ) near the melting level. The diagnosed vertical profiles of divergence in convective and stratiform systems are distinct. In shallow convective conditions, convergence was seen below 4 km with divergence above. Low-level convergence and upper level divergence are observed in deep convective profiles, while stratiform precipitation has midlevel convergence present between lower level and upper level divergence. The divergence profiles in stratiform precipitation exhibit intense shallow layers of "melting convergence" at 0°C level, near 4.5 km altitude, with a steep gradient on the both sides of the peak. The level of nondivergence in stratiform situations is lower than that in convective situations. These observed vertical structures of divergence are largely indicative of latent heating profiles in the atmosphere, an important ingredient of monsoon dynamics.

On 13 April 2009 an extensive and intense wake low event occurred over northeastern Mississippi, northern Alabama, and northern and central GA, at the trailing (western) edge of a mesoscale convective system (MCS). This was a significant weather event, as many trees were toppled over this large region, some onto homes and vehicles. Approximately 150,000 Alabama Power customers lost power and power outages of a similar magnitude also occurred in Georgia. Structural damage occurred, and one fatality was reported. A wind gust of 26 m s -1 was recorded in downtown Birmingham, AL, with gusts > 20 m s -1