WorldWideScience

Sample records for ground-based doppler radar

  1. Pulse Doppler radar

    CERN Document Server

    Alabaster, Clive

    2012-01-01

    This book is a practitioner's guide to all aspects of pulse Doppler radar. It concentrates on airborne military radar systems since they are the most used, most complex, and most interesting of the pulse Doppler radars; however, ground-based and non-military systems are also included. It covers the fundamental science, signal processing, hardware issues, systems design and case studies of typical systems. It will be a useful resource for engineers of all types (hardware, software and systems), academics, post-graduate students, scientists in radar and radar electronic warfare sectors and milit

  2. Doppler radar physiological sensing

    CERN Document Server

    Lubecke, Victor M; Droitcour, Amy D; Park, Byung-Kwon; Singh, Aditya

    2016-01-01

    Presents a comprehensive description of the theory and practical implementation of Doppler radar-based physiological monitoring. This book includes an overview of current physiological monitoring techniques and explains the fundamental technology used in remote non-contact monitoring methods. Basic radio wave propagation and radar principles are introduced along with the fundamentals of physiological motion and measurement. Specific design and implementation considerations for physiological monitoring radar systems are then discussed in detail. The authors address current research and commercial development of Doppler radar based physiological monitoring for healthcare and other applications.

  3. Comparison of Precipitation Observations from a Prototype Space-based Cloud Radar and Ground-based Radars

    Institute of Scientific and Technical Information of China (English)

    LIU Liping; ZHANG Zhiqiang; YU Danru; YANG Hu; ZHAO Chonghui; ZHONG Lingzhi

    2012-01-01

    A prototype space-based cloud radar has been developed and was installed on an airplane to observe a precipitation system over Tianjin,China in July 2010.Ground-based S-band and Ka-band radars were used to examine the observational capability of the prototype. A cross-comparison algorithm between different wavelengths,spatial resolutions and platform radars is presented.The reflectivity biases,correlation coefficients and standard deviations between the radars are analyzed.The equivalent reflectivity bias between the S- and Ka-band radars were simulated with a given raindrop size distribution.The results indicated that reflectivity bias between the S- and Ka-band radars due to scattering properties was less than 5 dB,and for weak precipitation the bias was negligible. The prototype space-based cloud radar was able to measure a reasonable vertical profile of reflectivity,but the reflectivity below an altitude of 1.5 km above ground level was obscured by ground clutter.The measured reflectivity by the prototype space-based cloud radar was approximately 10.9 dB stronger than that by the S-band Doppler radar (SA radar),and 13.7 dB stronger than that by the ground-based cloud radar.The reflectivity measured by the SA radar was 0.4 dB stronger than that by the ground-based cloud radar.This study could provide a method for the quantitative examination of the observation ability for space-based radars.

  4. Precipitation and microphysical processes observed by three polarimetric X-band radars and ground-based instrumentation during HOPE

    OpenAIRE

    Xie, Xinxin; Evaristo, Raquel; Simmer, Clemens; Handwerker, Jan; Trömel, Silke

    2016-01-01

    This study presents a first analysis of precipitation and related microphysical processes observed by three polarimetric X-band Doppler radars (BoXPol, JuXPol and KiXPol) in conjunction with a ground-based network of disdrometers, rain gauges and vertically pointing micro rain radars (MRRs) during the High Definition Clouds and Precipitation for advancing Climate Prediction (HD(CP)2) Observational Prototype Experiment (HOPE) during April and May 2013 in Germany. While JuXPol...

  5. The Next Generation Airborne Polarimetric Doppler Radar

    Science.gov (United States)

    Vivekanandan, J.; Lee, Wen-Chau; Loew, Eric; Salazar, Jorge; Chandrasekar, V.

    2013-04-01

    NCAR's Electra Doppler radar (ELDORA) with a dual-beam slotted waveguide array using dual-transmitter, dual-beam, rapid scan and step-chirped waveform significantly improved the spatial scale to 300m (Hildebrand et al. 1996). However, ELDORA X-band radar's penetration into precipitation is limited by attenuation and is not designed to collect polarimetric measurements to remotely estimate microphysics. ELDORA has been placed on dormancy because its airborne platform (P3 587) was retired in January 2013. The US research community has strongly voiced the need to continue measurement capability similar to the ELDORA. A critical weather research area is quantitative precipitation estimation/forecasting (QPE/QPF). In recent years, hurricane intensity change involving eye-eyewall interactions has drawn research attention (Montgomery et al., 2006; Bell and Montgomery, 2006). In the case of convective precipitation, two issues, namely, (1) when and where convection will be initiated, and (2) determining the organization and structure of ensuing convection, are key for QPF. Therefore collocated measurements of 3-D winds and precipitation microphysics are required for achieving significant skills in QPF and QPE. Multiple radars in dual-Doppler configuration with polarization capability estimate dynamical and microphysical characteristics of clouds and precipitation are mostly available over land. However, storms over complex terrain, the ocean and in forest regions are not observable by ground-based radars (Bluestein and Wakimoto, 2003). NCAR/EOL is investigating potential configurations for the next generation airborne radar that is capable of retrieving dynamic and microphysical characteristics of clouds and precipitation. ELDORA's slotted waveguide array radar is not compatible for dual-polarization measurements. Therefore, the new design has to address both dual-polarization capability and platform requirements to replace the ELDORA system. NCAR maintains a C-130

  6. Experiments on a Ground-Based Tomographic Synthetic Aperture Radar

    Directory of Open Access Journals (Sweden)

    Hoonyol Lee

    2016-08-01

    Full Text Available This paper presents the development and experiment of three-dimensional image formation by using a ground-based tomographic synthetic aperture radar (GB-TomoSAR system. GB-TomoSAR formulates two-dimensional synthetic aperture by the motion of antennae, both in azimuth and vertical directions. After range compression, three-dimensional image focusing is performed by applying Deramp-FFT (Fast Fourier Transform algorithms, both in azimuth and vertical directions. Geometric and radiometric calibrations were applied to make an image cube, which is then projected into range-azimuth and range-vertical cross-sections for visualization. An experiment with a C-band GB-TomoSAR system with a scan length of 2.49 m and 1.86 m in azimuth and vertical-direction, respectively, shows distinctive three-dimensional radar backscattering of stable buildings and roads with resolutions similar to the theoretical values. Unstable objects such as trees and moving cars generate severe noise due to decorrelation during the eight-hour image-acquisition time.

  7. Validation of TRMM Precipitation Radar Through Comparison of its Multi-Year Measurements to Ground-Based Radar

    Science.gov (United States)

    Liao, Liang; Meneghini, Robert

    2010-01-01

    A procedure to accurately resample spaceborne and ground-based radar data is described, and then applied to the measurements taken from the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) and the ground-based Weather Surveillance Radar-1988 Doppler (WSR-88D or WSR) for the validation of the PR measurements and estimates. Through comparisons with the well-calibrated, non-attenuated WSR at Melbourne, Florida for the period 1998-2007, the calibration of the Precipitation Radar (PR) aboard the TRMM satellite is checked using measurements near the storm top. Analysis of the results indicates that the PR, after taking into account differences in radar reflectivity factors between the PR and WSR, has a small positive bias of 0.8 dB relative to the WSR, implying a soundness of the PR calibration in view of the uncertainties involved in the comparisons. Comparisons between the PR and WSR reflectivities are also made near the surface for evaluation of the attenuation-correction procedures used in the PR algorithms. It is found that the PR attenuation is accurately corrected in stratiform rain but is underestimated in convective rain, particularly in heavy rain. Tests of the PR estimates of rainfall rate are conducted through comparisons in the overlap area between the TRMM overpass and WSR scan. Analyses of the data are made both on a conditional basis, in which the instantaneous rain rates are compared only at those pixels where both the PR and WSR detect rain, and an unconditional basis, in which the area-averaged rain rates are estimated independently for the PR and WSR. Results of the conditional rain comparisons show that the PR-derived rain is about 9% greater and 19% less than the WSR estimates for stratiform and convective storms, respectively. Overall, the PR tends to underestimate the conditional mean rain rate by 8% for all rain categories, a finding that conforms to the results of the area-averaged rain (unconditional) comparisons.

  8. Radar Doppler Processing with Nonuniform Sampling.

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-07-01

    Conventional signal processing to estimate radar Doppler frequency often assumes uniform pulse/sample spacing. This is for the convenience of t he processing. More recent performance enhancements in processor capability allow optimally processing nonuniform pulse/sample spacing, thereby overcoming some of the baggage that attends uniform sampling, such as Doppler ambiguity and SNR losses due to sidelobe control measures.

  9. Wideband radar micro-doppler applications

    Science.gov (United States)

    Tahmoush, Dave

    2013-05-01

    Wideband radar provides a significant improvement over traditional narrowband radars for micro-Doppler analysis because the high bandwidth can be used to separate many of the signals in range, allowing a simpler decomposition of the micro-Doppler signals. Recent wideband radar work has focused on micro-Doppler, but there is a point where the narrowband approach used to analyze the micro-Doppler signals breaks down. The effect is shown to be independent of frequency, but the error relative to the bandwidth is shown to be inversely proportional to the frequency and proportional to the velocity of the subject. This error can create a smearing effect in the observed Doppler if it is not corrected, leading to reduced signal-to-noise and the appearance of more diffuse targets in Doppler space. In range-space, wideband data can also break the subject into several range bins, affecting the observed signal to noise ratio. The possible applications of wideband micro-Doppler radar are also shown, including the separation of arm movement from human motion which implies that the arms are not encumbered.

  10. Doppler micro sense and avoid radar

    Science.gov (United States)

    Gorwara, Ashok; Molchanov, Pavlo; Asmolova, Olga

    2015-10-01

    There is a need for small Sense and Avoid (SAA) systems for small and micro Unmanned Aerial Systems (UAS) to avoid collisions with obstacles and other aircraft. The proposed SAA systems will give drones the ability to "see" close up and give them the agility to maneuver through tight areas. Doppler radar is proposed for use in this sense and avoid system because in contrast to optical or infrared (IR) systems Doppler can work in more harsh conditions such as at dusk, and in rain and snow. And in contrast to ultrasound based systems, Doppler can better sense small sized obstacles such as wires and it can provide a sensing range from a few inches to several miles. An SAA systems comprised of Doppler radar modules and an array of directional antennas that are distributed around the perimeter of the drone can cover the entire sky. These modules are designed so that they can provide the direction to the obstacle and simultaneously generate an alarm signal if the obstacle enters within the SAA system's adjustable "Protection Border". The alarm signal alerts the drone's autopilot to automatically initiate an avoidance maneuver. A series of Doppler radar modules with different ranges, angles of view and transmitting power have been designed for drones of different sizes and applications. The proposed Doppler radar micro SAA system has simple circuitry, works from a 5 volt source and has low power consumption. It is light weight, inexpensive and it can be used for a variety of small unmanned aircraft.

  11. On reconciling ground-based with spaceborne normalized radar cross section measurements

    DEFF Research Database (Denmark)

    Baumgartner, Francois; Munk, Jens; Jezek, K C

    2002-01-01

    This study examines differences in the normalized radar cross section, derived from ground-based versus spaceborne radar data. A simple homogeneous half-space model, indicates that agreement between the two improves as 1) the distance from the scatterer is increased; and/or 2) the extinction...

  12. Operational Bright-Band Snow Level Detection Using Doppler Radar

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A method to detect the bright-band snow level from radar reflectivity and Doppler vertical velocity data collection with an atmospheric profiling Doppler radar. The...

  13. Precipitation and microphysical processes observed by three polarimetric X-band radars and ground-based instrumentation during HOPE

    Science.gov (United States)

    Xie, Xinxin; Evaristo, Raquel; Simmer, Clemens; Handwerker, Jan; Trömel, Silke

    2016-06-01

    This study presents a first analysis of precipitation and related microphysical processes observed by three polarimetric X-band Doppler radars (BoXPol, JuXPol and KiXPol) in conjunction with a ground-based network of disdrometers, rain gauges and vertically pointing micro rain radars (MRRs) during the High Definition Clouds and Precipitation for advancing Climate Prediction (HD(CP)2) Observational Prototype Experiment (HOPE) during April and May 2013 in Germany. While JuXPol and KiXPol were continuously observing the central HOPE area near Forschungszentrum Jülich at a close distance, BoXPol observed the area from a distance of about 48.5 km. MRRs were deployed in the central HOPE area and one MRR close to BoXPol in Bonn, Germany. Seven disdrometers and three rain gauges providing point precipitation observations were deployed at five locations within a 5 km × 5 km region, while three other disdrometers were collocated with the MRR in Bonn. The daily rainfall accumulation at each rain gauge/disdrometer location estimated from the three X-band polarimetric radar observations showed very good agreement. Accompanying microphysical processes during the evolution of precipitation systems were well captured by the polarimetric X-band radars and corroborated by independent observations from the other ground-based instruments.

  14. Evaluation of turbulent dissipation rate retrievals from Doppler Cloud Radar

    Directory of Open Access Journals (Sweden)

    M. D. Shupe

    2012-06-01

    Full Text Available Turbulent dissipation rate retrievals from cloud radar Doppler velocity measurements are evaluated using independent, in situ observations in Arctic stratocumulus clouds. In situ validation data sets of dissipation rate are derived using sonic anemometer measurements from a tethered balloon and high frequency pressure variation observations from a research aircraft, both flown in proximity to stationary, ground-based radars. Modest biases are found among the data sets in particularly low- or high-turbulence regimes, but in general the radar-retrieved values correspond well with the in situ measurements. Root mean square differences are typically a factor of 4–6 relative to any given magnitude of dissipation rate. These differences are no larger than those found when comparing dissipation rates computed from tethered-balloon and meteorological tower-mounted sonic anemometer measurements made at spatial distances of a few hundred meters. Temporal lag analyses suggest that approximately half of the observed differences are due to spatial sampling considerations, such that the anticipated radar-based retrieval uncertainty is on the order of a factor of 2–3. Moreover, radar retrievals are clearly able to capture the vertical dissipation rate structure observed by the in situ sensors, while offering substantially more information on the time variability of turbulence profiles. Together these evaluations indicate that radar-based retrievals can, at a minimum, be used to determine the vertical structure of turbulence in Arctic stratocumulus clouds.

  15. Radar micro-doppler signatures processing and applications

    CERN Document Server

    Chen, Victor C; Miceli, William J

    2014-01-01

    Radar Micro-Doppler Signatures: Processing and applications concentrates on the processing and application of radar micro-Doppler signatures in real world situations, providing readers with a good working knowledge on a variety of applications of radar micro-Doppler signatures.

  16. A Fast Method for Embattling Optimization of Ground-Based Radar Surveillance Network

    Science.gov (United States)

    Jiang, H.; Cheng, H.; Zhang, Y.; Liu, J.

    A growing number of space activities have created an orbital debris environment that poses increasing impact risks to existing space systems and human space flight. For the safety of in-orbit spacecraft, a lot of observation facilities are needed to catalog space objects, especially in low earth orbit. Surveillance of Low earth orbit objects are mainly rely on ground-based radar, due to the ability limitation of exist radar facilities, a large number of ground-based radar need to build in the next few years in order to meet the current space surveillance demands. How to optimize the embattling of ground-based radar surveillance network is a problem to need to be solved. The traditional method for embattling optimization of ground-based radar surveillance network is mainly through to the detection simulation of all possible stations with cataloged data, and makes a comprehensive comparative analysis of various simulation results with the combinational method, and then selects an optimal result as station layout scheme. This method is time consuming for single simulation and high computational complexity for the combinational analysis, when the number of stations increases, the complexity of optimization problem will be increased exponentially, and cannot be solved with traditional method. There is no better way to solve this problem till now. In this paper, target detection procedure was simplified. Firstly, the space coverage of ground-based radar was simplified, a space coverage projection model of radar facilities in different orbit altitudes was built; then a simplified objects cross the radar coverage model was established according to the characteristics of space objects orbit motion; after two steps simplification, the computational complexity of the target detection was greatly simplified, and simulation results shown the correctness of the simplified results. In addition, the detection areas of ground-based radar network can be easily computed with the

  17. Evaluation of turbulent dissipation rate retrievals from Doppler cloud radar

    Directory of Open Access Journals (Sweden)

    M. D. Shupe

    2012-01-01

    Full Text Available Turbulent dissipation rate retrievals from cloud radar Doppler velocity measurements are evaluated using independent, in situ observations in Arctic stratocumulus clouds. In situ validation data sets of dissipation rate are derived using sonic anemometer measurements from a tethered balloon and high frequency pressure variation observations from a research aircraft, both flown in proximity to stationary, ground-based radars. Modest biases are found among the data sets in particularly low- or high-turbulence regimes, but in general the radar-retrieved values correspond well with the in situ measurements. Root mean square differences are typically a factor of 4–6 relative to any given magnitude of dissipation rate. These differences are no larger than those found when comparing dissipation rates computed from tethered-balloon and 15-m tower sonic measurements made at spatial distances of a few hundred meters. Moreover, radar retrievals are able to capture the vertical dissipation rate structure observed by the in situ sensors, while offering substantially more information on the time variability of turbulence profiles. Together these evaluations indicate that radar-based retrievals can, at a minimum, be used to determine the vertical structure of turbulence in Arctic stratocumulus clouds.

  18. Using doppler radar images to estimate aircraft navigational heading error

    Science.gov (United States)

    Doerry, Armin W [Albuquerque, NM; Jordan, Jay D [Albuquerque, NM; Kim, Theodore J [Albuquerque, NM

    2012-07-03

    A yaw angle error of a motion measurement system carried on an aircraft for navigation is estimated from Doppler radar images captured using the aircraft. At least two radar pulses aimed at respectively different physical locations in a targeted area are transmitted from a radar antenna carried on the aircraft. At least two Doppler radar images that respectively correspond to the at least two transmitted radar pulses are produced. These images are used to produce an estimate of the yaw angle error.

  19. Analytic radar micro-Doppler signatures classification

    Science.gov (United States)

    Oh, Beom-Seok; Gu, Zhaoning; Wang, Guan; Toh, Kar-Ann; Lin, Zhiping

    2017-06-01

    Due to its capability of capturing the kinematic properties of a target object, radar micro-Doppler signatures (m-DS) play an important role in radar target classification. This is particularly evident from the remarkable number of research papers published every year on m-DS for various applications. However, most of these works rely on the support vector machine (SVM) for target classification. It is well known that training an SVM is computationally expensive due to its nature of search to locate the supporting vectors. In this paper, the classifier learning problem is addressed by a total error rate (TER) minimization where an analytic solution is available. This largely reduces the search time in the learning phase. The analytically obtained TER solution is globally optimal with respect to the classification total error count rate. Moreover, our empirical results show that TER outperforms SVM in terms of classification accuracy and computational efficiency on a five-category radar classification problem.

  20. Acoustic micro-Doppler radar for human gait imaging.

    Science.gov (United States)

    Zhang, Zhaonian; Pouliquen, Philippe O; Waxman, Allen; Andreou, Andreas G

    2007-03-01

    A portable acoustic micro-Doppler radar system for the acquisition of human gait signatures in indoor and outdoor environments is reported. Signals from an accelerometer attached to the leg support the identification of the components in the measured micro-Doppler signature. The acoustic micro-Doppler system described in this paper is simpler and offers advantages over the widely used electromagnetic wave micro-Doppler radars.

  1. Comparison of airborne radar altimeter and ground-based Ku-band radar measurements on the ice cap Austfonna, Svalbard

    Directory of Open Access Journals (Sweden)

    O. Brandt

    2008-11-01

    Full Text Available We compare coincident data from the European Space Agency's Airborne SAR/Interferometric Radar Altimeter System (ASIRAS with ground-based Very High Bandwidth (VHB stepped-frequency radar measurements in the Ku-band. The ASIRAS instrument obtained data from ~700 m above the surface, using a 13.5 GHz center frequency and a 1 GHz bandwidth. The ground-based VHB radar measurements were acquired using the same center frequency, but with a variable bandwidth of either 1 or 8 GHz. Four sites were visited with the VHB radar; two sites within the transition region from superimposed ice to firn, and two sites in the long-term firn area (wet-snow zone. The greater bandwidth VHB measurements show that the first peak in the airborne data is a composite of the return from the surface (i.e. air-snow interface and returns of similar or stronger amplitude from reflectors in the upper ~30 cm of the subsurface. The peak position in the airborne data is thus not necessarily a good proxy for the surface since the maximum and width of the first return depend on the degree of interference between surface and subsurface reflectors. The major response from the winter snowpack was found to be caused by units of thin crust/ice layers (0.5–2 mm surrounded by large crystals (>3 mm. In the airborne data, it is possible to track such layers for tens of kilometers. The winter snowpack lacked thicker ice layers. The last year's summer surface, characterized by a low density large crystal layer overlaying a harder denser layer, gives a strong radar response, frequently the strongest. The clear relationship observed between the VHB and ASIRAS waveforms, justifies the use of ground-based radar measurements in the validation of air- or spaceborne radars.

  2. SCENARIO AND TARGET SIMULATION FOR A GROUND BASED MULTIFUNCTION PHASED ARRAY RADAR

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    This paper describes a scenario and target simulation which operates in non real-time to provide full closed-loop operation of the ground based multifunction phased array radar simulation system in support of ballistic missile defence experiments against countermeasure.By simulating the target scattering signature and dynamical signature,this scenario and target simulation provide re- alistic scenario source to evaluate the system performance of multifunction phased array radar,and the key algorithms verification and validation such as target tracking,multi-target imaging and target recognition.

  3. Space Fence Ground-Based Radar System Increment 1 (Space Fence Inc 1)

    Science.gov (United States)

    2015-12-01

    Selected Acquisition Report (SAR) RCS: DD-A&T(Q&A)823-438 Space Fence Ground-Based Radar System Increment 1 (Space Fence Inc 1) As of FY 2017...11 Track to Budget 17 Cost and Funding 18 Low Rate Initial Production 23 Foreign Military Sales 24 Nuclear Costs 24 Unit Cost...Document CLIN - Contract Line Item Number CPD - Capability Production Document CY - Calendar Year DAB - Defense Acquisition Board DAE - Defense Acquisition

  4. Comparison of the TRMM Precipitation Radar rainfall estimation with ground-based disdrometer and radar measurements in South Greece

    Science.gov (United States)

    Ioannidou, Melina P.; Kalogiros, John A.; Stavrakis, Adrian K.

    2016-11-01

    The performance of the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) rainfall estimation algorithm is assessed, locally, in Crete island, south Greece, using data from a 2D-video disdrometer and a ground-based, X-band, polarimetric radar. A three-parameter, normalized Gamma drop size distribution is fitted to the disdrometer rain spectra; the latter are classified in stratiform and convective rain types characterized by different relations between distribution parameters. The method of moments estimates more accurately the distribution parameters than the best fit technique, which exhibits better agreement with and is more biased by the observed droplet distribution at large diameter values. Power laws between the radar reflectivity factor (Z) and the rainfall rate (R) are derived from the disdrometer data. A significant diversity of the prefactor and the exponent of the estimated power laws is observed, depending on the scattering model and the regression technique. The Z-R relationships derived from the disdrometer data are compared to those obtained from TRMM-PR data. Generally, the power laws estimated from the two datasets are different. Specifically, the greater prefactor found for the disdrometer data suggests an overestimation of rainfall rate by the TRMM-PR algorithm for light and moderate stratiform rain, which was the main rain type in the disdrometer dataset. Finally, contemporary data from the TRMM-PR and a ground-based, X-band, polarimetric radar are analyzed. Comparison of the corresponding surface rain rates for a rain event with convective characteristics indicates a large variability of R in a single TRMM-PR footprint, which typically comprises several hundreds of radar pixels. Thus, the coarse spatial resolution of TRMM-PR may lead to miss of significant high local peaks of convective rain. Also, it was found that the high temporal variability of convective rain may introduce significant errors in the estimation of bias of

  5. Numerical Modeling of Doppler Radar Signals of Strombolian Eruptions

    Science.gov (United States)

    Gouhier, M.; Donnadieu, F.

    2006-12-01

    VOLDORAD is a ground-based UHF Doppler radar developed specifically for the remote sounding of volcanic eruptions. Its 23.5 cm wavelength allows us to monitor and quantify eruption intensity in real time from several km, with negligible attenuation by meteorological effects or volcanic ash. In particular, the signal can penetrate inside volcanic jets or plumes to measure the reflectivity and velocities of ejecta in several sampling volumes. The precise knowledge of these parameters is crucial to monitoring the evolution of an eruption and to provide more stringent constraints on assumptions included in models of volcanic processes. To improve our interpretation of radar signals, we have developed a numerical model simulating radar echoes from Strombolian jets. Ballistic projectiles of various sizes are accelerated upwards, over a range of angles, by gas with a given imposed initial velocity , and the equations of motion are solved with a fourth-order Runge-Kutta algorithm. The power backscattered to the radar is simulated by Rayleigh scattering from spheres. Taking into account the sounding geometry used for measurements on Etna in July 2001, our model is able to reproduce many characteristic trends of the time series and Doppler spectra measured during repeated Strombolian outbursts. Models show that measured radar velocities depend mostly on jet geometry, particle size, and initial gas velocity. For wide emission angles, measured radial velocities can be considered as the real ejecta velocities, whereas in the case of narrow vertical or asymmetrical jets, real velocity might be underestimated. However, video analyses confirm that for the majority of explosions, although most particles concentrate in the inner part of the jets, many blocks are also emitted at wide angles. For instance, maximum radial velocities recorded during the July 4 episode of Etna reached 70 m/s. The model radar signal obtained is strongly dependent on the degree of coupling between

  6. Validation of GPM Ka-Radar Algorithm Using a Ground-based Ka-Radar System

    Science.gov (United States)

    Nakamura, Kenji; Kaneko, Yuki; Nakagawa, Katsuhiro; Furukawa, Kinji; Suzuki, Kenji

    2016-04-01

    GPM led by the Japan Aerospace Exploration Agency (JAXA) and the National Aeronautics and Space Administration of US (NASA) aims to observe global precipitation. The core satellite is equipped with a microwave radiometer (GMI) and a dual-frequency radar (DPR) which is the first spaceborne Ku/Ka-band dual-wavelength radar dedicated for precipitation measurement. In the DPR algorithm, measured radar reflectivity is converted to effective radar reflectivity by estimating the rain attenuation. Here, the scattering/attenuation characteristics of Ka-band radiowaves are crucial, particularly for wet snow. A melting layer observation using a dual Ka-band radar system developed by JAXA was conducted along the slope of Mt. Zao in Yamagata Prefecture, Japan. The dual Ka-band radar system consists of two nearly identical Ka-band FM-CW radars, and the precipitation systems between two radars were observed in opposite directions. From this experiment, equivalent radar reflectivity (Ze) and specific attenuation (k) were obtained. The experiments were conducted for two winter seasons. During the data analyses, it was found that k estimate easily fluctuates because the estimate is based on double difference calculation. With much temporal and spatial averaging, k-Ze relationship was obtained for melting layers. One of the results is that the height of the peak of k seems slightly higher than that of Ze. The results are compared with in-situ precipitation particle measurements.

  7. Investigation of Rainfall Characteristics Using TRMM PR and Ground Based Radar

    Science.gov (United States)

    Dolan, B.; Lang, T. J.; Nesbitt, S. W.; Cifelli, R.; Rutledge, S. A.

    2011-12-01

    Despite relatively good agreement between reflectivity profiles, comparisons of rainfall statistics derived from TRMM Precipitation Radar (PR) deviate from ground-based radar (GR) observations in various field locations across the globe. TRMM PR rain rate probability distribution functions underestimate the occurrence of high rain rates (> 80 mm hr-1) compared with similar ground-based statistics, and similarly, GR distributes the total rain volume over a larger range of rain rates. Analysis of ten years of TRMM data over three field sites has shown that the greatest disagreements occur in the most intense convection, such as over land and during the east and break wind regimes over the Amazon and Australia, respectively. These differences are investigated further in this study. Ten years of TRMM PR data are analyzed in conjunction with data collected during two field experiments involving the NCAR S-Pol radar. S-Pol was deployed in Brazil in the Amazon during TRMM LBA in 1998-1999 and near Mazatlan, Mexico as part of the North American Monsoon Experiment (NAME) in 2004. Additionally, multiple years of data from the Australian Bureau of Meteorology CPOL radar located in Darwin, Australia, are examined to extend the robustness of the GR observations beyond the relatively short field campaigns. Polarimetric data collected by the two radars are used to characterize the differences between TRMM PR and GR observations as a function of bulk hydrometeor type. For example, profiles with significant graupel, as identified by GR, are analyzed to investigate the role of mixed phase in the PR retrievals. The vertical variability of D0 is examined as a function of reflectivity and related to the underlying microphysical conditions using the polarimetric data provided by the GR observations. Spatial variability of D0 is also explored by correlating D0 values derived from GR at different heights. Several significant changes were made to the TRMM processing algorithms in the

  8. Boost-Phase ballistic missile trajectory estimation with ground based radar

    Institute of Scientific and Technical Information of China (English)

    Tang Yuyan; Huang Peikang

    2006-01-01

    A conditional boost-phase trajectory estimation method based on ballistic missile (BM) information database and classification is developed to estimate and predict boos-phase BM trajectory. The main uncertain factors to describe BM dynamics equation are reduced to the control law of trajectory pitch angle in boost-phase. After the BM mass at the beginning of estimation, the BM attack angle and the modification of engine thrust denoting BM acceleration are modeled reasonably, the boost-phase BM trajectory estimation with ground based radar is well realized. The validity of this estimation method is testified by computer simulation with a typical example.

  9. Monitoring and Analysis of Respiratory Patterns Using Microwave Doppler Radar

    Science.gov (United States)

    Pathirana, Pubudu N.; Steinfort, Christopher Louis; Caelli, Terry

    2014-01-01

    Noncontact detection characteristic of Doppler radar provides an unobtrusive means of respiration detection and monitoring. This avoids additional preparations, such as physical sensor attachment or special clothing, which can be useful for certain healthcare applications. Furthermore, robustness of Doppler radar against environmental factors, such as light, ambient temperature, interference from other signals occupying the same bandwidth, fading effects, reduce environmental constraints and strengthens the possibility of employing Doppler radar in long-term respiration detection, and monitoring applications such as sleep studies. This paper presents an evaluation in the of use of microwave Doppler radar for capturing different dynamics of breathing patterns in addition to the respiration rate. Although finding the respiration rate is essential, identifying abnormal breathing patterns in real-time could be used to gain further insights into respiratory disorders and refine diagnostic procedures. Several known breathing disorders were professionally role played and captured in a real-time laboratory environment using a noncontact Doppler radar to evaluate the feasibility of this noncontact form of measurement in capturing breathing patterns under different conditions associated with certain breathing disorders. In addition to that, inhalation and exhalation flow patterns under different breathing scenarios were investigated to further support the feasibility of Doppler radar to accurately estimate the tidal volume. The results obtained for both experiments were compared with the gold standard measurement schemes, such as respiration belt and spirometry readings, yielding significant correlations with the Doppler radar-based information. In summary, Doppler radar is highlighted as an alternative approach not only for determining respiration rates, but also for identifying breathing patterns and tidal volumes as a preferred nonwearable alternative to the conventional

  10. How to Create and Manipulate Radar Range-Doppler Plots

    Science.gov (United States)

    2014-12-01

    set of wave fronts with constant wavelength, direction, and relative phase. Electromagnetic waves produced by radar transmitters and lasers are... radars . The Matlab function fft orders its DFT amplitudes in a way that renders negative frequencies positive and greater than the Nyquist frequency. I...UNCLASSIFIED How to Create and Manipulate Radar Range–Doppler Plots Don Koks Cyber & Electronic Warfare Division Defence Science and Technology

  11. Polarimetric analysis of radar backscatter from ground-based scatterometers and wheat biomass monitoring with advanced synthetic aperture radar images

    Science.gov (United States)

    He, Lei; Tong, Ling; Li, Yuxia; Chen, Yan; Tan, Longfei; Guo, Caizheng

    2016-04-01

    This article presents an analysis of the scattering measurements for an entire wheat growth cycle by ground-based scatterometers at a frequency of 5.3 GHz. Since wheat ears are related to wheat growth and yield, the radar backscatter of wheat was analyzed at two different periods, i.e., with and without wheat ears. Simultaneously, parameters such as wheat and soil characteristics as well as volume scattering and soil scattering were analyzed for the two periods during the entire growth cycle. Wheat ears have been demonstrated to have a great influence on radar backscatter; therefore, a modified version of water-cloud model used for retrieving biomass should consider the effect of wheat ears. This work presents two retrieval models based on the water-cloud model and adopts the advanced integral equation model to simulate the soil backscatter before the heading stage and the backscatter from the layer under wheat ears after the heading stage. The research results showed that the biomass retrieved from the advanced synthetic aperture radar (ASAR) images to agree well with the data measured in situ after setting the modified water-cloud model for the growth stages with ears. Furthermore, it was concluded that wheat ears should form an essential component of theoretical modeling as they influence the final yield.

  12. DATA PROCESSING AND ANALYSIS TOOLS BASED ON GROUND-BASED SYNTHETIC APERTURE RADAR IMAGERY

    Directory of Open Access Journals (Sweden)

    M. Crosetto

    2017-09-01

    Full Text Available The Ground-Based SAR (GBSAR is a terrestrial remote sensing technique used to measure and monitor deformation. In this paper we describe two complementary approaches to derive deformation measurements using GBSAR data. The first approach is based on radar interferometry, while the second one exploits the GBSAR amplitude. In this paper we consider the so-called discontinuous GBSAR acquisition mode. The interferometric process is not always straightforward: it requires appropriate data processing and analysis tools. One of the main critical steps is phase unwrapping, which can critically affect the deformation measurements. In this paper we describe the procedure used at the CTTC to process and analyse discontinuous GBSAR data. In the second part of the paper we describe the approach based on GBSAR amplitude images and an image-matching method.

  13. Micro-Doppler processing for ultra-wideband radar data

    Science.gov (United States)

    Smith, Graeme E.; Ahmad, Fauzia; Amin, Moeness G.

    2012-06-01

    In this paper, we describe an operational pulse Doppler radar imaging system for indoor target localization and classification, and show how a target's micro-Doppler signature (μDS) can be processed when ultra-wideband (UWB) waveforms are employed. Unlike narrowband radars where time-frequency signal representations can be applied to reveal the target time-Doppler frequency signatures, the UWB system permits joint range-time-frequency representation (JRTFR). JRTFR outputs the data in a 3D domain representing range, frequency, and time, allowing both the μDS and high range resolution (HRR) signatures to be observed. We delineate the relationship between the μDS and the HRR signature, showing how they would form a complimentary joint feature for classification. We use real-data to demonstrate the effectiveness of the UWB pulse-Doppler radar, combined with nonstationary signal analyses, in gaining valuable insights into human positioning and motions.

  14. Volcanic Ash Cloud Observation using Ground-based Ka-band Radar and Near-Infrared Lidar Ceilometer during the Eyjafjallajökull eruption

    Directory of Open Access Journals (Sweden)

    Frank S. Marzano

    2015-03-01

    Full Text Available Active remote sensing techniques can probe volcanic ash plumes, but their sensitivity at a given distance depends upon the sensor transmitted power, wavelength and polarization capability. Building on a previous numerical study at centimeter wavelength, this work aims at i simulating the distal ash particles polarimetric response of millimeter-wave radar and multi-wavelength optical lidar; ii developing and applying a model-based statistical retrieval scheme using a multi-sensor approach. The microphysical electromagnetic forward model of volcanic ash particle distribution, previously set up at microwaves, is extended to include non-spherical particle shapes, vesicular composition, silicate content and orientation phenomena for both millimeter and optical bands. Monte Carlo generation of radar and lidar signatures are driven by random variability of volcanic particle main parameters, using constraints from available data and experimental evidences. The considered case study is related to the ground-based observation of the Eyjafjallajökull (Iceland volcanic ash plume on May 15, 2010, carried out by the Atmospheric Research Station at Mace Head (Ireland with a 35-GHz Ka-band Doppler cloud radar and a 1064-nm ceilometer lidar. The detection and estimation of ash layer presence and composition is carried out using a Bayesian approach, which is trained by the Monte Carlo model-based dataset. Retrieval results are corroborated exploiting auxiliary data such as those from a ground-based microwave radiometer also positioned at Mace Head.

  15. Sub-Seasonal Variability of Tropical Rainfall Observed by TRMM and Ground-based Polarimetric Radar

    Science.gov (United States)

    Dolan, Brenda; Rutledge, Steven; Lang, Timothy; Cifelli, Robert; Nesbitt, Stephen

    2010-05-01

    Studies of tropical precipitation characteristics from the TRMM-LBA and NAME field campaigns using ground-based polarimetric S-band data have revealed significant differences in microphysical processes occurring in the various meteorological regimes sampled in those projects. In TRMM-LMA (January-February 1999 in Brazil; a TRMM ground validation experiment), variability is driven by prevailing low-level winds. During periods of low-level easterlies, deeper and more intense convection is observed, while during periods of low-level westerlies, weaker convection embedded in widespread stratiform precipitation is common. In the NAME region (North American Monsoon Experiment, summer 2004 along the west coast of Mexico), strong terrain variability drives differences in precipitation, with larger drops and larger ice mass aloft associated with convection occurring over the coastal plain compared to convection over the higher terrain of the Sierra Madre Occidental, or adjacent coastal waters. Comparisons with the TRMM precipitation radar (PR) indicate that such sub-seasonal variability in these two regions are not well characterized by the TRMM PR reflectivity and rainfall statistics. TRMM PR reflectivity profiles in the LBA region are somewhat lower than S-Pol values, particularly in the more intense easterly regime convection. In NAME, mean reflectivities are even more divergent, with TRMM profiles below those of S-Pol. In both regions, the TRMM PR does not capture rain rates above 80 mm hr-1 despite much higher rain rates estimated from the S-Pol polarimetric data, and rain rates are generally lower for a given reflectivity from TRMM PR compared to S-Pol. These differences between TRMM PR and S-Pol may arise from the inability of Z-R relationships to capture the full variability of microphysical conditions or may highlight problems with TRMM retrievals over land. In addition to the TRMM-LBA and NAME regions, analysis of sub-seasonal precipitation variability and

  16. HPRF pulse Doppler stepped frequency radar

    Institute of Scientific and Technical Information of China (English)

    LONG Teng; REN LiXiang

    2009-01-01

    Stepped frequency radar Is a well known scheme to generate high range resolution profile (HRRP) of targets. Through appropriate radar parameter design, the radar enables both unambiguous velocity measurement and high resolution ranging within a single dwell in a high pulse repetition frequency (HPRF) mode. This paper analyzes in detail the design principle of the HPRF stepped frequency radar system, the solution to its ambiguity issue, as well as its signal processing method. Both theoretical analysis and simulation results demonstrate that the proposed radar scheme can work independently to solve the problem of motion compensation, and is therefore highly applicable to many new types of radar.

  17. Fpga based L-band pulse doppler radar design and implementation

    Science.gov (United States)

    Savci, Kubilay

    As its name implies RADAR (Radio Detection and Ranging) is an electromagnetic sensor used for detection and locating targets from their return signals. Radar systems propagate electromagnetic energy, from the antenna which is in part intercepted by an object. Objects reradiate a portion of energy which is captured by the radar receiver. The received signal is then processed for information extraction. Radar systems are widely used for surveillance, air security, navigation, weather hazard detection, as well as remote sensing applications. In this work, an FPGA based L-band Pulse Doppler radar prototype, which is used for target detection, localization and velocity calculation has been built and a general-purpose Pulse Doppler radar processor has been developed. This radar is a ground based stationary monopulse radar, which transmits a short pulse with a certain pulse repetition frequency (PRF). Return signals from the target are processed and information about their location and velocity is extracted. Discrete components are used for the transmitter and receiver chain. The hardware solution is based on Xilinx Virtex-6 ML605 FPGA board, responsible for the control of the radar system and the digital signal processing of the received signal, which involves Constant False Alarm Rate (CFAR) detection and Pulse Doppler processing. The algorithm is implemented in MATLAB/SIMULINK using the Xilinx System Generator for DSP tool. The field programmable gate arrays (FPGA) implementation of the radar system provides the flexibility of changing parameters such as the PRF and pulse length therefore it can be used with different radar configurations as well. A VHDL design has been developed for 1Gbit Ethernet connection to transfer digitized return signal and detection results to PC. An A-Scope software has been developed with C# programming language to display time domain radar signals and detection results on PC. Data are processed both in FPGA chip and on PC. FPGA uses fixed

  18. The ELDORA/ASTRAIA Airborne Doppler Weather Radar: High-Resolution Observations from TOGA COARE.

    Science.gov (United States)

    Hildebrand, Peter H.; Lee, Wen-Chau; Walther, Craig A.; Frush, Charles; Randall, Mitchell; Loew, Eric; Neitzel, Richard; Parsons, Richard; Testud, Jacques; Baudin, François; Lecornec, Alain

    1996-02-01

    The ELDORA/ASTRAIA (Electra Doppler Radar/Analyese Stereoscopic par Impulsions Aeroporte) airborne Doppler weather radar was recently placed in service by the National Center for Atmospheric Research and the Centre d'étude des Environnements Terrestre et Planetaires in France. After a multiyear development effort, the radar saw its first field tests in the TOGA COARE (Tropical Oceans-Global Atmosphere Coupled Ocean-Atmosphere Response Experiment) field program during January and February 1993. The ELDORA/ASTRAIA radar (herein referred to as ELDORA) is designed to provide high-resolution measurements of the air motion and rainfall characteristics of very large storms, storms that are frequently too large or too remote to be adequately observed by ground-based radars. This paper discusses the measurement requirements and the design goals of the radar and concludes with an evaluation of the performance of the system using data from TOGA COARE.The performance evaluation includes data from two cases. First, observations of a mesoscale convective system on 9 February 1993 are used to compare the data quality of the ELDORA radar with the National Oceanic and Atmospheric Administration P-3 airborne Doppler radars. The large-scale storm structure and airflow from ELDORA are seen to compare quite well with analyses using data from the P-3 radars. The major differences observed between the ELDORA and P-3 radar analyses were due to the higher resolution of the ELDORA data and due to the different domains observed by the individual radars, a result of the selection of flight track past the storm for each aircraft. In a second example, the high-resolution capabilities of ELDORA are evaluated using observations of a shear-parallel mesoscale convective system (MCS) that occurred on 18 February 1993. This MCS line was characterized by shear-parallel clusters of small convective cells, clusters that were moving quickly with the low-level winds. High-resolution analysis of these

  19. Signal Processing for Radar with Array Antennas and for Radar with Micro-Doppler Measurements

    OpenAIRE

    Björklund, Svante

    2017-01-01

    Radar (RAdio Detection And Ranging) uses radio waves to detect the presence of a target and measure its position and other properties. This sensor has found many civilian and military applications due to advantages such as possible large surveillance areas and operation day and night and in all weather. The contributions of this thesis are within applied signal processing for radar in two somewhat separate research areas: 1) radar with array antennas and 2) radar with micro-Doppler measuremen...

  20. MetaSensing's FastGBSAR: ground based radar for deformation monitoring

    Science.gov (United States)

    Rödelsperger, Sabine; Meta, Adriano

    2014-10-01

    The continuous monitoring of ground deformation and structural movement has become an important task in engineering. MetaSensing introduces a novel sensor system, the Fast Ground Based Synthetic Aperture Radar (FastGBSAR), based on innovative technologies that have already been successfully applied to airborne SAR applications. The FastGBSAR allows the remote sensing of deformations of a slope or infrastructure from up to a distance of 4 km. The FastGBSAR can be setup in two different configurations: in Real Aperture Radar (RAR) mode it is capable of accurately measuring displacements along a linear range profile, ideal for monitoring vibrations of structures like bridges and towers (displacement accuracy up to 0.01 mm). Modal parameters can be determined within half an hour. Alternatively, in Synthetic Aperture Radar (SAR) configuration it produces two-dimensional displacement images with an acquisition time of less than 5 seconds, ideal for monitoring areal structures like dams, landslides and open pit mines (displacement accuracy up to 0.1 mm). The MetaSensing FastGBSAR is the first ground based SAR instrument on the market able to produce two-dimensional deformation maps with this high acquisition rate. By that, deformation time series with a high temporal and spatial resolution can be generated, giving detailed information useful to determine the deformation mechanisms involved and eventually to predict an incoming failure. The system is fully portable and can be quickly installed on bedrock or a basement. The data acquisition and processing can be fully automated leading to a low effort in instrument operation and maintenance. Due to the short acquisition time of FastGBSAR, the coherence between two acquisitions is very high and the phase unwrapping is simplified enormously. This yields a high density of resolution cells with good quality and high reliability of the acquired deformations. The deformation maps can directly be used as input into an Early

  1. Analysis of Radar Doppler Signature from Human Data

    Directory of Open Access Journals (Sweden)

    M. ANDRIĆ

    2014-04-01

    Full Text Available This paper presents the results of time (autocorrelation and time-frequency (spectrogram analyses of radar signals returned from the moving human targets. When a radar signal falls on the human target which is moving toward or away from the radar, the signals reflected from different parts of his body produce a Doppler shift that is proportional to the velocity of those parts. Moving parts of the body causes the characteristic Doppler signature. The main contribution comes from the torso which causes the central Doppler frequency of target. The motion of arms and legs induces modulation on the returned radar signal and generates sidebands around the central Doppler frequency, referred to as micro-Doppler signatures. Through analyses on experimental data it was demonstrated that the human motion signature extraction is better using spectrogram. While the central Doppler frequency can be determined using the autocorrelation and the spectrogram, the extraction of the fundamental cadence frequency using the autocorrelation is unreliable when the target is in the clutter presence. It was shown that the fundamental cadence frequency increases with increasing dynamic movement of people and simultaneously the possibility of its extraction is proportional to the degree of synchronization movements of persons in the group.

  2. Radar target recognition based on micro-Doppler effect

    Institute of Scientific and Technical Information of China (English)

    DONG Wei-guang; LI Yan-jun

    2008-01-01

    Mechanical vibration of target structures will modulate the phase function of radar backscattering, and will induce thefrequency modulation of returned signals from the target. It generates a side bands of the target body Doppler frequencyshift, which is helpful for target recognition. Based on this.a micro-Doppler atomic storehouse is built for the targetrecognition, and four kinds of common classifiers are used separately to perform the classified recognition. The simulationexperimental results show that this method has high recognition rate above 90%.

  3. Doppler visibility of coherent random noise radar systems

    Science.gov (United States)

    Li, Zhixi; Narayanan, Ram M.

    2005-05-01

    Random noise radar has recently been used in a variety of imaging and surveillance applications. These systems can be made phase coherent using the technique of heterodyne correlation. Phase coherence has been exploited to measure Doppler and thereby the velocity of moving targets. The Doppler visibility, i.e., the ability to extract Doppler information over the inherent clutter spectra, is constrained by system parameters, especially the phase noise generated by microwave components. Our paper proposes a new phase noise model for the heterodyne mixer as applicable for ultrawideband (UWB) random noise radar and for the local oscillator in the time domain. The Doppler spectra are simulated by including phase noise contamination effects and compared to our previous experimental results. A Genetic Algorithm (GA) optimization routine is applied to synthesize the effects of a variety of parameter combinations to derive a suitable empirical formula for estimating the Doppler visibility in dB. According to the phase noise analysis and the simulation results, the Doppler visibility of UWB random noise radar depends primarily on the following parameters: (a) the local oscillator (LO) drive level of the receiver heterodyne mixer; (b) the saturation current in the receiver heterodyne mixer; (c) the bandwidth of the transmit noise source, and; (d) the target velocity. Other parameters such as the carrier frequency of the receiver LO and the loaded quality factor of the LO have a small effect over the range of applicability of the model and are therefore neglected in the model formulation. The Doppler visibility curves generated from this formula match the simulation results very well over the applicable parameter range within 1 dB. Our model may therefore be used to quickly estimate the Doppler visibility of random noise radars for trade-off analysis.

  4. Doppler radar fall activity detection using the wavelet transform.

    Science.gov (United States)

    Su, Bo Yu; Ho, K C; Rantz, Marilyn J; Skubic, Marjorie

    2015-03-01

    We propose in this paper the use of Wavelet transform (WT) to detect human falls using a ceiling mounted Doppler range control radar. The radar senses any motions from falls as well as nonfalls due to the Doppler effect. The WT is very effective in distinguishing the falls from other activities, making it a promising technique for radar fall detection in nonobtrusive inhome elder care applications. The proposed radar fall detector consists of two stages. The prescreen stage uses the coefficients of wavelet decomposition at a given scale to identify the time locations in which fall activities may have occurred. The classification stage extracts the time-frequency content from the wavelet coefficients at many scales to form a feature vector for fall versus nonfall classification. The selection of different wavelet functions is examined to achieve better performance. Experimental results using the data from the laboratory and real inhome environments validate the promising and robust performance of the proposed detector.

  5. Ground based interferometric radar initial look at Longview, Blue Springs, Tuttle Creek, and Milford Dams

    Science.gov (United States)

    Deng, Huazeng

    Measuring millimeter and smaller deformation has been demonstrated in the literature using RADAR. To address in part the limitations in current commercial satellite-based SAR datasets, a University of Missouri (MU) team worked with GAMMA Remote Sensing to develop a specialized (dual-frequency, polarimetric, and interferometric) ground-based real-aperture RADAR (GBIR) instrument. The GBIR device is portable with its tripod system and control electronics. It can be deployed to obtain data with high spatial resolution (i.e. on the order of 1 meter) and high temporal resolution (i.e. on the order 1 minute). The high temporal resolution is well suited for measurements of rapid deformation. From the same geodetic position, the GBIR may collect dual frequency data set using C-band and Ku-band. The overall goal of this project is to measure the deformation from various scenarios by applying the GBIR system. Initial efforts have been focusing on testing the system performance on different types of targets. This thesis details a number of my efforts on experimental and processing activities at the start of the MU GBIR imaging project. For improved close range capability, a wideband dual polarized antenna option was produced and tested. For GBIR calibration, several trihedral corner reflectors were designed and fabricated. In addition to experimental activities and site selection, I participated in advanced data processing activities. I processed GBIR data in several ways including single-look-complex (SLC) image generation, imagery registration, and interferometric processing. A number of initial-processed GBIR image products are presented from four dams: Longview, Blue Springs, Tuttle Creek, and Milford. Excellent imaging performance of the MU GBIR has been observed for various target types such as riprap, concrete, soil, rock, metal, and vegetation. Strong coherence of the test scene has been observed in the initial interferograms.

  6. Evaluation of Radar Vegetation Indices for Vegetation Water Content Estimation Using Data from a Ground-Based SMAP Simulator

    Science.gov (United States)

    Srivastava, Prashant K.; O'Neill, Peggy; Cosh, Michael; Lang, Roger; Joseph, Alicia

    2015-01-01

    Vegetation water content (VWC) is an important component of microwave soil moisture retrieval algorithms. This paper aims to estimate VWC using L band active and passive radar/radiometer datasets obtained from a NASA ground-based Soil Moisture Active Passive (SMAP) simulator known as ComRAD (Combined Radar/Radiometer). Several approaches to derive vegetation information from radar and radiometer data such as HH, HV, VV, Microwave Polarization Difference Index (MPDI), HH/VV ratio, HV/(HH+VV), HV/(HH+HV+VV) and Radar Vegetation Index (RVI) are tested for VWC estimation through a generalized linear model (GLM). The overall analysis indicates that HV radar backscattering could be used for VWC content estimation with highest performance followed by HH, VV, MPDI, RVI, and other ratios.

  7. Wave heave spectra from radar Doppler velocities at extreme low grazing angles

    Science.gov (United States)

    Flampouris, Stylianos; Seemann, Joerg; Ziemer, Friedwart

    2013-04-01

    The ground based microwaves radar systems are used for the measurement of the sea surface phenomena for more than three decades. By calibrating the radar cross section, the extraction of the wave spectral characteristics is a well established empirical methodology (Ziemer et al. 1993) with theoretical background (Alpers et al. 1978) and commercial applications (Nieto et al. 2004), which provides comparable measurements with wave buoys. The transfer function is necessary mainly due to the imaging mechanisms, like shadowing and or tilt modulation (Seemann 1997). To avoid the obligatory use of a transfer function, instead of the radar cross section, the Doppler velocity, which is a direct measurement of the sea surface, could be used. In this poster, a methodology for the determination of heave spectra based on time series of Doppler velocity acquired under extreme low grazing angle conditions, is presented. We prove that for the determination of the peak frequency the analysis of the binary shadow mask is sufficient, but for the calculation of the spectral density, a transfer function is necessary because of the gaps of the time series due to the shadowing. The physical and technical limitations are discussed and the algorithm is tested with in situ measurements from the coastal area of German Bight. Both properties, peak frequency and significant wave height from radar, have significant correlation with buoy measurements.

  8. Interferometric millimeter wave and THz wave doppler radar

    Science.gov (United States)

    Liao, Shaolin; Gopalsami, Nachappa; Bakhtiari, Sasan; Raptis, Apostolos C.; Elmer, Thomas

    2015-08-11

    A mixerless high frequency interferometric Doppler radar system and methods has been invented, numerically validated and experimentally tested. A continuous wave source, phase modulator (e.g., a continuously oscillating reference mirror) and intensity detector are utilized. The intensity detector measures the intensity of the combined reflected Doppler signal and the modulated reference beam. Rigorous mathematics formulas have been developed to extract bot amplitude and phase from the measured intensity signal. Software in Matlab has been developed and used to extract such amplitude and phase information from the experimental data. Both amplitude and phase are calculated and the Doppler frequency signature of the object is determined.

  9. Radar Micro-Doppler classification of Mini-UAVs

    NARCIS (Netherlands)

    Harmanny, R.L.A.; Prémel-Cabic, G.; Wit, J.J.M.

    2015-01-01

    The radar micro-Doppler signature of a target depends on its micro-motion, i.e., the motion of parts of a target relative to the motion of the target as a whole. These micro-motions are very characteristic considering different target classes, e.g., the slow pendulum-like motion of a bird’s wings ve

  10. Study of an airborne Doppler radar: Project Asterix

    Science.gov (United States)

    Testud, Jacques; Baudin, F.; Amayenc, P.

    Specifications for an airborne Doppler radar for meteorological applications are given. The following areas are covered: (1) principle for measuring three-dimensional speed field; (2) pulse pattern and detectability; (3) antenna; (4) processing of data; (5) analog system; (6) data control and recording; (7) attitude control and vibrations; and (8) logistics.

  11. Radar Micro-Doppler classification of Mini-UAVs

    NARCIS (Netherlands)

    Harmanny, R.L.A.; Prémel-Cabic, G.; Wit, J.J.M.

    2015-01-01

    The radar micro-Doppler signature of a target depends on its micro-motion, i.e., the motion of parts of a target relative to the motion of the target as a whole. These micro-motions are very characteristic considering different target classes, e.g., the slow pendulum-like motion of a bird’s wings

  12. Extracting radar micro-Doppler signatures of helicopter rotating rotor blades using K-band radars

    Science.gov (United States)

    Chen, Rachel; Liu, Baokun

    2014-06-01

    Helicopter identification has been an attractive topic. In this paper, we applied radar micro-Doppler signatures to identify helicopter. For identifying the type of a helicopter, besides its shape and size, the number of blades, the length of the blade, and the rotation rate of the rotor are important features, which can be estimated from radar micro-Doppler signatures of the helicopter's rotating rotor blades. In our study, K-band CW/FMCW radars are used for collecting returned signals from helicopters. By analyzing radar micro-Doppler signatures, we can estimate the number of blades, the length of the blade, the angular rotation rate of the rotating blade, and other necessary parameters for identifying the type of a helicopter.

  13. Coherent Doppler Laser Radar: Technology Development and Applications

    Science.gov (United States)

    Kavaya, Michael J.; Arnold, James E. (Technical Monitor)

    2000-01-01

    NASA's Marshall Space Flight Center has been investigating, developing, and applying coherent Doppler laser radar technology for over 30 years. These efforts have included the first wind measurement in 1967, the first airborne flights in 1972, the first airborne wind field mapping in 1981, and the first measurement of hurricane eyewall winds in 1998. A parallel effort at MSFC since 1982 has been the study, modeling and technology development for a space-based global wind measurement system. These endeavors to date have resulted in compact, robust, eyesafe lidars at 2 micron wavelength based on solid-state laser technology; in a factor of 6 volume reduction in near diffraction limited, space-qualifiable telescopes; in sophisticated airborne scanners with full platform motion subtraction; in local oscillator lasers capable of rapid tuning of 25 GHz for removal of relative laser radar to target velocities over a 25 km/s range; in performance prediction theory and simulations that have been validated experimentally; and in extensive field campaign experience. We have also begun efforts to dramatically improve the fundamental photon efficiency of the laser radar, to demonstrate advanced lower mass laser radar telescopes and scanners; to develop laser and laser radar system alignment maintenance technologies; and to greatly improve the electrical efficiency, cooling technique, and robustness of the pulsed laser. This coherent Doppler laser radar technology is suitable for high resolution, high accuracy wind mapping; for aerosol and cloud measurement; for Differential Absorption Lidar (DIAL) measurements of atmospheric and trace gases; for hard target range and velocity measurement; and for hard target vibration spectra measurement. It is also suitable for a number of aircraft operations applications such as clear air turbulence (CAT) detection; dangerous wind shear (microburst) detection; airspeed, angle of attack, and sideslip measurement; and fuel savings through

  14. Coupling Between Doppler Radar Signatures and Tornado Damage Tracks

    Science.gov (United States)

    Jedlovec, Gary J.; Molthan, Andrew L.; Carey, Lawrence; Carcione, Brian; Smith, Matthew; Schultz, Elise V.; Schultz, Christopher; Lafontaine, Frank

    2011-01-01

    On April 27, 2011, the southeastern United States was raked with several episodes of severe weather. Numerous tornadoes caused extensive damage, and tragically, the deaths of over 300 people. In Alabama alone, there were 61 confirmed tornados, 4 of them produced EF5 damage, and several were on the ground an hour or more with continuous damage tracks exceeding 80km. The use of Doppler radars covering the region provided reflectivity and velocity signatures that allowed forecasters to monitors the severe storms from beginning to end issuing hundreds of severe weather warnings throughout the day. Meteorologists from the the NWS performed extensive surveys to assess the intensity, duration, and ground track of tornadoes reported during the event. Survey activities included site visits to the affected locations, analysis of radar and satellite data, aerial surveys, and interviews with eyewitnesses. Satellite data from NASA's MODIS and ASTER instruments played a helpful role in determining the location of tornado damage paths and in the assessment. High resolution multispectral and temporal composites helped forecasters corroborate their damage assessments, determine starting and ending points for tornado touchdowns, and helped to provide forecasters with a better big-picture view of the damage region. The imagery also helped to separate damage from the April 27th tornados from severe weather that occurred earlier that month. In a post analysis of the outbreak, tornado damage path signatures observed in the NASA satellite data have been correlated to "debris ball" signatures in the NWS Doppler radars and a special ARMOR dual-polarization radar operated by the University of Alabama Huntsville during the event. The Doppler radar data indicates a circular enhanced reflectivity signal and rotational couplet in the radial velocity likely associated with the tornado that is spatially correlated with the damage tracks in the observed satellite data. An algorithm to detect and

  15. Ground-based Radar Detection of Near-Earth Asteroids%近地小行星地基雷达探测研究现状

    Institute of Scientific and Technical Information of China (English)

    张翔; 季江徽

    2014-01-01

    Ground-based radar detection may act as a powerful means to determine the shape and physical properties of the asteroids in our Solar system. By measuring time delay and doppler frequency of the received echoes, radar systems provide information in ranging and radial velocity of the asteroids. Over the past few decades, more than 500 asteroids (mostly near-Earth ob jects) were detected using radar observations. There are two categories of radar detection: (1) The continuous wave detection, which is adopted to determine the roughness of an asteroid’s surface. (2) The delay-Doppler de-tection,which is likely to produce its three-dimensional model, and to define the rotational state. In the delay-Doppler detection, target asteroids are resolved in line-of-sight distance and line-of-sight velocity, providing two-dimensional images with spatial resolution as fine as meter-scale. Besides radar detection, several other techniques would also provide the shape model of the asteroids, among which the lightcurve inverse method is the most popular one to do that. In comparison with other methods, radar observation may have an advantage on spacial resolution. The lightcurves cannot reveal elaborate information on small features, and the intermediate-scale features of the inversed model are only suggestive. By contrast, radar detection produces resolved images. In this review, we present the radar observation technique and the method for recon-structing three-dimensional models of asteroids from radar measurements. In addition, we also provide several examples of asteroid models by radar detection, and then compare them with other observations for the shape reconstruction for the asteroids.%地基雷达探测是研究太阳系中小行星的重要方法。雷达探测主要有两种方式:(1)连续波探测,可得到小行星表面的粗糙度等参数;(2)延迟多普勒探测,用于反演小行星的三维形状模型并确定自转轴状态。与其他探测方法

  16. Ground-based radar reflectivity mosaic of mei-yu precipitation systems over the Yangtze River-Huaihe River basins

    Science.gov (United States)

    Luo, Yali; Qian, Weimiao; Gong, Yu; Wang, Hongyan; Zhang, Da-Lin

    2016-11-01

    The 3D radar reflectivity produced by a mosaic software system, with measurements from 29 operational weather radars in the Yangtze River-Huaihe River Basins (YRHRB) during the mei-yu season of 2007, is compared to coincident TRMM PR observations in order to evaluate the value of the ground-based radar reflectivity mosaic in characterizing the 3D structures of mei-yu precipitation. Results show reasonable agreement in the composite radar reflectivity between the two datasets, with a correlation coefficient of 0.8 and a mean bias of -1 dB. The radar mosaic data at constant altitudes are reasonably consistent with the TRMM PR observations in the height range of 2-5 km, revealing essentially the same spatial distribution of radar echo and nearly identical histograms of reflectivity. However, at altitudes above 5 km, the mosaic data overestimate reflectivity and have slower decreasing rates with height compared to the TRMM PR observations. The areas of convective and stratiform precipitation, based on the mosaic reflectivity distribution at 3-km altitude, are highly correlated with the corresponding regions in the TRMM products, with correlation coefficients of 0.92 and 0.97 and mean relative differences of -7.9% and -2.5%, respectively. Finally, the usefulness of the mosaic reflectivity at 3-km altitude at 6-min intervals is illustrated using a mesoscale convective system that occurred over the YRHRB.

  17. Wind measurements in Saturn's atmosphere with UVES/VLT ground-based Doppler velocimetry

    Science.gov (United States)

    Machado, Pedro; Silva, Miguel; Peralta, Javier; Luz, David; Sánchez-Lavega, Agustin; Hueso, Ricardo

    2016-04-01

    We will present preliminary Doppler wind velocity results of Saturn's zonal flow at cloud level. Our aim is help to constrain the characterization of the equatorial jet at cloud level and the latitudinal variation of the zonal winds, to measure its spatial and temporal variability, to contribute to monitor the variability in order to achieve a better understanding of the dynamics of Saturn's zonal winds, whose equatorial jet has a complex vertical structure and temporal variability (Sanchez-Lavega et al., Nature, 423, 623, 3003; Garcia-Melendo et al., Geophys. Res. Lett., 37, L22204. 2010). Finally, the complementarity with Cassini, providing an independent set of observations. The UVES/VLT instrument has been used, which simultaneously achieves high spectral resolving power and high spatial resolution. The field has been derotated in order to have the aperture aligned perpendicularly to Saturn's rotation axis. In this configuration, spatial information in the East-West direction is preserved in a set of spectra in the direction perpendicular to dispersion. The technique of absolute accelerometry (AA, Connes, 1985, ApSS 110, 211) has been applied to the backscattered solar spectrum in order to determine the Doppler shift associated with the zonal circulation. Our measurements have been made in the wavelength range of 480-680 nm. Previously we successfully adapted this Doppler velocimetry technique for measuring winds at Venus cloud tops (Machado et al. 2012). In the present study we will show the adaptation of this method for Saturn's case. Since the AA technique only allows to compare spectra where the line shifts are within the line width, in fast rotating atmospheres (as is the case of Saturn) the spectra must be compared by pairs from adjacent areas of the disk (adjacent pixels in the slit). We will use coordinated observations from the Cassini's Visible and Infrared Mapping Spectrometer (VIMS), in order to compare with the Doppler winds obtained from the UVES

  18. Ground-based microwave weather radar observations and retrievals during the 2014 Holuhraun eruption (Bárðarbunga, Iceland)

    Science.gov (United States)

    Mereu, Luigi; Silvio Marzano, Frank; Barsotti, Sara; Montopoli, Mario; Yeo, Richard; Arngrimsson, Hermann; Björnsson, Halldór; Bonadonna, Costanza

    2015-04-01

    During an eruptive event the real-time forecasting of ash dispersal into the atmosphere is a key factor to prevent air traffic disasters. The ash plume is extremely hazardous to aircraft that inadvertently may fly through it. Real-time monitoring of such phenomena is crucial, particularly to obtain specific data for the initialization of eruption and dispersion models in terms of source parameters. The latter, such as plume height, ash concentration, mass flow rate and size spectra, are usually very difficult to measure or to estimate with a relatively good accuracy. Over the last years different techniques have been developed to improved ash plume detection and retrieval. Satellite-based observations, using multi-frequency visible and infrared radiometers, are usually exploited for monitoring and measuring dispersed ash clouds. The observations from geostationary orbit suffer from a relatively poor spatial resolution, whereas the low orbit level has a relatively poor temporal resolution. Moreover, the field-of-view of infrared radiometric measurements may be reduced by obstructions caused by water and ice clouds lying between the ground and the sensor's antenna. Weather radar-based observations represent an emerging technique to detect and, to a certain extent, mitigate the hazard from the ash plumes. Ground-based microwave scanning radar systems can provide the three-dimensional information about the detected ash volume with a fairly high spatial resolution every few minutes and in all weather conditions. Methodological studies have recently investigated the possibility of using single-polarization and dual-polarization ground-based radar for the remote sensing of volcanic ash cloud. In this respect, radar observations can be complementary to satellite observations. A microphysical electromagnetic characterization of volcanic ash was carried out in terms of dielectric properties, composition, size and orientation of ash particles. An extended Volcanic Ash Radar

  19. Microphysical Retrieval from Doppler Radar Reflectivity Using Variational Data Assimilation

    Institute of Scientific and Technical Information of China (English)

    LI Yongping; ZHU Guofu; XUE Jishan

    2006-01-01

    One of the microphysical variables, the rainwater mixing ratio qr, is retrieved from the observed reflectivity of Doppler radar by a 3D variational data assimilation system. The qr as an analysis variable is obtained by minimizing a cost function defined as the difference between observed radar reflectivity and its retrieval from qr, plus the difference between qr and its background field from a mesoscale model's prediction. Covariance matrix of the background field's error is determined by the so-called NMC method. A method called the second-order auto-regression (SOAR) is used to calculate the coefficients of regressive filtering to fit in with small spatial scale such as cumulus in the process of spatial transformation. An ideal experiment demonstrates the correctness of this system and a sensitivity experiment proves that the random error of observed reflectivity has effect on the analyzed results. At last an experiment with observed data from the Doppler radar at Ma'anshan City in Anhui Province on 19 June 2002 was performed. The retrieved analysis variable qr in this test shows structures in detail, which coincide with the distribution of the echo picture observed by the radar.

  20. Doppler radar sensor positioning in a fall detection system.

    Science.gov (United States)

    Liu, Liang; Popescu, Mihail; Ho, K C; Skubic, Marjorie; Rantz, Marilyn

    2012-01-01

    Falling is a common health problem for more than a third of the United States population over 65. We are currently developing a Doppler radar based fall detection system that already has showed promising results. In this paper, we study the sensor positioning in the environment with respect to the subject. We investigate three sensor positions, floor, wall and ceiling of the room, in two experimental configurations. Within each system configuration, subjects performed falls towards or across the radar sensors. We collected 90 falls and 341 non falls for the first configuration and 126 falls and 817 non falls for the second one. Radar signature classification was performed using a SVM classifier. Fall detection performance was evaluated using the area under the ROC curves (AUCs) for each sensor deployment. We found that a fall is more likely to be detected if the subject is falling toward or away from the sensor and a ceiling Doppler radar is more reliable for fall detection than a wall mounted one.

  1. Formulation of geopotential difference determination using optical-atomic clocks onboard satellites and on ground based on Doppler cancellation system

    Science.gov (United States)

    Shen, Ziyu; Shen, Wen-Bin; Zhang, Shuangxi

    2016-08-01

    In this study, we propose an approach for determining the geopotential difference using high-frequency-stability microwave links between satellite and ground station based on Doppler cancellation system. Suppose a satellite and a ground station are equipped with precise optical-atomic clocks (OACs) and oscillators. The ground oscillator emits a signal with frequency fa towards the satellite and the satellite receiver (connected with the satellite oscillator) receives this signal with frequency fb which contains the gravitational frequency shift effect and other signals and noises. After receiving this signal, the satellite oscillator transmits and emits, respectively, two signals with frequencies fb and fc towards the ground station. Via Doppler cancellation technique, the geopotential difference between the satellite and the ground station can be determined based on gravitational frequency shift equation by a combination of these three frequencies. For arbitrary two stations on ground, based on similar procedures as described above, we may determine the geopotential difference between these two stations via a satellite. Our analysis shows that the accuracy can reach 1 m2 s- 2 based on the clocks' inaccuracy of about 10-17 (s s-1) level. Since OACs with instability around 10-18 in several hours and inaccuracy around 10-18 level have been generated in laboratory, the proposed approach may have prospective applications in geoscience, and especially, based on this approach a unified world height system could be realized with one-centimetre level accuracy in the near future.

  2. Radar micro-Doppler simulations of classification capability with frequency

    Science.gov (United States)

    Tahmoush, David; Silvious, Jerry

    2012-06-01

    Classifying human signatures using radar requires a detailed understanding of the RF scattering phenomenology associated with humans as well as their motion. We model humans engaged in the activity of walking and analyze the separability of different body parts with frequency as well as lookdown angle. This work seeks to estimate the ability to classify the micro-Doppler signals generated by human motion, and especially arm motion, as a function of the radar frequency and other parameters. The simulations imply that for classification using arm motion, frequencies at Ku-band or higher are probably required, and that lookdown angle has a significant effect on the classification capability of the radar. Additionally, the sensitivity of the system required to isolate the motion of different body parts is estimated.

  3. Doppler weather Radar based Nowcasting of cyclone Ogni

    Indian Academy of Sciences (India)

    Soma Sen Roy; V Lakshmanan; S K Roy Bhowmik; S B Thampi

    2010-04-01

    In this paper, we describe offline analysis of Indian Doppler Weather Radar (DWR) data from cyclone Ogni using a suite of radar algorithms as implemented on NEXRAD and the advanced algorithms developed jointly by the National Severe Storms Laboratory (NSSL) and the University of Oklahoma. We demonstrate the applicability of the various algorithms to Indian radar data, the improvement in the quality control and evaluate the benefit of nowcasting capabilities in Indian conditions. New information about the tropical cyclone structure, as derived from application of the algorithms is also discussed in this study. Finally, we suggest improvements that could be made to the Indian data collection strategies, networking and real-time analysis. Since this is the first study of its kind to process and utilize DWR data in a tropical climate, the suggestions on real-time analysis and data collection strategies made in this paper, would in many cases, be beneficial to other countries embarking on DWR network modernization programs.

  4. Intercomparison of Vertical Structure of Storms Revealed by Ground-Based (NMQ and Spaceborne Radars (CloudSat-CPR and TRMM-PR

    Directory of Open Access Journals (Sweden)

    Veronica M. Fall

    2013-01-01

    Full Text Available Spaceborne radars provide great opportunities to investigate the vertical structure of clouds and precipitation. Two typical spaceborne radars for such a study are the W-band Cloud Profiling Radar (CPR and Ku-band Precipitation Radar (PR, which are onboard NASA’s CloudSat and TRMM satellites, respectively. Compared to S-band ground-based radars, they have distinct scattering characteristics for different hydrometeors in clouds and precipitation. The combination of spaceborne and ground-based radar observations can help in the identification of hydrometeors and improve the radar-based quantitative precipitation estimation (QPE. This study analyzes the vertical structure of the 18 January, 2009 storm using data from the CloudSat CPR, TRMM PR, and a NEXRAD-based National Mosaic and Multisensor QPE (NMQ system. Microphysics above, within, and below the melting layer are studied through an intercomparison of multifrequency measurements. Hydrometeors’ type and their radar scattering characteristics are analyzed. Additionally, the study of the vertical profile of reflectivity (VPR reveals the brightband properties in the cold-season precipitation and its effect on the radar-based QPE. In all, the joint analysis of spaceborne and ground-based radar data increases the understanding of the vertical structure of storm systems and provides a good insight into the microphysical modeling for weather forecasts.

  5. Developments in target micro-Doppler signatures analysis: radar imaging, ultrasound and through-the-wall radar

    Science.gov (United States)

    Clemente, Carmine; Balleri, Alessio; Woodbridge, Karl; Soraghan, John J.

    2013-12-01

    Target motions, other than the main bulk translation of the target, induce Doppler modulations around the main Doppler shift that form what is commonly called a target micro-Doppler signature. Radar micro-Doppler signatures are generally both target and action specific and hence can be used to classify and recognise targets as well as to identify possible threats. In recent years, research into the use of micro-Doppler signatures for target classification to address many defence and security challenges has been of increasing interest. In this article, we present a review of the work published in the last 10 years on emerging applications of radar target analysis using micro-Doppler signatures. Specifically we review micro-Doppler target signatures in bistatic SAR and ISAR, through-the-wall radar and ultrasound radar. This article has been compiled to provide radar practitioners with a unique reference source covering the latest developments in micro-Doppler analysis, extraction and mitigation techniques. The article shows that this research area is highly active and fast moving and demonstrates that micro-Doppler techniques can provide important solutions to many radar target classification challenges.

  6. A Semiautomated Multilayer Picking Algorithm for Ice-sheet Radar Echograms Applied to Ground-Based Near-Surface Data

    Science.gov (United States)

    Onana, Vincent De Paul; Koenig, Lora Suzanne; Ruth, Julia; Studinger, Michael; Harbeck, Jeremy P.

    2014-01-01

    Snow accumulation over an ice sheet is the sole mass input, making it a primary measurement for understanding the past, present, and future mass balance. Near-surface frequency-modulated continuous-wave (FMCW) radars image isochronous firn layers recording accumulation histories. The Semiautomated Multilayer Picking Algorithm (SAMPA) was designed and developed to trace annual accumulation layers in polar firn from both airborne and ground-based radars. The SAMPA algorithm is based on the Radon transform (RT) computed by blocks and angular orientations over a radar echogram. For each echogram's block, the RT maps firn segmented-layer features into peaks, which are picked using amplitude and width threshold parameters of peaks. A backward RT is then computed for each corresponding block, mapping the peaks back into picked segmented-layers. The segmented layers are then connected and smoothed to achieve a final layer pick across the echogram. Once input parameters are trained, SAMPA operates autonomously and can process hundreds of kilometers of radar data picking more than 40 layers. SAMPA final pick results and layer numbering still require a cursory manual adjustment to correct noncontinuous picks, which are likely not annual, and to correct for inconsistency in layer numbering. Despite the manual effort to train and check SAMPA results, it is an efficient tool for picking multiple accumulation layers in polar firn, reducing time over manual digitizing efforts. The trackability of good detected layers is greater than 90%.

  7. Mobile Ground-Based Radar Sensor for Localization and Mapping: An Evaluation of two Approaches

    Directory of Open Access Journals (Sweden)

    Damien Vivet

    2013-08-01

    Full Text Available This paper is concerned with robotic applications using a ground‐based radar sensor for simultaneous localization and mapping problems. In mobile robotics, radar technology is interesting because of its long range and the robustness of radar waves to atmospheric conditions, making these sensors well‐suited for extended outdoor robotic applications. Two localization and mapping approaches using data obtained from a 360° field of view microwave radar sensor are presented and compared. The first method is a trajectory‐ oriented simultaneous localization and mapping technique, which makes no landmark assumptions and avoids the data association problem. The estimation of the ego‐motion makes use of the Fourier‐Mellin transform for registering radar images in a sequence, from which the rotation and translation of the sensor motion can be estimated. The second approach uses the consequence of using a rotating range sensor in high speed robotics. In such a situation, movement combinations create distortions in the collected data. Velocimetry is achieved here by explicitly analysing these measurement distortions. As a result, the trajectory of the vehicle and then the radar map of outdoor environments can be obtained. The evaluation of experimental results obtained by the two methods is presented on real‐world data from a vehicle moving at 30 km/h over a 2.5 km course.

  8. Radar Measurement of Human Polarimetric Micro-Doppler

    Directory of Open Access Journals (Sweden)

    David Tahmoush

    2013-01-01

    Full Text Available We use polarimetric micro-Doppler for the detection of arm motion, especially for the classification of whether someone has their arms swinging and is thus unloaded. The arm is often bent at the elbow, providing a surface somewhat similar to a dihedral. This is distinct from the more planar surfaces of the body which allows us to isolate the signals of the arm (and knee. The dihedral produces a double bounce that can be seen in polarimetric radar data by measuring the phase difference between HH and VV. This measurement can then be used to determine whether the subject is unloaded.

  9. Synchrosqueezing an effective method for analyzing Doppler radar physiological signals.

    Science.gov (United States)

    Yavari, Ehsan; Rahman, Ashikur; Jia Xu; Mandic, Danilo P; Boric-Lubecke, Olga

    2016-08-01

    Doppler radar can monitor vital sign wirelessly. Respiratory and heart rate have time-varying behavior. Capturing the rate variability provides crucial physiological information. However, the common time-frequency methods fail to detect key information. We investigate Synchrosqueezing method to extract oscillatory components of the signal with time varying spectrum. Simulation and experimental result shows the potential of the proposed method for analyzing signals with complex time-frequency behavior like physiological signals. Respiration and heart signals and their components are extracted with higher resolution and without any pre-filtering and signal conditioning.

  10. Range ambiguity resolution for high PRF pulse-Doppler radar

    Science.gov (United States)

    Postema, G. B.

    The range ambiguity resolution for high 'PRF pulse-Doppler radars can be resolved using a simple algorithm based on residue arithmetic. The unambiguous range is found from R = T + R(a), where T is the output of a look-up table and R(a) is one of the measured ambiguous ranges. This formula is easily extended to multiple PRF ranging systems, where three or more measurements are required for the ambiguity resolution. Target obscuration in clutter reduces the visibility and leads, especially in dense target environments, to ghost ranges. It is shown that long range coverage requires a small resolved pulse length and PRFs as low as practical in the intended clutter and target environment. Special attention is given to the generation of sparsely populated look-up tables that reduce the ghosting problem. A practical example for an S-band surveillance radar is presented.

  11. Determining human target facing orientation using bistatic radar micro-Doppler signals

    Science.gov (United States)

    Fairchild, Dustin P.; Narayanan, Ram M.

    2014-06-01

    Micro-Doppler radar signals can be used to separate moving human targets from stationary clutter and also to identify and classify human movements. Traditional micro-Doppler radar systems which use a single sensor, monostatic system, suffer from the drawback that only the radial component of the micro-Doppler signal will be observed by the radar operator. This reduces the sensitivity of human activity recognition if the movements are not directly towards or away with respect to the line-of-sight to the radar antenna. In this paper, we propose the use of two bistatic micro-Doppler sensors to overcome this limitation. By using multiple sensors, the orientation of oscillating targets with respect to the radar line-of-sight can be inferred, thereby providing additional information to the radar operator. This approach can be used to infer the facing direction of the human with respect to the radar beam.

  12. Simultaneous ground-based thermospheric wind measurements using Doppler asymmetric spatial heterodyne spectroscopy (DASH) and Fabry-Perot Interferometry

    Science.gov (United States)

    Englert, C. R.; Harlander, J. M.; Meriwether, J. W.; Brown, C. M.; Drob, D. P.; Emmert, J. T.; Castelaz, M.; Roesler, F. L.

    2011-12-01

    The concept of Doppler Asymmetric Spatial Heterodyne (DASH) instruments to measure upper atmospheric winds was initially published in 2006. The DASH approach is identical to the concept of Spatial Heterodyne Spectroscopy (SHS) except that one interferometer arm includes an additional fixed optical path offset, similar to the phase stepping Michelson technique which was used for the WINDII (Wind Imaging Interferometer) experiment. The advantages of DASH include having no moving parts, high sensitivity, and the ability to simultaneously observe multiple isolated emission lines, including a known light source for real time calibration. Since it was first proposed, the development of the DASH technique has progressed significantly. Major milestones include a proof of concept in the laboratory, the design, fabrication and test of a monolithic DASH interferometer for the thermospheric red line (O I 630nm), and initial ground based thermospheric wind measurements using this interferometer. To further increase the technical readiness level (TRL) of DASH for a future satellite instrument, we have conducted coordinated measurements with a DASH prototype and Fabry-Perot interferometer (FPI) from the Pisgah Astronomical Research Institute in North Carolina in the summer of 2011. We will present a comparison of the two experimental data sets and examine how they compare with the empirical horizontal wind model HWM-07.

  13. Effect of DRFM phase responsext on the doppler spectrum of a coherent radar: critical implications and possible mitigation techniques

    CSIR Research Space (South Africa)

    Herselman, PL

    2006-02-01

    Full Text Available In this research, the critical implications of the phase response of a Digital Radio Frequency Memory (DRFM) based repeater system on the Doppler spectrum of a modern, coherently processing radar system (for example pulsed Doppler radar...

  14. An image-based approach for classification of human micro-doppler radar signatures

    Science.gov (United States)

    Tivive, Fok Hing Chi; Phung, Son Lam; Bouzerdoum, Abdesselam

    2013-05-01

    With the advances in radar technology, there is an increasing interest in automatic radar-based human gait identification. This is because radar signals can penetrate through most dielectric materials. In this paper, an image-based approach is proposed for classifying human micro-Doppler radar signatures. The time-varying radar signal is first converted into a time-frequency representation, which is then cast as a two-dimensional image. A descriptor is developed to extract micro-Doppler features from local time-frequency patches centered along the torso Doppler frequency. Experimental results based on real data collected from a 24-GHz Doppler radar showed that the proposed approach achieves promising classification performance.

  15. First middle-atmospheric zonal wind profile measurements with a new ground-based microwave Doppler-spectro-radiometer

    Directory of Open Access Journals (Sweden)

    R. Rüfenacht

    2012-11-01

    Full Text Available We report on the wind radiometer WIRA, a new ground-based microwave Doppler-spectro-radiometer specifically designed for the measurement of middle-atmospheric horizontal wind by observing ozone emission spectra at 142.17504 GHz. Currently, wind speeds in five levels between 30 and 79 km can be retrieved which makes WIRA the first instrument able to continuously measure horizontal wind in this altitude range. For an integration time of one day the measurement error on each level lies at around 25 m s−1. With a planned upgrade this value is expected to be reduced by a factor of 2 in the near future. On the altitude levels where our measurement can be compared to wind data from the European Centre for Medium-Range Weather Forecasts (ECMWF very good agreement in the long-term statistics as well as in short time structures with a duration of a few days has been found.

    WIRA uses a passive double sideband heterodyne receiver together with a digital Fourier transform spectrometer for the data acquisition. A big advantage of the radiometric approach is that such instruments can also operate under adverse weather conditions and thus provide a continuous time series for the given location. The optics enables the instrument to scan a wide range of azimuth angles including the directions east, west, north, and south for zonal and meridional wind measurements. The design of the radiometer is fairly compact and its calibration does not rely on liquid nitrogen which makes it transportable and suitable for campaign use. WIRA is conceived in a way that it can be operated remotely and does hardly require any maintenance.

    In the present paper, a description of the instrument is given, and the techniques used for the wind retrieval based on the determination of the Doppler shift of the measured atmospheric ozone emission spectra are outlined. Their reliability was tested using Monte Carlo simulations. Finally, a time series of 11

  16. Radar micro-Doppler of wind turbines: Simulation and analysis using rotating linear wire structures

    NARCIS (Netherlands)

    Krasnov, O.A.; Yarovoy, A.

    2015-01-01

    A simple electromagnetic model of wind-turbine's main structural elements as the linear wired structures is developed to simulate the temporal patterns of observed radar return Doppler spectra (micro-Doppler). Using the model, the micro-Doppler for different combinations of the turbines rotation

  17. Automatic Identification of Storm Cells Using Doppler Radars

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Three storm automatic identification algorithms for Doppler radar axe discussed. The WSR-88D Build 7.0 (B7SI) tests the intensity and continuity of the objective echoes by multiple-prescribed thresholds to build 3D storms, and when storms are merging, splitting, or clustered closely, the detection errors become larger. The B9SI algorithm is part of the Build 9.0 Radar Products Generator of the WSR-88D system. It uses multiple thresholds of reflectivity, newly designs the techniques of cell nucleus extraction and close-storms processing, and therefore is capable of identifying embedded cells in multi-cellular storms. The strong area components at a long distance are saved as 2D storms. However, the B9SI cannot give information on the convection strength of storm, because texture and gradient of reflectivity are not calculated and radial velocity data are not used. To overcome this limitation, the CSI (Convective Storm Identification) algorithm is designed in this paper. By using the fuzzy logic technique, and under the condition that the levels of the seven reflectivity thresholds of B9SI are lowered, the CSI processes the radar base data and the output of B9SI to obtain the convection index of storm. Finally, the CSI is verified with the case of a supercell occurring in Guangzhou on 11 August 2004. The computational and analysis results show that the two rises of convection index matched well with a merging growth and strong convergent growth of the supercell, and the index was 0.744 when the supercell was the strongest, and then decreased. Correspondingly, the height of the maximum reflectivity, detected by the radar also reduced, and heavy rain also occurred in a large-scale area.

  18. Maritime target and sea clutter measurements with a coherent Doppler polarimetric surveillance radar

    NARCIS (Netherlands)

    Smith, A.J.E.; Gelsema, S.J.; Kester, L.J.H.M.; Melief, H.W.; Premel Cabic, G.; Theil, A.; Woudenberg, E.

    2002-01-01

    Doppler polarimetry in a surveillance radar for the maritime surface picture is considered. This radar must be able to detect low-RCS targets in littoral environments. Measurements on such targets have been conducted with a coherent polarimetric measurement radar in March 2001 and preliminary

  19. Maritime target and sea clutter measurements with a coherent Doppler polarimetric surveillance radar

    NARCIS (Netherlands)

    Smith, A.J.E.; Gelsema, S.J.; Kester, L.J.H.M.; Melief, H.W.; Premel Cabic, G.; Theil, A.; Woudenberg, E.

    2002-01-01

    Doppler polarimetry in a surveillance radar for the maritime surface picture is considered. This radar must be able to detect low-RCS targets in littoral environments. Measurements on such targets have been conducted with a coherent polarimetric measurement radar in March 2001 and preliminary result

  20. Advanced Doppler radar physiological sensing technique for drone detection

    Science.gov (United States)

    Yoon, Ji Hwan; Xu, Hao; Garcia Carrillo, Luis R.

    2017-05-01

    A 24 GHz medium-range human detecting sensor, using the Doppler Radar Physiological Sensing (DRPS) technique, which can also detect unmanned aerial vehicles (UAVs or drones), is currently under development for potential rescue and anti-drone applications. DRPS systems are specifically designed to remotely monitor small movements of non-metallic human tissues such as cardiopulmonary activity and respiration. Once optimized, the unique capabilities of DRPS could be used to detect UAVs. Initial measurements have shown that DRPS technology is able to detect moving and stationary humans, as well as largely non-metallic multi-rotor drone helicopters. Further data processing will incorporate pattern recognition to detect multiple signatures (motor vibration and hovering patterns) of UAVs.

  1. Combining dual-polarization radar and ground-based observations to study the effect of riming on ice particles

    Science.gov (United States)

    Moisseev, Dmitri; von Lerber, Annakaisa; Tiira, Jussi

    2017-04-01

    Recently a new microphysical scheme based on a single ice-phase category was proposed for the use in numerical weather prediction models. In the proposed scheme, ice particle properties are predicted and vary in time and space. One of the attributes of the proposed scheme is that the prefactor of a power-law relation that links mass and size of ice particles is determined by the rime mass fraction, while the exponent is kept constant. According to this the maximum dimensions of ice particles do not change during riming until graupel growth phase is reached. The dual-polarization radar observations given an additional insight on what are the physical properties of ice particles. Often, it is assumed that differential reflectivity should decrease because of riming. The motivation for this is that heavy riming would transform an ice particle to graupel. A graupel particle typically would have an almost spherical shape and therefore the differential reflectivity will become smaller. On the other hand, at the earlier stages ice particle shape may not change much, while its mass and therefore the density increases. This would lead to the increase of the differential reflectivity, for example. By combining ground-based observations, which allow to quantify the effect of riming on snowfall, and dual-polarization radar observations we investigate the impact of riming on ice particle properties, i.e. mass, density and shape. Furthermore, a connection between, bulk properties of ice particles, liquid water path, radar equivalent reflectivity factor and precipitation rate observations is established. The study is based on data collected during US DOE Biogenic Aerosols - Effects on Clouds and Climate (BAECC) field campaign that took place in Hyytiala, Finland. A detailed analysis of two events is presented to illustrate the method.

  2. A Doppler Radar System for Sensing Physiological Parameters in Walking and Standing Positions

    Directory of Open Access Journals (Sweden)

    Malikeh Pour Ebrahim

    2017-03-01

    Full Text Available Doppler radar can be implemented for sensing physiological parameters wirelessly at a distance. Detecting respiration rate, an important human body parameter, is essential in a range of applications like emergency and military healthcare environments, and Doppler radar records actual chest motion. One challenge in using Doppler radar is being able to monitor several patients simultaneously and in different situations like standing, walking, or lying. This paper presents a complete transmitter-receiver Doppler radar system, which uses a 4 GHz continuous wave radar signal transmission and receiving system, to extract base-band data from a phase-shifted signal. This work reports experimental evaluations of the system for one and two subjects in various standing and walking positions. It provides a detailed signal analysis of various breathing rates of these two subjects simultaneously. These results will be useful in future medical monitoring applications.

  3. A Micro-Doppler Modulation of Spin Projectile on CW Radar

    Directory of Open Access Journals (Sweden)

    Liu Zhi-Xue

    2017-01-01

    Full Text Available To obtain the spin speed of projectile effectively, a micro-Doppler modulation model of rotating projectile measured by continuous-wave radar (CW radar is introduced. High spin speed of projectile brings micro-Doppler modulation on echoes of CW radar, and there are many micro-Doppler modulation harmonic waves in the zero intermediate frequency (ZIF echoes. The frequency interval of the adjacent harmonic waves is several times of rotational frequency, but the integral multiple is unknown. The simulation results prove correctness of the proposed mathematic model.

  4. Development of a Low-Cost UAV Doppler Radar Data System

    Science.gov (United States)

    Knuble, Joseph; Li, Lihua; Heymsfield, Gerry

    2005-01-01

    A viewgraph presentation on the design of a low cost unmanned aerial vehicle (UAV) doppler radar data system is presented. The topics include: 1) Science and Mission Background; 2) Radar Requirements and Specs; 3) Radar Realization: RF System; 4) Processing of RF Signal; 5) Data System Design Process; 6) Can We Remove the DSP? 7) Determining Approximate Speed Requirements; 8) Radar Realization: Data System; 9) Data System Operation; and 10) Results.

  5. Processing Doppler Lidar and Cloud Radar Observations for Analysis of Convective Mass Flux Parameterizations Using DYNAMO Direct Observations

    Science.gov (United States)

    2014-09-30

    1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Processing Doppler Lidar and Cloud Radar Observations...campaign the data gathered from the High Resolution Doppler Lidar (HRDL) and the 94-GHz cloud Doppler radar Report Documentation Page Form ApprovedOMB No...00-00-2014 to 00-00-2014 4. TITLE AND SUBTITLE Processing Doppler Lidar and Cloud Radar Observations for Analysis of Convective Mass Flux

  6. Intercomparison of snowfall estimates derived from the CloudSat Cloud Profiling Radar and the ground-based weather radar network over Sweden

    Directory of Open Access Journals (Sweden)

    L. Norin

    2015-12-01

    Full Text Available Accurate snowfall estimates are important for both weather and climate applications. Ground-based weather radars and space-based satellite sensors are often used as viable alternatives to rain gauges to estimate precipitation in this context. In particular, the Cloud Profiling Radar (CPR on board CloudSat is proving to be a useful tool to map snowfall globally, in part due to its high sensitivity to light precipitation and its ability to provide near-global vertical structure. CloudSat snowfall estimates play a particularly important role in the high-latitude regions as other ground-based observations become sparse and passive satellite sensors suffer from inherent limitations. In this paper, snowfall estimates from two observing systems – Swerad, the Swedish national weather radar network, and CloudSat – are compared. Swerad offers a well-calibrated data set of precipitation rates with high spatial and temporal resolution, at very high latitudes. The measurements are anchored to rain gauges and provide valuable insights into the usefulness of CloudSat CPR's snowfall estimates in the polar regions. In total, 7.2 × 105 matchups of CloudSat and Swerad observations from 2008 through 2010 were intercompared, covering all but the summer months (June to September. The intercomparison shows encouraging agreement between the two observing systems despite their different sensitivities and user applications. The best agreement is observed when CloudSat passes close to a Swerad station (46–82 km, where the observational conditions for both systems are comparable. Larger disagreements outside this range suggest that both platforms have difficulty with shallow snow but for different reasons. The correlation between Swerad and CloudSat degrades with increasing distance from the nearest Swerad station, as Swerad's sensitivity decreases as a function of distance. Swerad also tends to overshoot low-level precipitating systems further away from the station

  7. UWB micro-doppler radar for human gait analysis using joint range-time-frequency representation

    Science.gov (United States)

    Wang, Yazhou; Fathy, Aly E.

    2013-05-01

    In this paper, we present a novel, standalone ultra wideband (UWB) micro-Doppler radar sensor that goes beyond simple range or micro-Doppler detection to combined range-time-Doppler frequency analysis. Moreover, it can monitor more than one human object in both line-of-sight (LOS) and through wall scenarios, thus have full human objects tracking capabilities. The unique radar design is based on narrow pulse transceiver, high speed data acquisition module, and wideband antenna array. For advanced radar post-data processing, joint range-time-frequency representation has been performed. Characteristics of human walking activity have been analyzed using the radar sensor by precisely tracking the radar object and acquiring range-time-Doppler information simultaneously. The UWB micro-Doppler radar prototype is capable of detecting Doppler frequency range from -180 Hz to +180 Hz, which allows a maximum target velocity of 9 m/s. The developed radar sensor can also be extended for many other applications, such as respiration and heartbeat detection of trapped survivors under building debris.

  8. Characteristics of Deep Tropical and Subtropical Convection from Nadir-Viewing High-Altitude Airborne Doppler Radar

    Science.gov (United States)

    Heymsfield, Gerald M.; Tian, Lin; Heymsfield, Andrew J.; Li, Lihua; Guimond, Stephen

    2010-01-01

    This paper presents observations of deep convection characteristics in the tropics and subtropics that have been classified into four categories: tropical cyclone, oceanic, land, and sea breeze. Vertical velocities in the convection were derived from Doppler radar measurements collected during several NASA field experiments from the nadir-viewing high-altitude ER-2 Doppler radar (EDOP). Emphasis is placed on the vertical structure of the convection from the surface to cloud top (sometimes reaching 18-km altitude). This unique look at convection is not possible from other approaches such as ground-based or lower-altitude airborne scanning radars. The vertical motions from the radar measurements are derived using new relationships between radar reflectivity and hydrometeor fall speed. Various convective properties, such as the peak updraft and downdraft velocities and their corresponding altitude, heights of reflectivity levels, and widths of reflectivity cores, are estimated. The most significant findings are the following: 1) strong updrafts that mostly exceed 15 m/s, with a few exceeding 30 m/s, are found in all the deep convection cases, whether over land or ocean; 2) peak updrafts were almost always above the 10-km level and, in the case of tropical cyclones, were closer to the 12-km level; and 3) land-based and sea-breeze convection had higher reflectivities and wider convective cores than oceanic and tropical cyclone convection. In addition, the high-resolution EDOP data were used to examine the connection between reflectivity and vertical velocity, for which only weak linear relationships were found. The results are discussed in terms of dynamical and microphysical implications for numerical models and future remote sensors.

  9. Estimation of physiological sub-millimeter displacement with CW Doppler radar.

    Science.gov (United States)

    Jia Xu; Xiaomeng Gao; Padasdao, Bryson E; Boric-Lubecke, Olga

    2015-01-01

    Doppler radar physiological sensing has been studied for non-contact detection of vital signs including respiratory and heartbeat rates. This paper presents the first micrometer resolution Wi-Fi band Doppler radar for sub-millimeter physiological displacement measurement. A continuous-wave Doppler radar working at 2.4GHz is used for the measurement. It is intended for estimating small displacements on the body surface resulting from physiological activity. A mechanical mover was used as target, and programmed to conduct sinusoidal motions to simulate pulse motions. Measured displacements were compared with a reference system, which indicates a superior performance in accuracy for having absolute errors less than 10μm, and relative errors below 4%. It indicates the feasibility of highly accurate non-contact monitoring of physiological movements using Doppler radar.

  10. Passive Microwave Soil Moisture Retrieval through Combined Radar/Radiometer Ground Based Simulator with Special Reference to Dielectric Schemes

    Science.gov (United States)

    Srivastava, Prashant K., ,, Dr.; O'Neill, Peggy, ,, Dr.

    2014-05-01

    Soil moisture is an important element for weather and climate prediction, hydrological sciences, and applications. Hence, measurements of this hydrologic variable are required to improve our understanding of hydrological processes, ecosystem functions, and the linkages between the Earth's water, energy, and carbon cycles (Srivastava et al. 2013). The retrieval of soil moisture depends not only on parameterizations in the retrieval algorithm but also on the soil dielectric mixing models used (Behari 2005). Although a number of soil dielectric mixing models have been developed, testing these models for soil moisture retrieval has still not been fully explored, especially with SMAP-like simulators. The main objective of this work focuses on testing different dielectric models for soil moisture retrieval using the Combined Radar/Radiometer (ComRAD) ground-based L-band simulator developed jointly by NASA/GSFC and George Washington University (O'Neill et al., 2006). The ComRAD system was deployed during a field experiment in 2012 in order to provide long active/passive measurements of two crops under controlled conditions during an entire growing season. L-band passive data were acquired at a look angle of 40 degree from nadir at both horizontal & vertical polarization. Currently, there are many dielectric models available for soil moisture retrieval; however, four dielectric models (Mironov, Dobson, Wang & Schmugge and Hallikainen) were tested here and found to be promising for soil moisture retrieval (some with higher performances). All the above-mentioned dielectric models were integrated with Single Channel Algorithms using H (SCA-H) and V (SCA-V) polarizations for the soil moisture retrievals. All the ground-based observations were collected from test site-United States Department of Agriculture (USDA) OPE3, located a few miles away from NASA GSFC. Ground truth data were collected using a theta probe and in situ sensors which were then used for validation. Analysis

  11. Integrated Range-Doppler Map and Extended Target Classification with Adaptive Waveform for Cognitive Radar

    Science.gov (United States)

    2014-12-01

    RANGE-DOPPLER MAP AND EXTENDED TARGET CLASSIFICATION WITH ADAPTIVE WAVEFORM FOR COGNITIVE RADAR by Jo-Yen Nieh December 2014 Dissertation...TYPE AND DATES COVERED Dissertation 4. TITLE AND SUBTITLE INTEGRATED RANGE-DOPPLER MAP AND EXTENDED TARGET CLASSIFICATION WITH ADAPTIVE WAVEFORM ...design an extended target classification scheme while determining the target’s range-and-Doppler location with the use of adaptive waveform for a

  12. Analysis of the computational requirements of a pulse-doppler radar signal processor

    CSIR Research Space (South Africa)

    Broich, R

    2012-05-01

    Full Text Available architectures [1]. These simplifications are often degrading to algorithmic performance and thus to the entire radar system. In this paper the different computational operations that are used in pulse-Doppler radar signal processing are explored, in order...H z to 10 GH z Fig. 1. Radar signal processor (RSP) flow of operations purpose computer architectures [3]. An abstract machine, in which only memory reads, writes, additions and multiplica- tions are considered to be significant operations...

  13. A case study of microphysical structures and hydrometeor phase in convection using radar Doppler spectra at Darwin, Australia

    Science.gov (United States)

    Riihimaki, L. D.; Comstock, J. M.; Luke, E.; Thorsen, T. J.; Fu, Q.

    2017-07-01

    To understand the microphysical processes that impact diabatic heating and cloud lifetimes in convection, we need to characterize the spatial distribution of supercooled liquid water. To address this observational challenge, ground-based vertically pointing active sensors at the Darwin Atmospheric Radiation Measurement site are used to classify cloud phase within a deep convective cloud. The cloud cannot be fully observed by a lidar due to signal attenuation. Therefore, we developed an objective method for identifying hydrometeor classes, including mixed-phase conditions, using k-means clustering on parameters that describe the shape of the Doppler spectra from vertically pointing Ka-band cloud radar. This approach shows that multiple, overlapping mixed-phase layers exist within the cloud, rather than a single region of supercooled liquid. Diffusional growth calculations show that the conditions for the Wegener-Bergeron-Findeisen process exist within one of these mixed-phase microstructures.

  14. Reduced Complexity Angle-Doppler-Range Estimation for MIMO Radar That Employs Compressive Sensing

    CERN Document Server

    Yu, Yao; Poor, H Vincent

    2009-01-01

    The authors recently proposed a MIMO radar system that is implemented by a small wireless network. By applying compressive sensing (CS) at the receive nodes, the MIMO radar super-resolution can be achieved with far fewer observations than conventional approaches. This previous work considered the estimation of direction of arrival and Doppler. Since the targets are sparse in the angle-velocity space, target information can be extracted by solving an l1 minimization problem. In this paper, the range information is exploited by introducing step frequency to MIMO radar with CS. The proposed approach is able to achieve high range resolution and also improve the ambiguous velocity. However, joint angle-Doppler-range estimation requires discretization of the angle-Doppler-range space which causes a sharp rise in the computational burden of the l1 minimization problem. To maintain an acceptable complexity, a technique is proposed to successively estimate angle, Doppler and range in a decoupled fashion. The proposed ...

  15. Proposal for a spaceborne dual-beam rain radar with Doppler capability

    Science.gov (United States)

    Amayenc, Paul; Testud, Jacques; Marzoug, Mongi

    1993-06-01

    The feasibility of adding a Doppler capability to a spaceborne dual-beam radar is discussed. The dual-beam Doppler radar is capable of determining two components of the air velocity: the along-track component of the horizontal air velocity and a component directed between 0 and 20 deg off the vertical. Both components can be calculated with an accuracy of about 1.2 m/s within each resolution cell in standard conditions. THese data can be used by monitoring the mesoscale wind field within stratiform precipitation areas, or by estimating the horizontal transport of vertical momentum associated with deep convection on the climatological level. It is concluded that implementation of the Doppler capability on the radar operating at 24 GHz seems to be possible without jeopardizing the primary objective, i.e., the rain rate estimate at the global scale using a stereo-radar algorithm.

  16. Characterization of micro-Doppler radar signature of commercial wind turbines

    Science.gov (United States)

    Kong, Fanxing; Zhang, Yan; Palmer, Robert

    2014-05-01

    The large utility-scale wind turbines are reported to have negative impact on nearby radars due to complex scattering mechanisms, which is usually referred to as the radar Wind Turbine Clutter (WTC). Extremely complicated time-varying Doppler spectrum have been observed. Conventional ground clutter filter techniques thus have failed in mitigating the non-stationary components in the frequency domain. Rotation of the blades is a micro-motion as the wind turbine always stays at the same location. The time-evolving spectrum associated with the blade rotation is therefore a Micro-Doppler signature, which is important in characterizing radar WTC. This paper will disclose some latest findings from our recent studies in characterizing the Micro-Doppler radar signatures of wind turbine through electromagnetic modeling.

  17. Non-contact physiological signal detection using continuous wave Doppler radar.

    Science.gov (United States)

    Qiao, Dengyu; He, Tan; Hu, Boping; Li, Ye

    2014-01-01

    The aim of this work is to show non-contact physiological signal monitoring system based on continuous-wave (CW) Doppler radar, which is becoming highly attractive in the field of health care monitoring of elderly people. Two radar signal processing methods were introduced in this paper: one to extract respiration and heart rates of a single person and the other to separate mixed respiration signals. To verify the validity of the methods, physiological signal is obtained from stationary human subjects using a CW Doppler radar unit. The sensor operating at 24 GHz is located 0.5 meter away from the subject. The simulation results show that the respiration and heart rates are clearly extracted, and the mixed respiration signals are successfully separated. Finally, reference respiration and heart rate signals are measured by an ECG monitor and compared with the results tracked by the CW Doppler radar monitoring system.

  18. Doppler-radar wind-speed measurements in tornadoes: A comparison of real and simulated spectra

    Energy Technology Data Exchange (ETDEWEB)

    Bluestein, H.B.; LaDue, J.G.; Stein, H.; Speheger, D. (Oklahoma Univ., Norman, OK (United States)); Unruh, W.P. (Los Alamos National Lab., NM (United States))

    1993-01-01

    Bluestein and Unruh have discussed the advantages of using a portable doppler radar to map the wind field in tornadoes. during the spring of 1991 a storm-intercept team from the University of Oklahoma (OU) collected data near five supercell tornadoes in Oklahoma and Kansas. Details about the 1-W, 3-cm, 5-deg half-power beamwidth, CW/FM-CW Doppler radar we used and the methods of data collection and analysis are found in Bluestein and Unruh and Bluestein et al. Using the portable radar, we approximately doubled in only one year the number of tornado spectra that had been collected over a period of almost 20 years by NSSL's fixed-site Doppler radar. In this paper we will compare observed tornado wind spectra with simulated wind spectra (Zmic and Doviak 1975) in order to learn more about tornado structure.

  19. A Compensation Algorithm Based on RSPWVD-Hough Transform for Doppler Expansion in Passive Radar

    Directory of Open Access Journals (Sweden)

    Guan Xin

    2013-12-01

    Full Text Available For passive radar, long integration time is used to achieve high processing gain to detect weak target. But range migration and Doppler expansion may occur for high-speed targets. Keystone transform can be used to rectify range migration introduced by radial-speed. But tangential-speed may still lead to Doppler expansion, which entails a loss of integration gain. In this paper, signal model is presented to analyze the reason for Doppler expansion. Then, a Doppler expansion compensation method is introduced based on RSPWVD-Hough transform for multi-target scenario. Simulation results show that the proposed method can compensate the energy loss caused by Doppler expansion for multi-target scene, and it achieves good performance. The proposed method is also effective for weak targets, which means it can improve the detection ability of weak target in passive radar systems.

  20. AMSNEXRAD-Automated detection of meteorite strewnfields in doppler weather radar

    Science.gov (United States)

    Hankey, Michael; Fries, Marc; Matson, Rob; Fries, Jeff

    2017-09-01

    For several years meteorite recovery in the United States has been greatly enhanced by using Doppler weather radar images to determine possible fall zones for meteorites produced by witnessed fireballs. While most fireball events leave no record on the Doppler radar, some large fireballs do. Based on the successful recovery of 10 meteorite falls 'under the radar', and the discovery of radar on more than 10 historic falls, it is believed that meteoritic dust and or actual meteorites falling to the ground have been recorded on Doppler weather radar (Fries et al., 2014). Up until this point, the process of detecting the radar signatures associated with meteorite falls has been a manual one and dependent on prior accurate knowledge of the fall time and estimated ground track. This manual detection process is labor intensive and can take several hours per event. Recent technological developments by NOAA now help enable the automation of these tasks. This in combination with advancements by the American Meteor Society (Hankey et al., 2014) in the tracking and plotting of witnessed fireballs has opened the possibility for automatic detection of meteorites in NEXRAD Radar Archives. Here in the processes for fireball triangulation, search area determination, radar interfacing, data extraction, storage, search, detection and plotting are explained.

  1. The relationship between VHF radar auroral backscatter amplitude and Doppler velocity: a statistical study

    Directory of Open Access Journals (Sweden)

    B. A. Shand

    Full Text Available A statistical investigation of the relationship between VHF radar auroral backscatter intensity and Doppler velocity has been undertaken with data collected from 8 years operation of the Wick site of the Sweden And Britain Radar-auroral Experiment (SABRE. The results indicate three different regimes within the statistical data set; firstly, for Doppler velocities <200 m s–1, the backscatter intensity (measured in decibels remains relatively constant. Secondly, a linear relationship is observed between the backscatter intensity (in decibels and Doppler velocity for velocities between 200 m s–1 and 700 m s–1. At velocities greater than 700 m s–1 the backscatter intensity saturates at a maximum value as the Doppler velocity increases. There are three possible geophysical mechanisms for the saturation in the backscatter intensity at high phase speeds: a saturation in the irregularity turbulence level, a maximisation of the scattering volume, and a modification of the local ambient electron density. There is also a difference in the dependence of the backscatter intensity on Doppler velocity for the flow towards and away from the radar. The results for flow towards the radar exhibit a consistent relationship between backscatter intensity and measured velocities throughout the solar cycle. For flow away from the radar, however, the relationship between backscatter intensity and Doppler velocity varies during the solar cycle. The geometry of the SABRE system ensures that flow towards the radar is predominantly associated with the eastward electrojet, and flow away is associated with the westward electrojet. The difference in the backscatter intensity variation as a function of Doppler velocity is attributed to asymmetries between the eastward and westward electrojets and the geophysical parameters controlling the backscatter amplitude.

  2. Micro-doppler radar classification of human motions under various training scenarios

    Science.gov (United States)

    Fairchild, Dustin P.; Narayanan, Ram M.

    2013-05-01

    The identification and classification of human motions has become a popular area of research due to its broad range of applications. Knowledge of a person's movements can be a useful tool in surveillance, security, military combat, search and rescue operations, and the medical fields. Classification of common stationary human movements has been performed under various scenarios for two different micro-Doppler radar systems: S-band radar and millimeter-wave (mm-wave) radar. Each radar system has been designed for a specific scenario. The S-band radar is intended for through-the-wall situations at close distances, whereas the mm-wave radar is designed for long distance applications and also for through light foliage. Here, the performance of these radars for different training scenarios is investigated. The S-band radar will be analyzed for classification without a wall barrier, through a brick wall, and also through a cinder block wall. The effect of a wall barrier on micro-Doppler signatures will be briefly discussed. The mm-wave radar will be analyzed for classification at distances of 30, 60, and 91 meters.

  3. Simultaneous PMC and PMSE observations with a ground-based lidar and SuperDARN HF radar at Syowa Station, Antarctica

    Directory of Open Access Journals (Sweden)

    H. Suzuki

    2013-10-01

    Full Text Available A Rayleigh–Raman lidar system was installed in January 2011 at Syowa Station, Antarctica (69.0° S, 39.6° E. Polar mesospheric clouds (PMCs were detected by lidar at around 22:30 UTC (LT −3 h on 4 February 2011, which was the first day of observation. This was the first detection of PMCs over Syowa Station by lidar. On the same day, a Super Dual Auroral Radar Network (SuperDARN HF radar with oblique-incidence beams detected polar mesospheric summer echoes (PMSE between 21:30 and 23:00 UTC. This event is regarded as the last PMC activity around Syowa Station during the austral summer season (2010–2011, since no other PMC signals were detected by lidar in February 2011. This is consistent with results of PMC and mesopause temperature observations by satellite-born instruments of AIM (Aeronomy of Ice in the Mesosphere/CIPS (Cloud Imaging and Particle Size and AURA/MLS (Microwave Limb Sounder and horizontal wind measurements taken by a separate MF radar. Doppler velocity of PMSE observed by the HF radar showed motion toward Syowa Station (westward. This westward motion is consistent with the wind velocities obtained by the MF radar. However, the PMSE region showed horizontal motion from a north-to-south direction during the PMC event. This event indicates that the apparent horizontal motion of the PMSE region can deviate from neutral wind directions and observed Doppler velocities.

  4. Simultaneous PMC and PMSE observations with a ground-based lidar and SuperDARN HF radar at Syowa Station, Antarctica

    Science.gov (United States)

    Suzuki, H.; Nakamura, T.; Ejiri, M. K.; Ogawa, T.; Tsutsumi, M.; Abo, M.; Kawahara, T. D.; Tomikawa, Y.; Yukimatu, A. S.; Sato, N.

    2013-10-01

    A Rayleigh-Raman lidar system was installed in January 2011 at Syowa Station, Antarctica (69.0° S, 39.6° E). Polar mesospheric clouds (PMCs) were detected by lidar at around 22:30 UTC (LT -3 h) on 4 February 2011, which was the first day of observation. This was the first detection of PMCs over Syowa Station by lidar. On the same day, a Super Dual Auroral Radar Network (SuperDARN) HF radar with oblique-incidence beams detected polar mesospheric summer echoes (PMSE) between 21:30 and 23:00 UTC. This event is regarded as the last PMC activity around Syowa Station during the austral summer season (2010-2011), since no other PMC signals were detected by lidar in February 2011. This is consistent with results of PMC and mesopause temperature observations by satellite-born instruments of AIM (Aeronomy of Ice in the Mesosphere)/CIPS (Cloud Imaging and Particle Size) and AURA/MLS (Microwave Limb Sounder) and horizontal wind measurements taken by a separate MF radar. Doppler velocity of PMSE observed by the HF radar showed motion toward Syowa Station (westward). This westward motion is consistent with the wind velocities obtained by the MF radar. However, the PMSE region showed horizontal motion from a north-to-south direction during the PMC event. This event indicates that the apparent horizontal motion of the PMSE region can deviate from neutral wind directions and observed Doppler velocities.

  5. Very low-phase noise, coherent 94GHz radar for micro-Doppler and vibrometry studies

    Science.gov (United States)

    Robertson, Duncan A.; Brooker, Graham M.; Beasley, Patrick D. L.

    2014-05-01

    Micro-Doppler and vibrometry measurements require coherent radars with low phase noise. We report the development of a novel, very low phase noise 94 GHz radar, called T-220, which offers superior performance for micro-Doppler and vibrometry studies compared with our previous work. The radar uses a combination of direct digital synthesis (DDS) chirp generation, frequency upconversion and frequency multiplication to yield very low phase noise and rapid, contiguous chirps, necessary for Doppler studies and other coherent processing applications. Dual fan beam antennas are used to achieve negligible transmit-receive leakage, with fine azimuth resolution and modest elevation coverage. The resulting PPI imagery is very high fidelity with little or no evidence of phase noise effects.

  6. Sparse Representation Based Range-Doppler Processing for Integrated OFDM Radar-Communication Networks

    Directory of Open Access Journals (Sweden)

    Bo Kong

    2017-01-01

    Full Text Available In an integrated radar-communication network, multiuser access techniques with minimal performance degradation and without range-Doppler ambiguities are required, especially in a dense user environment. In this paper, a multiuser access scheme with random subcarrier allocation mechanism is proposed for orthogonal frequency division multiplexing (OFDM based integrated radar-communication networks. The expression of modulation Symbol-Domain method combined with sparse representation (SR for range-Doppler estimation is introduced and a parallel reconstruction algorithm is employed. The radar target detection performance is improved with less spectrum occupation. Additionally, a Doppler frequency detector is exploited to decrease the computational complexity. Numerical simulations show that the proposed method outperforms the traditional modulation Symbol-Domain method under ideal and realistic nonideal scenarios.

  7. Noncontact Detection and Analysis of Respiratory Function Using Microwave Doppler Radar

    Directory of Open Access Journals (Sweden)

    Yee Siong Lee

    2015-01-01

    Full Text Available Real-time respiratory measurement with Doppler Radar has an important advantage in the monitoring of certain conditions such as sleep apnoea, sudden infant death syndrome (SIDS, and many other general clinical uses requiring fast nonwearable and non-contact measurement of the respiratory function. In this paper, we demonstrate the feasibility of using Doppler Radar in measuring the basic respiratory frequencies (via fast Fourier transform for four different types of breathing scenarios: normal breathing, rapid breathing, slow inhalation-fast exhalation, and fast inhalation-slow exhalation conducted in a laboratory environment. A high correlation factor was achieved between the Doppler Radar-based measurements and the conventional measurement device, a respiration strap. We also extended this work from basic signal acquisition to extracting detailed features of breathing function (I : E ratio. This facilitated additional insights into breathing activity and is likely to trigger a number of new applications in respiratory medicine.

  8. Micro-Doppler Ambiguity Resolution for Wideband Terahertz Radar Using Intra-Pulse Interference.

    Science.gov (United States)

    Yang, Qi; Qin, Yuliang; Deng, Bin; Wang, Hongqiang; You, Peng

    2017-04-29

    Micro-Doppler, induced by micro-motion of targets, is an important characteristic of target recognition once extracted via parameter estimation methods. However, micro-Doppler is usually too significant to result in ambiguity in the terahertz band because of its relatively high carrier frequency. Thus, a micro-Doppler ambiguity resolution method for wideband terahertz radar using intra-pulse interference is proposed in this paper. The micro-Doppler can be reduced several dozen times its true value to avoid ambiguity through intra-pulse interference processing. The effectiveness of this method is proved by experiments based on a 0.22 THz wideband radar system, and its high estimation precision and excellent noise immunity are verified by Monte Carlo simulation.

  9. Micro-Doppler Ambiguity Resolution for Wideband Terahertz Radar Using Intra-Pulse Interference

    Directory of Open Access Journals (Sweden)

    Qi Yang

    2017-04-01

    Full Text Available Micro-Doppler, induced by micro-motion of targets, is an important characteristic of target recognition once extracted via parameter estimation methods. However, micro-Doppler is usually too significant to result in ambiguity in the terahertz band because of its relatively high carrier frequency. Thus, a micro-Doppler ambiguity resolution method for wideband terahertz radar using intra-pulse interference is proposed in this paper. The micro-Doppler can be reduced several dozen times its true value to avoid ambiguity through intra-pulse interference processing. The effectiveness of this method is proved by experiments based on a 0.22 THz wideband radar system, and its high estimation precision and excellent noise immunity are verified by Monte Carlo simulation.

  10. Combined vertical-velocity observations with Doppler lidar, cloud radar and wind profiler

    Directory of Open Access Journals (Sweden)

    J. Bühl

    2015-01-01

    Full Text Available Case studies of combined vertical-velocity measurements of Doppler lidar, cloud radar and wind profiler are presented. The measurements were taken at the Meteorological Observatory Lindenberg, Germany. Synergistic products are presented that are derived from the vertical-velocity measurements of the three instruments: A comprehensive classification mask of vertically moving atmospheric targets and the terminal fall velocity of water droplets and ice crystals corrected for vertical air motion. It is shown that the measurements of the Doppler lidar can extent the view of the cloud radar and the wind profiler, especially when observing clouds.

  11. Rain Forecasting for Ho Chi Minh City Using Doppler Weather Radar Dwsr-2500C

    Directory of Open Access Journals (Sweden)

    Dung Dang Quoc

    2016-03-01

    Full Text Available Rainfall amounts vary randomly over time and space. Rainfall monitoring and forecasting is a difficult task, especially for a short-term period from 30 minutes to 3 hours. Recently Doppler weather radars have been used as one of the new solutions in the short-term forecasting of extreme rain or storm. This research presents some results of forecasting the wind direction, velocity, and rainfall of a typical rainy day, 14 September 2010, based on CAPPI images of a DWSR-2500C radar in the Nha Be district, Ho Chi Minh City (HCMC. The results showed that the Doppler radar, in a scanning radius of 30 km, is very effective in forecasting extreme rainfall for each region and district when reflected radar signals from clouds moving towards the city are detected. This research provides useful information in the forecast of extreme rainfall for flood prevention works in the HCM City.

  12. A quantitative analysis of the impact of wind turbines on operational Doppler weather radar data

    Directory of Open Access Journals (Sweden)

    L. Norin

    2014-08-01

    Full Text Available In many countries wind turbines are rapidly growing in numbers as the demand for energy from renewable sources increases. The continued deployment of wind turbines can, however, be problematic for many radar systems, which are easily disturbed by turbines located in radar line-of-sight. Wind turbines situated in the vicinity of Doppler weather radars can lead to erroneous precipitation estimates as well as to inaccurate wind- and turbulence measurements. This paper presents a quantitative analysis of the impact of a wind farm, located in southeastern Sweden, on measurements from a nearby Doppler weather radar. The analysis is based on six years of operational radar data. In order to evaluate the impact of the wind farm, average values of all three spectral moments (the radar reflectivity factor, absolute radial velocity, and spectrum width of the nearby Doppler weather radar were calculated, using data before and after the construction of the wind farm. It is shown that all spectral moments, from a large area at and downrange from the wind farm, were impacted by the wind turbines. It was also found that data from radar cells far above the wind farm (near 3 km altitude were affected by the wind farm. We show that this is partly explained by changes in the atmospheric refractive index, bending the radar beams closer to the ground. In a detailed analysis, using data from a single radar cell, frequency distributions of all spectral moments were used to study the competition between the weather signal and wind turbine clutter. We show that when weather echoes give rise to higher reflectivity values than that of the wind farm, the negative impact of the wind turbines disappears for all spectral moments.

  13. Projectile Impact Point Prediction Based on Self-Propelled Artillery Dynamics and Doppler Radar Measurements

    Directory of Open Access Journals (Sweden)

    Mostafa Khalil

    2013-01-01

    Full Text Available Any trajectory calculation method has three primary sources of errors, which are model error, parameter error, and initial state error. In this paper, based on initial projectile flight trajectory data measured using Doppler radar system; a new iterative method is developed to estimate the projectile attitude and the corresponding impact point to improve the second shot hit probability. In order to estimate the projectile initial state, the launch dynamics model of practical 155 mm self-propelled artillery is defined, and hence, the vibration characteristics of the self-propelled artillery is obtained using the transfer matrix method of linear multibody system MSTMM. A discrete time transfer matrix DTTM-4DOF is developed using the modified point mass equations of motion to compute the projectile trajectory and set a direct algebraic relation between any two successive radar data. During iterations, adjustments to the repose angle are made until an agreement with acceptable tolerance occurs between the Doppler radar measurements and the estimated values. Simulated Doppler radar measurements are generated using the nonlinear six-degree-of-freedom trajectory model using the resulted initial disturbance. Results demonstrate that the data estimated using the proposed algorithm agrees well with the simulated Doppler radar data obtained numerically using the nonlinear six-degree-of-freedom model.

  14. Mapping plasma structures in the high-latitude ionosphere using beacon satellite, incoherent scatter radar and ground-based magnetometer observations

    Directory of Open Access Journals (Sweden)

    T. Neubert

    2002-06-01

    Full Text Available In the autumn of the year 2000, four radio receivers capable of tracking various beacon satellites were set up along the southwestern coast of Greenland. They are used to reconstruct images of the ionospheric plasma density distribution via the tomographic method. In order to test and validate tomographic imaging under the highly variable conditions often prevailing in the high-latitude ionosphere, a time interval was selected when the Sondrestrom incoherent scatter radar conducted measurements of the ionospheric plasma density while the radio receivers tracked a number of beacon satellites. A comparison between two-dimensional images of the plasma density distribution obtained from the radar and the satellite receivers revealed generally good agreement between radar measurements and tomographic images. Observed discrepancies can be attributed to F region plasma patches moving through the field of view with a speed of several hundred meters per second, thereby smearing out the tomographic image. A notable mismatch occurred around local magnetic midnight when a magnetospheric substorm breakup occurred in the vicinity of southwest Greenland (identified from ground-based magnetometer observations. The breakup was associated with a sudden intensification of the westward auroral electrojet which was centered at about 69 and extended up to some 73 corrected geomagnetic latitude. Ground-based magnetometer data may thus have the potential of indicating when the tomographic method is at risk and may fail. We finally outline the application of tomographic imaging, when combined with magnetic field data, to estimate ionospheric Joule heating rates.

  15. Analysis of Terminal Velocity and VHF Backscatter of Precipitation Particles Using Chung-Li VHF Radar Combined with Ground-Based Disdrometer

    Directory of Open Access Journals (Sweden)

    Ching-Lun Su and Yen-Hsyang Chu

    2007-01-01

    Full Text Available The backscatter from precipitation particles observed by the vertically pointed antenna beam of the Chung-Li VHF radar and the drop size distributions measured by a ground-based disdrometer co-located at the radar site are analyzed and studied in this article. We find that the disdrometermeasured drop size distribution can be well approximated to a Gamma distribution. On the basis of this property and a power law approximation to the fallspeed-diameter relation VD = ADB, we derive the theoretical relation between terminal velocity VD and range-corrected VHF backscatter P of the precipitation particles. We find that the VD - P relation follows a power law in the form of VD = _ where _ _ both the functions of the precipitation parameters. Chu et al. (1999 first found that the relation between _ _ be empirically approximated to an exponential form of _ _ where _ a function of B and _ a factor associated with precipitation. In this article, under the assumptions of the Gamma distribution of the drop size distribution and the power-law relation between VD and D, we theoretically show that the analytical relation between _ _ follows an exponential form of _ _ where _ a function of the drop size distribution. The experimental results obtained by the Chung-Li VHF radar combined with the ground-based disdrometer measurements validate the exponential approximation to the _ _ The uses of the _ _ for the investigations of the rainfall rate and properties of drop size distribution are presented and discussed.

  16. The PARAFAC-MUSIC Algorithm for DOA Estimation with Doppler Frequency in a MIMO Radar System

    Directory of Open Access Journals (Sweden)

    Nan Wang

    2014-01-01

    Full Text Available The PARAFAC-MUSIC algorithm is proposed to estimate the direction-of-arrival (DOA of the targets with Doppler frequency in a monostatic MIMO radar system in this paper. To estimate the Doppler frequency, the PARAFAC (parallel factor algorithm is firstly utilized in the proposed algorithm, and after the compensation of Doppler frequency, MUSIC (multiple signal classification algorithm is applied to estimate the DOA. By these two steps, the DOA of moving targets can be estimated successfully. Simulation results show that the proposed PARAFAC-MUSIC algorithm has a higher accuracy than the PARAFAC algorithm and the MUSIC algorithm in DOA estimation.

  17. Micro-Doppler Estimation and Analysis of Slow Moving Objects in Forward Scattering Radar System

    Directory of Open Access Journals (Sweden)

    Raja Syamsul Azmir Raja Abdullah

    2017-07-01

    Full Text Available Micro-Doppler signature can convey information of detected targets and has been used for target recognition in many Radar systems. Nevertheless, micro-Doppler for the specific Forward Scattering Radar (FSR system has yet to be analyzed and investigated in detail; consequently, information carried by the micro-Doppler in FSR is not fully understood. This paper demonstrates the feasibility and effectiveness of FSR in detecting and extracting micro-Doppler signature generated from a target’s micro-motions. Comprehensive theoretical analyses and simulation results followed by experimental investigations into the feasibility of using the FSR for detecting micro-Doppler signatures are presented in this paper. The obtained results verified that the FSR system is capable of detecting micro-Doppler signature of a swinging pendulum placed on a moving trolley and discriminating different swinging speeds. Furthermore, human movement and micro-Doppler from hand motions can be detected and monitored by using the FSR system which resembles a potential application for human gait monitoring and classification.

  18. Aerosol backscatter measurements at 10. 6 micrometers with airborne and ground-based CO sub 2 Doppler lidars over the Colorado high plains. 1. Lidar intercomparison

    Energy Technology Data Exchange (ETDEWEB)

    Bowdle, D.A. (Univ. of Alabama, Huntsville (USA)); Rothermel, J. (NASA Marshall Space Flight Center, Huntsville, AL (USA)); Vaughan, J.M.; Brown, D.W. (Royal Signals and Radar Establishment, Worcestershire (England)); Post, M.J. (National Oceanic and Atmospheric Administration, Boulder, CO (USA))

    1991-03-20

    An airborne continuous wave (CW) focused CO{sub 2} Doppler lidar and a ground-based pulsed CO{sub 2} Doppler lidar were used to obtain seven pairs of comparative measurements of tropospheric aerosol backscatter profiles at 10.6 {mu}m wavelength, near Denver, Colorado, during a 20-day period in July 1982. In regions of uniform backscatter the two lidars show good agreement, with differences usually less than {approximately}50% near 8-km altitude and less than a factor of 2 or 3 elsewhere but with the pulsed lidar often lower than the CW lidar. Near sharp backscatter gradients the two lidars show poorer agreement, with the pulsed lidar usually higher than the CW lidar. Most discrepancies arise from a combination of atmospheric factors and instrument factors, particularly small-scale areal and temporal backscatter heterogeneity above the planetary boundary layer, unusual large-scale vertical backscatter structure in the upper troposphere and lower stratosphere, and differences in the spatial resolution, detection threshold, and noise estimation for the two lidars.

  19. A 35-GHz Polarimetric Doppler Radar and Its Application for Observing Clouds Associated with Typhoon Nuri

    Institute of Scientific and Technical Information of China (English)

    ZHONG Lingzhi; LIU Liping; FENG Sheng; GE Runsheng; ZHANG Zhe

    2011-01-01

    Millimeter-wavelength radar has proved to be an effective instrument for cloud observation and research.In this study, 8-mm-wavelength cloud radar (MMCR) with Doppler and polarization capabilities was used to investigate cloud dynamics in China for the first time. Its design, system specifications, calibration,and application in measuring clouds associated with typhoon are discussed in this article. The cloud radar measurements of radar refiectivity (Z), Doppler velocity (Vr), velocity spectrum width (Sw) and the depolarization ratio (LDR) at vertical incidence were used to analyze the microphysical and dynamic processes of the cloud system and precipitation associated with Typhoon Nuri, which occurred in southern China in August 2008. The results show the refiectivity observed using MMCR to be consistent with the echo height and the melting-layer location data obtained by the nearby China S-band new-generation weather radar (SA),but the Ka-band MMCR provided more detailed structural information about clouds and weak precipitation data than did the SA radar. The variation of radar refiectivity and LDR in vertical structure reveals the transformation of particle phase from ice to water. The vertical velocity and velocity spectrum width of MMCR observations indicate an updraft and strong turbulence in the stratiform cloud layer. MMCR provides a valuable new technology for meteorological research in China.

  20. Improved Micro Rain Radar snow measurements using Doppler spectra post-processing

    Directory of Open Access Journals (Sweden)

    M. Maahn

    2012-11-01

    Full Text Available The Micro Rain Radar 2 (MRR is a compact Frequency Modulated Continuous Wave (FMCW system that operates at 24 GHz. The MRR is a low-cost, portable radar system that requires minimum supervision in the field. As such, the MRR is a frequently used radar system for conducting precipitation research. Current MRR drawbacks are the lack of a sophisticated post-processing algorithm to improve its sensitivity (currently at +3 dBz, spurious artefacts concerning radar receiver noise and the lack of high quality Doppler radar moments. Here we propose an improved processing method which is especially suited for snow observations and provides reliable values of effective reflectivity, Doppler velocity and spectral width. The proposed method is freely available on the web and features a noise removal based on recognition of the most significant peak. A dynamic dealiasing routine allows observations even if the Nyquist velocity range is exceeded. Collocated observations over 115 days of a MRR and a pulsed 35.2 GHz MIRA35 cloud radar show a very high agreement for the proposed method for snow, if reflectivities are larger than −5 dBz. The overall sensitivity is increased to −14 and −8 dBz, depending on range. The proposed method exploits the full potential of MRR's hardware and substantially enhances the use of Micro Rain Radar for studies of solid precipitation.

  1. Radar Micro-Doppler Feature Extraction Using the Spectrogram and the Cepstrogram

    NARCIS (Netherlands)

    Harmanny, R.I.A.; Wit, J.J.M. de; Prémel Cabic, G.

    2014-01-01

    The radar micro-Doppler signature of a target is determined by parts of the target moving or rotating in addition to the main body motion. The relative motion of parts is characteristic for different classes of targets, e.g. the flapping motion of a bird's wings vs. the spinning of propeller blades.

  2. Through Wall Radar Classification of Human Micro-Doppler Using Singular Value Decomposition Analysis

    National Research Council Canada - National Science Library

    Ritchie, Matthew; Ash, Matthew; Chen, Qingchao; Chetty, Kevin

    2016-01-01

    ...) Frequency Modulated Continuous Wave (FMCW) C-Band radar system named Soprano. The objective of this analysis was to classify whether an individual was carrying an item in both hands or not using micro-Doppler information from a FMCW sensor...

  3. Radar Micro-Doppler Feature Extraction Using the Spectrogram and the Cepstrogram

    NARCIS (Netherlands)

    Harmanny, R.I.A.; Wit, J.J.M. de; Prémel Cabic, G.

    2014-01-01

    The radar micro-Doppler signature of a target is determined by parts of the target moving or rotating in addition to the main body motion. The relative motion of parts is characteristic for different classes of targets, e.g. the flapping motion of a bird's wings vs. the spinning of propeller blades.

  4. Radar Micro-Doppler Mini-UAV Classification using Spectrograms and Cepstrograms

    NARCIS (Netherlands)

    Harmanny, R.I.A.; Wit, J.J.M. de; Prémel-Cabic, G.

    2015-01-01

    The radar micro-Doppler signature of a target is determined by parts of the target moving or rotating in addition to the main body motion. The relative motion of these parts is characteristic for different classes of targets, e.g. the flapping motion of a bird’s wings versus the spinning of

  5. Microwave Doppler Radar for Heart Beat Detection Versus Electrocardiogram: A Validation Approach

    OpenAIRE

    Obeid, Dany; Sadek, Sawsan; Zaharia, Gheorghe; El Zein, Ghais

    2013-01-01

    International audience; This paper provides a validation approach for a microwave Doppler Radar system used for heartbeat detection. The proposed system is tested at 16 GHz with several transmitted power, simultaneously with a pc-based electrocardiogram. Obtained results show accurate detection for the heartbeat signal in terms of heartbeat rate and heart rate variability.

  6. THE STATISTIC RELATION BETWEEN LIGHTNING AND CINRAD DOPPLER RADAR ECHOES IN CENTRAL GUANGDONG

    Institute of Scientific and Technical Information of China (English)

    PENG Li-ying; WAN Qi-lin; WANG Qian-qian; YI Yan-ming

    2007-01-01

    Based on the CINRAD Doppler radar data in Guangzhou and the lightning data in 2004 by power suppliers of Guangdong, statistical study is done by overlaying lightning's position on radar's echo. The result shows the followings. The concentrated period in which more negative lightning occurred at the middle levels (2 - 14 km), where radar echo was moderate (12 - 45 dBz), rather than at the low levels with the weakest echoes or at high levels with the strongest echoes. At levels 3 - 11 km, where the radar echo was between 10 dBz and 35 dBz, the area of negative lightning was much larger in central Guangdong than in the rest of the province. At levels 0.5 - 7 km where the radar echoes were between 44 dBz and 51 dBz,the probability for a point to have negative lightning varies from 0.4 to 0.7.

  7. Exploring microphysical, radiative, dynamic and thermodynamic processes driving fog and low stratus clouds using ground-based Lidar and Radar measurements

    Science.gov (United States)

    Haeffelin, Martial

    2016-04-01

    Radiation fog formation is largely influenced by the chemical composition, size and number concentration of cloud condensation nuclei and by heating/cooling and drying/moistening processes in a shallow mixing layer near the surface. Once a fog water layer is formed, its development and dissipation become predominantly controlled by radiative cooling/heating, turbulent mixing, sedimentation and deposition. Key processes occur in the atmospheric surface layer, directly in contact with the soil and vegetation, and throughout the atmospheric column. Recent publications provide detailed descriptions of these processes for idealized cases using very high-resolution models and proper representation of microphysical processes. Studying these processes in real fog situations require atmospheric profiling capabilities to monitor the temporal evolution of key parameters at several heights (surface, inside the fog, fog top, free troposphere). This could be done with in-situ sensors flown on tethered balloons or drones, during dedicated intensive field campaigns. In addition Backscatter Lidars, Doppler Lidars, Microwave Radiometers and Cloud Doppler Radars can provide more continuous, yet precise monitoring of key parameters throughout the fog life cycle. The presentation will describe how Backscatter Lidars can be used to study the height and kinetics of aerosol activation into fog droplets. Next we will show the potential of Cloud Doppler Radar measurements to characterize the temporal evolution of droplet size, liquid water content, sedimentation and deposition. Contributions from Doppler Lidars and Microwave Radiometers will be discussed. This presentation will conclude on the potential to use Lidar and Radar remote sensing measurements to support operational fog nowcasting.

  8. ASSIMILATION OF DOPPLER RADAR DATA INTO NUMERICAL WEATHER MODELS

    Energy Technology Data Exchange (ETDEWEB)

    Chiswell, S.; Buckley, R.

    2009-01-15

    During the year 2008, the United States National Weather Service (NWS) completed an eight fold increase in sampling capability for weather radars to 250 m resolution. This increase is expected to improve warning lead times by detecting small scale features sooner with increased reliability; however, current NWS operational model domains utilize grid spacing an order of magnitude larger than the radar data resolution, and therefore the added resolution of radar data is not fully exploited. The assimilation of radar reflectivity and velocity data into high resolution numerical weather model forecasts where grid spacing is comparable to the radar data resolution was investigated under a Laboratory Directed Research and Development (LDRD) 'quick hit' grant to determine the impact of improved data resolution on model predictions with specific initial proof of concept application to daily Savannah River Site operations and emergency response. Development of software to process NWS radar reflectivity and radial velocity data was undertaken for assimilation of observations into numerical models. Data values within the radar data volume undergo automated quality control (QC) analysis routines developed in support of this project to eliminate empty/missing data points, decrease anomalous propagation values, and determine error thresholds by utilizing the calculated variances among data values. The Weather Research and Forecasting model (WRF) three dimensional variational data assimilation package (WRF-3DVAR) was used to incorporate the QC'ed radar data into input and boundary conditions. The lack of observational data in the vicinity of SRS available to NWS operational models signifies an important data void where radar observations can provide significant input. These observations greatly enhance the knowledge of storm structures and the environmental conditions which influence their development. As the increase in computational power and availability has

  9. A simple method for retrieving significant wave height from Dopplerized X-band radar

    Science.gov (United States)

    Carrasco, Ruben; Streßer, Michael; Horstmann, Jochen

    2017-02-01

    Retrieving spectral wave parameters such as the peak wave direction and wave period from marine radar backscatter intensity is very well developed. However, the retrieval of significant wave height is difficult because the radar image spectrum (a backscatter intensity variance spectrum) has to be transferred to a wave spectrum (a surface elevation variance spectrum) using a modulation transfer function (MTF) which requires extensive calibration for each individual radar setup. In contrast to the backscatter intensity, the Doppler velocity measured by a coherent radar is induced by the radial velocity (or line-of-sight velocity) of the surface scattering and its periodic component is mainly the contribution of surface waves. Therefore, the variance of the Doppler velocity can be utilized to retrieve the significant wave height. Analyzing approximately 100 days of Doppler velocity measurements of a coherent-on-receive radar operating at X-band with vertical polarization in transmit and receive, a simple relation was derived and validated to retrieve significant wave heights. Comparison to wave measurements of a wave rider buoy as well as an acoustic wave and current profiler resulted in a root mean square error of 0.24 m with a bias of 0.08 m. Furthermore, the different sources of error are discussed and investigated.

  10. The Next Generation of Airborne Polarimetric Doppler Weather Radar: NCAR/EOL Airborne Phased Array Radar (APAR) Development

    Science.gov (United States)

    Moore, James; Lee, Wen-Chau; Loew, Eric; Vivekanandan, Jothiram; Grubišić, Vanda; Tsai, Peisang; Dixon, Mike; Emmett, Jonathan; Lord, Mark; Lussier, Louis; Hwang, Kyuil; Ranson, James

    2017-04-01

    The National Center for Atmospheric Research (NCAR) Earth observing Laboratory (EOL) is entering the third year of preliminary system design studies, engineering prototype testing and project management plan preparation for the development of a novel Airborne Phased Array Radar (APAR). This system being designed by NCAR/EOL will be installed and operated on the NSF/NCAR C-130 aircraft. The APAR system will consist of four removable C-band Active Electronically Scanned Arrays (AESA) strategically placed on the fuselage of the aircraft. Each AESA measures approximately 1.5 x 1.9 m and is composed of 3000 active radiating elements arranged in an array of line replaceable units (LRU) to simplify maintenance. APAR will provide unprecedented observations, and in conjunction with the advanced radar data assimilation schema, will be able to address the key science questions to improve understanding and predictability of significant and high-impact weather APAR, operating at C-band, allows the measurement of 3-D kinematics of the more intense portions of storms (e.g. thunderstorm dynamics and tornadic development, tropical cyclone rainband structure and evolution) with less attenuation compared with current airborne Doppler radar systems. Polarimetric measurements are not available from current airborne tail Doppler radars. However, APAR, with dual-Doppler and dual polarization diversity at a lesser attenuating C-band wavelength, will further advance the understanding of the microphysical processes within a variety of precipitation systems. The radar is sensitive enough to provide high resolution measurements of winter storm dynamics and microphysics. The planned APAR development that would bring the system to operational readiness for research community use aboard the C-130 is expected to take 8 years once major funding support is realized. The authors will review the overall APAR design and provide new details of the system based on our Technical Requirements Document

  11. Study on the method of polarization suppression of cheating jamming in pulse Doppler radar

    Institute of Scientific and Technical Information of China (English)

    Song Lizhong; Qiao Xiaolin; Meng Xiande; Jin Ming

    2005-01-01

    A jamming suppression method based on polarization signal detection is proposed under common range and velocity cheating jammingfor pulse Doppler radar. On the basis of the separation of the target and the jamming, the range and velocity track on the true target are realized. Firstly the signal processing model of the full polarization pulse Doppler radar is introduced. Secondly the method of correct target separation is discussed, which is the twice detections of energy and polarization state on the two dimension resolution cells of range and velocity of the radar echo. Finally the simulations are performed and the results prove the validity. What' s more, multiple range and velocity cheating jamming can be suppressed at the same time if the target and the jamming are different in the polarization domain.

  12. Nonsearching Doppler parameter and velocity estimation method for synthetic aperture radar ground moving target imaging

    Science.gov (United States)

    Li, Zhongyu; Wu, Junjie; Huang, Yunlin; Yang, Haiguang; Yang, Jianyu

    2016-07-01

    For synthetic aperture radar (SAR), ground moving target (GMT) imaging necessitates the compensation of the additional azimuth modulation contributed by the unknown movement of the GMT. That is to say, it is necessary to estimate the Doppler parameters of the GMT without a priori knowledge of the GMT's motion parameters. This paper presents a Doppler parameter and velocity estimation method to refocus the GMT from its smeared response in SAR image. The main idea of this method is that an azimuth reference function is constructed to do the correlation integral with the azimuth signal of the GMT. And in general, the Doppler parameters of the presumed azimuth reference function are different from those of the GMT's azimuth signal since the velocity parameters of the GMT are unknown. Therefore, the correlation operation referred to here is actually mismatched, and the processing result of is shifted and defocused. The shifted and defocused result is utilized to get the real Doppler parameters and the velocity parameters of the GMT. One advantage of this method is that it is a nonsearching method. Another advantage is that both the Doppler centroid and the Doppler frequency rate of the GMT can be simultaneously estimated according to the relationships between the Doppler parameters and the smeared response of the GMT. In addition, the velocity of the GMT can also be obtained based on the estimated Doppler parameters. Numerical simulations and experimental data processing verify the validity of the method proposed.

  13. Retrieving Microphysical Properties and Air Motion of Cirrus Clouds Based on the Doppler Moments Method Using Cloud Radar

    Institute of Scientific and Technical Information of China (English)

    ZHONG Lingzhi; LIU Liping; DENG Min; ZHOU Xiuji

    2012-01-01

    Radar parameters including radar reflectivity,Doppler velocity,and Doppler spectrum width were obtained from Doppler spectrum moments.The Doppler spectrum moment is the convolution of both the particle spectrum and the mean air vertical motion.Unlike strong precipitation,the motion of particles in cirrus clouds is quite close to the air motion around them.In this study,a method of Doppler moments was developed and used to retrieve cirrus cloud microphysical properties such as the mean air vertical velocity,mass-weighted diameter,effective particle size,and ice content. Ice content values were retrieved using both the Doppler spectrum method and classic Z-IWC (radar reflectivity-ice water content) relationships;however,the former is a more reasonable method.

  14. Velocity profiles inside volcanic clouds from three-dimensional scanning microwave dual-polarization Doppler radars

    Science.gov (United States)

    Montopoli, Mario

    2016-07-01

    In this work, velocity profiles within a volcanic tephra cloud obtained by dual-polarization Doppler radar acquisitions with three-dimensional (3-D) mechanical scanning capability are analyzed. A method for segmenting the radar volumes into three velocity regimes: vertical updraft, vertical fallout, and horizontal wind advection within a volcanic tephra cloud using dual-polarization Doppler radar moments is proposed. The horizontal and vertical velocity components within the regimes are retrieved using a novel procedure that makes assumptions concerning the characteristics of the winds inside these regimes. The vertical velocities retrieved are combined with 1-D simulations to derive additional parameters including particle fallout, mass flux, and particle sizes. The explosive event occurred on 23 November 2013 at the Mount Etna volcano (Sicily, Italy), is considered a demonstrative case in which to analyze the radar Doppler signal inside the tephra column. The X-band radar (3 cm wavelength) in the Catania, Italy, airport observed the 3-D scenes of the Etna tephra cloud ~32 km from the volcano vent every 10 min. From the radar-derived vertical velocity profiles of updraft, particle fallout, and horizontal transportation, an exit velocity of 150 m/s, mass flux rate of 1.37 • 107 kg/s, particle fallout velocity of 18 m/s, and diameters of precipitating tephra particles equal to 0.8 cm are estimated on average. These numbers are shown to be consistent with theoretical 1-D simulations of plume dynamics and local reports at the ground, respectively. A thickness of 3 ± 0.36 km for the downwind ash cloud is also inferred by differentiating the radar-derived cloud top and the height of transition between the convective and buoyancy regions, the latter being inferred by the estimated vertical updraft velocity profile. The unique nature of the case study as well as the novelty of the segmentation and retrieval methods presented potentially give new insights into the

  15. Micro-Doppler measurement of insect wing-beat frequencies with W-band coherent radar.

    Science.gov (United States)

    Wang, Rui; Hu, Cheng; Fu, Xiaowei; Long, Teng; Zeng, Tao

    2017-05-03

    The wingbeat frequency of insect migrant is regarded potentially valuable for species identification and has long drawn widespread attention in radar entomology. Principally, the radar echo signal can be used to extract wingbeat information, because both the signal amplitude and phase could be modulated by wing-beating. With respect to existing entomological radars, signal amplitude modulation has been used for wingbeat frequency measurement of large insects for many years, but the wingbeat frequency measurement of small insects remains a challenge. In our research, W-band and S-band coherent radars are used to measure the insect wingbeat frequency. The results show that the wingbeat-induced amplitude modulation of W-band radar is more intense than that of the S-band radar and the W-band radar could measure the wingbeat frequency of smaller insects. In addition, it is validated for the first time that the signal phase could also be used to measure the insect wingbeat frequency based on micro-Doppler effect. However, whether the wingbeat frequency measurement is based on the amplitude or phase modulation, it is found that the W-band coherent radar has better performance on both the measurement precision and the measurable minimum size of the insect.

  16. Novel Analytic Method for Determining Micro-Doppler Measurement Sensitivity in Life-detection Radar

    Directory of Open Access Journals (Sweden)

    Hu Cheng

    2016-10-01

    Full Text Available In recent years, a new non-contact life detecting device has been developed, known as life-detection radar, which can measure bodily movement and locate human subjects. Typically, the amplitude of the vibration being measured is quite small, so the measurement is easily contaminated by noise in the radar system. To date, there is no effective index for judging the influence of noise on the vibration measurements in this radar system. To solve this problem, in this paper, we define the micro-Doppler measurement sensitivity to analyze the influence of noise on the measurement. We then perform a simulation to generate a performance curve for the radar system.

  17. Study on the Variational Assimilation Technique for the Retrieval of Wind Fields from Doppler Radar Data

    Institute of Scientific and Technical Information of China (English)

    WAN Qilin; XUE Jishan; ZHUANG Shiyu

    2006-01-01

    This paper introduces a variational assimilation technique for the retrieval of wind fields from Doppler radar data. The assimilated information included both the radial velocity (RV) and the movement of radar echo. In this assimilation technique, the key is transforming the movement of radar echo to a new radar measuring variable- "apparent velocity" (AV). Thus, the information of wind is added, and the indeterminacy of recovering two-dimensional wind only by AV was overcome effectively by combining RV with AV. By means of CMA GRAPES-3Dvar and CINRAD data, some experiments were performed. The results show that the method of retrieval of wind fields is useful in obtaining the construction of the weather system.

  18. HF Doppler radar observations of sporadic E at an Indian low latitude station, Visakhapatnam

    Directory of Open Access Journals (Sweden)

    M. S. S. R. K. N Sarma

    2009-02-01

    Full Text Available 5.5 MHz HF Doppler radar observations of Sporadic E over an Indian low latitude station, Visakhapatnam (17.7° N, 83.3° E and Dip 20° with 10 s resolution showed quasi-periodic variations of the echo strength and Doppler velocity variations with periods of a few minutes to a few tens of minutes. The echo strength and Doppler velocity variations with time in different range bins of the ES echo showed variations which are some times similar and some times significantly different in successive range bins at intervals of 7.5 km. The ES echo occurs with the height of maximum echo strength in the range of 100 km to 120 km and some times at 130 km. The altitude variation of the average Doppler velocity is highly variable and the height of maximum echo strength is not the same as the height of maximum Doppler velocity. Observations of ES echoes at different times of the day are presented to bring out the differences between the day and night time ES echoes. The relationship between Radar and ES parameters derived from Ionograms is poorer than that of mid latitudes which is quite consistent with the expectations based on gradient drift instability.

  19. Aerosol backscatter measurements at 10. 6 micrometers with airborne and ground-based CO sub 2 Doppler lidars over the Colorado high plains. 2. Backscatter structure

    Energy Technology Data Exchange (ETDEWEB)

    Bowdle, D.A. (Univ. of Alabama, Huntsville (USA)); Rothermel, J. (NASA Marshall Space Flight Center, Huntsville, AL (USA)); Vaughan, J.M. (Royal Signals and Radar Establishment, Worcestershire (England)); Post, M.J. (National Oceanic and Atmospheric Administration, Boulder, CO (USA))

    1991-03-20

    Measurements of tropospheric aerosol volume backscatter coefficients at 10.6-{mu}m wavelength were obtained with airborne continuous wave and ground-based pulsed CO{sub 2} Doppler lidars over the Colorado High Plains during a 20-day period in summer 1982. A persistent 'background' layer was found between 6- and 10-km altitude, with a generally uniform backscatter mixing ratio of {approximately}10{sup {minus}10} m{sup 2} kg{sup {minus}1} sr{sup {minus}1}. The upper boundary of this background layer varied with the tropopause height; the lower boundary varied with the strength and diurnal cycle of convective mixing in the planetary boundary layer (PBL). For quiescent meteorological conditions the transition from the PBL to the background layer was usually very sharp, with backscatter decreases sometimes as large as 3 decades in {approximately}70 m. Sharp gradients were also found at the boundaries of shallow (tens of meters) subvisible cirrus clouds. For less stable conditions, associated with vertical aerosol transport by deep comuliform clouds, backscatter tended to decrease exponentially with altitude.

  20. A Gaussian Random Field Approach for Merging Radar and Ground-Based Rainfall Data on Small Spatial and Temporal Scales

    Science.gov (United States)

    Krebsbach, K.; Friederichs, P.

    2014-12-01

    The generation of reliable precipitation products that explicitly account for spatial and temporal structures of precipitation events requires a combination of data with a variety of error structures and temporal resolutions. In-situ measurements are relatively accurate, but available only at sparse and irregularly distributed locations, whereas remote measurements cover areas but suffer from spatially and temporally inhomogeneous systematic errors. Besides gauge measurements are available on coarser spatial and temporal resolution in contrast to remote sensing measurements which are given on a fine spatial and temporal resolution. In our study we use precipitation rates from the composit of two X-band radars in Bonn and Jülich in Germany. Our aim is to formulate a statistical space-time model that aggregates and disaggregates precipitation rates from radar and gauge observations. We model a Gaussian random field as underlying process, where we face the task of dealing with a large non-Gaussian data set. To start the analysis of the unadjusted radar rainfall rates, we follow the work of D. Allcroft and C. Glasbey (2003) and transform the data to a truncated Gaussian distribution. The advantage of the latent variable approach is that it takes account of the occurence of rainfall and the intensity using a single process. We proceed by estimating the empirical correlation from these transformed values with maximum likelihood methods and fit a parametric correlation function that gives rise to a Gaussian random field. Since the transformation gives censored values to dry locations, we simulate values for this area that lie below some threshold and extend the Gaussian field to the whole domain. In order to merge gauge and radar data for precipitation, we first aggregate the data to a scale on which the comparison is reasonable and then disaggregate again back to smaller desirable scales. The disaggregation step consists of calculating the difference between radar

  1. A proposal on the study of solar-terrestrial coupling processes with atmospheric radars and ground-based observation network

    Science.gov (United States)

    Tsuda, Toshitaka; Yamamoto, Mamoru; Hashiguchi, Hiroyuki; Shiokawa, Kazuo; Ogawa, Yasunobu; Nozawa, Satonori; Miyaoka, Hiroshi; Yoshikawa, Akimasa

    2016-09-01

    The solar energy can mainly be divided into two categories: the solar radiation and the solar wind. The former maximizes at the equator, generating various disturbances over a wide height range and causing vertical coupling processes of the atmosphere between the troposphere and middle and upper atmospheres by upward propagating atmospheric waves. The energy and material flows that occur in all height regions of the equatorial atmosphere are named as "Equatorial Fountain." These processes from the bottom also cause various space weather effects, such as satellite communication and Global Navigation Satellite System positioning. While, the electromagnetic energy and high-energy plasma particles in the solar wind converge into the polar region through geomagnetic fields. These energy/particle inflow results in auroral Joule heating and ion drag of the atmosphere particularly during geomagnetic storms and substorms. The ion outflow from the polar ionosphere controls ambient plasma constituents in the magnetosphere and may cause long-term variation of the atmosphere. We propose to clarify these overall coupling processes in the solar-terrestrial system from the bottom and from above through high-resolution observations at key latitudes in the equator and in the polar region. We will establish a large radar with active phased array antenna, called the Equatorial Middle and Upper atmosphere radar, in west Sumatra, Indonesia. We will participate in construction of the EISCAT_3D radar in northern Scandinavia. These radars will enhance the existing international radar network. We will also develop a global observation network of compact radio and optical remote sensing equipment from the equator to polar region.

  2. Software Defined Doppler Radar as a Contactless Multipurpose Microwave Sensor for Vibrations Monitoring

    Science.gov (United States)

    Raffo, Antonio; Costanzo, Sandra; Di Massa, Giuseppe

    2017-01-01

    A vibration sensor based on the use of a Software-Defined Radio (SDR) platform is adopted in this work to provide a contactless and multipurpose solution for low-cost real-time vibrations monitoring. In order to test the vibration detection ability of the proposed non-contact method, a 1 GHz Doppler radar sensor is simulated and successfully assessed on targets at various distances, with various oscillation frequencies and amplitudes. Furthermore, an SDR Doppler platform is practically realized, and preliminary experimental validations on a device able to produce a harmonic motion are illustrated to prove the effectiveness of the proposed approach. PMID:28075345

  3. The Characteristics of the Cold Front Cloud in Doppler Radar Reflectivity Factor

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    [Objective] The aim was to summarize the characteristics of refelectivity factors of Doppler radar of the cold front cloud system. [Method] Judging from the characteristics of reflectivity factors, by dint of the new generation weather radar in Harbin from 2002 to 2007, the features of the reflectivity factors of the cold front cloud system were summarized. [Result] The cloud formed by the cold front was in banded form in general. However, there was void in the cloud and its intensity was uneven. Most fast ...

  4. Measurement of velocities in noisy environments with a microwave Doppler-effect radar

    Energy Technology Data Exchange (ETDEWEB)

    Lozano-Rogado, J. [Departamento de Fisica Aplicada III, Facultad de Fisicas, Universidad Complutense de Madrid, Madrid (Spain)]. E-mail: jesloz@eucmos.sim.ucm.es; Miranda-Pantoja, J.M.; Sebastian, J.L. [Departamento de Fisica Aplicada III, Facultad de Fisicas, Universidad Complutense de Madrid, Madrid (Spain)

    2001-05-01

    An undergraduate experiment is proposed to facilitate the understanding of the basic principles related to radar systems and signal analysis. A Doppler-effect radar has been installed and used to measure the velocities of a target under different conditions. This system features the use of a low-power generator and a general purpose data acquisition card. The analysis of the measured IF (intermediate frequency) voltage has been made by using the fast Fourier transform in order to illustrate the relevance of the basic spectral techniques for the characterization of weak signals in noisy environments. (author)

  5. X-Band to W-Band Doppler Radar Using Reconfigurable RF T/R MMIC Series Project

    Data.gov (United States)

    National Aeronautics and Space Administration — TLC demonstrated a high performance remote Doppler Radar adjustable X-band to W-band transceiver chip that can perform well as a FMCW, super-heterodyne or pulse...

  6. A Cramer Rao analysis on receiver placement in a FM band commensal radar system based on doppler only measurements

    CSIR Research Space (South Africa)

    Maasdorp, FDV

    2014-10-01

    Full Text Available This paper investigates the theoretical placement of receivers in an Commensal Radar (CR), Doppler only tracking system with a single transmitter multiple receiver configuration. Theory, based on the Fisher Information matrix (FIM), is developed...

  7. Advanced W-Band Gallium Nitride Monolithic Microwave Integrated Circuits (MMICs) for Cloud Doppler Radar Supporting ACE Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Develop W-band Gallium Nitride (GaN) MMICs to enable the advanced cross-track scanning, dual-frequency Doppler cloud radar concept in support of the...

  8. Software-defined radar and waveforms for studying micro-Doppler signatures

    Science.gov (United States)

    Liu, Baokun; Chen, Rachel

    2014-05-01

    In this paper, we investigate the use of software defined radar (SDR) to analyze the micro-Doppler signatures. The first SDR we use is based on the Universal Software Radio Peripheral (USRP) and GNU Radio, and another SDR which has several operation modes is based on field-programmable gate arrays (FPGA). Typically, the USRP-based SDR is not optimized for radar applications due to its narrow bandwidth and time-varying additional delay caused by USRP components and operating system. The FPGA-based SDR is more suitable for applications where high-resolution range information is required. Our studies indicate that both of the SDR systems are capable of producing the micro-Doppler signatures. System design challenges and measurement results will be discussed in detail.

  9. Radar micro-Doppler based human activity classification for indoor and outdoor environments

    Science.gov (United States)

    Zenaldin, Matthew; Narayanan, Ram M.

    2016-05-01

    This paper presents the results of our experimental investigation into how different environments impact the classification of human motion using radar micro-Doppler (MD) signatures. The environments studied include free space, through-thewall, leaf tree foliage, and needle tree foliage. Results on presented on classification of the following three motions: crawling, walking, and jogging. The classification task was designed how to best separate these movements. The human motion data were acquired using a monostatic coherent Doppler radar operating in the C-band at 6.5 GHz from a total of six human subjects. The received signals were analyzed in the time-frequency domain using the Short-time Fourier Transform (STFT) which was used for feature extraction. Classification was performed using a Support Vector Machine (SVM) using a Radial Basis Function (RBF). Classification accuracies in the range 80-90% were achieved to separate the three movements mentioned.

  10. Low Complexity Direction and Doppler Frequency Estimation for Bistatic MIMO Radar in Spatial Colored Noise

    Directory of Open Access Journals (Sweden)

    Lingyun Xu

    2014-01-01

    Full Text Available We investigate the algorithm of direction and Doppler frequency estimation for bistatic multiple-input multiple-output (MIMO radar in spatial colored noise. A novel method of joint estimation of direction and Doppler frequency in spatial colored noise based on propagator method (PM for bistatic MIMO radar is discussed. Utilizing the cross-correlation matrix which is formed by the adjacent outputs of match filter in the time domain, the special matrix is constructed to eliminate the influence of spatial colored noise. The proposed algorithm provides lower computational complexity and has very close parameters estimation compared to estimation of signal parameters via rotational invariance technique (ESPRIT algorithm in high signal-to-noise ratio (SNR. It is applicable even if the transmitted waveforms are not orthogonal. The estimated parameters can be paired automatically and the Cramér-Rao Bound (CRB is given in spatial colored noise. Simulation results confirm the effectiveness of the proposed method.

  11. SEVERAL PROBLEMS IN DESIGNING DBS SYSTEMS FOR AIRBORNE PULSE DOPPLER RADAR

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    Some bases are presented for determining and calculating the airborne pulse doppler radar's DBS system parameters.Major problems discussed here are the limitation to the beam sharpening ratio and azimuth resolution, and the limitation to maximum pitch angle and minimum azimuth angle.Some basic formulas are given for calculating the batch processing period, framescan time and antenna rotating speed.Also discussed are the limiting condition and determining principle of the pulse repetition frequency.

  12. Single-Doppler Radar Analysis of a Mesocyclone in the Taiwan Strait

    Institute of Scientific and Technical Information of China (English)

    ZHAO Kun; JOU Ben Jongdao; PAN Yujie; GE Wenzhong

    2009-01-01

    In this study, the kinematic and precipitation structures of a mesocyclone associated with a hook echo were analyzed using single Doppler radar data. The mesocyclone was embedded in a mesoscale convective rainband near northern Taiwan coastline on 10 September 2004. The synoptic environment was characterized by a moderate convective available potential energy (CAPE) and a moderate ambient vertical shear from surface to 5 kin. In addition, a pronounced low-level mesoscale shear/convergence zone, which resulted from the interaction of two tropical depressions, was also identified in the northwest coast of Taiwan, providing a favorable dynamic condition for the development of the rnesocyclone. Analyzing single Doppler dipole signature shows that this mesocyclone formed initially at low levels, then deepened and strengthened rapidly into mature stage with the vertical depth exceeding 8 km. The diameter of the mesocyclone decreased with the height at the time of vortexgenesis, and then evolved into columnar structure accompanied with the broader diameter in middle layer. The mesocyclone lasted for about 2 h. The Ground-Based Velocity Track Display (GBVTD) method was applied to retrieve the ax-isymmetric circulation of the mesocyclone. The GBVTD-derived primary circulation showed the radius of maximum wind (RMW) of the mesocyclone was about 5-6 km and varied from inward tilting to outward tilting with time. The axisymmetric radial wind field was initially characterized by a low-level inflow in-side the RMW and outflow outside the RMW, respectively. The strongest reflectivity was associated with a stronger updraft near the RMW, and a weak downdraft was located at the center of the mesocyclone. Subsequently the downdraft and reflectivity near the mesocyclone center strengthened obviously, accompa-nied with the low-level outflow, strong updraft as well as high reflectivity extending outside the RMW. The relative tangential wind initially exhibited a wavenumber 1 asymmetric

  13. Extended Kalman Doppler tracking and model determination for multi-sensor short-range radar

    Science.gov (United States)

    Mittermaier, Thomas J.; Siart, Uwe; Eibert, Thomas F.; Bonerz, Stefan

    2016-09-01

    A tracking solution for collision avoidance in industrial machine tools based on short-range millimeter-wave radar Doppler observations is presented. At the core of the tracking algorithm there is an Extended Kalman Filter (EKF) that provides dynamic estimation and localization in real-time. The underlying sensor platform consists of several homodyne continuous wave (CW) radar modules. Based on In-phase-Quadrature (IQ) processing and down-conversion, they provide only Doppler shift information about the observed target. Localization with Doppler shift estimates is a nonlinear problem that needs to be linearized before the linear KF can be applied. The accuracy of state estimation depends highly on the introduced linearization errors, the initialization and the models that represent the true physics as well as the stochastic properties. The important issue of filter consistency is addressed and an initialization procedure based on data fitting and maximum likelihood estimation is suggested. Models for both, measurement and process noise are developed. Tracking results from typical three-dimensional courses of movement at short distances in front of a multi-sensor radar platform are presented.

  14. An Assessment of Wind Plant Complex Flows Using Advanced Doppler Radar Measurements

    Science.gov (United States)

    Gunter, W. S.; Schroeder, J.; Hirth, B.; Duncan, J.; Guynes, J.

    2015-12-01

    As installed wind energy capacity continues to steadily increase, the need for comprehensive measurements of wind plant complex flows to further reduce the cost of wind energy has been well advertised by the industry as a whole. Such measurements serve diverse perspectives including resource assessment, turbine inflow and power curve validation, wake and wind plant layout model verification, operations and maintenance, and the development of future advanced wind plant control schemes. While various measurement devices have been matured for wind energy applications (e.g. meteorological towers, LIDAR, SODAR), this presentation will focus on the use of advanced Doppler radar systems to observe the complex wind flows within and surrounding wind plants. Advanced Doppler radars can provide the combined advantage of a large analysis footprint (tens of square kilometers) with rapid data analysis updates (a few seconds to one minute) using both single- and dual-Doppler data collection methods. This presentation demonstrates the utility of measurements collected by the Texas Tech University Ka-band (TTUKa) radars to identify complex wind flows occurring within and nearby operational wind plants, and provide reliable forecasts of wind speeds and directions at given locations (i.e. turbine or instrumented tower sites) 45+ seconds in advance. Radar-derived wind maps reveal commonly observed features such as turbine wakes and turbine-to-turbine interaction, high momentum wind speed channels between turbine wakes, turbine array edge effects, transient boundary layer flow structures (such as wind streaks, frontal boundaries, etc.), and the impact of local terrain. Operational turbine or instrumented tower data are merged with the radar analysis to link the observed complex flow features to turbine and wind plant performance.

  15. Cyclostationary Approach for Heart and Respiration Rates Monitoring with Body Movement Cancellation Using Radar Doppler System

    CERN Document Server

    Kazemi, Somayeh; Amindavar, Hamidreza; Li, Changzhi

    2013-01-01

    Heart and respiration rate measurement using Doppler radar is a non-contact and non-obstructive way for remote thorough-clothing monitoring of vital signs. The modulated back-scattered radar signal in the presence of high noise and interference is non-stationary with hidden periodicities, which cannot be detected by ordinary Fourier analysis. In this paper we propose a cyclostationary approach for such signals and show that by using non-linear transformation and then Fourier analysis of the radar signal, the hidden periodicities can be accurately obtained. Numerical results show that the vital signs can be extracted as cyclic frequencies, independent of SNR and without any filtering or phase unwrapping.

  16. Classification of ground moving targets using bicepstrum-based features extracted from Micro-Doppler radar signatures

    Science.gov (United States)

    Molchanov, Pavlo O.; Astola, Jaakko T.; Egiazarian, Karen O.; Totsky, Alexander V.

    2013-12-01

    In this article, a novel bicepstrum-based approach is suggested for ground moving radar target classification. Distinctive classification features were extracted from short-time backscattering bispectrum estimates of the micro-Doppler signature. Real radar data were obtained using surveillance Doppler microwave radar operating at 34 GHz. Classifier performance was studied in detail using the Gaussian Mixture Mode and Maximum Likelihood decision making rule, and the results were verified on a multilayer perceptron and Support Vector Machine. Experimental real radar measurements demonstrated that it is quite feasible to discern three classes of humans (single, two and three persons) walking in a vegetation cluttered environment using proposed bicepstrum-based classification features. Sophisticated bispectrum-based signal processing provides the extraction of new classification features in the form of phase relationships in the radar data. It provides a novel insight into moving radar target classification compared to the commonly used energy-based strategy.

  17. Analysis of Doppler Radar Data about a Super Monomer Hailstorms in the Northeastern Qinghai-Tibet Plateau

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    [Objective] The Doppler radar data about a super monomer hailstorms in the northeastern Qinghai-Tibet Plateau in the Zhongchuan Airport in the Lanzhou City on September 6,2010 was studied.[Method] By dint of routine data and radar data,the low vortex shear line type and the super monomer hailstorm around the Zhongchuan Airport in the Lanzhou City on September 6,2010 were expounded.Basic product and secondary product of Doppler radar were used in this process to reflect the characteristics of strong convecti...

  18. Moving Target Detection and Doppler Extraction Using Digital Spread Spectrum Radar

    Directory of Open Access Journals (Sweden)

    Subhankar Shome

    2014-09-01

    Full Text Available In this paper, we discuss a Spread Spectrum based radar system for car detection in the road and autonomous guidance of vehicles. An autonomous intelligent vehicle has to perform a number of functionalities. Segmentation of the road, determining the boundaries to drive in and recognizing the vehicles and obstacles around are the main tasks for vision guided vehicle navigation. In this article we propose a set of algorithms which lead to the solution of road and vehicle collision using carrier recovery method from car velocity using DSSS RADAR. In such a spread spectrum system, the transmitted signal is spread over a larger bandwidth, which is much wider than the minimum bandwidth required to transmit the information. Automotive radar systems can take advantage of spread spectrum techniques because of their interference rejection, immunity from noise and multipath distortion, and high resolution ranging properties. In addition, there is no need for high-speed, fast-settling frequency synthesizers. Moreover, spread spectrum techniques can improve the reliability of automotive radars. The data from different sensors on different cars can be combined in order to observe the complete car environment. Thus a spread spectrum radar system will allow sharing the same bandwidth also for data link needed by car-to-car communication systems. The algorithm described here is to recover Doppler frequency using 2P power method from which we are able to detect the vehicle condition in road.

  19. Assessment of human respiration patterns via noncontact sensing using Doppler multi-radar system.

    Science.gov (United States)

    Gu, Changzhan; Li, Changzhi

    2015-03-16

    Human respiratory patterns at chest and abdomen are associated with both physical and emotional states. Accurate measurement of the respiratory patterns provides an approach to assess and analyze the physical and emotional states of the subject persons. Not many research efforts have been made to wirelessly assess different respiration patterns, largely due to the inaccuracy of the conventional continuous-wave radar sensor to track the original signal pattern of slow respiratory movements. This paper presents the accurate assessment of different respiratory patterns based on noncontact Doppler radar sensing. This paper evaluates the feasibility of accurately monitoring different human respiration patterns via noncontact radar sensing. A 2.4 GHz DC coupled multi-radar system was used for accurate measurement of the complete respiration patterns without any signal distortion. Experiments were carried out in the lab environment to measure the different respiration patterns when the subject person performed natural breathing, chest breathing and diaphragmatic breathing. The experimental results showed that accurate assessment of different respiration patterns is feasible using the proposed noncontact radar sensing technique.

  20. Dynamical and Microphysical Retrieval from Simulated Doppler Radar Observations Using the 4DVAR Assimilation Technique

    Institute of Scientific and Technical Information of China (English)

    XU Xiaoyong; LIU Liping; ZHENG Guoguang

    2005-01-01

    Based on a cloud model and the four-dimensional variational (4DVAR) data assimilation method developed by Sun and Crook (1997), simulated experiments of dynamical and microphysical retrieval from Doppler radar data were performed. The 4DVAR data assimilation technique was applied to a cloud scale model with a warm rain parameterization scheme. The 3D wind, thermodynamical, and microphysical fields were determined by minimizing a cost function, defined by the difference between both radar observed radial velocities and reflectivities and their model predictions. The adjoint of the numerical model was used to provide the gradient of the cost function with respect to the control variables. Experiments have demonstrated that the 4DVAR assimilation method is able to retrieve the detailed structure of wind, thermodynamics, and microphysics by using either dual-Doppler or single-Doppler information. The quality of retrieval depends strongly on the magnitude of constraint with respect to the variables. Retrieving the temperature field,cloud water and water vapor is more difficult than the recovery of the wind field and rainwater. Accurate thermodynamic retrieval requires a longer assimilation period. The inclusion of a background term, even mean fields from a single sounding, helped reduce the retrieval errors. Less accurate velocity fields were obtained when single-Doppler data were used. It was found that the retrieved velocity is sensitive to the location of the retrieval domain relative to the radars while the other fields have very little changes. Two radar volumetric scans are generally adequate for providing the evolution, although the use of additional volumes improves the retrieval. As the amount of the observations decreases, the performance of the retrieval is degraded. However, the missing observations can be compensated by adding a background term to the cost function. The technique is robust to random errors in radial velocity and calibration errors in

  1. Design And Analysis Of Doppler Radar-Based Vehicle Speed Detection

    Directory of Open Access Journals (Sweden)

    Su Myat Paing

    2015-08-01

    Full Text Available The most unwanted thing to happen to a road user is road accident. Most of the fatal accidents occur due to over speeding. Faster vehicles are more prone to accident than the slower one. Among the various methods for detecting speed of the vehicle object detection systems based on Radar have been replaced for about a century for various purposes like detection of aircrafts spacecraft ships navigation reading weather formations and terrain mapping. The essential feature in adaptive vehicle activated sign systems is the accurate measurement of a vehicles velocity. The velocities of the vehicles are acquired from a continuous wave Doppler radar. A very low amount of power is consumed in this system and only batteries can use to operate. The system works on the principle of Doppler Effect by detecting the Doppler shift in microwaves reflected from a moving object. Since the output of the sensor is sinusoidal wave with very small amplitude and needs to be amplified with the help of the amplifier before further processing. The purpose to calculate and display the speed on LCD is performed by the microcontroller.

  2. New Approaches For Asteroid Spin State and Shape Modeling From Delay-Doppler Radar Images

    Science.gov (United States)

    Raissi, Chedy; Lamee, Mehdi; Mosiane, Olorato; Vassallo, Corinne; Busch, Michael W.; Greenberg, Adam; Benner, Lance A. M.; Naidu, Shantanu P.; Duong, Nicholas

    2016-10-01

    Delay-Doppler radar imaging is a powerful technique to characterize the trajectories, shapes, and spin states of near-Earth asteroids; and has yielded detailed models of dozens of objects. Reconstructing objects' shapes and spins from delay-Doppler data is a computationally intensive inversion problem. Since the 1990s, delay-Doppler data has been analyzed using the SHAPE software. SHAPE performs sequential single-parameter fitting, and requires considerable computer runtime and human intervention (Hudson 1993, Magri et al. 2007). Recently, multiple-parameter fitting algorithms have been shown to more efficiently invert delay-Doppler datasets (Greenberg & Margot 2015) - decreasing runtime while improving accuracy. However, extensive human oversight of the shape modeling process is still required. We have explored two new techniques to better automate delay-Doppler shape modeling: Bayesian optimization and a machine-learning neural network.One of the most time-intensive steps of the shape modeling process is to perform a grid search to constrain the target's spin state. We have implemented a Bayesian optimization routine that uses SHAPE to autonomously search the space of spin-state parameters. To test the efficacy of this technique, we compared it to results with human-guided SHAPE for asteroids 1992 UY4, 2000 RS11, and 2008 EV5. Bayesian optimization yielded similar spin state constraints within a factor of 3 less computer runtime.The shape modeling process could be further accelerated using a deep neural network to replace iterative fitting. We have implemented a neural network with a variational autoencoder (VAE), using a subset of known asteroid shapes and a large set of synthetic radar images as inputs to train the network. Conditioning the VAE in this manner allows the user to give the network a set of radar images and get a 3D shape model as an output. Additional development will be required to train a network to reliably render shapes from delay-Doppler

  3. High-Resolution Mapping of Sea Ice, Icebergs and Growlers in Kongsfjorden, Svalbard, using Ground Based Radar, Satellite, and UAV

    Science.gov (United States)

    Lauknes, T. R.; Rouyet, L.; Solbø, S. A.; Sivertsen, A.; Storvold, R.; Akbari, V.; Negrel, J.; Gerland, S.

    2016-12-01

    The dynamics of sea ­ice has a well­ recognized role in the climate system and its extent and evolution is impacted by the global warming. In addition, calving of icebergs and growlers at the tidewater glacier fronts is a component of the mass loss in polar regions. Understanding of calving and ice ­ocean interaction, in particular at tidewater glacier front remains elusive, and a problematic uncertainty in climate change projections. Studying the distribution, volumetry and motion of sea ­ice, icebergs and growlers is thus essential to understand their interactions with the environment in order to be able to predict at short­term their drifts, e.g. to mitigate the risk for shipping, and at longer term the multiple relations with climate changes. Here, we present the results from an arctic fieldwork campaign conducted in Kongsfjorden, Svalbard in April 2016, where we used different remote sensing instruments to observe dynamics of sea ice, icebergs, and growlers. We used a terrestrial radar system, imaging the study area every second minute during the observation period. At the front of the Kronebreen glacier, calving events can be detected and the drift of the generated icebergs and growlers tracked with unprecedented spatial and temporal resolution. During the field campaign, we collected four Radarsat-2 quad-pol images, that will be used to classify the different types of sea ice. In addition, we used small unmanned aircraft (UAS) instrumented with high resolution cameras capturing HD video and still pictures. This allows to map and measure the size of icebergs and ice floes. Such information is essential to validate sensitivity and detection limits from the ground and satellite based measurements.

  4. Accurate Measurements of Free Flight Drag Coefficients with Amateur Doppler Radar

    CERN Document Server

    Courtney, Elya; Courtney, Michael

    2016-01-01

    In earlier papers, techniques have been described using optical chronographs to determine free flight drag coefficients with an accuracy of 1-2%, accomplished by measuring near and far velocities of projectiles in flight over a known distance. Until recently, Doppler radar has been prohibitively expensive for many users. This paper reports results of exploring potential applications and accuracy using a recently available, inexpensive (< $600 US) amateur Doppler radar system to determine drag coefficients for projectiles of various sizes (4.4 mm to 9 mm diameter) and speeds (M0.3 to M3.0). In many cases, drag coefficients can be determined with an accuracy of 1% or better if signal-to-noise ratio is sufficient and projectiles vary little between trials. It is also straightforward to design experiments for determining drag over a wide range of velocities. Experimental approaches and limitations are described. Overall, the amateur radar system shows greater accuracy, ease of use, and simplicity compared with...

  5. Through Wall Radar Classification of Human Micro-Doppler Using Singular Value Decomposition Analysis.

    Science.gov (United States)

    Ritchie, Matthew; Ash, Matthew; Chen, Qingchao; Chetty, Kevin

    2016-08-31

    The ability to detect the presence as well as classify the activities of individuals behind visually obscuring structures is of significant benefit to police, security and emergency services in many situations. This paper presents the analysis from a series of experimental results generated using a through-the-wall (TTW) Frequency Modulated Continuous Wave (FMCW) C-Band radar system named Soprano. The objective of this analysis was to classify whether an individual was carrying an item in both hands or not using micro-Doppler information from a FMCW sensor. The radar was deployed at a standoff distance, of approximately 0.5 m, outside a residential building and used to detect multiple people walking within a room. Through the application of digital filtering, it was shown that significant suppression of the primary wall reflection is possible, significantly enhancing the target signal to clutter ratio. Singular Value Decomposition (SVD) signal processing techniques were then applied to the micro-Doppler signatures from different individuals. Features from the SVD information have been used to classify whether the person was carrying an item or walking free handed. Excellent performance of the classifier was achieved in this challenging scenario with accuracies up to 94%, suggesting that future through wall radar sensors may have the ability to reliably recognize many different types of activities in TTW scenarios using these techniques.

  6. Through Wall Radar Classification of Human Micro-Doppler Using Singular Value Decomposition Analysis

    Directory of Open Access Journals (Sweden)

    Matthew Ritchie

    2016-08-01

    Full Text Available The ability to detect the presence as well as classify the activities of individuals behind visually obscuring structures is of significant benefit to police, security and emergency services in many situations. This paper presents the analysis from a series of experimental results generated using a through-the-wall (TTW Frequency Modulated Continuous Wave (FMCW C-Band radar system named Soprano. The objective of this analysis was to classify whether an individual was carrying an item in both hands or not using micro-Doppler information from a FMCW sensor. The radar was deployed at a standoff distance, of approximately 0.5 m, outside a residential building and used to detect multiple people walking within a room. Through the application of digital filtering, it was shown that significant suppression of the primary wall reflection is possible, significantly enhancing the target signal to clutter ratio. Singular Value Decomposition (SVD signal processing techniques were then applied to the micro-Doppler signatures from different individuals. Features from the SVD information have been used to classify whether the person was carrying an item or walking free handed. Excellent performance of the classifier was achieved in this challenging scenario with accuracies up to 94%, suggesting that future through wall radar sensors may have the ability to reliably recognize many different types of activities in TTW scenarios using these techniques.

  7. Comparative of signal processing techniques for micro-Doppler signature extraction with automotive radar systems

    Science.gov (United States)

    Rodriguez-Hervas, Berta; Maile, Michael; Flores, Benjamin C.

    2014-05-01

    In recent years, the automotive industry has experienced an evolution toward more powerful driver assistance systems that provide enhanced vehicle safety. These systems typically operate in the optical and microwave regions of the electromagnetic spectrum and have demonstrated high efficiency in collision and risk avoidance. Microwave radar systems are particularly relevant due to their operational robustness under adverse weather or illumination conditions. Our objective is to study different signal processing techniques suitable for extraction of accurate micro-Doppler signatures of slow moving objects in dense urban environments. Selection of the appropriate signal processing technique is crucial for the extraction of accurate micro-Doppler signatures that will lead to better results in a radar classifier system. For this purpose, we perform simulations of typical radar detection responses in common driving situations and conduct the analysis with several signal processing algorithms, including short time Fourier Transform, continuous wavelet or Kernel based analysis methods. We take into account factors such as the relative movement between the host vehicle and the target, and the non-stationary nature of the target's movement. A comparison of results reveals that short time Fourier Transform would be the best approach for detection and tracking purposes, while the continuous wavelet would be the best suited for classification purposes.

  8. Cardio-respiratory and daily activity monitor based on FMCW Doppler radar embedded in a wheelchair.

    Science.gov (United States)

    Postolache, Octavian; Girão, Pedro Silva; Postolache, Gabriela; Gabriel, Joaquim

    2011-01-01

    Unobtrusive monitoring of the cardio-respiratory and daily activity for wheelchair users became nowadays an important challenge, considering population aging phenomena and the increasing of the elderly with chronic diseases that affect their motion capabilities. This work reports the utilization of FMCW (frequency modulated continuous wave) Doppler radar sensors embedded in a manual wheelchair to measure the cardiac and respiratory activities and the physical activity of the wheelchair user. Another radar sensor is included in the system in order to quantify the motor activity through the wheelchair traveled distance, when the user performs the manual operation of the wheelchair. A conditioning circuit including active filters and a microcontroller based primary processing module was designed and implemented to deliver the information through Bluetooth communication protocol to an Android OS tablet computer. The main capabilities of the software developed using Android SDK and Java were the signal processing of Doppler radar measurement channel signals, graphical user interface, data storage and Wi-Fi data synchronization with remote physiological and physical activity database.

  9. Statiscal characteristics of measurement noise included in DME output. Compatibility check with doppler radar output. Hiko shiken de erareta DME data no zatsuon tokusei. Doppler radar data tono seigosei kento

    Energy Technology Data Exchange (ETDEWEB)

    Ono, Koji.

    1988-02-01

    VOR and DME data can be accurate enough for the purpose of navigation. The accuracy is, however, not satisfactory for the analysis of flight test data, and must be improved by the combined use of other sensor systems. The result of the experiment carried out to clarify and model the statistical characteristics of noises contained in the DME output is reported. The statistical characteristics of noises in DME data were studied by flight tests using two DME systems and one Doppler radar system currently installed in VSRA (variable stability and response airplane). 2 residuals are obtained by a compatibility check of the data of the 2 DME and 1 Doppler radar, and the statistical characteristics of noises contained in the DME data and Doppler radar data can be separately identified. 23 references, 11 figures, 1 table.

  10. Polarimetric and Multi-Doppler Radar Observations of Electrified and Unelectrified Wildfire Smoke Plumes

    Science.gov (United States)

    Lang, Timothy J.; Rutledge, Steven A.; Dolan, Brenda; Krehbiel, Paul; Rison, William; Lindsey, Daniel T.

    2013-01-01

    Pyrocumulus clouds above three Colorado wildfires (Hewlett Gulch, High Park, and Waldo Canyon; all occurred during summer 2012) electrified and produced small intracloud discharges whenever the smoke plumes grew to high altitudes (over 10 km above mean sea level, or MSL). This occurred during periods of rapid wildfire growth, as indicated by the shortwave infrared channel on a geostationary satellite, as well as by incident reports. In the Hewlett Gulch case, the fire growth led to increased updrafts within the plume, as inferred by multiple- Doppler radar syntheses, which led to the vertical development and subsequent electrification - a life cycle as short as 30 minutes. The lightning, detected by a threedimensional lightning mapping network, was favored in high-altitude regions (10 km MSL) containing modest reflectivities (25 dBZ and lower), 0 dB differential reflectivity, and reduced correlation coefficient (0.6-0.7). This indicated the likely presence of ice particles (crystals and aggregates, possibly rimed) mixed with ash. Though neither multiple-Doppler nor polarimetric observations were available during the electrification of the High Park and Waldo Canyon plumes, their NEXRAD observations showed reflectivity structures consistent with Hewlett Gulch. In addition, polarimetric and multiple-Doppler scanning of unelectrified High Park plumes indicated only irregularly shaped ash, and not ice, was present (i.e., reflectivities 5 dB, correlation < 0.4), and there was no broaching of the 10 km altitude. Based on these results, the electrification likely was caused by ice-based processes that did not involve significant amounts of graupel. The results demonstrate the scientific value of multiple-Doppler and polarimetric radar observations of wildfire smoke plumes - including the ability to distinguish between regions of pure hydrometeors, regions of pure ash, and mixtures of both - and also suggest a possible new application for lightning data in monitoring

  11. A radar unattended ground sensor with micro-Doppler capabilities for false alarm reduction

    Science.gov (United States)

    Tahmoush, Dave; Silvious, Jerry; Burke, Ed

    2010-10-01

    Unattended ground sensors (UGS) provide the capability to inexpensively secure remote borders and other areas of interest. However, the presence of normal animal activity can often trigger a false alarm. Accurately detecting humans and distinguishing them from natural fauna is an important issue in security applications to reduce false alarm rates and improve the probability of detection. In particular, it is important to detect and classify people who are moving in remote locations and transmit back detections and analysis over extended periods at a low cost and with minimal maintenance. We developed and demonstrate a compact radar technology that is scalable to a variety of ultra-lightweight and low-power platforms for wide area persistent surveillance as an unattended, unmanned, and man-portable ground sensor. The radar uses micro-Doppler processing to characterize the tracks of moving targets and to then eliminate unimportant detections due to animals as well as characterize the activity of human detections. False alarms from sensors are a major liability that hinders widespread use. Incorporating rudimentary intelligence into sensors can reduce false alarms but can also result in a reduced probability of detection. Allowing an initial classification that can be updated with new observations and tracked over time provides a more robust framework for false alarm reduction at the cost of additional sensor observations. This paper explores these tradeoffs with a small radar sensor for border security. Multiple measurements were done to try to characterize the micro-Doppler of human versus animal and vehicular motion across a range of activities. Measurements were taken at the multiple sites with realistic but low levels of clutter. Animals move with a quadrupedal motion, which can be distinguished from the bipedal human motion. The micro-Doppler of a vehicle with rotating parts is also shown, along with ground truth images. Comparisons show large variations for

  12. Using convolutional neural networks for human activity classification on micro-Doppler radar spectrograms

    Science.gov (United States)

    Jordan, Tyler S.

    2016-05-01

    This paper presents the findings of using convolutional neural networks (CNNs) to classify human activity from micro-Doppler features. An emphasis on activities involving potential security threats such as holding a gun are explored. An automotive 24 GHz radar on chip was used to collect the data and a CNN (normally applied to image classification) was trained on the resulting spectrograms. The CNN achieves an error rate of 1.65 % on classifying running vs. walking, 17.3 % error on armed walking vs. unarmed walking, and 22 % on classifying six different actions.

  13. Features associated with radar micro-Doppler signatures of various human activities

    Science.gov (United States)

    Zenaldin, Matthew; Narayanan, Ram M.

    2015-05-01

    This paper presents the results of our experimental investigation into the radar micro-Doppler signatures (MDS) of various human activities both in free-space and through-wall environments. The collection of MDS signatures was divided into two categories: stationary and forward-moving. Each category of MDS signatures encompassed a variety of movements associated with it, adding up to a total of 14 human movements. Using a 6.5-GHz C-band coherent radar, the MDS of six human subjects were gathered in free-space and through-wall environments. The MDS for these cases were analyzed in detail and the general properties of the signatures were related to their associated phenomenological characteristics. Based upon the MDS, specific features for designing detectors and classifiers of human targets performing such movements are extracted.

  14. CLUJ-NAPOCA PRECIPITATION FORECAST USING WSR-98D DOPPLER RADAR

    Directory of Open Access Journals (Sweden)

    Narcis MAIER

    2011-11-01

    Full Text Available CLUJ-NAPOCA precipitation forecast using WSR-98D Doppler radar. Forecasting inundations requires accurate spatial and temporal estimation of rainfalls in an area. Depending on the Z-R relationship (reflectivity-precipitation rate, the thresholds, maximum reflectivity data processing, VIL, cloud height or speed, provided by the WSR-98D affects the estimated precipitation used in the prediction of inundations. How much precipitation receives a watershed during an extreme event and what response will result depends on the basin hydrographic characteristics. A study of summer weather events between the years 2004-2008 and a new method in establishing relations between the radar estimated and recorded precipitations led to the determination of new relations between them which will balance the connections between them.

  15. Near-source Doppler radar monitoring of tephra plumes at Etna

    Science.gov (United States)

    Donnadieu, F.; Freville, P.; Hervier, C.; Coltelli, M.; Scollo, S.; Prestifilippo, M.; Valade, S.; Rivet, S.; Cacault, P.

    2016-02-01

    Over the last twenty years Mount Etna has produced more than one hundred explosive events ranging from light ash emissions to violent sub-plinian eruptions. Significant hazards arise from tephra plumes which directly threaten air traffic, and generate fallout affecting surrounding towns and infrastructures. We describe the first radar system, named VOLDORAD 2B, fully integrated into a volcano instrumental network dedicated to the continuous near-source monitoring of tephra emissions from Etna's summit craters. This 23.5 cm wavelength pulsed Doppler radar is operated in collaboration between the Observatoire de Physique du Globe de Clermont-Ferrand (OPGC) and the Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Etneo (INGV-OE) since 2009. Probed volumes inside the fixed, northward-pointing conical beam total about 1.5 km in length, covering the summit craters which produced all recent tephra plumes. The backscattered power, related to the amount of particles crossing the beam, and particle along-beam velocities are recorded every 0.23 s, providing a proxy for the tephra mass eruption rate. Radar raw data are transmitted in real-time to the volcano monitoring center of INGV-OE in Catania and are used to automatically release alerts at onset and end of eruptive events. Processed radar parameters are also made available from the VOLDORAD database online.

  16. The Coplane Analysis Technique for Three-Dimensional Wind Retrieval Using the HIWRAP Airborne Doppler Radar

    Science.gov (United States)

    Didlake, Anthony C., Jr.; Heymsfield, Gerald M.; Tian, Lin; Guimond, Stephen R.

    2015-01-01

    The coplane analysis technique for mapping the three-dimensional wind field of precipitating systems is applied to the NASA High Altitude Wind and Rain Airborne Profiler (HIWRAP). HIWRAP is a dual-frequency Doppler radar system with two downward pointing and conically scanning beams. The coplane technique interpolates radar measurements to a natural coordinate frame, directly solves for two wind components, and integrates the mass continuity equation to retrieve the unobserved third wind component. This technique is tested using a model simulation of a hurricane and compared to a global optimization retrieval. The coplane method produced lower errors for the cross-track and vertical wind components, while the global optimization method produced lower errors for the along-track wind component. Cross-track and vertical wind errors were dependent upon the accuracy of the estimated boundary condition winds near the surface and at nadir, which were derived by making certain assumptions about the vertical velocity field. The coplane technique was then applied successfully to HIWRAP observations of Hurricane Ingrid (2013). Unlike the global optimization method, the coplane analysis allows for a transparent connection between the radar observations and specific analysis results. With this ability, small-scale features can be analyzed more adequately and erroneous radar measurements can be identified more easily.

  17. The 3 December 2015 paroxysm of Voragine crater at Etna: insights from Doppler radar measurements

    Science.gov (United States)

    Donnadieu, Franck; Freret-Lorgeril, Valentin; Gouhier, Mathieu; Coltelli, Mauro; Scollo, Simona; Fréville, Patrick; Hervier, Claude; Prestifilippo, Michele

    2016-04-01

    After a progressive intensification of Strombolian activity inside the Voragine crater in the evening of December 2 2015, Mount Etna produced a short but violent paroxysm in the night of 3 December 2015, the most intense of the last two decades at Voragine. Lava fountains, observed with the network of thermal and visible cameras of INGV-OE, reached well over 1 km in height with some jets of incandescent material reaching 3 km. A tephra column several kilometers high was produced and pyroclastic material was dispersed by winds in altitude to the NE, causing ash fallouts to affect many towns in Sicily and Reggio Calabria. A 23 cm-wavelength Doppler radar (VOLDORAD 2B), located about 3 km from NSEC at the Montagnola station and integrated into the INGV-OE instrumental network, has been continuously monitoring the explosive activity of Mt. Etna's summit craters since 2009. The radar beam probes 13 successive volumes 150 m deep aligned northward above the summit craters, providing two sets of parameters (echo power and velocity) at a rate of 0.2 s. We analyze the paroxysmal event of Voragine using the radar echoes and Doppler signals coming from volumes inside the lava fountain feeding the tephra column in combination with thermal and visible imagery and satellite data. The radar range gating allowed us to immediately discriminate the central craters as the source of the tephra emission and to estimate the lava fountain width between 300 and 450 m. The backscattered power, which is related to the erupted tephra mass load in the beam, and Doppler velocities help to mark the transition from Strombolian activity to lava fountaining, providing onset and end times of the fountain. The tephra flux into the radar beam started to increase after 02:00 UTC with a strong increase at 02:20 UTC marking the transition to continuous lava fountaining. The climax was reached between ca. 02:35 and 03:15 UTC with maintained high echo power and ejection velocities of 190 m/s in average

  18. The radar signal simulation based on the analysis of Pulse-Doppler radar for digital signal processing implementation in the Matlab environment

    Directory of Open Access Journals (Sweden)

    Yu. Yu. Reutskaya

    2015-03-01

    Full Text Available Introduction. The complexity of modern radar (RLS due to their versatility and the need to adapt to the interference situation is constantly changed. The models to test the basic ideas to be implemented in the radar are required. It is important to consider the main stages of the simulation of the radar signal based on the analysis of radar operation. Problem statement. The creation of a universal analytical model to build a radar signal in Matlab is considered. Theoretical results. Stages and results of the radar signal simulation are presented and based on the analysis of pulse – Doppler radar. Basic analytical relations ofthe task are given. Features of simulation when signals of additive fluctuation noise and clutter together with the echo target signals arrive are considered. Conclusion. As a result of analysis of radar interference conditions on the basis of existing relations an optimum variant model of radar signal in Matlab environment is reached. This is the basis for further evaluation of the digital processing effectiveness of the radar signal to background noise and interference (clutter, namely to determine the distance to targets and target’s speeds. . The main advantages of the Mellin transform using for recognizing signals at different scales are presented is conclusions.

  19. Non-contact multi-radar smart probing of body orientation based on micro-Doppler signatures.

    Science.gov (United States)

    Li, Yiran; Pal, Ranadip; Li, Changzhi

    2014-01-01

    Micro-Doppler signatures carry useful information about body movements and have been widely applied to different applications such as human activity recognition and gait analysis. In this paper, micro-Doppler signatures are used to identify body orientation. Four AC-coupled continuous-wave (CW) smart radar sensors were used to form a multiple-radar network to carry out the experiments in this paper. 162 tests were performed in total. The experiment results showed a 100% accuracy in recognizing eight body orientations, i.e., facing north, northeast, east, southeast, south, southwest, west, and northwest.

  20. A comparative analysis of two wind velocity retrieval techniques by using a single Doppler radar

    Directory of Open Access Journals (Sweden)

    H.-C. Lim

    2009-05-01

    Full Text Available This study compares the theoretical basis of the two wind velocity retrieval methods, Velocity Azimuth Display (VAD and Velocity Area Display (VARD by using data obtained by a single Doppler radar. Two pre-assumed shapes of the wind velocity distribution with altitude are considered, uniform and parabolic. The former presents an approximation of the non-sheared or low-sheared wind flow in the upper troposphere, while the latter is a simplified representation of the Atmospheric Boundary Layer (ABL in lower troposphere or high-sheared wind flow at the edges of the tropospheric jet streams. Both techniques for the wind velocity retrieval considered in this study are reformulated in order to get more precise information on the wind velocity components. An algorithm is proposed to decrease the uncertainty in retrieving by evaluating the coefficients of the polynomial equation and applying a transfer function with respect to the angle formed between the wind flow direction and direction of radar beam. It is concluded that, provided the formulated transformation functions are used, the application of the VAD and VARD techniques to the single-Doppler data may be an invaluable tool for solving various climate and wind engineering problems.

  1. Doppler weather radar observations of the 2009 eruption of Redoubt Volcano, Alaska

    Science.gov (United States)

    Schneider, David J.; Hoblitt, Richard P.

    2013-06-01

    The U.S. Geological Survey (USGS) deployed a transportable Doppler C-band radar during the precursory stage of the 2009 eruption of Redoubt Volcano, Alaska that provided valuable information during subsequent explosive events. We describe the capabilities of this new monitoring tool and present data captured during the Redoubt eruption. The MiniMax 250-C (MM-250C) radar detected seventeen of the nineteen largest explosive events between March 23 and April 4, 2009. Sixteen of these events reached the stratosphere (above 10 km) within 2-5 min of explosion onset. High column and proximal cloud reflectivity values (50 to 60 dBZ) were observed from many of these events, and were likely due to the formation of mm-sized accretionary tephra-ice pellets. Reflectivity data suggest that these pellets formed within the first few minutes of explosion onset. Rapid sedimentation of the mm-sized pellets was observed as a decrease in maximum detection cloud height. The volcanic cloud from the April 4 explosive event showed lower reflectivity values, due to finer particle sizes (related to dome collapse and related pyroclastic flows) and lack of significant pellet formation. Eruption durations determined by the radar were within a factor of two compared to seismic and pressure-sensor derived estimates, and were not well correlated. Ash dispersion observed by the radar was primarily in the upper troposphere below 10 km, but satellite observations indicate the presence of volcanogenic clouds in the stratosphere. This study suggests that radar is a valuable complement to traditional seismic and satellite monitoring of explosive eruptions.

  2. Doppler weather radar observations of the 2009 eruption of Redoubt Volcano, Alaska

    Science.gov (United States)

    Schneider, David J.; Hoblitt, Richard P.

    2013-01-01

    The U.S. Geological Survey (USGS) deployed a transportable Doppler C-band radar during the precursory stage of the 2009 eruption of Redoubt Volcano, Alaska that provided valuable information during subsequent explosive events. We describe the capabilities of this new monitoring tool and present data captured during the Redoubt eruption. The MiniMax 250-C (MM-250C) radar detected seventeen of the nineteen largest explosive events between March 23 and April 4, 2009. Sixteen of these events reached the stratosphere (above 10 km) within 2–5 min of explosion onset. High column and proximal cloud reflectivity values (50 to 60 dBZ) were observed from many of these events, and were likely due to the formation of mm-sized accretionary tephra-ice pellets. Reflectivity data suggest that these pellets formed within the first few minutes of explosion onset. Rapid sedimentation of the mm-sized pellets was observed as a decrease in maximum detection cloud height. The volcanic cloud from the April 4 explosive event showed lower reflectivity values, due to finer particle sizes (related to dome collapse and related pyroclastic flows) and lack of significant pellet formation. Eruption durations determined by the radar were within a factor of two compared to seismic and pressure-sensor derived estimates, and were not well correlated. Ash dispersion observed by the radar was primarily in the upper troposphere below 10 km, but satellite observations indicate the presence of volcanogenic clouds in the stratosphere. This study suggests that radar is a valuable complement to traditional seismic and satellite monitoring of explosive eruptions.

  3. Nexrad-In-Space - A Geostationary Satellite Doppler Weather Radar for Hurricane Studies

    Science.gov (United States)

    Im, E.; Chandrasekar, V.; Chen, S. S.; Holland, G. J.; Kakar, R.; Lewis, W. E.; Marks, F. D.; Smith, E. A.; Tanelli, S.; Tripoli, G. J.

    2007-12-01

    The Nexrad-In-Space (NIS) is a revolutionary atmospheric radar observation concept from the geostationary orbiting platform. It was developed over the last 4 years under the auspices of NASA's Earth Science Instrument Incubator Program (IIP). The NIS radar would provide Ka-band (35 GHz) reflectivity and line-of-sight Doppler velocity profiles over a circular Earth region of approximately 5200 km in diameter with a 12-km horizontal resolution, and a minimum detectable signal of 5 dBZ. The NIS radar achieves its superb sampling capabilities by use of a 35-m diameter, deployable antenna made from lightweight membrane material. The antenna has two transmit-receive array pairs that create a dual-beam, spiral-feed combined profile image of both reflectivity and Doppler velocity approximately every 60 minutes. This sampling time can be shortened even further by increasing the number of transmit-receive array pairs. It is generally recognized that the processes important in governing hurricane intensity and structure span a wide range of spatial and temporal scales. The environmental forcing considerations require a large domain. The vortex response to the environmental forcing ultimately involves convection on small horizontal scales in the eyewall and rainband regions. Resolving this environment-vortex-convection feedback in a numerical model requires observations on the space and time scales necessary to unambiguously define these structures within and surrounding the tropical cyclone. Because the time and space scales of these processes are small, continuous 3-dimensional independent observations of the 3-dimensional wind and precipitation structures will be needed to initialize numerical models critical for this purpose. The proposed NIS Doppler radar would be the first instrument capable of accomplishing this feat at time scales less than hours, and would create the opportunity for hurricane science to enter a new era of understanding and improved prediction. This

  4. Improved Doppler Velocity Dealiasing for Radar Data Assimilation and Storm-Scale Vortex Detection

    Directory of Open Access Journals (Sweden)

    Qin Xu

    2013-01-01

    Full Text Available The Doppler velocity dealiasing technique based on alias-robust VAD and variational (AR-Var analyses developed at the National Severe Storms Laboratory for radar data quality control and assimilation is further improved in its two-step procedures: the reference check in the first step and the continuity check in the second step. In the first step, the alias-robust variational analysis is modified adaptively and used in place of the alias-robust velocity-azimuth display (VAD analysis for all scan modes (rather than solely the WSR-88D volume coverage pattern 31 with the Nyquist velocity vN reduced below 12 m s−1 and the TDWR Mod80 with vN reduced below 15 m s−1, so more raw data can pass the stringent threshold conditions used by the reference check in the first step. This improves the dealiased data coverage without false dealiasing to better satisfy the high data quality standard required by radar data assimilation. In the second step, new procedures are designed and added to the continuity check to increase the dealiased data coverage over storm-scale areas threatened by intense mesocyclones and their generated tornados. The performances of the improved dealiasing technique versus the existing techniques are exemplified by the results obtained for tornadic storms scanned by the operational KTLX radar in Oklahoma.

  5. Polarimetric and Multi-Doppler Radar Observations of Sprite-producing Storms

    Science.gov (United States)

    Lang, TImothy J.; Lyons, Walter A.; Rutledge, Steven A.; Dolan, Brenda; Cummer, Steven A.; Krehbiel, Paul; Rison, William

    2014-01-01

    Sprites are caused by luminous electrical breakdown of the upper atmosphere, and frequently occur over large mesoscale precipitation systems. Two sprite-producing storms (on 8 and 25 June) were observed in Colorado during the summer of 2012. Unlike most past studies of sprites, these storms were observed by a polarimetric radar - the CSU-CHILL facility - which provided both PPI and RHI scans of the cases. Also available were multiple-Doppler syntheses from CSU-CHILL, local NEXRAD radars, and the CSU-Pawnee radar; as well as data from the Colorado Lightning Mapping Array (COLMA), high speed cameras, and other lightning-detection instrumentation. This unique dataset provided an unprecedented look at the detailed kinematic and microphysical structures of the thunderstorms as they produced sprites, including electrical alignment signatures in the immediate location of the charge layers neutralized by sprite-parent positive cloud-to-ground lightning strokes. One of the sprite-producing cases (25 June) featured an anomalous charge structure and may serve as a model for how sprites can be produced over convection rather than the more typical stratiform regions. Also to be presented will be evidence for advection of charge into a common stratiform precipitation region (on 8 June), which was then tapped by lightning originating from multiple different convective cores to produce sprites. Depending on the outcome of the 2013 convective season, polarimetric data from additional storms that produce sprites and other transient luminous events (TLEs) may be presented.

  6. Using a low-order model to detect and characterize intense vortices in multiple-Doppler radar data

    Science.gov (United States)

    Potvin, Corey Keith

    A new multiple-Doppler radar analysis technique is presented for the objective detection and characterization of intense vortices. The technique consists of fitting radial wind data from two or more radars to a simple analytical model of a vortex and its near-environment. The model combines a uniform flow, linear shear flow, linear divergence flow (all of which comprise a broadscale flow), and modified combined Rankine vortex. The vortex and its environment are allowed to translate. A cost-function accounting for the discrepancy between the model and observed radial winds is evaluated over space and time so that observations can be used at the actual times and locations they were acquired. The parameters in the low-order model are determined by minimizing this cost function. The development of the method is initially guided by emulated radial velocity observations of analytical vortices. A high-resolution Advanced Regional Prediction System (ARPS) simulation of a supercellular tornado is then used to generate more realistic pseudo-observations. Finally, the technique is tested using real dual-Doppler tornado and mesocyclone observations from a variety of radar platforms including Weather Surveillance Radar - 1988 Doppler (WSR-88D), Terminal Doppler Weather Radar (TDWR), Shared Mobile Atmospheric Research and Teaching Radar (SMART-R), and Doppler on Wheels (DOW). The technique shows skill in detecting intense vortices and, when the vortex is well-resolved, in retrieving key model parameters including vortex location, translational velocity, radius and maximum tangential wind speed. In cases where the vortex is not well-resolved, additional vortex characteristics computed from the retrieved model parameters and verified against radial velocity observations can still provide useful information about vortex size and strength.

  7. Improvements to the OMI O2-O2 operational cloud algorithm and comparisons with ground-based radar-lidar observations

    Science.gov (United States)

    Pepijn Veefkind, J.; de Haan, Johan F.; Sneep, Maarten; Levelt, Pieternel F.

    2016-12-01

    The OMI (Ozone Monitoring Instrument on board NASA's Earth Observing System (EOS) Aura satellite) OMCLDO2 cloud product supports trace gas retrievals of for example ozone and nitrogen dioxide. The OMCLDO2 algorithm derives the effective cloud fraction and effective cloud pressure using a DOAS (differential optical absorption spectroscopy) fit of the O2-O2 absorption feature around 477 nm. A new version of the OMI OMCLDO2 cloud product is presented that contains several improvements, of which the introduction of a temperature correction on the O2-O2 slant columns and the updated look-up tables have the largest impact. Whereas the differences in the effective cloud fraction are on average limited to 0.01, the differences of the effective cloud pressure can be up to 200 hPa, especially at cloud fractions below 0.3. As expected, the temperature correction depends on latitude and season. The updated look-up tables have a systematic effect on the cloud pressure at low cloud fractions. The improvements at low cloud fractions are very important for the retrieval of trace gases in the lower troposphere, for example for nitrogen dioxide and formaldehyde. The cloud pressure retrievals of the improved algorithm are compared with ground-based radar-lidar observations for three sites at mid-latitudes. For low clouds that have a limited vertical extent the comparison yields good agreement. For higher clouds, which are vertically extensive and often contain several layers, the satellite retrievals give a lower cloud height. For high clouds, mixed results are obtained.

  8. Radar observations of the 2009 eruption of Redoubt Volcano, Alaska: Initial deployment of a transportable Doppler radar system for volcano-monitoring

    Science.gov (United States)

    Hoblitt, R. P.; Schneider, D. J.

    2009-12-01

    The rapid detection of explosive volcanic eruptions and accurate determination of eruption-column altitude and ash-cloud movement are critical factors in the mitigation of volcanic risks to aviation and in the forecasting of ash fall on nearby communities. The U.S. Geological Survey (USGS) deployed a transportable Doppler radar during the precursory stage of the 2009 eruption of Redoubt Volcano, Alaska, and it provided valuable information during subsequent explosive events. We describe the capabilities of this new monitoring tool and present data that it captured during the Redoubt eruption. The volcano-monitoring Doppler radar operates in the C-band (5.36 cm) and has a 2.4-m parabolic antenna with a beam width of 1.6 degrees, a transmitter power of 330 watts, and a maximum effective range of 240 km. The entire disassembled system, including a radome, fits inside a 6-m-long steel shipping container that has been modified to serve as base for the antenna/radome, and as a field station for observers and other monitoring equipment. The radar was installed at the Kenai Municipal Airport, 82 km east of Redoubt and about 100 km southwest of Anchorage. In addition to an unobstructed view of the volcano, this secure site offered the support of the airport staff and the City of Kenai. A further advantage was the proximity of a NEXRAD Doppler radar operated by the Federal Aviation Administration. This permitted comparisons with an established weather-monitoring radar system. The new radar system first became functional on March 20, roughly a day before the first of nineteen explosive ash-producing events of Redoubt between March 21 and April 4. Despite inevitable start-up problems, nearly all of the events were observed by the radar, which was remotely operated from the Alaska Volcano Observatory office in Anchorage. The USGS and NEXRAD radars both detected the eruption columns and tracked the directions of drifting ash clouds. The USGS radar scanned a 45-degree sector

  9. Coastal heavy rainband formed along Sumatera Island, Indonesia, observed with X-band Doppler radars during HARIMAU2011 campaign

    Science.gov (United States)

    Mori, Shuichi; Jun-Ichi, Hamada; Hattori, Miki; Kamimera, Hideyuki; Wu, Peiming; Arbain, Ardhi A.; Lestari, Sopia; Syamsudin, Fadli; Yamanaka, Manabu D.

    2013-04-01

    Coastal heavy rainbands (CHeRs) are widely identified over Asian monsoon region (e.g., Western Ghats, Bay of Bengal, Gulf of Thailand, and western Philippines) by satellite observations. Some of them are explained by synoptic wind-terrain interaction (Xie et al., 2006 JC) because they are anchored along mountain ranges face to southwest direction and predominant during boreal summer southwesterly monsoon season. Most Asian megacities are located in coastal regions, thus they have much chance to be suffered from torrential rainfall embedded in CHeRs which may cause flash floods in downtown cities and landslides in mountainous regions. Moreover, rainfall amount over the coastal land varies quite largely if those CHeRs change their lateral location a little, therefore water resource management for social community is seriously sensitive to their variability. Satellite observations show that CHeRs are modified by various kinds of environmental variations, e.g., diurnal, intraseasonal, monsoonal, ENSO, and IOD. However, climatology, structure, and mechanism of CHeRs have not been examined in detail from mesoscale points of view because there are quite few studies based on ground based radar observations. Previous studies (e.g., Mori et al. 2004 MWR; Yamanaka et al. 2008 JDR; Wu et al. 2007 SOLA) showed most CHeRs in Indonesia are identified along coastlines where convective diurnal variation is predominant, and coastal heavy rain are brought mainly in the nighttime observed with a radar-profiler network deployed by Hydrometeorological ARray for Intraseasonal variation (ISV) - Monsoon AUtomonitoring (HARIMAU) project. In addition, they are confirmed even in the seasons when the wind-terrain interaction cannot explain them well. These results suggest that CHeRs are formed by not only the synoptic wind-terrain effect but also mesoscale convections which developed nocturnally everyday along coastlines. We carried out the HARIMAU2011 campaign observation over Sumatera Island

  10. Detection Performance Assessment of Ground-Based Phased Array Radar for Ballistic Targets%地基相控阵雷达对弹道目标的探测性能评估

    Institute of Scientific and Technical Information of China (English)

    李星星; 姚汉英; 孙文峰

    2014-01-01

    为解决地基相控阵雷达对弹道目标探测的最优部署问题,建立弹道中段目标轨道运动和进动模型,提出弹道中段多部地基相控阵雷达的弹道目标探测概率模型,以及平均检测概率、稳定跟踪时间和资源冗余时间3种组合的雷达探测性能评估指标。依据弹道目标RCS及探测距离随观测时间的变化情况,通过仿真实验对多种部署方式下地基雷达对弹道目标探测性能评估指标的分析,得出的结论为弹道导弹防御系统中地基雷达的部署方式提供了有效的参考依据。%In order to solve the optimal deployment problem of ground-based phased array radar in detecting ballistic targets,the orbit motion and precession motion models of ballistic targets were built up,and the detection probability model for ballistic targets by using several ground-based phased array radars was proposed.Three evaluation indexes of radars'detection performance were given: average detection probability,stable tracking time and resource redundancy time .According to the variation of RCS and detection range for ballistic targets in midcourse,detection performance evaluation indexes of several radar deployment schemes were analyzed through experiments .The conclusion in this paper may provide some reference for deploying the ground-based radar in ballistic missile defense (BMD) system for targets'optimal detection.

  11. Radar Sensor Networks: Algorithms for Waveform Design and Diversity with Application to ATR with Delay-Doppler Uncertainty

    Directory of Open Access Journals (Sweden)

    Qilian Liang

    2007-01-01

    Full Text Available Automatic target recognition (ATR in target search phase is very challenging because the target range and mobility are not yet perfectly known, which results in delay-Doppler uncertainty. In this paper, we firstly perform some theoretical studies on radar sensor network (RSN design based on linear frequency modulation (LFM waveform: (1 the conditions for waveform coexistence, (2 interferences among waveforms in RSN, (3 waveform diversity in RSN. Then we apply RSN to ATR with delay-Doppler uncertainty and propose maximum-likeihood (ML ATR algorithms for fluctuating targets and nonfluctuating targets. Simulation results show that our RSN vastly reduces the ATR error compared to a single radar system in ATR with delay-Doppler uncertainty. The proposed waveform design and diversity algorithms can also be applied to active RFID sensor networks and underwater acoustic sensor networks.

  12. A conceptual framework for using Doppler radar acquired atmospheric data for flight simulation

    Science.gov (United States)

    Campbell, W.

    1983-01-01

    A concept is presented which can permit turbulence simulation in the vicinity of microbursts. The method involves a large data base, but should be fast enough for use with flight simulators. The model permits any pilot to simulate any flight maneuver in any aircraft. The model simulates a wind field with three-component mean winds and three-component turbulent gusts, and gust variation over the body of an aircraft so that all aerodynamic loads and moments can be calculated. The time and space variation of mean winds and turbulent intensities associated with a particular atmospheric phenomenon such as a microburst is used in the model. In fact, Doppler radar data such as provided by JAWS is uniquely suited for use with the proposed model. The concept is completely general and is not restricted to microburst studies. Reentry and flight in terrestrial or planetary atmospheres could be realistically simulated if supporting data of sufficient resolution were available.

  13. Comparison of numerical hindcasted severe waves with Doppler radar measurements in the North Sea

    Science.gov (United States)

    Ponce de León, Sonia; Bettencourt, João H.; Dias, Frederic

    2017-01-01

    Severe sea states in the North Sea present a challenge to wave forecasting systems and a threat to offshore installations such as oil and gas platforms and offshore wind farms. Here, we study the ability of a third-generation spectral wave model to reproduce winter sea states in the North Sea. Measured and modeled time series of integral wave parameters and directional wave spectra are compared for a 12-day period in the winter of 2013-2014 when successive severe storms moved across the North Atlantic and the North Sea. Records were obtained from a Doppler radar and wave buoys. The hindcast was performed with the WAVEWATCH III model (Tolman 2014) with high spectral resolution both in frequency and direction. A good general agreement was obtained for integrated parameters, but discrepancies were found to occur in spectral shapes.

  14. Quality Control of Wind Data from 50-MHz Doppler Radar Wind Profiler

    Science.gov (United States)

    Vacek, Austin

    2016-01-01

    Upper-level wind profiles obtained from a 50-MHz Doppler Radar Wind Profiler (DRWP) instrument at Kennedy Space Center are incorporated in space launch vehicle design and day-of-launch operations to assess wind effects on the vehicle during ascent. Automated and manual quality control (QC) techniques are implemented to remove spurious data in the upper-level wind profiles caused from atmospheric and non-atmospheric artifacts over the 2010-2012 period of record (POR). By adding the new quality controlled profiles with older profiles from 1997-2009, a robust database will be constructed of upper-level wind characteristics. Statistical analysis will determine the maximum, minimum, and 95th percentile of the wind components from the DRWP profiles over recent POR and compare against the older database. Additionally, this study identifies specific QC flags triggered during the QC process to understand how much data is retained and removed from the profiles.

  15. Kinematic Structure of a Heavy Rain Event from Dual-Doppler Radar Observations

    Institute of Scientific and Technical Information of China (English)

    邵爱梅; 邱崇践; 刘黎平

    2004-01-01

    The detailed kinematic structure of a heavy rain event that occurred in the middle reaches of the Yangtze River was investigated using dual-Doppler radar observation. A variational analysis method was developed to obtain the three-dimensional wind fields. Before the analysis, a data preprocessing procedure was carried out, in which the temporal variation with the scanning time interval and the effect of the earth curvature on the data position were taken into account. The analysis shows that a shear line in the lower and middle levels played an important role in the rainfall event. The precipitation fell mainly on the south end of the shear line where southerly flow prevailed and convergence and updraft were obvious. With the movement and decay of the shear line, the precipitation moved and decayed correspondingly.

  16. Homodyne detection of short-range Doppler radar using a forced oscillator model

    Science.gov (United States)

    Kittipute, Kunanon; Saratayon, Peerayudh; Srisook, Suthasin; Wardkein, Paramote

    2017-01-01

    This article presents the homodyne detection in a self-oscillation system, which represented by a short-range radar (SRR) circuit, that is analysed using a multi-time forced oscillator (MTFO) model. The MTFO model is based on a forced oscillation perspective with the signal and system theory, a second-order differential equation, and the multiple time variable technique. This model can also apply to analyse the homodyne phenomenon in a difference kind of the oscillation system under same method such as the self-oscillation system, and the natural oscillation system with external forced. In a free oscillation system, which forced by the external source is represented by a pendulum with an oscillating support experiment, and a modified Colpitts oscillator circuit in the UHF band with input as a Doppler signal is a representative of self-oscillation system. The MTFO model is verified with the experimental result, which well in line with the theoretical analysis. PMID:28252000

  17. 微波雷达海洋回波多普勒频谱的数值仿真%Numerical Simulation of Doppler Spectrum of Sea Echo for Microwave Radar

    Institute of Scientific and Technical Information of China (English)

    陈泽宗; 金燕; 陈曦; 范林刚

    2013-01-01

    研究了微波与海面相互作用的散射机理,在Plant等人研究成果的基础上对多普勒频谱仿真模型进行改进和完善.根据Bragg散射原理、复合表面理论和线性波理论,引入不同极化机制下的NRCS,给出多普勒频谱的谱型、幅度和时域变化特征,比较分析了不同海况下的仿真结果.%An improved numerical simulation method of Doppler Spectrum of sea echo for ground-based microwave wave radar is presented based on a study of scattering mechanism of microwave with ocean surface and some research results by W.J.Plant et al.According to the theories of Bragg scattering,composite surface,linear wave,and the expressions for NRCS of different polarization types,the characteristics of Doppler spectrum is displayed in shape,amplitude and time domain,and Doppler spectra of different ocean conditions are compared and qualitatively analyzed.Accordingly,it can be concluded that the simulation results reflect actual ocean environment and accord with objective law,which provides significant theoretical model for oceanographic observation by microwave wave radar and information extraction of sea state,especially parameters of wind,wave and current.

  18. West African Squall-Line Thermodynamic Structure Retrieved from Dual-Doppler Radar Observations.

    Science.gov (United States)

    Roux, Frank; Testud, Jacques; Payen, Marc; Pinty, Bernard

    1984-11-01

    Pressure and temperature fields within a West African squall line, retrieved from dual-Doppler radar data collected during the `COPT 81' (Convection Profonde Tropicale) experiment are presented. The method for derivation of thew results is approximately similar to that proposed by Gal-Chen, based on the anelastic equation of motion.Comparisons between pressure and temperature fields deduced from radar data at the lowest levels and surface network measurements show good agreement. The inferred thermodynamic structure displays the influence of a low-level frontward flow which is mainly due to a density current of cold air, generated in the stratiform region of the squall line and resulting from a mesoscale downdraft. This frontward flow contributes to initiate and maintain a frontal updraft through both nonhydrostatic pressure perturbation and temperature difference between entering air and colder frontward flow. At higher altitudes, mixing with the environment reduces buoyancy in the frontal updraft, while weaker convective updrafts develop in the inner region.Comparisons between these results and the kinematic and thermodynamic structures deduced from a previous observation (Le Mone, 1983) display different types of dynamics of organized convective systems.

  19. Wind Retrieval Algorithms for the IWRAP and HIWRAP Airborne Doppler Radars with Applications to Hurricanes

    Science.gov (United States)

    Guimond, Stephen Richard; Tian, Lin; Heymsfield, Gerald M.; Frasier, Stephen J.

    2013-01-01

    Algorithms for the retrieval of atmospheric winds in precipitating systems from downward-pointing, conically-scanning airborne Doppler radars are presented. The focus in the paper is on two radars: the Imaging Wind and Rain Airborne Profiler(IWRAP) and the High-altitude IWRAP (HIWRAP). The IWRAP is a dual-frequency (Cand Ku band), multi-beam (incidence angles of 30 50) system that flies on the NOAAWP-3D aircraft at altitudes of 2-4 km. The HIWRAP is a dual-frequency (Ku and Kaband), dual-beam (incidence angles of 30 and 40) system that flies on the NASA Global Hawk aircraft at altitudes of 18-20 km. Retrievals of the three Cartesian wind components over the entire radar sampling volume are described, which can be determined using either a traditional least squares or variational solution procedure. The random errors in the retrievals are evaluated using both an error propagation analysis and a numerical simulation of a hurricane. These analyses show that the vertical and along-track wind errors have strong across-track dependence with values of 0.25 m s-1 at nadir to 2.0 m s-1 and 1.0 m s-1 at the swath edges, respectively. The across-track wind errors also have across-track structure and are on average, 3.0 3.5 m s-1 or 10 of the hurricane wind speed. For typical rotated figure four flight patterns through hurricanes, the zonal and meridional wind speed errors are 2 3 m s-1.Examples of measured data retrievals from IWRAP during an eyewall replacement cycle in Hurricane Isabel (2003) and from HIWRAP during the development of Tropical Storm Matthew (2010) are shown.

  20. Statistical characteristics of Doppler spectral width as observed by the conjugate SuperDARN radars

    Directory of Open Access Journals (Sweden)

    K. Hosokawa

    Full Text Available We performed a statistical analysis of the occurrence distribution of Doppler spectral width around the day-side high-latitude ionosphere using data from the conjugate radar pair composed of the CUTLASS Iceland-East radar in the Northern Hemisphere and the SENSU Syowa-East radar in the Southern Hemisphere. Three types of spectral width distribution were identified: (1 an exponential-like distribution in the lower magnetic latitudes (below 72°, (2 a Gaussian-like distribution around a few degrees magnetic latitude, centered on 78°, and (3 another type of distribution in the higher magnetic latitudes (above 80°. The first two are considered to represent the geophysical regimes such as the LLBL and the cusp, respectively, because they are similar to the spectral width distributions within the LLBL and the cusp, as classified by Baker et al. (1995. The distribution found above 80° magnetic latitude has been clarified for the first time in this study. This distribution has similarities to the exponential-like distribution in the lower latitude part, although clear differences also exist in their characteristics. These three spectral width distributions are commonly identified in conjugate hemispheres. The latitudinal transition from one distribution to another exhibits basically the same trend between two hemispheres. There is, however, an interhemispheric difference in the form of the distribution around the cusp latitudes, such that spectral width values obtained from Syowa-East are larger than those from Iceland-East. On the basis of the spectral width characteristics, the average locations of the cusp and the open/closed field line boundary are estimated statistically.

    Key words. Ionosphere (ionosphere-magnetosphere inter-actions; plasma convection – Magnetospheric physics (magnetopause, cusp, and boundary layers

  1. Analysis of the heavy rainfall from Typhoon Plum using Doppler Radar

    Science.gov (United States)

    Jin, W.; Qu, Y.

    2013-12-01

    Using reanalysis and observational data and Doppler radar data, the structure and characteristics of the synoptic and mesoscale meteorological background are analyzed for a heavy rainfall over Xiaoshipeng town of Yingkou City in Liaoning province, China. The results show that: (1) several synoptic scale patterns formed the background for the heavy rainfall: the Pacific subtropical high extended to the West; a strong tropical storm named "Plum" moved to the northwest after it had landed; Northwest jet transported a lot of the water vapor to Liaoning; the weak cold air of Baikal Lake moved to south along the ridge before the northwest flow impact to Liaoning. (2) the factors conducive to strong convective precipitation: the existence of a deep wet layer, a narrow CAPE zone and a relative weak vertical wind sheer. (3) there is nonstop generation of new mesoscale convective cells during the heavy rainfall. There exists a maximum wind zone of 24m/s in the lower layer and a strong radar echo with 35dBz above 5km. And the variation of the low level southwest jet is in step with the variation of rainfall amount. The cyclonic convergence of the warm wet air in the mid-low level is a factor triggering and strengthening convection. The nonstop generation of mesoscale convective cells and the water vapor transport from the low level southwest jet are pushing the rainfall radar echo to above 40dBz and lasting for more than 5 hours and are considered the direct cause of this heavy rainfall.

  2. Using a Ground Based radar interferometer during emergency: the case of A3 motorway (Salerno Reggio-Calabria) treated by landslide

    Science.gov (United States)

    Del Ventisette, Chiara; Intrieri, Emanuele; Luzi, Guido; Casagli, Nicola

    2010-05-01

    An application of Ground Based radar interferometry (GB-InSAR) technique to monitor a landslide threatening infrastructures in emergency conditions is presented. During December 2008 and January 2009 intense rainfalls occurred in Italy, especially in the southern regions. These rain events occurred in the last days of January, worsened the already critical hydrogeological conditions of some areas and triggered many landslides. One of these landslides, named Santa Trada landslide, is located close to a periodical stream called Fiumara di Santa Trada, near Villa San Giovanni municipality (Reggio Calabria, Calabria Region). The volume involved is about 100 000 m3. This estimate represents the case of a collapse of the landslide which destabilize a larger part of the slope, involving other areas delimited by some fractures observed upstream. Nevertheless the landslide does not directly threaten the roadway, its complete collapse would hit the pillars of a motorway viaduct. Through GB-InSAR data it has been possible to obtain an overview of the area affected by movement and to quantify the displacements magnitude. The main benefit of the system was not only limited to the capability of fully characterizing the landslide in spatial terms, it also permitted emergency operators to follow, during the whole campaign, the evolution of the mass movement and to study its cinematic behaviour. This aspect is fundamental to evaluate the volume of the material involved and to assess the temporal evolution of the risk scenario. The GB-InSAR installed at Santa Trada points up toward the landslide from a distance of 250 m. The apparatus produces a synthesized radar image of the observed area every 6 minutes, night and day, with a pixel resolution of about 0.75 m in range and 1.2 m on average in cross range, performing a millimeter accuracy on the final displacement maps. The interferometric analysis of sequences of consecutive images allows the operator to derive the entire line of

  3. Doppler lidar observations of sensible heat flux and intercomparisons with a ground-based energy balance station and WRF model output

    Directory of Open Access Journals (Sweden)

    Jenny Davis

    2009-05-01

    Full Text Available During the Convective and Orographically induced Precipitation Study (COPS, a scanning Doppler lidar was deployed at Achern, Baden-Wüttemberg, Germany from 13th June to 16th August 2007. Vertical velocity profiles ('rays' through the boundary layer were measured every 3 seconds with vertical profiles of horizontal wind velocity being derived from performing azimuth scans every 30 minutes. During Intense Observation Periods radiosondes were launched from the site. In this paper, a case study of convective boundary layer development on 15th July 2007 is investigated. Estimates of eddy dissipation rate are made from the vertically pointing lidar data and used as one input to the velocity-temperature co-variance equation to estimate sensible heat flux. The sensible heat flux values calculated from Doppler lidar data are compared with a surface based energy balance station and output from the Weather Research and Forecasting (WRF model.

  4. Comparison of D-region Doppler drift winds measured by the SuperDARN Finland HF radar over an annual cycle using the Kiruna VHF meteor radar

    Directory of Open Access Journals (Sweden)

    N. F. Arnold

    Full Text Available The SuperDARN chain of oblique HF radars has provided an opportunity to generate a unique climatology of horizontal winds near the mesopause at a number of high latitude locations, via the Doppler shifted echoes from sources of ionisation in the D-region. Ablating meteor trails form the bulk of these targets, but other phenomena also contribute to the observations. Due to the poor vertical resolution of the radars, care must be taken to reduce possible biases from sporadic-E layers and Polar Mesospheric Summer echoes that can affect the effective altitude of the geophysical parameters being observed. Second, there is strong theoretical and observational evidence to suggest that the radars are picking up echoes from the backward looking direction that will tend to reduce the measured wind strengths. The effect is strongly frequency dependent, resulting in a 20% reduction at 12 MHz and a 50% reduction at 10 MHz. A comparison of the climatologies observed by the Super-DARN Finland radar between September 1999 and September 2000 and that obtained from the adjacent VHF meteor radar located at Kiruna is also presented. The agreement between the two instruments was very good. Extending the analysis to the SuperDARN Iceland East radar indicated that the principles outlined above could be applied successfully to the rest of the SuperDARN network.

    Key words. Ionosphere (ionosphere-atmosphere interactions; instruments and techniques – Meteorology and atmospheric dynamics (waves and tides

  5. The variability of tropical ice cloud properties as a function of the large-scale context from ground-based radar-lidar observations over Darwin, Australia

    Directory of Open Access Journals (Sweden)

    A. Protat

    2010-08-01

    Full Text Available The statistical properties of non-precipitating tropical ice clouds over Darwin, Australia are characterized using ground-based radar-lidar observations from the Atmospheric Radiation Measurement (ARM Program. The ice cloud properties analysed are the frequency of ice cloud occurrence, the morphological properties (cloud top height and thickness, cloud fraction as derived considering a typical large-scale model grid box, and the microphysical and radiative properties (ice water content, visible extinction, effective radius, terminal fall speed, and total concentration. The variability of these tropical ice cloud properties is then studied as a function of the large-scale cloud regimes derived from the International Satellite Cloud Climatology Project (ISCCP, the amplitude and phase of the Madden–Julian Oscillation (MJO, and the large-scale atmospheric regime as derived from a long-term record of radiosonde observations over Darwin. The rationale for characterizing this variability is to provide an observational basis to which model outputs can be compared for the different regimes or large-scale characteristics and from which new parameterizations accounting for the large-scale context can be derived.

    The mean vertical variability of ice cloud occurrence and microphysical properties is large (1.5 order of magnitude for ice water content and extinction, a factor 3 in effective radius, and three orders of magnitude in concentration, typically. 98% of ice clouds in our dataset are characterized by either a small cloud fraction (smaller than 0.3 or a very large cloud fraction (larger than 0.9. Our results also indicate that, at least in the northern Australian region, the upper part of the troposphere can be split into three distinct layers characterized by different statistically-dominant microphysical processes. The variability of the ice cloud properties as a function of the large-scale atmospheric regime, cloud regime, and MJO phase

  6. Target detection in pulse-Doppler radar based on multi-scanning signal integration

    Directory of Open Access Journals (Sweden)

    O. S. Neuimin

    2013-07-01

    Full Text Available Introduction. Development of multi-scanning signal integration algorithms for pulseDoppler radars which are widely used in practice is of great practical importance. Problem statement. The problem of multi-scanning signal integration measuring range and range-rate is considered. The reflected signal from a target is a distorted white noise coherent packet of radio pulses with random initial phase and known amplitude. Target detection in a sequence of radar scans is reduced to the detection of target track. Development of a two-step multi-scanning incoherent signal integration algorithm. Two-step integration method is applied to reduce the number of tracks. In the first stage the initial signals detection with a sufficiently high probability of false alarm is performed. In the second stage the tracking problem for selection target markers is solved and the multiscanning signal integration is implemented. It provides an optimal target detection solution over K surveys with low signal-to-noise ratio. Expressions for the correct target detection probability and false alarm incorporating quality track tracking are obtained. Simulation results. Analysis of the algorithm is carried out as example of the little maneuvering target detection using the statistical modeling. The methods of calculating the output threshold (the cumulative statistics are compared on it is presented. Conclusions. Increasing the number of scans (in which the integration are performed leads to a significant decreasing the probability of false alarm, which allows to increase the signal-to-noise ratio compared with the detection in a single scan up to 3.5 dB.

  7. Extracting Micro-Doppler Radar Signatures from Rotating Targets Using Fourier-Bessel Transform and Time-Frequency Analysis

    Science.gov (United States)

    2014-10-16

    1 Extracting micro-Doppler radar signatures from rotating targets using Fourier- Bessel Transform and Time-Frequency analysis P. Suresh1,T...kvenkataramanaiah@sssihl.edu.in Abstract In this paper, we report the efficiency of Fourier Bessel transform and time-frequency based method in conjunction with...decomposed into stationary and non-stationary components using Fourier Bessel transform in conjunction with the fractional Fourier transform. The

  8. A Pedestrian Detection Scheme Using a Coherent Phase Difference Method Based on 2D Range-Doppler FMCW Radar

    Directory of Open Access Journals (Sweden)

    Eugin Hyun

    2016-01-01

    Full Text Available For an automotive pedestrian detection radar system, fast-ramp based 2D range-Doppler Frequency Modulated Continuous Wave (FMCW radar is effective for distinguishing between moving targets and unwanted clutter. However, when a weak moving target such as a pedestrian exists together with strong clutter, the pedestrian may be masked by the side-lobe of the clutter even though they are notably separated in the Doppler dimension. To prevent this problem, one popular solution is the use of a windowing scheme with a weighting function. However, this method leads to a spread spectrum, so the pedestrian with weak signal power and slow Doppler may also be masked by the main-lobe of clutter. With a fast-ramp based FMCW radar, if the target is moving, the complex spectrum of the range- Fast Fourier Transform (FFT is changed with a constant phase difference over ramps. In contrast, the clutter exhibits constant phase irrespective of the ramps. Based on this fact, in this paper we propose a pedestrian detection for highly cluttered environments using a coherent phase difference method. By detecting the coherent phase difference from the complex spectrum of the range-FFT, we first extract the range profile of the moving pedestrians. Then, through the Doppler FFT, we obtain the 2D range-Doppler map for only the pedestrian. To test the proposed detection scheme, we have developed a real-time data logging system with a 24 GHz FMCW transceiver. In laboratory tests, we verified that the signal processing results from the proposed method were much better than those expected from the conventional 2D FFT-based detection method.

  9. A Pedestrian Detection Scheme Using a Coherent Phase Difference Method Based on 2D Range-Doppler FMCW Radar

    Science.gov (United States)

    Hyun, Eugin; Jin, Young-Seok; Lee, Jong-Hun

    2016-01-01

    For an automotive pedestrian detection radar system, fast-ramp based 2D range-Doppler Frequency Modulated Continuous Wave (FMCW) radar is effective for distinguishing between moving targets and unwanted clutter. However, when a weak moving target such as a pedestrian exists together with strong clutter, the pedestrian may be masked by the side-lobe of the clutter even though they are notably separated in the Doppler dimension. To prevent this problem, one popular solution is the use of a windowing scheme with a weighting function. However, this method leads to a spread spectrum, so the pedestrian with weak signal power and slow Doppler may also be masked by the main-lobe of clutter. With a fast-ramp based FMCW radar, if the target is moving, the complex spectrum of the range- Fast Fourier Transform (FFT) is changed with a constant phase difference over ramps. In contrast, the clutter exhibits constant phase irrespective of the ramps. Based on this fact, in this paper we propose a pedestrian detection for highly cluttered environments using a coherent phase difference method. By detecting the coherent phase difference from the complex spectrum of the range-FFT, we first extract the range profile of the moving pedestrians. Then, through the Doppler FFT, we obtain the 2D range-Doppler map for only the pedestrian. To test the proposed detection scheme, we have developed a real-time data logging system with a 24 GHz FMCW transceiver. In laboratory tests, we verified that the signal processing results from the proposed method were much better than those expected from the conventional 2D FFT-based detection method. PMID:26805835

  10. A Pedestrian Detection Scheme Using a Coherent Phase Difference Method Based on 2D Range-Doppler FMCW Radar.

    Science.gov (United States)

    Hyun, Eugin; Jin, Young-Seok; Lee, Jong-Hun

    2016-01-20

    For an automotive pedestrian detection radar system, fast-ramp based 2D range-Doppler Frequency Modulated Continuous Wave (FMCW) radar is effective for distinguishing between moving targets and unwanted clutter. However, when a weak moving target such as a pedestrian exists together with strong clutter, the pedestrian may be masked by the side-lobe of the clutter even though they are notably separated in the Doppler dimension. To prevent this problem, one popular solution is the use of a windowing scheme with a weighting function. However, this method leads to a spread spectrum, so the pedestrian with weak signal power and slow Doppler may also be masked by the main-lobe of clutter. With a fast-ramp based FMCW radar, if the target is moving, the complex spectrum of the range- Fast Fourier Transform (FFT) is changed with a constant phase difference over ramps. In contrast, the clutter exhibits constant phase irrespective of the ramps. Based on this fact, in this paper we propose a pedestrian detection for highly cluttered environments using a coherent phase difference method. By detecting the coherent phase difference from the complex spectrum of the range-FFT, we first extract the range profile of the moving pedestrians. Then, through the Doppler FFT, we obtain the 2D range-Doppler map for only the pedestrian. To test the proposed detection scheme, we have developed a real-time data logging system with a 24 GHz FMCW transceiver. In laboratory tests, we verified that the signal processing results from the proposed method were much better than those expected from the conventional 2D FFT-based detection method.

  11. Quality Control Algorithms for the Kennedy Space Center 50-Megahertz Doppler Radar Wind Profiler Winds Database

    Science.gov (United States)

    Barbre, Robert E., Jr.

    2012-01-01

    This paper presents the process used by the Marshall Space Flight Center Natural Environments Branch (EV44) to quality control (QC) data from the Kennedy Space Center's 50-MHz Doppler Radar Wind Profiler for use in vehicle wind loads and steering commands. The database has been built to mitigate limitations of using the currently archived databases from weather balloons. The DRWP database contains wind measurements from approximately 2.7-18.6 km altitude at roughly five minute intervals for the August 1997 to December 2009 period of record, and the extensive QC process was designed to remove spurious data from various forms of atmospheric and non-atmospheric artifacts. The QC process is largely based on DRWP literature, but two new algorithms have been developed to remove data contaminated by convection and excessive first guess propagations from the Median Filter First Guess Algorithm. In addition to describing the automated and manual QC process in detail, this paper describes the extent of the data retained. Roughly 58% of all possible wind observations exist in the database, with approximately 100 times as many complete profile sets existing relative to the EV44 balloon databases. This increased sample of near-continuous wind profile measurements may help increase launch availability by reducing the uncertainty of wind changes during launch countdown

  12. A Methodology for Determining Statistical Performance Compliance for Airborne Doppler Radar with Forward-Looking Turbulence Detection Capability

    Science.gov (United States)

    Bowles, Roland L.; Buck, Bill K.

    2009-01-01

    The objective of the research developed and presented in this document was to statistically assess turbulence hazard detection performance employing airborne pulse Doppler radar systems. The FAA certification methodology for forward looking airborne turbulence radars will require estimating the probabilities of missed and false hazard indications under operational conditions. Analytical approaches must be used due to the near impossibility of obtaining sufficient statistics experimentally. This report describes an end-to-end analytical technique for estimating these probabilities for Enhanced Turbulence (E-Turb) Radar systems under noise-limited conditions, for a variety of aircraft types, as defined in FAA TSO-C134. This technique provides for one means, but not the only means, by which an applicant can demonstrate compliance to the FAA directed ATDS Working Group performance requirements. Turbulence hazard algorithms were developed that derived predictive estimates of aircraft hazards from basic radar observables. These algorithms were designed to prevent false turbulence indications while accurately predicting areas of elevated turbulence risks to aircraft, passengers, and crew; and were successfully flight tested on a NASA B757-200 and a Delta Air Lines B737-800. Application of this defined methodology for calculating the probability of missed and false hazard indications taking into account the effect of the various algorithms used, is demonstrated for representative transport aircraft and radar performance characteristics.

  13. An Integrating VAP Method for Single-Doppler Radar Wind Retrieval

    Institute of Scientific and Technical Information of China (English)

    LIANG Xudong; WANG Bin

    2009-01-01

    Some traditional methods, such as the velocity-azimuth display (VAD) and the velocity-azimuth pro-cessing (VAP), have been widely used to retrieve the 3-D wind field from single-Doppler radar data because of their relative conceptual and practical simplicity. The advantage of VAD is that it is not affected by small-scale perturbations of the radial wind along the azimuth, to which the VAP method is very sensitive. Nevertheless, the spatial resolution of the VAD method is very poor compared to the VAP method. We show, in this study, that these two retrieval methods are actually related with each other and they are two special applications of a retrieval function based on the azimuthal uniform-wind assumption for a given azimuthal interval [θ1,θ2]. When using this retrieval function to retrieve wind fields, the azimuthal interval used in retrieval can be adjusted according to the requirement of smoothness or resolution. The larger (smaller) the azimuthal interval is, the coarser (finer) the horizontal resolution of retrieved wind field is, and the more insensitive (sensitive) the retrieval method is to small-scale perturbations. Because the full information within the azimuthal interval [θ1,θ2], instead of the information at two terminal points only, i.e., azimuths θ1 and θ2, is used to retrieve the wind fields, this method is referred to as the integrating VAP (IVAP) method, wherein the horizontal wind field is retrieved by using the Doppler velocity over the part of circumference, delimited by the given azimuthal interval times the scan radius. By contrast, the VAP method uses only the velocities at two terminal points of the given azimuthal interval. Therefore, the IVAP method has a filtering function, and the filtering rate can be controlled by adjusting the azimuthal interval. The filter such as that used in the pre-processing of the VAP method is no longer necessary for the IVAP method. When the retrieval azimuthal interval is as large as a whole

  14. WHIRL WIND DETECTION AND IDENTIFICATION IN INDONESIA UTILIZING SINGLE POLARIZATION DOPPLER WEATHER RADAR VOLUMETRIC DATA

    Directory of Open Access Journals (Sweden)

    A. Ali

    2016-06-01

    Full Text Available Whirl wind occurrence frequency in Indonesia tends increasing in the last five years. Geospatial data from National Agency for Disaster Management (BNPB recorded 72 cases with the impact of the two victims died, ten injured, 485 people were evacuated, and 1285 buildings were destroyed at period of January-June 2015. Based on the impact, early warning through remote sensing by using single polarization Doppler weather radar is need to be efforted. Whirl wind detection is done by identifying the characteristic pattern of the rotating convective cloud system by hook echo, analyzing the exsistance of vortex and rotation, and the strength of turbulence. The results show horizontal wind profile with a rotational pattern at CAPPI (V and HWIND (V by the altitude of 0.5 km, strong turbulence through product CAPPI (W 0.5 km ranged of 1.75-2.05 ms-1, the vertical wind profile by product VVP (V with a maximum value updraft reaches more than 20 knots at a 100-200 meters height, strong horizontal wind shear through HSHEAR (V and CAPPI (HSHEAR altitude of 0.5 km with a range of 6.23 to 10.12 ms-1/km. SWI and SSA show that the cloud base height is very low ranged from 200-600 meters with a maximum reflectivity reached 61.5 dBZ by top cloud height reached 14 km, while the product CAPPI (Z 0.5 km and CMAX (Z is very difficult to identify patterns hook echo. The results of remote sensing are very representative with the physical properties of whirl wind even whirl wind in a smaller scale.

  15. KSC 50-MHz Doppler Radar Wind Profiler (DRWP) Operational Acceptance Test (OAT) Report

    Science.gov (United States)

    Barbre, Robert E.

    2015-01-01

    This report documents analysis results of the Kennedy Space Center updated 50-MHz Doppler Radar Wind Profiler (DRWP) Operational Acceptance Test (OAT). This test was designed to demonstrate that the new DRWP operates in a similar manner to the previous DRWP for use as a situational awareness asset for mission operations at the Eastern Range to identify rapid changes in the wind environment that weather balloons cannot depict. Data examination and two analyses showed that the updated DRWP meets the specifications in the OAT test plan and performs at least as well as the previous DRWP. Data examination verified that the DRWP provides complete profiles every five minutes from 1.8-19.5 km in vertical increments of 150 m. Analysis of 5,426 wind component reports from 49 concurrent DRWP and balloon profiles presented root mean square (RMS) wind component differences around 2.0 m/s. The DRWP's effective vertical resolution (EVR) was found to be 300 m for both the westerly and southerly wind component, which the best EVR possible given the DRWP's vertical sampling interval. A third analysis quantified the sensitivity to rejecting data that do not have adequate signal by assessing the number of first-guess propagations at each altitude. This report documents the data, quality control procedures, methodology, and results of each analysis. It also shows that analysis of the updated DRWP produced results that were at least as good as the previous DRWP with proper rationale. The report recommends acceptance of the updated DRWP for situational awareness usage as per the OAT's intent.

  16. Whirl Wind Detection and Identification in Indonesia Utilizing Single Polarization Doppler Weather Radar Volumetric Data

    Science.gov (United States)

    Ali, Abdullah; Hidayati, Sabitul

    2016-06-01

    Whirl wind occurrence frequency in Indonesia tends increasing in the last five years. Geospatial data from National Agency for Disaster Management (BNPB) recorded 72 cases with the impact of the two victims died, ten injured, 485 people were evacuated, and 1285 buildings were destroyed at period of January-June 2015. Based on the impact, early warning through remote sensing by using single polarization Doppler weather radar is need to be efforted. Whirl wind detection is done by identifying the characteristic pattern of the rotating convective cloud system by hook echo, analyzing the exsistance of vortex and rotation, and the strength of turbulence. The results show horizontal wind profile with a rotational pattern at CAPPI (V) and HWIND (V) by the altitude of 0.5 km, strong turbulence through product CAPPI (W) 0.5 km ranged of 1.75-2.05 ms-1, the vertical wind profile by product VVP (V) with a maximum value updraft reaches more than 20 knots at a 100-200 meters height, strong horizontal wind shear through HSHEAR (V) and CAPPI (HSHEAR) altitude of 0.5 km with a range of 6.23 to 10.12 ms-1/km. SWI and SSA show that the cloud base height is very low ranged from 200-600 meters with a maximum reflectivity reached 61.5 dBZ by top cloud height reached 14 km, while the product CAPPI (Z) 0.5 km and CMAX (Z) is very difficult to identify patterns hook echo. The results of remote sensing are very representative with the physical properties of whirl wind even whirl wind in a smaller scale.

  17. The WRF 3DVar System Combined with Physical Initialization for Assimilation of Doppler Radar Data

    Institute of Scientific and Technical Information of China (English)

    YANG Yi; QIU Chongjian; GONG Jiandong; Huang Jing

    2009-01-01

    The three-dimensional variational data assimilation (3DVar) system of the Weather Research and Fore-casting (WRF) model (WRF-Var) is further developed with a physical initialization (PI) procedure to assimilate Doppler radar radial velocity and reflectivity observations. In this updated 3DVar system, spe-cific humidity, cloud water content, and vertical velocity are first derived from reflectivity with PI, then the model fields of specific humidity and cloud water content are replaced with the modified ones, and finally, the estimated vertical velocity is added to the cost-function of the existing WRF-Var (version 2.0) as a new observation type, and radial velocity observations are assimilated directly by the method afforded by WRF-Var. The new assimilation scheme is tested with a heavy convective precipitation event in the middle reaches of Yangtze River on 19 June 2002 and a Meiyu front torrential rain event in the Huaihe River Basin on 5 July 2003. Assimilation results show that the increments of analyzed variables correspond well with the horizontal distribution of the observed reflectivity. There are positive increments of cloud water content, specific humidity, and vertical velocity in echo region and negative increments of vertical velocity in echo-free region where the increments of horizontal winds present a clockwise transition. Results of forecast experiments show that the effects of adjusting cloud water content or vertical velocity directly with PI on forecast are not obvious. Adjusting specific humidity shows better performance in forecasting the precipitation than directly adjusting cloud water content or vertical velocity. Significant improvement in predicting precipitation as well as in reducing the model's spin-up time are achieved when radial velocity and reflectivity observations are assimilated with the new scheme.

  18. A Doppler Radar Observation of a Cold Front: Three-Dimensional Air Circulation, Related Precipitation System, and Associated Wavelike Motions.

    Science.gov (United States)

    Testud, J.; Amayenc, P.; Chong, M.; Nutten, B.; Sauvaget, A.

    1980-01-01

    This paper is based on the observation of a cold front using a C-band Doppler radar. The extent of the precipitation system associated with the front allowed collection of Doppler radar data during 12 consecutive hours. The methodology for data acquisition presently used is conical scanning. The data analysis has been extended to the case of a nonuniform distribution of tracers.The air circulation is presented in a reference frame moving at the speed of the front. A pronounced cross-frontal circulation is found to be associated with significant cross-frontal acceleration. The thermal structure across the front is reconstructed by means of the equations of motion.From the vertical velocity field an estimate of the height-integrated condensation rate is made. It is found to agree with the rainfall rate inferred from the radar reflectivity data.Also, large-amplitude small-scale motions are detected and identified as a well-characterized atmospheric wave. Theoretical considerations support the explanation that it is the manifestation of a dynamical instability of the shear flow within the frontal zone.

  19. Assimilation of Doppler Radar Observations with an Ensemble Square Root Filter:A Squall Line Case Study

    Institute of Scientific and Technical Information of China (English)

    QIN Yanyan; GONG Jiandong; LI Zechun; SHENG Rifeng

    2014-01-01

    The effectiveness of using an Ensemble Square Root Filter (EnSRF) to assimilate real Doppler radar observations on convective scale is investigated by applying the technique to a case of squall line on 12 July 2005 in midwest Shandong Province using the Weather Research and Forecasting (WRF) model. The experimental results show that: (1) The EnSRF system has the potential to initiate a squall line accurately by assimilation of real Doppler radar data. The convective-scale information has been added into the WRF model through radar data assimilation and thus the analyzed fields are improved noticeably. The model spin-up time has been shortened, and the precipitation forecast is improved accordingly. (2) Compared with the control run, the deterministic forecast initiated with the ensemble mean analysis of EnSRF produces more accurate prediction of microphysical fields. The predicted wind and thermal fields are reasonable and in accordance with the characteristics of convective storms. (3) The propagation direction of the squall line from the ensemble mean analysis is consistent with that of the observation, but the propagation speed is larger than the observed. The effective forecast period for this squall line is about 5-6 h, probably because of the nonlinear development of the convective storm.

  20. Assimilation of Doppler weather radar observations in a mesoscale model for the prediction of rainfall associated with mesoscale convective systems

    Indian Academy of Sciences (India)

    S Abhilash; Someshwar Das; S R Kalsi; M Das Gupta; K Mohankumar; J P George; S K Banerjee; S B Thampi; D Pradhan

    2007-08-01

    Obtaining an accurate initial state is recognized as one of the biggest challenges in accurate model prediction of convective events. This work is the first attempt in utilizing the India Meteorological Department (IMD) Doppler radar data in a numerical model for the prediction of mesoscale convective complexes around Chennai and Kolkata. Three strong convective events both over Chennai and Kolkata have been considered for the present study. The simulation experiments have been carried out using fifth-generation Pennsylvania State University–National Center for Atmospheric Research (PSU–NCAR) mesoscale model (MM5) version 3.5.6. The variational data assimilation approach is one of the most promising tools available for directly assimilating the mesoscale observations in order to improve the initial state. The horizontal wind derived from the DWR has been used alongwith other conventional and non-conventional data in the assimilation system. The preliminary results from the three dimensional variational (3DVAR) experiments are encouraging. The simulated rainfall has also been compared with that derived from the Tropical Rainfall Measuring Mission (TRMM) satellite. The encouraging result from this study can be the basis for further investigation of the direct assimilation of radar reflectivity data in 3DVAR system. The present study indicates that Doppler radar data assimilation improves the initial field and enhances the Quantitative Precipitation Forecasting (QPF) skill.

  1. Comparison of HRDI wind measurements with radar and rocket observations

    Energy Technology Data Exchange (ETDEWEB)

    Burrage, M.D.; Skinner, W.R.; Marshall, A.R.; Hays, P.B.; Lieberman, R.S.; Gell, D.A.; Ortland, D.A.; Morton, Y.T.; Wu, D.L.; Franke, S.J.; Schmidlin, F.J.; Vincent, R.A.

    1993-06-18

    This paper reports wind measurements in the mesosphere and lower thermosphere made by the high resolution doppler imager (HRDI) on board the upper atmosphere research satellite (UARS). These measurements are correlated with ground based radar and rocket measurements. The HRDI makes measurements by observing doppler shifts in molecular oxygen lines. The intercomparison helps to validate the remote sensing results, helps to verify the on board calibration system, and also gives a common measurement which other measurements systems can be compared against.

  2. Improving Quantitative Precipitation Estimation via Data Fusion of High-Resolution Ground-based Radar Network and CMORPH Satellite-based Product

    Science.gov (United States)

    Cifelli, R.; Chen, H.; Chandrasekar, V.; Xie, P.

    2015-12-01

    A large number of precipitation products at multi-scales have been developed based upon satellite, radar, and/or rain gauge observations. However, how to produce optimal rainfall estimation for a given region is still challenging due to the spatial and temporal sampling difference of different sensors. In this study, we develop a data fusion mechanism to improve regional quantitative precipitation estimation (QPE) by utilizing satellite-based CMORPH product, ground radar measurements, as well as numerical model simulations. The CMORPH global precipitation product is essentially derived based on retrievals from passive microwave measurements and infrared observations onboard satellites (Joyce et al. 2004). The fine spatial-temporal resolution of 0.05o Lat/Lon and 30-min is appropriate for regional hydrologic and climate studies. However, it is inadequate for localized hydrometeorological applications such as urban flash flood forecasting. Via fusion of the Regional CMORPH product and local precipitation sensors, the high-resolution QPE performance can be improved. The area of interest is the Dallas-Fort Worth (DFW) Metroplex, which is the largest land-locked metropolitan area in the U.S. In addition to an NWS dual-polarization S-band WSR-88DP radar (i.e., KFWS radar), DFW hosts the high-resolution dual-polarization X-band radar network developed by the center for Collaborative Adaptive Sensing of the Atmosphere (CASA). This talk will present a general framework of precipitation data fusion based on satellite and ground observations. The detailed prototype architecture of using regional rainfall instruments to improve regional CMORPH precipitation product via multi-scale fusion techniques will also be discussed. Particularly, the temporal and spatial fusion algorithms developed for the DFW Metroplex will be described, which utilizes CMORPH product, S-band WSR-88DP, and X-band CASA radar measurements. In order to investigate the uncertainties associated with each

  3. Parameter estimation for rigid body after micro-Doppler removal based on L-statistics in the radar analysis

    Institute of Scientific and Technical Information of China (English)

    Yong Wang; Jian Kang

    2015-01-01

    In traditional inverse synthetic aperture radar (ISAR) imaging of moving targets with rotational parts, the micro-Doppler (m-D) effects caused by the rotational parts influence the quality of the radar images. Recently, L. Stankovic proposed an m-D removal method based on L-statistics, which has been proved effective and simple. The algorithm can extract the m-D effects according to different behaviors of signals induced by rotational parts and rigid bodies in time-frequency (T-F) domain. However, by removing m-D effects, some useful short time Fourier transform (STFT) samples of rigid bodies are also extracted, which induces the side lobe problem of rigid bodies. A parameter estimation method for rigid bodies after m-D removal is proposed, which can accurately re-cover rigid bodies and avoid the side lobe problem by only using m-D removal. Simulations are given to validate the effectiveness of the proposed method.

  4. Hardware description ADSP-21020 40-bit floating point DSP as designed in a remotely controlled digital CW Doppler radar

    Energy Technology Data Exchange (ETDEWEB)

    Morrison, R.E.; Robinson, S.H.

    1991-01-01

    A continuous wave Doppler radar system has been designed which is portable, easily deployed, and remotely controlled. The heart of this system is a DSP/control board using Analog Devices ADSP-21020 40-bit floating point digital signal processor (DSP) microprocessor. Two 18-bit audio A/D converters provide digital input to the DSP/controller board for near real time target detection. Program memory for the DSP is dual ported with an Intel 87C51 microcontroller allowing DSP code to be up-loaded or down-loaded from a central controlling computer. The 87C51 provides overall system control for the remote radar and includes a time-of-day/day-of-year real time clock, system identification (ID) switches, and input/output (I/O) expansion by an Intel 82C55 I/O expander. 5 refs., 8 figs., 2 tabs.

  5. Retrieval of Vertical Profiles of Liquid Water and Ice Content in Mixed Clouds from Doppler Radar and Microwave Radiometer Measurements.

    Science.gov (United States)

    Sauvageot, Henri

    1996-01-01

    A new method to retrieve vertical profiles of liquid water content Mw(z), ice water content Mi(z), and ice particle size distribution Ni(D, z), (where D is the ice particle size and z the vertical coordinate) in mixed nonprecipitating clouds using the observations of a zenith-viewing Doppler radar and of a microwave radiometer is proposed. In this method, the profile of the vertical air velocity deduced from Doppler radar measurements is used to describe the rate of production by the updrafts of water. vapor in excess of saturation with respect to ice. Using a Zi Mi power-law relation with an unknown linear parameter (let i, be this parameter) and initially assuming that Zw is negligible with respect to Zi, (where Zw and Zi are the radar reflectivity factors of liquid water and ice particles respectively), the measured radar reflectivity factor profile Zm ( Zi) is inverted to estimate Ni(D, z). From Ni(D, z), the profile of the rate of water vapor that can be consumed by pure deposition on ice particles is calculated. The difference between the rate of production of the exam water vapor and the rate of deposited water vapor is an expression of the rate of liquid water generation at each level. By writing that the integral of the liquid water along the profile has to be equal to the total liquid water deduced from the microwave radiometer measurement, an estimation of the i parameter is obtained. From i, an estimation of the profiles Mw(z), Mi(z), Zw(z), Zi(z) (=Zm Zw), and Ni(D, z) is calculated. If Zw is effectively negligible with respect to Zi, the computation of the retrieved profiles is ended. If not, Zi(z) is corrected and a new estimation of the profiles is computed. The results of the numerical simulation of the algorithm are presented.

  6. Radar Micro-Doppler Feature Extraction Using the Singular Value Decomposition

    NARCIS (Netherlands)

    Wit, J.J.M. de; Harmanny, R.I.A.; Molchanov, P.

    2014-01-01

    Abstract—The micro-Doppler spectrogram depends on parts of a target moving and rotating in addition to the main body motion (e.g., spinning rotor blades) and is thus characteristic for the type of target. In this study, the micro-Doppler spectrogram is exploited to distinguish between birds and smal

  7. Radar Micro-Doppler Feature Extraction Using the Singular Value Decomposition

    NARCIS (Netherlands)

    Wit, J.J.M. de; Harmanny, R.I.A.; Molchanov, P.

    2014-01-01

    Abstract—The micro-Doppler spectrogram depends on parts of a target moving and rotating in addition to the main body motion (e.g., spinning rotor blades) and is thus characteristic for the type of target. In this study, the micro-Doppler spectrogram is exploited to distinguish between birds and

  8. The EarthCARE space-borne Doppler 94 GHz radar simulator: correction of multiple scattering, aliasing and NUBF and effects of variable along track integration

    Science.gov (United States)

    Augustynek, T.; Battaglia, A.; Kollias, P.

    2011-12-01

    The primary goal of this work is to address several challenges related to spaceborne Doppler radars like future the EarthCARE mission and recent developments of data simulation, correction and processing. The 94 GHz Cloud Profiling Radar onboard the ESA EarthCARE mission will be the first radar in space with Doppler capability allowing mean Doppler velocity measurements. This will enable more accurate characterization of clouds and precipitation (classification, retrieval accuracy, dynamics). It is the only instrument of this kind planned for the immediate post-CloudSat era and represents an irreplaceable asset in regards to climate change studies. Meeting the scientific accuracy requirements of vertical motions of 1 m/s, with a horizontal resolution of 1 km, is very challenging. The five key factors that control the performance of spaceborne radar will be discussed, such as: contribution of multiple scattering (MS), attenuation, velocity folding, non uniform beam filling (NUBF) and effects of along track integration of the signal. The research utilizes an end-to-end simulator for spaceborne Doppler radars. The simulator uses a Monte Carlo module which accounts for MS and produces ideal Doppler spectra as measured by a spaceborne radar flying over 3D highly resolved scenes produced via WRF Model simulations. The estimates of the Doppler moments (reflectivity, mean Doppler velocity and spectrum width) are achieved via the pulse pair technique. The objective method for identification of MS-contaminated range-bins based purely on the reflectivity-derived variables is described, with most important one, cumulative integrated reflectivity, found to be 41 dBZ_int which serves as the threshold value for identification of radar range gates contaminated by MS. This is further demonstrated in a CloudSat case study with the threshold value for CloudSat is found to be 41.9 dBZ_int. The unfolding procedure of Doppler velocities will be presented. Then we will describe the

  9. Numerical Research on Effects Upon Precipitation Forecast of Doppler-Radar Estimated Precipitation and Retrieved Wind Field Under Different Model Initial Schemes

    Institute of Scientific and Technical Information of China (English)

    WANG Yehong; ZHAO Yuchun; CUI Chunguang

    2007-01-01

    On the basis of the joint estimated 1-h precipitation from Changde, Jingzhou, and Yichang Doppler radars as well as Wuhan digital radar, and the retrieved wind fields from Yichang and Jingzhou Doppler radars, a series of numerical experiments with an advanced regional η-coordinate model (AREM) under different model initial schemes, i.e., Grapes-3DVAR, Barnes objective analysis, and Barnes-3DVAR, are carried out for a torrential rain process occurring along the Yangtze River in the 24-h period from 2000 BT 22 July 2002 to investigate the effects of the Doppler-radar estimated rainfall and retrieved winds on the rainfall forecast. The main results are as follows: (1) The simulations are obviously different under three initial schemes with the same data source (the radiosounding and T213L31 analysis). On the whole,Barnes-3DVAR, which combines the advantages of the Barnes objective analysis and the Grapes-3DVAR method, gives the best simulations: well-simulated rain band and clear mesoscale structures, as well as their location and intensity close to observations. (2) Both Barnes-3DVAR and Grapes-3DVAR schemes are able to assimilate the Doppler-radar estimated rainfall and retrieved winds, but differences in simulation results are very large, with Barnes-3DVAR's simulation much better than Grapes-3DVAR's. (3) Under Grapes3DVAR scheme, the simulation of 24-h rainfall is improved obviously when assimilating the Doppler-radar estimated precipitation into the model in compared with the control experiment; but it becomes a little worse when assimilating the Doppler-radar retrieved winds into the model, and it becomes worse obviously when assimilating the Doppler-radar estimated precipitation as well as retrieved winds into the model. However,the simulation is different under Barnes-3DVAR scheme. The simulation is improved to a certain degree no matter assimilating the estimated precipitation or retrieved winds, or both of them. The result is the best when assimilating both

  10. 雷达目标微多普勒效应研究概述%Review of the Researches on Micro -Doppler Effect of Radar Targets

    Institute of Scientific and Technical Information of China (English)

    张群; 罗迎; 何劲

    2011-01-01

    近年来雷达目标微多普勒效应得到了较为广泛的关注,基于微多普勒特征的目标识别术被认为是雷达目标精确识别领域中极具发展潜力的技术途径之一.从微多普勒效应概念、多普勒分析及特征提取、微多普勒应用等方面论综述了当前国内外雷达目标微多普勒效应研的发展和应用现状,并对未来的技术发展趋势做了进一步展望.%The micro -Doppler effects of radar targets have attracted great research attention in recent years. The auto target recognition based on micro - Doppler signatures is considered as one of the most potential techniques in radar targets'accurate recognition. The achievements and applications of the micro - Doppler effects of radar targets are reviewed in some aspects such as the concept of micro - Doppler effect, the micro - Doppler analysis and feature extraction, the applications of micro - Doppler effect, and so on. Simultaneously the trends of the technique developments in this field are predicted.

  11. Modified Range-Doppler Processing for FM-CW Synthetic Aperture Radar

    NARCIS (Netherlands)

    Wit, J.J.M. de; Meta, A.; Hoogeboom, P.

    2006-01-01

    The combination of compact frequency-modulated continuous-wave (FM-CW) technology and high-resolution synthetic aperture radar (SAR) processing techniques should pave the way for the development of a lightweight, cost-effective, high-resolution, airborne imaging radar. Regarding FM-CW SAR signal pro

  12. Synthesizing radar maps of polar regions with a Doppler-only method.

    Science.gov (United States)

    Roulston, M S; Muhleman, D O

    1997-06-10

    A method for producing a radar-reflectivity map of the polar regions of the Moon or a planet from polar orbit with only the frequency shift of the reflected signals is described and simulated. A Radon transform of the reflectivity is obtained during multiple passes over the pole. Inversion of this Radon transform enables a map of radar reflectivity to be synthesized.

  13. Extracting bird migration information from C-band Doppler weather radars

    NARCIS (Netherlands)

    van Gasteren, H.; Holleman, I.; Bouten, W.; van Loon, E.; Shamoun-Baranes, J.

    2008-01-01

    Although radar has been used in studies of bird migration for 60 years, there is still no network in Europe for comprehensive monitoring of bird migration. Europe has a dense network of military air surveillance radars but most systems are not directly suitable for reliable bird monitoring. Since

  14. Micro-Doppler Feature Extraction and Recognition Based on Netted Radar for Ballistic Targets

    Directory of Open Access Journals (Sweden)

    Feng Cun-qian

    2015-12-01

    Full Text Available This study examines the complexities of using netted radar to recognize and resolve ballistic midcourse targets. The application of micro-motion feature extraction to ballistic mid-course targets is analyzed, and the current status of application and research on micro-motion feature recognition is concluded for singlefunction radar networks such as low- and high-resolution imaging radar networks. Advantages and disadvantages of these networks are discussed with respect to target recognition. Hybrid-mode radar networks combine low- and high-resolution imaging radar and provide a specific reference frequency that is the basis for ballistic target recognition. Main research trends are discussed for hybrid-mode networks that apply micromotion feature extraction to ballistic mid-course targets.

  15. Focusing vibrating targets in frequency-modulation continuous-wave-synthetic aperture radar with Doppler keystone transform

    Science.gov (United States)

    Hu, Yuxin; Zhang, Yuan; Sun, Jinping; Lei, Peng

    2016-04-01

    Vibrating targets generally induce sinusoidal micro-Doppler modulation in high resolution synthetic aperture radar (SAR). They could cause defocused and ghost results by conventional imaging algorithms. This paper proposes a method on vibrating target imaging in frequency-modulation continuous-wave (FMCW) SAR systems. The continuous motion of sensor platform during pulse time is considered in the signal model. Based on Bessel series expansion of the signal in the azimuth direction, the influence of platform motion on the azimuth frequency is eliminated after dechirp and deskew. In addition, the range walk is compensated in the two-dimensional frequency domain by Doppler keystone transform. Next, using range cell migration correction, the azimuth quadratic phase compensation and the range curvature correction are made in range-Doppler domain for the focus of paired echoes. The residual video phase of paired echoes is eliminated, and vibration parameters are estimated to compensate in the sinusoidal modulation phase. Then the deghosted image of vibrating targets can be obtained. The proposed method is applicable to multiple targets with various vibrating states due to no need of a priori knowledge of targets. Finally, simulations are carried out to validate the effectiveness of the method in FMCW-SAR imaging of vibrating targets.

  16. Weather Radar Stations

    Data.gov (United States)

    Department of Homeland Security — These data represent Next-Generation Radar (NEXRAD) and Terminal Doppler Weather Radar (TDWR) weather radar stations within the US. The NEXRAD radar stations are...

  17. A Joint Doppler Frequency Shift and DOA Estimation Algorithm Based on Sparse Representations for Colocated TDM-MIMO Radar

    Directory of Open Access Journals (Sweden)

    Tao Chen

    2014-01-01

    Full Text Available We address the problem of a new joint Doppler frequency shift (DFS and direction of arrival (DOA estimation for colocated TDM-MIMO radar that is a novel technology applied to autocruise and safety driving system in recent years. The signal model of colocated TDM-MIMO radar with few transmitter or receiver channels is depicted and “time varying steering vector” model is proved. Inspired by sparse representations theory, we present a new processing scheme for joint DFS and DOA estimation based on the new input signal model of colocated TDM-MIMO radar. An ultracomplete redundancy dictionary for angle-frequency space is founded in order to complete sparse representations of the input signal. The SVD-SR algorithm which stands for joint estimation based on sparse representations using SVD decomposition with OMP algorithm and the improved M-FOCUSS algorithm which combines the classical M-FOCUSS with joint sparse recovery spectrum are applied to the new signal model’s calculation to solve the multiple measurement vectors (MMV problem. The improved M-FOCUSS algorithm can work more robust than SVD-SR and JS-SR algorithms in the aspects of coherent signals resolution and estimation accuracy. Finally, simulation experiments have shown that the proposed algorithms and schemes are feasible and can be further applied to practical application.

  18. A multi-sensor study of the impact of ground-based glaciogenic seeding on clouds and precipitation over mountains in Wyoming. Part I: Project description

    Science.gov (United States)

    Pokharel, Binod; Geerts, Bart

    2016-12-01

    The AgI Seeding Cloud Impact Investigation (ASCII) campaign was conducted in early 2012 and 2013 over two mountain ranges in southern Wyoming to examine the impact of ground-based glaciogenic seeding on snow growth in winter orographic clouds. The campaign was supported by a network of ground-based instruments, including microwave radiometers, two profiling Ka-band Micro-Rain Radars (MRRs), a Doppler on Wheels (DOW) X-band radar, and a Parsivel disdrometer. The University of Wyoming King Air operated the profiling Wyoming Cloud Radar, the Wyoming Cloud Lidar, and in situ cloud and precipitation particle probes. The characteristics of the orographic clouds, flow field, and upstream stability profiles in 27 intensive observation periods (IOPs) are described here. A composite analysis of the impact of seeding on snow growth is presented in Part II of this study (Pokharel et al., 2017).

  19. Effects of Analog-to-Digital Converter Nonlinearities on Radar Range-Doppler Maps

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin Walter [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Dubbert, Dale F. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Tise, Bertice L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2014-07-01

    Radar operation, particularly Ground Moving Target Indicator (GMTI) radar modes, are very sensitive to anomalous effects of system nonlinearities. These throw off harmonic spurs that are sometimes detected as false alarms. One significant source of nonlinear behavior is the Analog to Digital Converter (ADC). One measure of its undesired nonlinearity is its Integral Nonlinearity (INL) specification. We examine in this report the relationship of INL to GMTI performance.

  20. Breaking Kelvin-Helmholtz waves and cloud-top entrainment as revealed by K-band Doppler radar

    Science.gov (United States)

    Martner, Brooks E.; Ralph, F. Martin

    1993-01-01

    Radars have occasionally detected breaking Kelvin-Helmholtz (KH) waves under clear-air conditions in the atmospheric boundary layer and in the free troposphere. However, very few direct measurements of such waves within clouds have previously been reported and those have not clearly documented wave breaking. In this article, we present some of the most detailed and striking radar observations to date of breaking KH waves within clouds and at cloud top and discuss their relevance to the issue of cloud-top entrainment, which is believed to be important in convective and stratiform clouds. Aircraft observations reported by Stith suggest that vortex-like circulations near cloud top are an entrainment mechanism in cumuliform clouds. Laboratory and modeling studies have examined possibility that KH instability may be responsible for mixing at cloud top, but direct observations have not yet been presented. Preliminary analyses shown here may help fill this gap. The data presented in this paper were obtained during two field projects in 1991 that included observations from the NOAA Wave Propagation Laboratory's K-band Doppler radar (wavelength = 8.7 mm) and special rawinsonde ascents. The sensitivity (-30 dBZ at 10 km range), fine spatial resolution (375-m pulse length and 0.5 degrees beamwidth), velocity measurement precision (5-10 cm s-1), scanning capability, and relative immunity to ground clutter make it sensitive to non-precipitating and weakly precipitating clouds, and make it an excellent instrument to study gravity waves in clouds. In particular, the narrow beam width and short pulse length create scattering volumes that are cylinders 37.5 m long and 45 m (90 m) in diameter at 5 km (10 km) range. These characteristics allow the radar to resolve the detailed structure in breaking KH waves such as have been seen in photographic cloud images.

  1. Comparison of natural and artificial forcing to study the dynamic behaviour of bell towers in low wind context by means of ground-based radar interferometry: the case of the Leaning Tower in Pisa

    Science.gov (United States)

    Marchisio, Mario; Piroddi, Luca; Ranieri, Gaetano; Calcina, Sergio V.; Farina, Paolo

    2014-10-01

    The study of Cultural Heritage assets needs the application of non-destructive and non-invasive monitoring techniques. In particular, monuments and historical buildings which are open to the visitors and/or subject to important stress must be studied for their dynamic response. In the last 10 years the new ground-based radar interferometry technology has been developed allowing to monitor displacements from a point of sight far from the studied targets. It virtually provides a continuous mapping of displacements of the observed structures up to 10 µm with a range resolution of 0.75 m. In this paper, the application of ground-based interferometry on one very important historical building, the Leaning Tower of Pisa in Italy, is reported. The analysis of these kind of structures is important to catch their dynamic response to natural actions in general, and also to assess the effects due to pedestrian and users, and consequently to define functional capabilities and levels of acceptable dynamic stress. The studied structure was subject to artificial loading by synchronous movement of about 20 people. Artificial forcing led the structure to a resonance condition with the same frequency of the one due to the natural noise excitation, which was separately measured, and with an oscillation amplitude more than thirty times greater than the natural one (in conditions of weak wind). During the passive stages of the survey the recorded structural vibrations were very closed to the instrumental sensitivity, making difficult to distinguish vibration amplitudes amplifications of various segments at various heights. Through the spectral analysis of the acquired data it was possible to estimate the vibration frequencies of the first modal shapes of the structure along two orthogonal directions. The power spectra of the passive survey data have the same maximum frequency of the active but contain more noise at low frequency.

  2. Detection on micro-Doppler effect based on 1550 nm laser coherent radar

    Science.gov (United States)

    Jun, Zhang; Yang, Sun; Zenghui, Cao; Tengfei, Sun; Tiantian, Zheng

    2014-01-01

    A laser coherent detection system of 1550 nm wavelength was presented, and experimental research on detecting micro-Doppler effect in a dynamic target was developed. In this paper, the return signal in the time domain is decomposed into a set of components in different wavelet-scales by multi-resolution analysis, and the components are associated with the vibrational motions in a target. The micro-Doppler signatures are extracted by applying the reconstruction (inverse wavelet transform). During the course of the final data processing frequency analysis and time-frequency analysis are applied to analyze the vibrational signals and estimate the motion parameters successfully. The experimental results indicate that the micro-Doppler information in a moving can be effectively detected, and tiny vibrational signatures also can be acquired effectively by wavelet multi-resolution analysis and time-frequency analysis.

  3. DETECTION ON MICRO-DOPPLER EFFECT BASED ON LASER COHERENT RADAR

    Institute of Scientific and Technical Information of China (English)

    Sun Yang; Zhang Jun

    2012-01-01

    A laser coherent detection system of 1550 nm wavelength was presented,and experimental research on detecting micro-Doppler effect in a dynamic target was developed.In the study,the return signal in the time domain is decomposed into a set of components in different wavelet scales by multi-resolution wavelet analysis,and the components are associated with the vibrational motions in a target.Then micro-Doppler signatures are extracted by applying the reconstruction.During the course of the final data processing frequency analysis and time-frequency analysis are applied to analyze the vibrational signals and estimate the motion parameters successfully.The experimental results indicate that the system can effectively detect micro-Doppler information in a moving target,and the tiny vibrational signatures also can be acquired effectively by wavelet multi-resolution analysis and time-frequency analysis.

  4. A case study of microphysical structures and hydrometeor phase in convection using radar Doppler spectra at Darwin, Australia

    Energy Technology Data Exchange (ETDEWEB)

    Riihimaki, Laura D.; Comstock, Jennifer M.; Luke, Edward; Thorsen, Tyler J.; Fu, Qiang

    2017-07-28

    To understand the microphysical processes that impact diabatic heating and cloud lifetimes in convection, we need to characterize the spatial distribution of supercooled liquid water. To address this observational challenge, vertically pointing active sensors at the Darwin Atmospheric Radiation Measurement (ARM) site are used to classify cloud phase within a deep convective cloud in a shallow to deep convection transitional case. The cloud cannot be fully observed by a lidar due to signal attenuation. Thus we develop an objective method for identifying hydrometeor classes, including mixed-phase conditions, using k-means clustering on parameters that describe the shape of the Doppler spectra from vertically pointing Ka band cloud radar. This approach shows that multiple, overlapping mixed-phase layers exist within the cloud, rather than a single region of supercooled liquid, indicating complexity to how ice growth and diabatic heating occurs in the vertical structure of the cloud.

  5. The application of the ADSP-21020 40-bit floating point DSP microprocessor in a digital Doppler radar

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, S.H.; Morrison, R.E.

    1991-08-26

    A continuous wave doppler radar system has been designed which is portable, easily deployable and can be remotely controlled. The system is immune to ground clutter and is used for wind speed detection and direction determination. Nearly real time digital signal processing is performed by an Analog Devices ADSP-21020, a 40-bit floating point Digital Signal Processing (DSP) microprocessor. This paper provides an overview of the design of the system including the radio frequency (RF) to digital interface. The various DSP detection algorithms are discussed and compared to system performance and sensitivity. Finally, DSP performance is compared to the performance of an earlier system using Analog Device's ADSP-2100. 6 refs.

  6. Novel Method of Unambiguous Moving Target Detection in Pulse-Doppler Radar with Random Pulse Repetition Interval

    Directory of Open Access Journals (Sweden)

    Liu Zhen

    2012-03-01

    Full Text Available Blind zones and ambiguities in range and velocity measurement are two important issues in traditional pulse-Doppler radar. By generating random deviations with respect to a mean Pulse Repetition Interval (PRI, this paper proposes a novel algorithm of Moving Target Detection (MTD based on the Compressed Sensing (CS theory, in which the random deviations of the PRIare converted to the Restricted Isometry Property (RIP of the observing matrix. The ambiguities of range and velocity are eliminated by designing the signal parameters. The simulation results demonstrate that this scheme has high performance of detection, and there is no ambiguity and blind zones as well. It can also shorten the coherent processing interval compared to traditional staggered PRI mode because only one pulse train is needed instead of several trains.

  7. Recalculation of an artificially released avalanche with SAMOS and validation with measurements from a pulsed Doppler radar

    Directory of Open Access Journals (Sweden)

    R. Sailer

    2002-01-01

    Full Text Available A joint experiment was carried out on 10 February 1999 by the Swiss Federal Institute for Snow and Avalanche Research (SFISAR and the Austrian Institute for Avalanche and Torrent Research (AIATR, of the Federal Office and Re-search Centre for Forests, BFW to measure forces and velocities at the full scale experimental site CRÊTA BESSE in VALLÉE DE LA SIONNE, Canton du Valais, Switzerland. A huge avalanche could be released artificially, which permitted extensive investigations (dynamic measurements, im-provement of measurement systems, simulation model verification, design of protective measures, etc.. The results of the velocity measurements from the dual frequency pulsed Doppler avalanche radar of the AIATR and the recalculation with the numerical simulation model SAMOS are explained in this paper.

  8. K-band Doppler radar for contact-less overnight sleep marker assessment: a pilot validation study.

    Science.gov (United States)

    Vasireddy, Rakesh; Roth, Corinne; Mathis, Johannes; Goette, Josef; Jacomet, Marcel; Vogt, Andreas

    2017-09-11

    An estimated 45 million persons in Europe are annually subjected to sleep-wake disorders. State-of-the-art polysomnography provides sophisticated insights into sleep (patho)physiology. A drawback of the method, however, is the obtrusive setting dependent on a clinical-based sleep laboratory with high operational costs. A contact-less prototype was developed to monitor limb movements and vital signs during sleep. A dual channel K-band Doppler radar transceiver captured limb movements and periodic chest wall motion due to respiration and heart activity. A wavelet transform based multi-resolution analysis (MRA) approach isolated limb movements, respiration, and heart rate from the demodulated signal. A test bench setup characterized the prototype simulating near physiological chest wall motions caused by periodic respiration and heartbeats in humans. Single- and multi-tone test bench simulations showed extremely low relative percentage errors of the prototype for respiratory and heart rate within -2 and 1%. The performance of the prototype was validated in overnight comparative studies, involving two healthy volunteers, with polysomnography as the reference. The prototype has successfully classified limb movements, with a sensitivity and specificity of 88.9 and 76.8% respectively, and has achieved accurate respiratory and heart rate measurement performance with overall absolute errors of 1 breath per minute for respiration and 3 beats per minute for heart rate. This pilot study shows that K-band Doppler radar and wavelet transform MRA seem to be valid for overnight sleep marker assessment. The contact-less approach might offer a promising solution for home-based sleep monitoring and assessment.

  9. Strombolian surface activity regimes at Yasur volcano, Vanuatu, as observed by Doppler radar, infrared camera and infrasound

    Science.gov (United States)

    Meier, K.; Hort, M.; Wassermann, J.; Garaebiti, E.

    2016-08-01

    In late 2008 we recorded a continuous multi-parameter data set including Doppler radar, infrared and infrasound data at Yasur volcano, Vanuatu. Our recordings cover a transition in explosive style from ash-rich to ash-free explosions followed again by a phase of high ash discharge. To assess the present paradigm of Strombolian behavior in this study we investigate the geophysical signature of these different explosive episodes and compare our results to observations at Stromboli volcano, Italy. To this end we characterize Yasur's surface activity in terms of material movement, temperature and excess pressure. The joint temporal trend in these data reveals smooth variations of surface activity and regime-like persistence of individual explosion forms over days. Analysis of all data types shows ash-free and ash-rich explosive styles similar to those found at Stromboli volcano. During ash-free activity low echo powers, high explosion velocities and high temperatures result from the movement of isolated hot ballistic clasts. In contrast, ash-rich episodes exhibit high echo powers, low explosion velocities and low temperatures linked to the presence of colder ash-rich plumes. Furthermore ash-free explosions cause high excess pressure signals exhibiting high frequencies opposed to low-amplitude, low-frequency signals accompanying ash-rich activity. To corroborate these findings we compare fifteen representative explosions of each explosive episode. Explosion onset velocities derived from Doppler radar and infrared camera data are in excellent agreement and consistent with overall observations in each regime. Examination of infrasound recordings likewise confirms our observations, although a weak coupling between explosion velocity and excess pressure indicates changes in wave propagation. The overall trend in explosion velocity and excess pressure however demonstrates a general correlation between explosive style and explosion intensity, and points to stability of the

  10. Exponential Decay in Windblown Radar Ground Clutter Doppler Spectra: Multifrequency Measurements and Model.

    Science.gov (United States)

    2007-11-02

    Reese Straw, William Dustin, Carol Bernhard, Joanne Bradley and Bob Graham-Munn. The manuscript was skillfully prepared by Pat DeCuir and kindly and...spreading of Ot° rees in Doppler, i.e., j^Krees’ Pto^dv = °trees- so Krees’ Ptot^ represents the normalized density of windblown tree clutter power

  11. Design Approach of Range Gate Generator for FMCW Doppler Radar as Presence Sensor(Short Communication

    Directory of Open Access Journals (Sweden)

    K.P.M. Bhat

    2002-04-01

    Full Text Available The paper presents the design philosophy and hardware details of a range gate generator as presence sensor suitable for an X-band frequency-modulated continuous wave radar. A logic circuit to indicate the target presence between 20 m to 30 m with a maximum of ± 0.5 Count cycle-limited error has been designed and incorporated.

  12. Adaptive OFDM Radar Waveform Design for Improved Micro-Doppler Estimation

    Energy Technology Data Exchange (ETDEWEB)

    Sen, Satyabrata [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Engineering Science Advanced Research, Computer Science and Mathematics Division

    2014-07-01

    Here we analyze the performance of a wideband orthogonal frequency division multiplexing (OFDM) signal in estimating the micro-Doppler frequency of a rotating target having multiple scattering centers. The use of a frequency-diverse OFDM signal enables us to independently analyze the micro-Doppler characteristics with respect to a set of orthogonal subcarrier frequencies. We characterize the accuracy of micro-Doppler frequency estimation by computing the Cramer-Rao bound (CRB) on the angular-velocity estimate of the target. Additionally, to improve the accuracy of the estimation procedure, we formulate and solve an optimization problem by minimizing the CRB on the angular-velocity estimate with respect to the OFDM spectral coefficients. We present several numerical examples to demonstrate the CRB variations with respect to the signal-to-noise ratios, number of temporal samples, and number of OFDM subcarriers. We also analysed numerically the improvement in estimation accuracy due to the adaptive waveform design. A grid-based maximum likelihood estimation technique is applied to evaluate the corresponding mean-squared error performance.

  13. Detecting and mitigating wind turbine clutter for airspace radar systems.

    Science.gov (United States)

    Wang, Wen-Qin

    2013-01-01

    It is well recognized that a wind turbine has a large radar cross-section (RCS) and, due to the movement of the blades, the wind turbine will generate a Doppler frequency shift. This scattering behavior may cause severe interferences on existing radar systems including static ground-based radars and spaceborne or airborne radars. To resolve this problem, efficient techniques or algorithms should be developed to mitigate the effects of wind farms on radars. Herein, one transponder-based mitigation technique is presented. The transponder is not a new concept, which has been proposed for calibrating high-resolution imaging radars. It modulates the radar signal in a manner that the retransmitted signals can be separated from the scene echoes. As wind farms often occupy only a small area, mitigation processing in the whole radar operation will be redundant and cost inefficient. Hence, this paper uses a transponder to determine whether the radar is impacted by the wind farms. If so, the effects of wind farms are then mitigated with subsequent Kalman filtering or plot target extraction algorithms. Taking airborne synthetic aperture radar (SAR) and pulse Doppler radar as the examples, this paper provides the corresponding system configuration and processing algorithms. The effectiveness of the mitigation technique is validated by numerical simulation results.

  14. Moving Target Detection and Doppler Extraction Using Digital Spread Spectrum Radar

    OpenAIRE

    2014-01-01

    In this paper, we discuss a Spread Spectrum based radar system for car detection in the road and autonomous guidance of vehicles. An autonomous intelligent vehicle has to perform a number of functionalities. Segmentation of the road, determining the boundaries to drive in and recognizing the vehicles and obstacles around are the main tasks for vision guided vehicle navigation. In this article we propose a set of algorithms which lead to the solution of road and vehicle collision using carrier...

  15. Performance comparison of pulse-pair and wavelets methods for the pulse Doppler weather radar spectrum

    CERN Document Server

    Lagha, Mohand; Bergheul, Said; Rezoug, Tahar; Bettayeb, Maamar

    2012-01-01

    In the civilian aviation field, the radar detection of hazardous weather phenomena (winds) is very important. This detection will allow the avoidance of these phenomena and consequently will enhance the safety of flights. In this work, we have used the wavelets method to estimate the mean velocity of winds. The results showed that the application of this method is promising compared with the classical estimators (pulse-pair, Fourier).

  16. Sleep stage classification by non-contact vital signs indices using Doppler radar sensors.

    Science.gov (United States)

    Kagawa, Masayuki; Suzumura, Kazuki; Matsui, Takemi

    2016-08-01

    Disturbed sleep has become more common in recent years. To improve the quality of sleep, undergoing sleep observation has gained interest as a means to resolve possible problems. In this paper, we evaluate a non-restrictive and non-contact method for classifying real-time sleep stages and report on its potential applications. The proposed system measures heart rate (HR), heart rate variability (HRV), body movements, and respiratory signals of a sleeping person using two 24-GHz microwave radars placed beneath the mattress. We introduce a method that dynamically selects the window width of the moving average filter to extract the pulse waves from the radar output signals. The Pearson correlation coefficient between two HR measurements derived from the radars overnight, and the reference polysomnography was the average of 88.3% and the correlation coefficient for HRV parameters was the average of 71.2%. For identifying wake and sleep periods, the body-movement index reached sensitivity of 76.0%, and a specificity of 77.0% with 10 participants. Low-frequency (LF) components of HRV and the LF/HF ratio had a high degree of contribution and differed significantly across the three sleep stages (REM, LIGHT, and DEEP; p sleep stages (p > 0.05). We applied a canonical discriminant analysis to identify wake or sleep periods and to classify the three sleep stages with leave-one-out cross validation. Classification accuracy was 66.4% for simply identifying wake and sleep, 57.1% for three stages (wake, REM, and NREM) and 34% for four stages (wake, REM, LIGHT, and DEEP). This is a novel system for measuring HRs, HRV, body movements, and respiratory intervals and for measuring high sensitivity pulse waves using two radar signals. It simplifies measurement of sleep stages and may be employed at nursing care facilities or by the general public to improve sleep quality.

  17. A Study on Technologies of Micro-Doppler Biological Detection Radar%微多普勒生物探测雷达技术研究

    Institute of Scientific and Technical Information of China (English)

    王德纯

    2011-01-01

    Micro-motions on subjects, such as human arm or leg swing and body movements caused by respiratory and circulatory contraction and expansion will induce a micro-Doppler shift on the returned signal. The extraction and analysis of these micro-Doppler signals can be served as a novel method for biological radar target detection and recognition. In this paper, the theoretical models for human-backscattered micro-Doppler signals will be firstly deduced, the critical technologies and realization of micro-Doppler biological detection radar will be then investigated, challenges and perspectives on micro-Doppler biological detection radar will be discussed lastly.%生物的微运动,例如人体肢体摆动以及呼吸和心跳运动,会对雷达入射电磁波产生微多普勒调制.通过对这些微多普勒调制回波信号的提取和分析,雷达能够实现对生物体微运动状态和生命特征的探测、测量和识别.文中首先对人体雷达回波微多普勒散射信号的理论模型进行了推导,然后对生物探测微多普勒雷达的实现和主要技术进行了分析和研究,最后对微多普勒生物探测雷达技术发展进行了讨论.

  18. Regional Prediction of Impending Debris Flow Based on Doppler Weather Radar

    Institute of Scientific and Technical Information of China (English)

    JIANG Yuhong; WEI Fangqiang; ZHANG Jinghong; GU Linkang; DENG Bo; LIU Hongjiang

    2007-01-01

    Debris flow prediction is one of the important means to reduce the loss caused by debris flow. This paper built a regional prediction model of impending debris flow based on regional environmentalbackground (including topography, geology, land use, and etc.), rainfalland debris flow data. A system of regional prediction of impending debris flow was set up on ArcGIS 9.0 platform according to the model.The system used forecast precipitation data of Doppler weather radarand observational precipitation data as its input data. It could provide aprediction about the possibility of debris flow one to three hours beforeit happened, and was put into use in Liangshan Meteorological Observatory in Sichuan province in the monsoon of 2006.

  19. Turbulent energy dissipation rates observed by Doppler MST Radar and by rocket-borne instruments during the MIDAS/MaCWAVE campaign 2002

    Directory of Open Access Journals (Sweden)

    N. Engler

    2005-06-01

    Full Text Available During the MIDAS/MaCWAVE campaign in summer 2002 we have observed turbulence using Doppler beam steering measurements obtained from the ALWIN VHF radar at Andøya/Northern Norway. This radar was operated in the Doppler beam steering mode for turbulence investigations during the campaign, as well as in spaced antenna mode, for continuously measuring the background wind field. The real-time data analysis of the Doppler radar backscattering provided the launch conditions for the sounding rockets. The spectral width data observed during the occurrence of PMSE were corrected for beam and shear broadening caused by the background wind field to obtain the turbulent part of the spectral width. The turbulent energy dissipation rates determined from the turbulent spectral width vary between 5 and 100mW kg-1 in the altitude range of 80-92km and increase with altitude. These estimations agree well with the in-situ measurements using the CONE sensor which was launched on 3 sounding rockets during the campaign.

  20. Low complexity joint estimation of reflection coefficient, spatial location, and Doppler shift for MIMO-radar by exploiting 2D-FFT

    KAUST Repository

    Jardak, Seifallah

    2014-10-01

    In multiple-input multiple-output (MIMO) radar, to estimate the reflection coefficient, spatial location, and Doppler shift of a target, maximum-likelihood (ML) estimation yields the best performance. For this problem, the ML estimation requires the joint estimation of spatial location and Doppler shift, which is a two dimensional search problem. Therefore, the computational complexity of ML estimation is prohibitively high. In this work, to estimate the parameters of a target, a reduced complexity optimum performance algorithm is proposed, which allow two dimensional fast Fourier transform to jointly estimate the spatial location and Doppler shift. To asses the performances of the proposed estimators, the Cramér-Rao-lower-bound (CRLB) is derived. Simulation results show that the mean square estimation error of the proposed estimators achieve the CRLB. © 2014 IEEE.

  1. Retrieval of Raindrop Size Distribution, Vertical Air Velocity and Water Vapor Attenuation Using Dual-Wavelength Doppler Radar Observations

    Science.gov (United States)

    Heymsfield, Gerald M.; Tian, Lin; Li, Lihua; Srivastava, C.

    2005-01-01

    Two techniques for retrieving the slope and intercept parameters of an assumed exponential raindrop size distribution (RSD), vertical air velocity, and attenuation by precipitation and water vapor in light stratiform rain using observations by airborne, nadir looking dual-wavelength (X-band, 3.2 cm and W-band, 3.2 mm) radars are presented. In both techniques, the slope parameter of the RSD and the vertical air velocity are retrieved using only the mean Doppler velocities at the two wavelengths. In the first method, the intercept of the RSD is estimated from the observed reflectivity at the longer wavelength assuming no attenuation at that wavelength. The attenuation of the shorter wavelength radiation by precipitation and water vapor are retrieved using the observed reflectivity at the shorter wavelength. In the second technique, it is assumed that the longer wavelength suffers attenuation only in the melting band. Then, assuming a distribution of water vapor, the melting band attenuation at both wavelengths and the rain attenuation at the shorter wavelength are retrieved. Results of the retrievals are discussed and several physically meaningful results are presented.

  2. Extraction of convective cloud parameters from Doppler Weather Radar MAX(Z) product using Image Processing Technique

    Science.gov (United States)

    Arunachalam, M. S.; Puli, Anil; Anuradha, B.

    2016-07-01

    In the present work continuous extraction of convective cloud optical information and reflectivity (MAX(Z) in dBZ) using online retrieval technique for time series data production from Doppler Weather Radar (DWR) located at Indian Meteorological Department, Chennai has been developed in MATLAB. Reflectivity measurements for different locations within the DWR range of 250 Km radii of circular disc area can be retrieved using this technique. It gives both time series reflectivity of point location and also Range Time Intensity (RTI) maps of reflectivity for the corresponding location. The Graphical User Interface (GUI) developed for the cloud reflectivity is user friendly; it also provides the convective cloud optical information such as cloud base height (CBH), cloud top height (CTH) and cloud optical depth (COD). This technique is also applicable for retrieving other DWR products such as Plan Position Indicator (Z, in dBZ), Plan Position Indicator (Z, in dBZ)-Close Range, Volume Velocity Processing (V, in knots), Plan Position Indicator (V, in m/s), Surface Rainfall Intensity (SRI, mm/hr), Precipitation Accumulation (PAC) 24 hrs at 0300UTC. Keywords: Reflectivity, cloud top height, cloud base, cloud optical depth

  3. Assimilating surface observations in a four-dimensional variational Doppler radar data assimilation system to improve the analysis and forecast of a squall line case

    Science.gov (United States)

    Chen, Xingchao; Zhao, Kun; Sun, Juanzhen; Zhou, Bowen; Lee, Wen-Chau

    2016-10-01

    This paper examines how assimilating surface observations can improve the analysis and forecast ability of a fourdimensional Variational Doppler Radar Analysis System (VDRAS). Observed surface temperature and winds are assimilated together with radar radial velocity and reflectivity into a convection-permitting model using the VDRAS four-dimensional variational (4DVAR) data assimilation system. A squall-line case observed during a field campaign is selected to investigate the performance of the technique. A single observation experiment shows that assimilating surface observations can influence the analyzed fields in both the horizontal and vertical directions. The surface-based cold pool, divergence and gust front of the squall line are all strengthened through the assimilation of the single surface observation. Three experiments—assimilating radar data only, assimilating radar data with surface data blended in a mesoscale background, and assimilating both radar and surface observations with a 4DVAR cost function—are conducted to examine the impact of the surface data assimilation. Independent surface and wind profiler observations are used for verification. The result shows that the analysis and forecast are improved when surface observations are assimilated in addition to radar observations. It is also shown that the additional surface data can help improve the analysis and forecast at low levels. Surface and low-level features of the squall line—including the surface warm inflow, cold pool, gust front, and low-level wind—are much closer to the observations after assimilating the surface data in VDRAS.

  4. Classification and modeling of human activities using empirical mode decomposition with S-band and millimeter-wave micro-Doppler radars

    Science.gov (United States)

    Fairchild, Dustin P.; Narayanan, Ram M.

    2012-06-01

    The ability to identify human movements can be an important tool in many different applications such as surveillance, military combat situations, search and rescue operations, and patient monitoring in hospitals. This information can provide soldiers, security personnel, and search and rescue workers with critical knowledge that can be used to potentially save lives and/or avoid a dangerous situation. Most research involving human activity recognition is focused on using the Short-Time Fourier Transform (STFT) as a method of analyzing the micro-Doppler signatures. Because of the time-frequency resolution limitations of the STFT and because Fourier transform-based methods are not well-suited for use with non-stationary and nonlinear signals, we have chosen a different approach. Empirical Mode Decomposition (EMD) has been shown to be a valuable time-frequency method for processing non-stationary and nonlinear data such as micro-Doppler signatures and EMD readily provides a feature vector that can be utilized for classification. For classification, the method of a Support Vector Machine (SVMs) was chosen. SVMs have been widely used as a method of pattern recognition due to their ability to generalize well and also because of their moderately simple implementation. In this paper, we discuss the ability of these methods to accurately identify human movements based on their micro-Doppler signatures obtained from S-band and millimeter-wave radar systems. Comparisons will also be made based on experimental results from each of these radar systems. Furthermore, we will present simulations of micro-Doppler movements for stationary subjects that will enable us to compare our experimental Doppler data to what we would expect from an "ideal" movement.

  5. Five years use of Pulse Doppler RADAR-utechnology in debris-flows monitoring - experience at three test sites so far

    Science.gov (United States)

    Koschuch, Richard; Brauner, Michael; Hu, Kaiheng; Hübl, Johannes

    2016-04-01

    Automatic monitoring of alpine mass movement is a major challenge in dealing with natural hazards. The presented research project shows a new approach in measurment and alarming technology for water level changes an debris flow by using a high-frequency Pulse Doppler RADAR. The detection system was implemented on 3 places (2 in Tirol/Austria within the monitoring systems of the IAN/BOKU; 1 in Dongchuan/China within the monitoring systems of the IMHE/Chinese Academy of Science) in order to prove the applicability of the RADAR in monitoring torrential activities (e.g. debris-flows, mudflows, flash floods, etc.). The main objective is to illustrate the principles and the potential of an innovative RADAR system and its versatility as an automatic detection system for fast (> 1 km/h - 300 km/h) alpine mass movements of any kind. The high frequency RADAR device was already successfully tested for snow avalanches in Sedrun/Switzerland (Lussi et al., 2012), in Ischgl/Austria (Kogelnig et al., 2012). The experience and the data of the five year showed the enormous potential of the presented RADAR technology in use as an independent warning and monitoring system in the field of natural hazard. We have been able to measure water level changes, surface velocities and several debris flows and can compare this data with the other installed systems.

  6. Applicability of Doppler weather radar based rainfall data for runoff estimation in Indian watersheds – A case study of Chennai basin

    Indian Academy of Sciences (India)

    V S Josephine; B V Mudgal; S B Thampi

    2014-08-01

    Traditionally, India has been vulnerable to various hazards such as floods, droughts and cyclones. About 8% of the total Indian landmass is prone to cyclones. A number of Doppler weather radars are installed in India and their products are utilized for weather predictions and detection of cyclones approaching the Indian coast. Radar-based hydrological studies in various countries have proven that computation of runoff using radar rainfall data could outperform rain gauge network measurements. There are no reported studies on their utilization for hydrological modelling and/or flood-related studies in Indian river basins. A comparison study between Doppler weather radar (DWR) derived rainfall data and the conventional rain gauge data was carried out with hourly inputs at one of the watersheds of Chennai basin, Tamil Nadu, India using HEC-HMS model. The model calibration and validation were performed by comparing the simulated outflow with the observed daily outflow data. The calibrated model was used to predict runoff from two post-monsoon cyclonic storm events with hourly inputs. It was noticed that the discrepancy in the runoff volume was small, but the difference in the peak flow was substantial. Additionally, there was a variation at the time to peak flow using daily and hourly inputs. The results show that the use of radar data may be optional for runoff volume estimation for the watersheds with sufficient rain gauge density, but highly desirable for peak flow and time to peak estimation. Therefore, the DWR derived rainfall data is a promising input for runoff estimation, especially in urban flood modelling.

  7. Ionospheric response to magnetar flare: signature of SGR J1550-5418 on coherent ionospheric Doppler radar

    Science.gov (United States)

    Mahrous, Ayman

    2017-03-01

    This paper presents observational evidence of frequent ionospheric perturbations caused by the magnetar flare of the source SGR J1550-5418, which took place on 22 January 2009. These ionospheric perturbations are observed in the relative change of the total electron content (ΔTEC/Δt) measurements from the coherent ionospheric Doppler radar (CIDR). The CIDR system makes high-precision measurements of the total electron content (TEC) change along ray-paths from ground receivers to low Earth-orbiting (LEO) beacon spacecraft. These measurements can be integrated along the orbital track of the beacon satellite to construct the relative spatial, not temporal, TEC profiles that are useful for determining the large-scale plasma distribution. The observed spatial TEC changes reveal many interesting features of the magnetar signatures in the ionosphere. The onset phase of the magnetar flare was during the CIDR's nighttime satellite passage. The nighttime small-scale perturbations detected by CIDR, with ΔTEC/Δt ≥ 0.05 TECU s-1, over the eastern Mediterranean on 22 January 2009 were synchronized with the onset phase of the magnetar flare and consistent with the emission of hundreds of bursts detected from the source. The maximum daytime large-scale perturbation measured by CIDR over northern Africa and the eastern Mediterranean was detected after ˜ 6 h from the main phase of the magnetar flare, with ΔTEC/Δt ≤ 0.10 TECU s-1. These ionospheric perturbations resembled an unusual poleward traveling ionospheric disturbance (TID) caused by the extraterrestrial source. The TID's estimated virtual velocity is 385.8 m s-1, with ΔTEC/Δt ≤ 0.10 TECU s-1.

  8. Three-Dimensional Wind Field Analysis from Dual-Doppler Radar Data. Part II: Minimizing the Error due to Temporal Variation.

    Science.gov (United States)

    Chong, M.; Testud, J.; Roux, F.

    1983-07-01

    One of the major problems in three-dimensional wind field analysis from dual (or multiple) Doppler radar data resides in the non-stationary of the observed air flow within the volume sampling time which ranges typically from 2 to 5 min. The present part II is focused on this problem. Most often, the storm moves horizontally at a speed of 5-25 m s1.Therefore, the temporal variation for a fixed observer at ground level results from the superposition of two effects: 1) the intrinsic temporal variation (or variation seen in a frame moving with the storm) and 2) the effect of horizontal advection.The first contribution of the paper concerns the development of an algorithm for correcting for the advection effect in the case of a dual-Doppler radar observation. This algorithm, which provides a mathematically exact solution to the problem of correcting for advection, can be very easily implemented in a computer program.The second contribution deals with the errors that may arise from an accurate (or lack of) evaluation of the advective velocity, or from an `Intrinsic' temporal variation in the moving frame. A spectral decomposition of the 3D wind field is considered, allowing us to study the dependence of the error on the scale of the motion. Specific conclusions are drawn about the requirements necessary to achieve a given accuracy in the vertical velocity field. i.e., admissible uncertainty in the advective velocity, and characteristic time of intrinsic temporal variation.Finally an example of application to actual Doppler radar data is presented. The results obtained from non-advected analyses are compared and discussed.

  9. Convective scale structure and evolution of a squall line observed by C-band dual Doppler radar in an arid region of northwestern China

    Science.gov (United States)

    Liu, Liping; Zhuang, Wei; Zhang, Pengfei; Mu, Rong

    2010-09-01

    A long-lived and loosely organized squall line moved rapidly across Ürümqi, the capital city of Xinjiang Uygur Autonomous Region of China on 26 June 2005, generating hail and strong winds. The squall line was observed by a dual Doppler radar system in a field experiment conducted in 2004 and 2005 by the Chinese Academy of Meteorological Sciences and the local meteorological bureau in northwestern China. The 3D wind fields within the squall line were retrieved through dual Doppler analyses and a variational Doppler radar analysis system (VDRAS). The formation and structure of the squall line as well as the genesis and evolution of embedded convective cells were investigated. During its life period, the squall line consisted of six storm cells extending about 100 km in length, and produced hail of about 25 mm in diameter and strong surface winds up to 11 m s-1. Radar observations revealed a broad region of stratiform rain in a meso- β cyclone, with the squall line located to the west of this. Two meso- γ scale vortices were found within the squall line. Compared to typical squall lines in moist regions, such as Guangdong Province and Shanghai, which tend to be around 300-400 km in length, have echo tops of 17-19 km, and produce maximum surface winds of about 25 m s-1 and temperature variations of about 8°C this squall line system had weaker maximum reflectivity (55 dB Z), a lower echo top (13 km) and smaller extension (about 100 km), relatively little stratiform rainfall preceding the convective line, and a similar moving speed and temperature variation at the surface.

  10. The Doppler Effect--A New Approach

    Science.gov (United States)

    Allen, J.

    1973-01-01

    Discusses the Doppler effect as it applies to different situations, such as a stationary source of sound with the observer moving, a stationary observer, and the sound source and observer both moving. Police radar, satellite surveillance radar, radar astronomy, and the Doppler navigator, are discussed as applications of Doppler shift. (JR)

  11. A long-term comparison of wind and tide measurements in the upper mesosphere recorded with an imaging Doppler interferometer and SuperDARN radar at Halley, Antarctica

    Directory of Open Access Journals (Sweden)

    R. E. Hibbins

    2008-03-01

    Full Text Available Data from a near co-located imaging Doppler interferometer (IDI and SuperDARN radar recorded since 1996 have been analysed in a consistent manner to compare the derived mean winds and tides in the upper mesosphere. By comparing only days when both techniques were recording good quality meridional wind data it is shown that the SuperDARN radar winds and tides correlate best with the IDI height bin 90–95 km. On timescales of one hour the winds derived from the IDI have a much greater associated variance and correlate poorly with the SuperDARN winds. Regression analysis reveals that the observed SuperDARN daily mean meridional wind strength is approximately 65% that recorded by the IDI, in good quantitative agreement with previous studies which have shown contamination to SuperDARN derived winds due to the significant back lobe of the radar radiation pattern. Climatologically the two techniques observe similar monthly mean winds with the SuperDARN meridional winds suppressed compared to the IDI which tends to record winds more poleward than those derived by the SuperDARN radar during the summer months, and to be slightly more equatorward during the winter. The 12-h tidal amplitude and phase derived from both techniques are in good agreement, whereas the 24-h tides are seen much more strongly in the SuperDARN radar, especially in wintertime, with poor phase agreement. Long term comparison of the two techniques reveals a tendency for the IDI meridional winds to be more poleward during solar maximum especially during summer time; an effect which is not reproduced in the meridional winds derived from the SuperDARN radar. These results are discussed in the context of previous studies to independently determine the veracity of each technique, and to highlight the circumstances where data derived from these two techniques can be used to draw reliable conclusions from comparative studies based on geographically distributed pairs of instruments.

  12. A Technique to Measure Energy Partitioning and Absolute Gas Pressures of Strombolian Explosions Using Doppler Radar at Erebus Volcano

    Science.gov (United States)

    Gerst, A.; Hort, M.; Kyle, P. R.; Voege, M.

    2008-12-01

    In 2005/06 we deployed three 24GHz (K-Band) continuous wave Doppler radar instruments at the crater rim of Erebus volcano in Antarctica. At the time there was a ~40 m wide, ~1000°C hot convecting phonolite lava lake, which was the source of ~0-6 Strombolian gas bubble explosions per day. We measured the velocities of ~50 explosions using a sample rate of 1-15 Hz. Data were downloaded in real-time through a wireless network. The measurements provide new insights into the still largely unknown mechanism of Strombolian eruptions, and help improve existing eruption models. We present a technique for a quasi in-situ measurement of the absolute pressure inside an eruption gas bubble. Pressures were derived using a simple eruption model and measured high resolution bubble surface velocities during explosions. Additionally, this technique allows us to present a comprehensive energy budget of a volcanic explosion as a time series of all important energy terms (i.e. potential, kinetic, dissipative, infrasonic, surface, seismic and thermal energy output). The absolute gas pressure inside rising expanding gas bubbles rapidly drops from ~3-10 atm (at the time when the lake starts to bulge) to ~1 atm before the bubble bursts, which usually occurs at radii of ~15-20m. These pressures are significantly lower than previously assumed for such explosions. The according internal energy of the gas agrees well with the observed total energy output. The results show that large explosions released about 109 to 1010 J each (equivalent to about 200-2000 kg of TNT), at a peak discharge rate frequently exceeding 109 W (the power output of a typical nuclear power plant). This dynamic output is mainly controlled by the kinetic and potential energy of the exploding magma shell, while other energy types were found to be much smaller (with the exception of thermal energy). Remarkably, most explosions at Erebus show two distinct surface acceleration peaks separated by ~0.3 seconds. This suggests

  13. Localized Optimization and Effectiveness Analysis of Medium PRF Airborne Pulse Doppler Radars in the Turkish Air Force

    Science.gov (United States)

    2011-09-01

    Clutter STT Single Target Tracker TWS Track-While-Scan xvi THIS PAGE INTENTIONALLY LEFT BLANK xvii ACKNOWLEDGEMENTS First of all, I would...radar: • Single Target Tracker ( STT ) • Automatic Detection and Tracking (ADT) • Track-While-Scan (TWS) • Phased array tracker • Imaging radar...601–611, April 2006. [33] E. J. Hughes and C. M. Alabaster, “Medium PRF radar PRF optimisation using evolutionary algorithms ,” Proceedings of the

  14. Real-Time Ionospheric Plasma Density Estimates in the Polar Cap using Simultaneous Dual Frequency Doppler Measurements at the SuperDARN McMurdo Radar

    Science.gov (United States)

    Spaleta, J.; Bristow, W. A.

    2012-12-01

    SuperDARN radars estimate plasma drift velocities from the Doppler shift observed on signals scattered from field-aligned density irregularities. The radars operate in the range of 8 MHz to 20 MHz and have ray paths covering a wide range of elevation angles, in order to maximize the range over which the scattering conditions are satisfied. Upward-propagating electromagnetic signals in this frequency range can be significantly refracted by the ionospheric plasma. The propagation paths of the refracted signals are bent earthward and at some point along this refracted path propagate perpendicular to the local magnetic field and scatter on the field-aligned density irregularities. The refraction results from gradients of the index of refraction in the ionospheric plasma. The index inside the ionosphere is lower than its free-space value, which depresses the measured line of sight velocity relative to the actual velocity of the plasma. One way to account for the depression of the measured velocity is to estimate the index of refraction in the scattering region by making multiple velocities measurements at different operating frequencies. Together with the appropriate plasma dispersion relations, multiple frequency measurements can be used to construct relations for the index of refraction, plasma density and the line of sight velocity correction factor as functions of frequency weighted measured velocity differences. Recent studies have used frequency-switching events spanning many days during traditional SuperDARN radar operation to build a statistical estimate for index of refraction, which is insensitive to the real-time spatial dynamics of the ionosphere. This statistical approach has motivated the development of a new mode of radar operation that provides simultaneous dual frequency measurements in order to resolve the temporal and spatial dynamics of the index of refraction calculations. Newly-developed multi-channel capabilities available in the SuperDARN radar

  15. A one year comparison of 482 MHz radar wind profiler, RS92-SGP Radiosonde and 1.5 μm Doppler Lidar wind measurements

    Directory of Open Access Journals (Sweden)

    E. Päschke

    2014-11-01

    Full Text Available We present the results of a one-year quasi-operational testing of the 1.5 μm StreamLine Doppler lidar developed by Halo Photonics from 2 October 2012 to 2 October 2013. The system was configured to continuously perform a velocity-azimuth display (VAD scan pattern using 24 azimuthal directions with a constant beam elevation angle of 75°. Radial wind estimates were selected using a rather conservative signal-to-noise ratio (SNR based threshold of −18.2 dB (0.015. A 30 min average wind vector was calculated based on the assumption of a horizontally homogeneous wind field through a singular-value decomposed Moore–Penrose pseudoinverse of the overdetermined linear system. A strategy for a quality control of the retrieved wind vector components is outlined which is used to ensure consistency between the retrieved winds and the assumptions inherent to the employed wind vector retrieval. Finally, the lidar measurements are compared with operational data from a collocated 482 MHz radar wind profiler running in a four-beam Doppler beam swinging (DBS mode and winds from operational radiosonde measurements. The intercomparisons show that the Doppler lidar is a reliable system for operational wind measurements in the atmospheric boundary layer (ABL.

  16. A Statistical study of the Doppler spectral width of high-latitude ionospheric F-region echoes recorded with SuperDARN coherent HF radars

    Directory of Open Access Journals (Sweden)

    J.-P. Villain

    Full Text Available The HF radars of the Super Dual Auroral Radar Network (SuperDARN provide measurements of the E × B drift of ionospheric plasma over extended regions of the high-latitude ionosphere. We have conducted a statistical study of the associated Doppler spectral width of ionospheric F-region echoes. The study has been conducted with all available radars from the Northern Hemisphere for 2 specific periods of time. Period 1 corresponds to the winter months of 1994, while period 2 covers October 1996 to March 1997. The distributions of data points and average spectral width are presented as a function of Magnetic Latitude and Magnetic Local Time. The databases are very consistent and exhibit the same features. The most stringent features are: a region of very high spectral width, collocated with the ionospheric LLBL/cusp/mantle region; an oval shaped region of high spectral width, whose equator-ward boundary matches the poleward limit of the Holzworth and Meng auroral oval. A simulation has been conducted to evaluate the geometrical and instrumental effects on the spectral width. It shows that these effects cannot account for the observed spectral features. It is then concluded that these specific spectral width characteristics are the signature of ionospheric/magnetospheric coupling phenomena.

    Key words. Ionosphere (auroral ionosphere; ionosphere-magnetosphere interactions; ionospheric irregularities

  17. Analysis and Forecast of a Tornadic Thunderstorm Using Multiple Doppler Radar Data, 3DVAR, and ARPS Model

    Directory of Open Access Journals (Sweden)

    Edward Natenberg

    2013-01-01

    Full Text Available A three-dimensional variational (3DVAR assimilation technique developed for a convective-scale NWP model—advanced regional prediction system (ARPS—is used to analyze the 8 May 2003, Moore/Midwest City, Oklahoma tornadic supercell thunderstorm. Previous studies on this case used only one or two radars that are very close to this storm. However, three other radars observed the upper-level part of the storm. Because these three radars are located far away from the targeted storm, they were overlooked by previous studies. High-frequency intermittent 3DVAR analyses are performed using the data from five radars that together provide a more complete picture of this storm. The analyses capture a well-defined mesocyclone in the midlevels and the wind circulation associated with a hook-shaped echo. The analyses produced through this technique are used as initial conditions for a 40-minute storm-scale forecast. The impact of multiple radars on a short-term NWP forecast is most evident when compared to forecasts using data from only one and two radars. The use of all radars provides the best forecast in which a strong low-level mesocyclone develops and tracks in close proximity to the actual tornado damage path.

  18. Real-time parallel implementation of Pulse-Doppler radar signal processing chain on a massively parallel machine based on multi-core DSP and Serial RapidIO interconnect

    Science.gov (United States)

    Klilou, Abdessamad; Belkouch, Said; Elleaume, Philippe; Le Gall, Philippe; Bourzeix, François; Hassani, Moha M'Rabet

    2014-12-01

    Pulse-Doppler radars require high-computing power. A massively parallel machine has been developed in this paper to implement a Pulse-Doppler radar signal processing chain in real-time fashion. The proposed machine consists of two C6678 digital signal processors (DSPs), each with eight DSP cores, interconnected with Serial RapidIO (SRIO) bus. In this study, each individual core is considered as the basic processing element; hence, the proposed parallel machine contains 16 processing elements. A straightforward model has been adopted to distribute the Pulse-Doppler radar signal processing chain. This model provides low latency, but communication inefficiency limits system performance. This paper proposes several optimizations that greatly reduce the inter-processor communication in a straightforward model and improves the parallel efficiency of the system. A use case of the Pulse-Doppler radar signal processing chain has been used to illustrate and validate the concept of the proposed mapping model. Experimental results show that the parallel efficiency of the proposed parallel machine is about 90%.

  19. MHHT-Based Method for Analysis of Micro-Doppler Signatures for Human Finer-Grained Activity Using Through-Wall SFCW Radar

    Directory of Open Access Journals (Sweden)

    Fugui Qi

    2017-03-01

    Full Text Available Ultra-wideband radar-based penetrating detection and recognition of human activities has become a focus on remote sensing in various military applications in recent years, such as urban warfare, hostage rescue, and earthquake post-disaster rescue. However, an excellent micro-Doppler signature (MDS extracting method of human motion with high time-frequency resolution, outstanding anti-interference ability, and extensive adaptability, which aims to provide favorable and more detailed features for human activity recognition and classification, especially in the non-free space detection environment, is in great urgency. To cope with the issue, a multiple Hilbert-Huang transform (MHHT method is proposed for high-resolution time-frequency analysis of finer-grained human activity MDS hidden in ultra-wideband (UWB radar echoes during the through-wall detection environment. Based on the improved HHT with effective intrinsic mode function (IMF selection according to the cosine similarity (CS principle, the improved HHT is applied to each channel signal in the effective channel scope of the UWB radar signal and then integrated along the range direction. The activities of swinging one or two arms while standing at a spot 3 m from a wall were used to validate the abilities of the proposed method for extracting and separating the MDS of different moving body structures with a high time-frequency resolution. Simultaneously, the corresponding relationship between the frequency components in MHHT-based spectra and structures of the moving human body was demonstrated according to the radar Doppler principle combined with the principle of human body kinematics. Moreover, six common finer-grained human activities and a piaffe at different ranges under the through-wall detection environment were exploited to confirm the adaptability of the novel method for different activities and pre-eminent anti-interference ability under a low signal-noise-clutter ratio (SNCR

  20. Pulsed Doppler Radar for Low Speed Target Detection%脉冲多普勒雷达低速目标检测技术

    Institute of Scientific and Technical Information of China (English)

    郭玲红; 李亚立

    2012-01-01

    The principles of pulsed doppler radar for target detection and the characteristics of low speed target detection are analysed. The leakages of emission signal, local oscillator signal, frequency multiply signal of synchronizing pulse and crystal oscillator output are the reasons that effecting of pulsed doppler radar on the low speed target detection. So isolation' s raising, wideband signal reception and emission signal frequency offset are the solution measures to realize low speed target detection effectively. Experimental study proved the validity of analysis and measures.%通过对脉冲多普勒雷达目标检测原理和低速目标检测特点的分析,确定了来自于雷达系统中的发射信号泄露、本振信号泄露、同步脉冲及DDS信号倍频分量泄露、晶振信号倍频分量泄露等是影响脉冲多普勒雷达对于低速目标检测的主要因素,依托现有硬件水平,通过提高系统的收发隔离度、采用宽带接收和发射频率预偏移等技术措施,保证泄漏信号远小于回波信号,从而有效地实现了对低速目标的检测,并通过实验验证了设计的正确性和措施的有效性。

  1. To See the Unseen: A History of Planetary Radar Astronomy

    Science.gov (United States)

    Butrica, Andrew J.

    1996-01-01

    This book relates the history of planetary radar astronomy from its origins in radar to the present day and secondarily to bring to light that history as a case of 'Big Equipment but not Big Science'. Chapter One sketches the emergence of radar astronomy as an ongoing scientific activity at Jodrell Bank, where radar research revealed that meteors were part of the solar system. The chief Big Science driving early radar astronomy experiments was ionospheric research. Chapter Two links the Cold War and the Space Race to the first radar experiments attempted on planetary targets, while recounting the initial achievements of planetary radar, namely, the refinement of the astronomical unit and the rotational rate and direction of Venus. Chapter Three discusses early attempts to organize radar astronomy and the efforts at MIT's Lincoln Laboratory, in conjunction with Harvard radio astronomers, to acquire antenna time unfettered by military priorities. Here, the chief Big Science influencing the development of planetary radar astronomy was radio astronomy. Chapter Four spotlights the evolution of planetary radar astronomy at the Jet Propulsion Laboratory, a NASA facility, at Cornell University's Arecibo Observatory, and at Jodrell Bank. A congeries of funding from the military, the National Science Foundation, and finally NASA marked that evolution, which culminated in planetary radar astronomy finding a single Big Science patron, NASA. Chapter Five analyzes planetary radar astronomy as a science using the theoretical framework provided by philosopher of science Thomas Kuhn. Chapter Six explores the shift in planetary radar astronomy beginning in the 1970s that resulted from its financial and institutional relationship with NASA Big Science. Chapter Seven addresses the Magellan mission and its relation to the evolution of planetary radar astronomy from a ground-based to a space-based activity. Chapters Eight and Nine discuss the research carried out at ground-based

  2. Detection of Aircraft Embedded in Ground Clutter by Means of Non-Doppler X-band Radar

    Science.gov (United States)

    Hwang, Seongin; Ishii, Seishiro; Sayama, Shuji; Sekine, Matsuo

    It is reported that various radar clutter obey a Weibull distribution under certain conditions. To suppress such Weibull-distributed clutter, a new adaptive method was proposed by the present author. In this method, the parameters of the Weibull distribution and the threshold level for an adaptive Constant False Alarm Rate (CFAR) detector are determined by calculating the variance before it passes through a logarithmic amplifier. To apply this new method to practical problems observed by an X-band radar, a computer simulation are made for a finite number of samples in order to obtain the CFAR maintenance in Weibull radar clutter. Finally an improvement value of target-to-clutter ratio 30.07 dB was obtained for the detection of an aircraft embedded in ground clutter.

  3. Joint Doppler frequency, 2D-DOD and 2D-DOA estimation for bistatic MIMO radar in spatial coloured noise

    Science.gov (United States)

    Xu, Lingyun; Zhang, Xiaofei; Xu, Zongze; Zeng, Xianwei; Yao, Fuqiang

    2015-06-01

    In this paper, we address the problem of four-dimensional angle and Doppler frequency estimation for L-shaped bistatic multiple input multiple output radar in spatial coloured noise. A novel method of joint estimation of Doppler frequency, two-dimensional direction of departure and two-dimensional direction of arrival based on the propagator method is discussed. Utilising the cross-correlation matrix which is formed by the adjacent outputs of matched filter in the time domain, the special matrix is constructed to eliminate the influence of spatial coloured noise. The proposed algorithm provides lower computational complexity and has very close parameter estimation to the estimation of signal parameters via rotational invariance techniques algorithm and DOA-matrix algorithm in high signal-to-noise ratio and Cramér-Rao bound is given. Furthermore, multidimensional parameters can be automatically paired by this algorithm to avoid the performance degradation resulting from wrong pairing. Numerical simulation results demonstrate the effectiveness of the proposed method.

  4. MAARSY - the new MST radar on Andøya: first results of spaced antenna and Doppler measurements of atmospheric winds in the troposphere and mesosphere using a partial array

    Science.gov (United States)

    Stober, G.; Latteck, R.; Rapp, M.; Singer, W.; Zecha, M.

    2012-09-01

    MST radars have been used to study the troposphere, stratosphere and mesosphere over decades. These radars have proven to be a valuable tool to investigate atmospheric dynamics. MAARSY, the new MST radar at the island of Andøya uses a phased array antenna and is able to perform spaced antenna and Doppler measurements at the same time with high temporal and spatial resolution. Here we present first wind observations using the initial expansion stage during summer 2010. The tropospheric spaced antenna and Doppler beam swinging experiments are compared to radiosonde measurements, which were launched at the nearby Andøya Rocket Range (ARR). The mesospheric wind observations are evaluated versus common volume meteor radar wind measurements. The beam steering capabilities of MAARSY are demonstrated by performing systematic scans of polar mesospheric summer echoes (PMSE) using 25 and 91 beam directions. These wind observations permit to evaluate the new radar against independent measurements from radiosondes and meteor radar measurements to demonstrate its capabilities to provide reliable wind data from the troposphere up to the mesosphere.

  5. The Stratiform Region of an MCS on 19 June in TELEX 2004 Observed With Polarimetric and Doppler Radars, Electric Field Soundings, and a Lightning Mapping Array

    Science.gov (United States)

    Ramig, N.; Macgorman, D.; Rust, D.; Schuur, T.; Bruning, E.; Krehbiel, P.; Rison, W.; Hamlin, T.; Straka, J.; Payne, C.; Apostolakopoulos, I.; Biggerstaff, M. I.; Biermann, N.; Carey, L.

    2005-12-01

    Polarimetric and Doppler radar data, balloon-borne soundings of the electric field, and three-dimensional lightning mapping array data were acquired from a mesoscale convective system (MCS) on 19 June 2004 during the Thunderstorm Electrification and Lightning Experiment (TELEX). A total of 10 partial and complete vertical soundings through the storm were obtained from the flights of four instrumented balloons: two launched in the convective region, one in the transition zone, and one in the stratiform region. Each balloon recorded ascent and descent soundings and the transition zone balloon recorded an additional two partial soundings due to a downdraft. At times, multiple soundings were in progress simultaneously. This study focuses on the stratiform region of the MCS, which was sampled by the last two soundings of balloon three and both soundings of balloon four. A comparison of the electrical structure of the stratiform region of this MCS with that of previously published conceptual models suggests that, during at least part of the MCS's lifetime, its electrical structure was Type A, which is more complex than Type B. The main difference between these classifications is the number of charge regions in the cloud. A one-dimensional analysis with Gauss's law indicates six vertically stacked charge layers that alternated polarity within the stratiform region during balloon four's ascent. The vector electric field pattern verified the 1-D Gauss analysis and showed the electric field structure to be primarily horizontally stratified. The maximum magnitude of the electric field was approximately 105 kV/m. The second stratiform sounding sampled by balloon three began fifty minutes after the first stratiform sounding. It showed a very different electric field profile, consistent with neither Type A nor Type B electrical structure, perhaps because the sounding was far from the front of the MCS. There were only three charge layers as opposed to the four charge layers

  6. Bistatic radar

    CERN Document Server

    Willis, Nick

    2004-01-01

    Annotation his book is a major extension of a chapter on bistatic radar written by the author for the Radar Handbook, 2nd edition, edited by Merrill Skolnik. It provides a history of bistatic systems that points out to potential designers the applications that have worked and the dead-ends not worth pursuing. The text reviews the basic concepts and definitions, and explains the mathematical development of relationships, such as geometry, Ovals of Cassini, dynamic range, isorange and isodoppler contours, target doppler, and clutter doppler spread.Key Features * All development and analysis are

  7. Radar scatter from equatorial electrojet waves: An explanation for the constancy of the Type I Doppler shift with zenith angle

    Science.gov (United States)

    Kelley, M. C.; Cuevas, R. A.; Hysell, D. L.

    2008-02-01

    The first results from the 430 MHz Advanced Modular Incoherent Scatter Radar Prototype (AMISR-P) at the Jicamarca Radio Observatory were reported by Hysell et al. (2007). We present additional data showing that the phase velocity of Type I echoes is independent of zenith angle, an unexplained property of these waves. We interpret the results using rocket data by predicting the total line-of-sight velocity at the four zenith angles used. We find that the radars preferentially detect waves within 10% of C s in at least four range gates for all beams and up to eight range gates for the 51 JULIA beam. This result is consistent with recent auroral observations that Type I waves are only generated with k vectors near the electron flow velocity, where the latter is the vector sum of the zero-order drift and the perturbation drift due to large-scale waves in the equatorial case.

  8. Airborne Radar Observations of Severe Hailstorms: Implications for Future Spaceborne Radar

    Science.gov (United States)

    Heymsfield, Gerald M.; Tian, Lin; Li, Lihua; McLinden, Matthew; Cervantes, Jaime I.

    2013-01-01

    A new dual-frequency (Ku and Ka band) nadir-pointing Doppler radar on the high-altitude NASA ER-2 aircraft, called the High-Altitude Imaging Wind and Rain Airborne Profiler (HIWRAP), has collected data over severe thunderstorms in Oklahoma and Kansas during the Midlatitude Continental Convective Clouds Experiment (MC3E). The overarching motivation for this study is to understand the behavior of the dualwavelength airborne radar measurements in a global variety of thunderstorms and how these may relate to future spaceborne-radar measurements. HIWRAP is operated at frequencies that are similar to those of the precipitation radar on the Tropical Rainfall Measuring Mission (Ku band) and the upcoming Global Precipitation Measurement mission satellite's dual-frequency (Ku and Ka bands) precipitation radar. The aircraft measurements of strong hailstorms have been combined with ground-based polarimetric measurements to obtain a better understanding of the response of the Ku- and Ka-band radar to the vertical distribution of the hydrometeors, including hail. Data from two flight lines on 24 May 2011 are presented. Doppler velocities were approx. 39m/s2at 10.7-km altitude from the first flight line early on 24 May, and the lower value of approx. 25m/s on a second flight line later in the day. Vertical motions estimated using a fall speed estimate for large graupel and hail suggested that the first storm had an updraft that possibly exceeded 60m/s for the more intense part of the storm. This large updraft speed along with reports of 5-cm hail at the surface, reflectivities reaching 70 dBZ at S band in the storm cores, and hail signals from polarimetric data provide a highly challenging situation for spaceborne-radar measurements in intense convective systems. The Ku- and Ka-band reflectivities rarely exceed approx. 47 and approx. 37 dBZ, respectively, in these storms.

  9. Localization and Mapping Using Only a Rotating FMCW Radar Sensor

    Directory of Open Access Journals (Sweden)

    Roland Chapuis

    2013-04-01

    Full Text Available Rotating radar sensors are perception systems rarely used in mobile robotics. This paper is concerned with the use of a mobile ground-based panoramic radar sensor which is able to deliver both distance and velocity of multiple targets in its surrounding. The consequence of using such a sensor in high speed robotics is the appearance of both geometric and Doppler velocity distortions in the collected data. These effects are, in the majority of studies, ignored or considered as noise and then corrected based on proprioceptive sensors or localization systems. Our purpose is to study and use data distortion and Doppler effect as sources of information in order to estimate the vehicle’s displacement. The linear and angular velocities of the mobile robot are estimated by analyzing the distortion of the measurements provided by the panoramic Frequency Modulated Continuous Wave (FMCW radar, called IMPALA. Without the use of any proprioceptive sensor, these estimates are then used to build the trajectory of the vehicle and the radar map of outdoor environments. In this paper, radar-only localization and mapping results are presented for a ground vehicle moving at high speed.

  10. Three-Dimensional Wind Field Analysis from Dual-Doppler Radar Data. Part I: Filtering, Interpolating and Differentiating the Raw Data.

    Science.gov (United States)

    Testud, J.; Chong, M.

    1983-07-01

    This paper is the first of three dealing with the three-dimensional wind field analysis from dual-Doppler radar data. Here we deal with the first step of the analysis which consists in interpolating and filtering the raw radial velocity fields within each coplane (or common plane simultaneously scanned by the two radars). To carry out such interpolation and filtering, a new method is proposed based on the principles of numerical variational analysis described by Sasaki (1970): the `filtered' representation of the observed field should be both `close' to the data points (in a least-squares sense) and verify some imperative of mathematical regularity. Any method for interpolating and smoothing data is inherently a filtering process. The proposed variational method enables this filtering to be controlled. The presented method is developed for any function of two variables but could be extended to the case of three or more variables.Numerical simulations substantiate the theoretically predicted filtering characteristics and show an improvement on other filtering schemes. It is found, compared to the classical filtering using the Cressman weighting function, that the variational method brings a substantial improvement of the gain curve (in the sense of a steeper cut-off), when the `regularity' of the second-order derivatives is imposed. It is worth noting that this improvement is achieved without increasing the computing time. It is also emphasized that an elaborate numerical differentiation scheme should be used to estimate the divergence, otherwise the gain curve for this parameter may be different from that for the Cartesian coplane velocities (which may induce distortion in the final three-dimensional wind field).

  11. Ground based materials science experiments

    Science.gov (United States)

    Meyer, M. B.; Johnston, J. C.; Glasgow, T. K.

    1988-01-01

    The facilities at the Microgravity Materials Science Laboratory (MMSL) at the Lewis Research Center, created to offer immediate and low-cost access to ground-based testing facilities for industrial, academic, and government researchers, are described. The equipment in the MMSL falls into three categories: (1) devices which emulate some aspect of low gravitational forces, (2) specialized capabilities for 1-g development and refinement of microgravity experiments, and (3) functional duplicates of flight hardware. Equipment diagrams are included.

  12. Ground based materials science experiments

    Science.gov (United States)

    Meyer, M. B.; Johnston, J. C.; Glasgow, T. K.

    1988-01-01

    The facilities at the Microgravity Materials Science Laboratory (MMSL) at the Lewis Research Center, created to offer immediate and low-cost access to ground-based testing facilities for industrial, academic, and government researchers, are described. The equipment in the MMSL falls into three categories: (1) devices which emulate some aspect of low gravitational forces, (2) specialized capabilities for 1-g development and refinement of microgravity experiments, and (3) functional duplicates of flight hardware. Equipment diagrams are included.

  13. A Wing Pod-based Millimeter Wave Cloud Radar on HIAPER

    Science.gov (United States)

    Vivekanandan, Jothiram; Tsai, Peisang; Ellis, Scott; Loew, Eric; Lee, Wen-Chau; Emmett, Joanthan

    2014-05-01

    One of the attractive features of a millimeter wave radar system is its ability to detect micron-sized particles that constitute clouds with lower than 0.1 g m-3 liquid or ice water content. Scanning or vertically-pointing ground-based millimeter wavelength radars are used to study stratocumulus (Vali et al. 1998; Kollias and Albrecht 2000) and fair-weather cumulus (Kollias et al. 2001). Airborne millimeter wavelength radars have been used for atmospheric remote sensing since the early 1990s (Pazmany et al. 1995). Airborne millimeter wavelength radar systems, such as the University of Wyoming King Air Cloud Radar (WCR) and the NASA ER-2 Cloud Radar System (CRS), have added mobility to observe clouds in remote regions and over oceans. Scientific requirements of millimeter wavelength radar are mainly driven by climate and cloud initiation studies. Survey results from the cloud radar user community indicated a common preference for a narrow beam W-band radar with polarimetric and Doppler capabilities for airborne remote sensing of clouds. For detecting small amounts of liquid and ice, it is desired to have -30 dBZ sensitivity at a 10 km range. Additional desired capabilities included a second wavelength and/or dual-Doppler winds. Modern radar technology offers various options (e.g., dual-polarization and dual-wavelength). Even though a basic fixed beam Doppler radar system with a sensitivity of -30 dBZ at 10 km is capable of satisfying cloud detection requirements, the above-mentioned additional options, namely dual-wavelength, and dual-polarization, significantly extend the measurement capabilities to further reduce any uncertainty in radar-based retrievals of cloud properties. This paper describes a novel, airborne pod-based millimeter wave radar, preliminary radar measurements and corresponding derived scientific products. Since some of the primary engineering requirements of this millimeter wave radar are that it should be deployable on an airborne platform

  14. Remote sensing of the sea by X-band, dual-polarized, coherent weather radar

    Science.gov (United States)

    Forget, Philippe; Saillard, Marc; Testud, Jacques; Le Bouar, Erwan

    2010-05-01

    Remote sensing of the sea surface over large areas with high resolution (<1km) and at high time rate (<1h) is still a challenge that space-borne radiometers and radars can only satisfy. This presentation is an investigation of the use for this purpose of a ground-based, rotating, coherent X-band, dual-polarized (HH-VV) weather radar. We studied the data acquired by such a meteorological device, dedicated to precipitation measurements and operated in South of France at the top of a mountain near the Ligurian Sea. One month of data was considered. We observed that the sea signal often dominated the atmospheric signal despite the only slight inclination from horizontal of the radar beam direction. The radar signals being calibrated for weather application, both atmosphere and ocean radar equations were used to extract the normalized radar cross section (NRCS) of the sea. Other useful experimental parameters provided by the radar were the mean Doppler velocity and, to mask the undesirable rain signals, the polarization ratio. In situ measurements on wind and wave conditions were recorded by an off-shore meteorological buoy. Furthermore, the surface wind field as computed by the meteorological model MM5 over the Ligurian Sea was available at high time and space resolution during the experimental period The main results concern the variation of NRCS and Doppler velocity with wind and wave conditions. In particular, for moderate to strong winds, we generally found a very good correlation between the Doppler velocity field and the wind velocity component along the radar azimuths. The preliminary results obtained in this experiment suggest that operational weather radars can be valuable means to monitor useful wind information over large sea surfaces.

  15. Doppler characteristics of sea clutter.

    Energy Technology Data Exchange (ETDEWEB)

    Raynal, Ann Marie; Doerry, Armin Walter

    2010-06-01

    Doppler radars can distinguish targets from clutter if the target's velocity along the radar line of sight is beyond that of the clutter. Some targets of interest may have a Doppler shift similar to that of clutter. The nature of sea clutter is different in the clutter and exo-clutter regions. This behavior requires special consideration regarding where a radar can expect to find sea-clutter returns in Doppler space and what detection algorithms are most appropriate to help mitigate false alarms and increase probability of detection of a target. This paper studies the existing state-of-the-art in the understanding of Doppler characteristics of sea clutter and scattering from the ocean to better understand the design and performance choices of a radar in differentiating targets from clutter under prevailing sea conditions.

  16. Evaluation of Cloud Microphysics Simulated using a Meso-Scale Model Coupled with a Spectral Bin Microphysical Scheme through Comparison with Observation Data by Ship-Borne Doppler and Space-Borne W-Band Radars

    Science.gov (United States)

    Iguchi, T.; Nakajima, T.; Khain, A. P.; Saito, K.; Takemura, T.; Okamoto, H.; Nishizawa, T.; Tao, W.-K.

    2012-01-01

    Equivalent radar reflectivity factors (Ze) measured by W-band radars are directly compared with the corresponding values calculated from a three-dimensional non-hydrostatic meso-scale model coupled with a spectral-bin-microphysical (SBM) scheme for cloud. Three case studies are the objects of this research: one targets a part of ship-borne observation using 95 GHz Doppler radar over the Pacific Ocean near Japan in May 2001; other two are aimed at two short segments of space-borne observation by the cloud profiling radar on CloudSat in November 2006. The numerical weather prediction (NWP) simulations reproduce general features of vertical structures of Ze and Doppler velocity. A main problem in the reproducibility is an overestimation of Ze in ice cloud layers. A frequency analysis shows a strong correlation between ice water contents (IWC) and Ze in the simulation; this characteristic is similar to those shown in prior on-site studies. From comparing with the empirical correlations by the prior studies, the simulated Ze is overestimated than the corresponding values in the studies at the same IWC. Whereas the comparison of Doppler velocities suggests that large-size snowflakes are necessary for producing large velocities under the freezing level and hence rules out the possibility that an overestimation of snow size causes the overestimation of Ze. Based on the results of several sensitivity tests, we conclude that the source of the overestimation is a bias in the microphysical calculation of Ze or an overestimation of IWC. To identify the source of the problems needs further validation research with other follow-up observations.

  17. The interaction of large scale and mesoscale environment leading to formation of intense thunderstorms over Kolkata. Part I: Doppler radar and satellite observations

    Indian Academy of Sciences (India)

    P Mukhopadhyay; M Mahakur; H A K Singh

    2009-10-01

    The weather systems that predominantly affect the eastern and northeastern parts of India during the pre-monsoon summer months (March,April and May)are severe thunderstorms,known as Nor ’westers.The storms derive their names from the fact that they frequently strike cities and towns in the southern part of West Bengal in the afternoon from the north-west direction while traveling far from its place of genesis over the Bihar plateau.The storms are devastating in nature particularly due to strong (gusty)winds,heavy rains and hails associated with it.Although these storms are well known for its power of causing damages,studies on them are relatively few due to their small size and sparse network of observations.To address this important issue,the evolution of two Nor ’westers of 12 March and 22 May 2003 over Kolkata is studied in detail in this paper using hourly Doppler weather radar (DWR)observations and high resolution Meteosat-5 imageries.In addition,supporting meteorological reports are used to find the large scale conditions that influence the moisture convergence and vertical wind shear.The genesis of both the storms is found to be over Bihar –Jharkhand region and beyond the range of the DWR.The satellite observations are found to be useful in identifying the location and initiation of the storms.The movements of the storms are captured by the DWR estimated vertical cross-section of reflectivities.The Doppler estimate shows that the 12 March storm had a vertical extent of about 10 –12 km at the time of maturity and that of 22 May reaching up to 18 km signifying deep convection associated with these events.The genesis, maturity and dissipation are well brought out by the hourly DWR and satellite imageries.The DWR observations suggest that the systems move at a speed of 20 –25 m/s.The DWR estimated precipitation shows a detailed spatial distribution around Kolkata with several localized zones of heavy rain and this is found to be well supported by

  18. Dual-Doppler Feasibility Study

    Science.gov (United States)

    Huddleston, Lisa L.

    2012-01-01

    When two or more Doppler weather radar systems are monitoring the same region, the Doppler velocities can be combined to form a three-dimensional (3-D) wind vector field thus providing for a more intuitive analysis of the wind field. A real-time display of the 3-D winds can assist forecasters in predicting the onset of convection and severe weather. The data can also be used to initialize local numerical weather prediction models. Two operational Doppler Radar systems are in the vicinity of Kennedy Space Center (KSC) and Cape Canaveral Air Force Station (CCAFS); these systems are operated by the 45th Space Wing (45 SW) and the National Weather Service Melbourne, Fla. (NWS MLB). Dual-Doppler applications were considered by the 45 SW in choosing the site for the new radar. Accordingly, the 45th Weather Squadron (45 WS), NWS MLB and the National Aeronautics and Space Administration tasked the Applied Meteorology Unit (AMU) to investigate the feasibility of establishing dual-Doppler capability using the two existing systems. This study investigated technical, hardware, and software requirements necessary to enable the establishment of a dual-Doppler capability. Review of the available literature pertaining to the dual-Doppler technique and consultation with experts revealed that the physical locations and resulting beam crossing angles of the 45 SW and NWS MLB radars make them ideally suited for a dual-Doppler capability. The dual-Doppler equations were derived to facilitate complete understanding of dual-Doppler synthesis; to determine the technical information requirements; and to determine the components of wind velocity from the equation of continuity and radial velocity data collected by the two Doppler radars. Analysis confirmed the suitability of the existing systems to provide the desired capability. In addition, it is possible that both 45 SW radar data and Terminal Doppler Weather Radar data from Orlando International Airport could be used to alleviate any

  19. Micro-Doppler Analysis of Small UAVs

    NARCIS (Netherlands)

    Wit, J.J.M. de; Harmanny, R.I.A.; Prémel Cabic, G.

    2012-01-01

    Coherent radar measures micro-Doppler properties of moving objects. The micro-Doppler signature depends on parts of an object moving and rotating in addition to the main body motion (e.g. rotor blades) and is therefore characteristic for the type of object. In this study, the micro-Doppler signature

  20. Micro-Doppler Analysis of Small UAVs

    NARCIS (Netherlands)

    Wit, J.J.M. de; Harmanny, R.I.A.; Prémel Cabic, G.

    2012-01-01

    Coherent radar measures micro-Doppler properties of moving objects. The micro-Doppler signature depends on parts of an object moving and rotating in addition to the main body motion (e.g. rotor blades) and is therefore characteristic for the type of object. In this study, the micro-Doppler signature

  1. Micro-Doppler classification of riders and riderless horses

    Science.gov (United States)

    Tahmoush, David

    2014-05-01

    Micro-range Micro-Doppler can be used to isolate particular parts of the radar signature, and in this case we demonstrate the differences in the signature between a walking horse versus a walking horse with a rider. Using micro-range micro-Doppler, we can distinguish the radar returns from the rider as separate from the radar returns of the horse.

  2. 基于连续波雷达微多普勒效应的弹丸转速测试方法%Testing Method of Projectile Rotating Speed Based on Micro-Doppler Effect of CW Radars

    Institute of Scientific and Technical Information of China (English)

    张万君; 吴晓颖; 冷雪冰; 李文珍; 纪兵

    2012-01-01

    Aiming at the limitation of testing methods for projectile rotating speed, a new testing method of projectile rotating speed is put forward. The radar echo micro-Doppler modulated mathematic model caused by projectile rotation is built by using micro-Doppler effect resulted from CW radar detection of projectile rotations, the internal relationship between micro-Doppler frequency and projectile rotating speed is derived, and testing methods of micro-Doppler data for projectile rotating speed is provided. The projectile rotating speed is extracted by micro-motion identification and digital demodulation of projectile rotation, and the good testing effect is validated by shooting range test.%针对目前弹丸转速测试方法的局限,提出了一种新的弹丸转速测试方法,利用连续波雷达探测弹丸旋转产生的微多普勒效应,建立了弹丸旋转运动引起的雷达回波微多普勒调制数学模型,推导了微多普勒频率与弹丸转速的解析关系,给出了弹丸转速微多普勒数据的实测方案,并通过弹丸旋转微动辨识与数字解调技术,提取出弹丸转速,经靶场试验验证,测试效果良好。

  3. Federal Weather Radar Stations in the United States as of September 2012

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data represent Next-Generation Radar (NEXRAD) and Terminal Doppler Weather Radar (TDWR) weather radar stations within the US. The NEXRAD radar stations are...

  4. Offshore Wind Measurements Using Doppler Aerosol Wind Lidar (DAWN) at NASA Langley Research Center

    Science.gov (United States)

    Beyon, Jeffrey Y.; Koch, Grady J.; Kavaya, Michael J.

    2014-01-01

    The latest flight demonstration of Doppler Aerosol Wind Lidar (DAWN) at NASA Langley Research Center (LaRC) is presented. The goal of the campaign was to demonstrate the improvement of DAWN system since the previous flight campaign in 2012 and the capabilities of DAWN and the latest airborne wind profiling algorithm APOLO (Airborne Wind Profiling Algorithm for Doppler Wind Lidar) developed at LaRC. The comparisons of APOLO and another algorithm are discussed utilizing two and five line-of-sights (LOSs), respectively. Wind parameters from DAWN were compared with ground-based radar measurements for validation purposes. The campaign period was June - July in 2013 and the flight altitude was 8 km in inland toward Charlotte, NC, and offshores in Virginia Beach, VA and Ocean City, MD. The DAWN system was integrated into a UC12B with two operators onboard during the campaign.

  5. Offshore wind measurements using Doppler aerosol wind lidar (DAWN) at NASA Langley Research Center

    Science.gov (United States)

    Beyon, Jeffrey Y.; Koch, Grady J.; Kavaya, Michael J.

    2014-06-01

    The latest flight demonstration of Doppler Aerosol Wind Lidar (DAWN) at NASA Langley Research Center (LaRC) is presented. The goal of the campaign was to demonstrate the improvement of DAWN system since the previous flight campaign in 2012 and the capabilities of DAWN and the latest airborne wind profiling algorithm APOLO (Airborne Wind Profiling Algorithm for Doppler Wind Lidar) developed at LaRC. The comparisons of APOLO and another algorithm are discussed utilizing two and five line-of-sights (LOSs), respectively. Wind parameters from DAWN were compared with ground-based radar measurements for validation purposes. The campaign period was June - July in 2013 and the flight altitude was 8 km in inland toward Charlotte, NC, and offshores in Virginia Beach, VA and Ocean City, MD. The DAWN system was integrated into a UC12B with two operators onboard during the campaign.

  6. Three-Dimensional Wind Field Analysis from Dual-Doppler Radar Data. Part III: The Boundary Condition: An Optimum Determination Based on a Variational Concept.

    Science.gov (United States)

    Chong, M.; Testud, J.

    1983-07-01

    The choice of the boundary condition when integrating the air mass continuity equation, is a major problem of the 3D wind field analysis from dual (or multiple) Doppler radar data. A zero vertical velocity at ground level seems the most natural boundary condition. Unfortunately, it is known that the integration processes is unstable with respect to this condition: it leads to errors amplifying exponentially with height. In order to overcome this difficulty various solutions have been proposed, the most recent ones using the variational analysis: (i) integrating from storm top level, (ii) integrating from storm top level while constraining the height integrated divergence to be as small as possible (Ziegier, 1978), and (iii) constraining the direct estimates of the 3D wind field to satisfy the continuity equation (Ray et al., 1980). The analysis proposed in this paper is also based upon a variational concept, but it differs in its principle from those previously cited. It consists in adjusting the boundary condition field at ground level in order to optimize the `mathematical regularity' of the vertical velocity field, followed by upward integration of the continuity equation. In such a formulation, the boundary condition at ground level is `floating' (i.e., not specified). However it is possible to require. as a subsidiary condition of the variational problem, that the vertical velocity at ground level fluctuate about zero with a specified variance 02 (thus the condition W0=0 at ground level is statistically verified). The optimum choice of 0 is established from considerations of statistical theory. It should be noted that the horizontal divergence (or coplane divergence) profile is unadjusted and that the equation of continuity is integrated upward from the optimum lower boundary condition to obtain W.An application to simulated or real data helps us to appreciate the improvements brought by the present variational approach with respect to standard methods of

  7. Ground-based observations of exoplanet atmospheres

    NARCIS (Netherlands)

    Mooij, Ernst Johan Walter de

    2011-01-01

    This thesis focuses on the properties of exoplanet atmospheres. The results for ground-based near-infrared secondary eclipse observations of three different exoplanets, TrES-3b, HAT-P-1b and WASP-33b, are presented which have been obtained with ground-based telescopes as part of the GROUSE project.

  8. Ground-based observations of exoplanet atmospheres

    NARCIS (Netherlands)

    Mooij, Ernst Johan Walter de

    2011-01-01

    This thesis focuses on the properties of exoplanet atmospheres. The results for ground-based near-infrared secondary eclipse observations of three different exoplanets, TrES-3b, HAT-P-1b and WASP-33b, are presented which have been obtained with ground-based telescopes as part of the GROUSE project.

  9. Analysis of the substorm trigger phase using multiple ground-based instrumentation

    Energy Technology Data Exchange (ETDEWEB)

    Kauristie, K.; Pulkkinen, T.I.; Pellinen, R.J. [Finnish Meteorological Institute, Helsinki (Finland)] [and others

    1995-08-01

    The authors discuss in detail the observation of an event of auroral activity fading during the trigger, or growth phase of a magnetic storm. This event was observed by all-sky cameras, EISCAT radar and magnetometers, riometers, and pulsation magnetometers, from ground based stations in Finland and Scandanavia. Based on their detailed analysis, they present a possible cause for the observed fading.

  10. ISAR imaging using the instantaneous range instantaneous Doppler method

    CSIR Research Space (South Africa)

    Wazna, TM

    2015-10-01

    Full Text Available In Inverse Synthetic Aperture Radar (ISAR) imaging, the Range Instantaneous Doppler (RID) method is used to compensate for the nonuniform rotational motion of the target that degrades the Doppler resolution of the ISAR image. The Instantaneous Range...

  11. Ka-band bistatic ground-based SAR using noise signals

    Science.gov (United States)

    Lukin, K.; Mogyla, A.; Vyplavin, P.; Palamarchuk, V.; Zemlyaniy, O.; Tarasenko, V.; Zaets, N.; Skretsanov, V.; Shubniy, A.; Glamazdin, V.; Natarov, M.; Nechayev, O.

    2008-01-01

    Currently, one of the actual problems is remote monitoring of technical state of large objects. Different methods can be used for that purpose. The most promising of them relies on application of ground based synthetic aperture radars (SAR) and differential interferometry. We have designed and tested Ground Based Noise Waveform SAR based on noise radar technology [1] and synthetic aperture antennas [2]. It enabled to build an instrument for precise all-weather monitoring of large objects in real-time. We describe main performance of ground-based interferometric SAR which uses continuous Ka-band noise waveform as a probe signal. Besides, results of laboratory trials and evaluation of its main performance are presented as well.

  12. 多江勒雷达/光纤捷联惯导组合导航同步方法研究%Research on Data Synchronization Method of Doppler Radar/FOG-SINS Integrated Navigation System

    Institute of Scientific and Technical Information of China (English)

    白宏阳; 薛晓中; 陈帅; 李松; 解宝同

    2011-01-01

    针对采用ARINC429总线通信的多普勒雷达/光纤捷联惯导直升机机载自主组合导航系统的时间同步问题,提出了一种有效的多普勒雷达同惯导间的软件同步方法;通过判断ARINC429总线上多普勒雷达信号的Label位标志,结合光纤捷联惯导的5ms中断时刻和嵌入式导航计算机提供的计时器,采用插值和外推的方法实现了多普勒雷达与光纡捷联惯导间信号的同步;最后对所设计的系统进行了长航时地面动态跑车试验,系统经同步后的的定位精度验证了所提方法的合理性和有效性.%Aiming at solving the time synchronization problem in Doppler Radar/Fiber Optical Gyroscope Strapdown Inertial Navigation System (FOG-SINS) integrated autonomous navigation system of helicopters where Doppler Radar sends data through ARINC429 data bus, an effective software algorithm of synchronization was designed. By judging the label-bit symbol of Doppler data sent through ARINC429 data bus, combined with the 5ms interrupt time of FOG-SINS as well as timer provided by DSP, the problem was solved using linear interpolation and extrapolation. Finally, aiming to validate the rationality, a long endurance van test was conducted , the excellent navigation result indicates the efficiency of the designed method.

  13. DEM extraction and its accuracy analysis with ground-based SAR interferometry

    Science.gov (United States)

    Dong, J.; Yue, J. P.; Li, L. H.

    2014-03-01

    Two altimetry models extracting DEM (Digital Elevation Model) with the GBSAR (Ground-Based Synthetic Aperture Radar) technology are studied and their accuracies are analyzed in detail. The approximate and improved altimetry models of GBSAR were derived from the spaceborne radar altimetry based on the principles of the GBSAR technology. The error caused by the parallel ray approximation in the approximate model was analyzed quantitatively, and the results show that the errors cannot be ignored for the ground-based radar system. For the improved altimetry model, the elevation error expression can be acquired by simulating and analyzing the error propagation coefficients of baseline length, wavelength, differential phase and range distance in the mathematical model. By analyzing the elevation error with the baseline and range distance, the results show that the improved altimetry model is suitable for high-precision DEM and the accuracy can be improved by adjusting baseline and shortening slant distance.

  14. 77 FR 53962 - Technical Standard Order (TSO)-C65a, Airborne Doppler Radar Ground Speed and/or Drift Angle...

    Science.gov (United States)

    2012-09-04

    ... production of articles with an existing TSO authorization (TSOA). Articles produced under an existing TSOA... aids. The system employed radar signals to detect and measure ground speed and drift angle, using...

  15. Initial Results from the DEEPWAVE Airborne and Ground-Based Measurement Program in New Zealand in 2014

    Science.gov (United States)

    Fritts, Dave; Smith, Ron; Taylor, Mike; Doyle, Jim; Eckermann, Steve; Dörnbrack, Andreas; Rapp, Markus; Williams, Biff; Bossert, Katrina; Pautet, Dominique

    2015-04-01

    The deep-propagating gravity wave experiment (DEEPWAVE) was performed on and over New Zealand, Tasmania, the Tasman Sea, and the Southern Ocean with core airborne measurements extending from 5 June to 21 July 2014 and supporting ground-based measurements beginning in late May and extending beyond the airborne component. DEEPWAVE employed two aircraft, the NSF/NCAR GV and the German DLR Falcon. The GV carried the standard flight-level instruments, dropsondes, and the Microwave Temperature Profiler (MTP). It also hosted new airborne lidar and imaging instruments built specifically to allow quantification of gravity waves (GWs) from sources at lower altitudes (e.g., orography, convection, jet streams, fronts, and secondary GW generation) throughout the stratosphere and into the mesosphere and lower thermosphere (MLT). The new GV lidars included a Rayleigh lidar measuring atmospheric density and temperature from ~20-60 km and a sodium resonance lidar measuring sodium density and temperature at ~75-100 km. An airborne Advanced Mesosphere Temperature Mapper (AMTM) was also developed for the GV, and together with additional IR "wing" cameras, imaged the OH airglow temperature and/or intensity fields extending ~900 km across the GV flight track. The DLR Falcon was equipped with its standard flight-level instruments and an aerosol Doppler lidar able to measure radial winds below the Falcon where aerosol backscatter was sufficient. Additional ground-based instruments included a 449 MHz boundary layer radar, balloons at multiple sites, two ground-based Rayleigh lidars, a second ground-based AMTM, a Fabry Perot interferometer measuring winds and temperatures at ~87 and 95 km, and a meteor radar measuring winds from ~80-100 km. DEEPWAVE performed 26 GV flights, 13 Falcon flights, and an extensive series of ground-based measurements whether or not the aircraft were flying. Together, these observed many diverse cases of GW forcing, propagation, refraction, and dissipation

  16. 多普勒天气雷达径向干扰回波的识别与消除%Identification and removal of radial interference echo of Doppler weather radar

    Institute of Scientific and Technical Information of China (English)

    郭春辉; 王旭; 袁微

    2014-01-01

    多普勒天气雷达在探测气象目标物同时,除了目标物的回波外,一些非目标物的同频电磁波有时也会被散射进入雷达接收系统形成杂波,被称为径向干扰回波。径向干扰回波是污染雷达回波资料的重要因素之一,严重影响雷达资料的定量应用。文章介绍了如何对径向干扰回波进行识别,并给出3种订正方法,即插值法、中值滤波法和多功能插值法,并对这3种方法进行了对比,分析了各种订正方法的优点和局限。实例分析表明通过以上对基数据的处理方法能够对径向干扰回波进行有效的识别和订正,从而获取更准确的雷达基产品及后期导出的二次雷达产品。%Meteorological targets can be detected by Doppler weather radar.Expect sounding the echo of meteorological targets,some electromagnetic wave of non-meteorological goals which has the same frequency with the radar also can be scattered into the radar receive system and forms clutter,which is called the radial interference echo.It is one of the important factors that pollutes radar echo data and has a great effect on the quantitative application of radar data.This paper introduces how to identify the radial interference echo.And three amendment methods including interpolation,median filter and multi-function interpolation are described.Meanwhile,the three methods are compared with each other and their advantages and limitations are analyzed.The results demonstrate that the above methods for base data processing can identify and eliminate the radial interference echo efficiently,which help to improve the quality of base products and post-secondary radar exported products.

  17. Ground-based optical observation system for LEO objects

    Science.gov (United States)

    Yanagisawa, T.; Kurosaki, H.; Oda, H.; Tagawa, M.

    2015-08-01

    We propose a ground-based optical observation system for monitoring LEO objects, which uses numerous optical sensors to cover a vast region of the sky. Its potential in terms of detection and orbital determination were examined. About 30 cm LEO objects at 1000 km altitude are detectable using an 18 cm telescope, a CCD camera and the analysis software developed. Simulations and a test observation showed that two longitudinally separate observation sites with arrays of optical sensors can identify the same objects from numerous data sets and determine their orbits precisely. The proposed system may complement or replace the current radar observation system for monitoring LEO objects, like space-situation awareness, in the near future.

  18. Noise Radar Technology Basics

    Science.gov (United States)

    2006-12-01

    poursuite, estimation Doppler, polarimétrie, interférométrie, sondage du sol ou profilage de la sous- surface , détection, imagerie SAR (radar à synthèse...mesure de distance et d’estimation Doppler. Deux récepteurs de traitement cohérent, soit le récepteur de corrélation et le récep- teur de traitement DSP... traitement spectral double) des échos radar sont décrits et une estimation de leur portée est présentée. Les capacités LPI (faible probabilité

  19. Mean winds observed with Indian MST radar over tropical mesosphere and comparison with various techniques

    Energy Technology Data Exchange (ETDEWEB)

    Venkat Ratnam, M.; Narayana Rao, D.; Narayana Rao, T. [Sri Venkateswara Univ., Tirupati (India). Dept. of Physics; Thulasiraman, S.; Nee, J.B. [National Central Univ., Chung Li (Taiwan); Gurubaran, S.; Rajaram, R. [Equatorial Geophysical Research Lab., Indian Inst. of Geomagnetism, Tirunelveli (India)

    2001-08-01

    Temporal variation of mean winds between the 65 to 85 km height region from the data collected over the course of approximately four years (1995-99), using the Indian MST radar located at Gadanki (13.5 N, 79.2 E), India is presented in this paper. Mesospheric mean winds and their seasonal variation in the horizontal and vertical components are presented in detail. Westward flows during each of the equinoxes and eastward flows during the solstices are observed in the zonal component. The features of the semi-annual oscillation (SAO) and the quasi-biennial oscillation (QBO) in the zonal component are noted. In the meridional component, contours reveal a northward motion during the winter and a southward motion during the summer. Large inter-annual variability is found in the vertical component with magnitudes of the order of {+-}2 ms{sup -1}. The MST observed winds are also compared with the winds observed by the MF radar located at Tirunelveli (8.7 N, 77.8 E), India, the high resolution Doppler imager (HRDI) onboard the upper atmospheric research satellite (UARS), and with the CIRA-86 model. A very good agreement is found between both the ground-based instruments (MST radar and MF radar) in the zonal component and there are few discrepancies in the meridional component. UARS/HRDI observed winds usually have larger magnitudes than the ground-based mean winds. Comparison of the MST derived winds with the CIRA-86 model in the zonal component shows that during the spring equinox and the summer, the winds agree fairly well, but there are a lot of discrepancies in the other seasons and the observed winds with the MST radar are less in magnitude, though the direction is same. The strengths and limitations in estimating reliable mesospheric mean winds using the MST radar are also discussed. (orig.)

  20. Radar Interferometric Imaging of Near-Earth Asteroids

    Science.gov (United States)

    Margot, J. L.; Nolan, M. C.

    1999-09-01

    High resolution imagery and a three-dimensional characterization of Near-Earth Asteroids (NEAs) can be obtained with ground-based radars. The Arecibo and Goldstone radar systems yield data at spatial resolutions comparable to the highest resolution spacecraft images of asteroids obtained to date. The use of radar interferometry techniques can further improve imaging and shape reconstruction algorithms [1],[2] and may allow direct measurements of the topography of NEAs. A two-element radar interferometer of appropriate baseline provides an observable, the interferometric phase, which can be used to extract three-dimensional information about the target [3], hence giving additional control in shape modeling procedures. The measurement of interferometric phase also opens the possibility of mapping the topography of an asteroid, in a manner similar to that applied recently to the Moon [4]. Simulations show that this is feasible when potential ambiguities in range-Doppler imaging are avoided, for instance when elongated objects are in a favorable orientation. Radar interferometric imaging of 6489 Golevka was attempted during its June 1999 close approach to Earth [5]. The Arecibo 305 m telescope was used to transmit, and the DSN 70 m antenna in Madrid formed the second element of the interferometer. The Arecibo-Madrid baseline defined an ideal fringe pattern for interferometric mapping, but technical difficulties prevented imaging of the Madrid data. Radar interferometry concepts and simulation results will be presented, as well as any new data acquired before the meeting. [1] R. S. Hudson and S. J. Ostro (1994). Science, 263, 940. [2] R. S. Hudson and S. J. Ostro (1995). Science, 270, 84. [3] I. I. Shapiro et al. (1972). Science, 178, 939. [4] J. L. Margot et al. (1999). Science, 284, 1658. [5] J. L. Margot and M. C. Nolan (1999). ACM Meeting, July 26-30, Cornell University, Ithaca, NY.

  1. Fresnel zones for ground-based antennas

    DEFF Research Database (Denmark)

    Andersen, J. Bach

    1964-01-01

    The ordinary Fresnel zone concept is modified to include the influence of finite ground conductivity. This is important for ground-based antennas because the influence on the radiation pattern of irregularities near the antenna is determined by the amplitude and phase of the groundwave. A new...

  2. Calibration of Ground-based Lidar instrument

    DEFF Research Database (Denmark)

    Villanueva, Héctor; Gómez Arranz, Paula

    This report presents the result of the lidar calibration performed for the given Ground-based Lidar at DTU’s test site for large wind turbines at Høvsøre, Denmark. Calibration is here understood as the establishment of a relation between the reference wind speed measurements with measurement unce...

  3. Calibration of Ground -based Lidar instrument

    DEFF Research Database (Denmark)

    Villanueva, Héctor; Yordanova, Ginka

    This report presents the result of the lidar calibration performed for the given Ground-based Lidar at DTU’s test site for large wind turbines at Høvsøre, Denmark. Calibration is here understood as the establishment of a relation between the reference wind speed measurements with measurement unce...

  4. Measuring human behaviour with radar

    NARCIS (Netherlands)

    Dorp, Ph. van

    2001-01-01

    The paper presents human motion measurements with the experimental Frequency Modulated Continuous Wave(FMCW) radar at TNO-FEL. The aim of these measurements is to analyse the Doppler velocity spectrum of humans. These analysis give insight in measuring human behaviour with radar for security applica

  5. Millimeter-wave micro-Doppler measurements of small UAVs

    Science.gov (United States)

    Rahman, Samiur; Robertson, Duncan A.

    2017-05-01

    This paper discusses the micro-Doppler signatures of small UAVs obtained from a millimeter-wave radar system. At first, simulation results are shown to demonstrate the theoretical concept. It is illustrated that whilst the propeller rotation rate of the small UAVs is quite high, millimeter-wave radar systems are capable of capturing the full micro-Doppler spread. Measurements of small UAVs have been performed with both CW and FMCW radars operating at 94 GHz. The CW radar was used for obtaining micro-Doppler signatures of individual propellers. The field test data of a flying small UAV was collected with the FMCW radar and was processed to extract micro-Doppler signatures. The high fidelity results clearly reveal features such as blade flashes and propeller rotation modulation lines which can be used to classify targets. This work confirms that millimeter-wave radar is suitable for the detection and classification of small UAVs at usefully long ranges.

  6. Validation of multiple-Doppler analysis of convective clouds using the ARM multi-frequency radar network during MC3E

    Science.gov (United States)

    North, K. W.; Collis, S. M.; Giangrande, S. E.; Kollias, P.

    2012-12-01

    Convective processes play an important role in Earth's energy balance by redistributing heat and moisture throughout the atmosphere. Vertical air motions associated with these processes are inherently linked to the life cycle of these convective systems and are therefore directly tied to their energetic impacts. Despite this importance, the spatial and temporal scales of these vertical air motions are poorly understood and not accurately represented in convective parameterization schemes found in numerical weather prediction models. A radar data assimilation tool based on a 3-dimensional variational technique has been developed to study these vertical air motions within convective clouds. However, in order to trust the output of this tool, its sensitivities and accuracies need to be properly characterized. Scanning precipitation radars located at the ARM Southern Great Plains (SGP) site are used in the assimilation process to retrieve vertical air motions for selected convective cases during the recent Midlatitude Continental Convective Clouds Experiment (MC3E). Using a statistical approach, the veracity of these retrievals is evaluated by comparing them with observations from the UHF ARM Zenith-pointing Radar (UAZR) network located at SGP.

  7. Ka-Band ARM Zenith Radar (KAZR) Instrument Handbook

    Energy Technology Data Exchange (ETDEWEB)

    Widener, K; Bharadwaj, N; Johnson, K

    2012-03-06

    The Ka-band ARM zenith radar (KAZR) is a zenith-pointing Doppler cloud radar operating at approximately 35 GHz. The KAZR is an evolutionary follow-on radar to ARM's widely successful millimeter-wavelength cloud radar (MMCR). The main purpose of the KAZR is to provide vertical profiles of clouds by measuring the first three Doppler moments: reflectivity, radial Doppler velocity, and spectra width. At the sites where the dual-polarization measurements are made, the Doppler moments for the cross-polarization channel are also available. In addition to the moments, velocity spectra are also continuously recorded for each range gate.

  8. Space and Ground-Based Infrastructures

    Science.gov (United States)

    Weems, Jon; Zell, Martin

    This chapter deals first with the main characteristics of the space environment, outside and inside a spacecraft. Then the space and space-related (ground-based) infrastructures are described. The most important infrastructure is the International Space Station, which holds many European facilities (for instance the European Columbus Laboratory). Some of them, such as the Columbus External Payload Facility, are located outside the ISS to benefit from external space conditions. There is only one other example of orbital platforms, the Russian Foton/Bion Recoverable Orbital Capsule. In contrast, non-orbital weightless research platforms, although limited in experimental time, are more numerous: sounding rockets, parabolic flight aircraft, drop towers and high-altitude balloons. In addition to these facilities, there are a number of ground-based facilities and space simulators, for both life sciences (for instance: bed rest, clinostats) and physical sciences (for instance: magnetic compensation of gravity). Hypergravity can also be provided by human and non-human centrifuges.

  9. Development of Ground-Based Plant Sentinels

    Science.gov (United States)

    2007-11-02

    plants in response to different strains of Pseudomonas syringae. Planta . 217:767-775. De Moraes CM, Schultz JC, Mescher MC, Tumlinson JH. (2004...09-30-2004 Final Technical _ April 2001 - April 2003 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Developing Plants as Ground-based Sentinels 5b. GRANT...SUPPLEMENTARY NOTES 14. ABSTRACT 9 "Z Plants emit volatile mixes characteristic of exposure to both plant and animal (insect) pathogens (bacteria and fungi). The

  10. Illumination compensation in ground based hyperspectral imaging

    Science.gov (United States)

    Wendel, Alexander; Underwood, James

    2017-07-01

    Hyperspectral imaging has emerged as an important tool for analysing vegetation data in agricultural applications. Recently, low altitude and ground based hyperspectral imaging solutions have come to the fore, providing very high resolution data for mapping and studying large areas of crops in detail. However, these platforms introduce a unique set of challenges that need to be overcome to ensure consistent, accurate and timely acquisition of data. One particular problem is dealing with changes in environmental illumination while operating with natural light under cloud cover, which can have considerable effects on spectral shape. In the past this has been commonly achieved by imaging known reference targets at the time of data acquisition, direct measurement of irradiance, or atmospheric modelling. While capturing a reference panel continuously or very frequently allows accurate compensation for illumination changes, this is often not practical with ground based platforms, and impossible in aerial applications. This paper examines the use of an autonomous unmanned ground vehicle (UGV) to gather high resolution hyperspectral imaging data of crops under natural illumination. A process of illumination compensation is performed to extract the inherent reflectance properties of the crops, despite variable illumination. This work adapts a previously developed subspace model approach to reflectance and illumination recovery. Though tested on a ground vehicle in this paper, it is applicable to low altitude unmanned aerial hyperspectral imagery also. The method uses occasional observations of reference panel training data from within the same or other datasets, which enables a practical field protocol that minimises in-field manual labour. This paper tests the new approach, comparing it against traditional methods. Several illumination compensation protocols for high volume ground based data collection are presented based on the results. The findings in this paper are

  11. Climatology of clouds and precipitation over East Antarctica using ground-based remote sensing at the Princess Elizabeth station

    Science.gov (United States)

    Souverijns, Niels; Gossart, Alexandra; Gorodetskaya, Irina; Lhermitte, Stef; Van Tricht, Kristof; Mangold, Alexander; Laffineur, Quentin; Van Lipzig, Nicole

    2016-04-01

    The surface mass balance of the Antarctic ice sheet is highly dependent on the interaction between clouds and precipitation. Our understanding of these processes is challenged by the limited availability of observations over the area and problems in Antarctic climate simulations by state-of-the-art climate models. Improvements are needed in this field, as the Antarctic ice sheet is expected to become a dominant contributor to sea level rise in the 21st century. In 2010, an observational site was established at the Princess Elisabeth (PE) Antarctic station. PE is located in the escarpment area of Dronning Maud Land, East Antarctica (72°S, 23°E). The instruments consist of several ground-based remote sensing instruments: a ceilometer (measuring cloud-base height and vertical structure), a 24-GHz Micro Rain Radar (MRR; providing vertical profiles of radar effective reflectivity and Doppler velocity), and a pyrometer (measuring effective cloud base temperature). An automatic weather station provides info on boundary-layer meteorology (temperature, wind speed and direction, humidity, pressure), as well as broadband radiative fluxes and snow height changes. This set of instruments can be used to infer the role of clouds in the Antarctic climate system, their interaction with radiation and their impact on precipitation. Cloud and precipitation characteristics are derived from 5-year-long measurement series, which is unprecedented for the Antarctic region. Here, we present an overview of the cloud and precipitation climatology. Statistics on cloud occurrence are calculated on annual / seasonal basis and a distinction between liquid / mixed phase and ice clouds is made. One can discriminate between liquid-bearing and ice-only clouds by investigating the ceilometer attenuated backscatter, since liquid phase clouds have a much higher signal. Furthermore, by using pyrometer measurements, we are able to identify the range of temperatures at which liquid / ice clouds are

  12. Ground based spectroscopy of hot Jupiters

    Science.gov (United States)

    Waldmann, Ingo

    2010-05-01

    It has been shown in recent years with great success that spectroscopy of exoplanetary atmospheres is feasible using space based observatories such as the HST and Spitzer. However, with the end of the Spitzer cold-phase, space based observations in the near to mid infra-red are limited, which will remain true until the the onset of the JWST. The importance of developing methods of ground based spectroscopic analysis of known hot Jupiters is therefore apparent. In the past, various groups have attempted exoplanetary spectroscopy using ground based facilities and various techniques. Here I will present results using a novel spectral retrieval method for near to mid infra-red emission and transmission spectra of exoplanetary atmospheres taken from the ground and discuss the feasibility of future ground-based spectroscopy in a broader context. My recently commenced PhD project is under the supervision of Giovanna Tinetti (University College London) and in collaboration with J. P. Beaulieu (Institut d'Astrophysique de Paris), Mark Swain and Pieter Deroo (Jet Propulsion Laboratory, Caltech).

  13. Analysis of Characteristic Indexes for Hail Cloud Identification in Chongqing by Means of Doppler Radar Products%利用多普勒雷达产品识别重庆冰雹云指标分析

    Institute of Scientific and Technical Information of China (English)

    廖向花; 林娜; 李轲; 王中

    2011-01-01

    利用重庆、万州、恩施三部多普勒天气雷达产品,分析了重庆2008-2010年的9次冰雹过程,总结了一些冰雹天气的多普勒雷达回波特征指标.发现当回波强度大于等于50dBZ,回波顶高大于等于11km,垂直累积液态含水量大于等于44kg/m2,冰雹指数出现连续几个实心三角标志,中层具有强的风速辐合或者中气旋时容易降雹;出现三体散射回波等冰雹典型特征时肯定降雹.垂直累积液态含水量越大,大于60kg/m2的强VIL持续时间越长,冰雹直径越大.在冰雹云发展阶段VIL存在≥15kg/m2的明显跃增且跃增后VIL≥50kg/m2,这是冰雹独特的特征,对判别冰雹云有较高应用价值.%The products of three Doppler radars located at Chongqing,Wanzhou and Enshi are used to analyze 8 hail processes between 2008 and 2010 in Chongqing.Some characteristic indexes of Doppler radar echoes for hail weather are summed up.The results show that hailfall is likely to occur when the echo intensity is above 50 dBZ,the echo top is greater than 11 km,the vertically integral liquid water(VIL) is above 44 kg/m2,some hail index solid triangles appear in a row,and the middle layer has a strong wind convergence or meso-cyclone.Some certain typical characteristics such as three-body scattering echo mean that hailfall is inevitable.The diameter of a hail increases with the vertically integrated liquid water content and the duration of the strong VIL(greater than 60 kg/m2).In the development of a hail,an abrupt jump of ≧15kg/m2 in VIL occurs,and the VIL after the jump is 50 kg/m2,which is a unique feature for hailfall,valuable for hail cloud identification.

  14. TIMED Doppler Interferometer: Overview and recent results

    Science.gov (United States)

    Killeen, T. L.; Wu, Q.; Solomon, S. C.; Ortland, D. A.; Skinner, W. R.; Niciejewski, R. J.; Gell, D. A.

    2006-10-01

    adjusted to mitigate their effects on data quality. The analysis techniques used to derive winds are described. The TIDI wind measurements from multiple yaw cycles of TIMED have been used to extract migrating diurnal and semidiurnal tides. The migrating tide results are compared with predictions from the Global Scale Wave Model (GSWM), and results from the Upper Atmospheric Research Satellite, High Resolution Doppler Imager (HRDI) instrument. TIDI wind measurements are also compared with ground-based meteor radar observations, showing consistent results.

  15. Calibration of Ground-based Lidar instrument

    DEFF Research Database (Denmark)

    Yordanova, Ginka; Gómez Arranz, Paula

    This report presents the result of the lidar calibration performed for the given Ground-based Lidar at DTU’s test site for large wind turbines at Høvsøre, Denmark. Calibration is here understood as the establishment of a relation between the reference wind speed measurements with measurement...... uncertainties provided by measurement standard and corresponding lidar wind speed indications with associated measurement uncertainties. The lidar calibration concerns the 10 minute mean wind speed measurements. The comparison of the lidar measurements of the wind direction with that from wind vanes...

  16. Calibration of Ground-based Lidar instrument

    DEFF Research Database (Denmark)

    Yordanova, Ginka; Gómez Arranz, Paula

    This report presents the result of a test of a ground-based lidar of other type. The test was performed at DTU’s test site for large wind turbines at Høvsøre, Denmark. The result as an establishment of a relation between the reference wind speed measurements with measurement uncertainties provided...... by measurement standard and corresponding lidar wind speed indications with associated measurement uncertainties. The comparison of the lidar measurements of the wind direction with that from the wind vanes is also given....

  17. Calibration of Ground -based Lidar instrument

    DEFF Research Database (Denmark)

    Villanueva, Héctor; Yordanova, Ginka

    This report presents the result of the lidar calibration performed for the given Ground-based Lidar at DTU’s test site for large wind turbines at Høvsøre, Denmark. Calibration is here understood as the establishment of a relation between the reference wind speed measurements with measurement...... uncertainties provided by measurement standard and corresponding lidar wind speed indications with associated measurement uncertainties. The lidar calibration concerns the 10 minute mean wind speed measurements. The comparison of the lidar measurements of the wind direction with that from wind vanes...

  18. Calibration of Ground-based Lidar instrument

    DEFF Research Database (Denmark)

    Yordanova, Ginka; Gómez Arranz, Paula

    This report presents the result of the lidar calibration performed for the given Ground-based Lidar at DTU’s test site for large wind turbines at Høvsøre, Denmark. Calibration is here understood as the establishment of a relation between the reference wind speed measurements with measurement...... uncertainties provided by measurement standard and corresponding lidar wind speed indications with associated measurement uncertainties. The lidar calibration concerns the 10 minute mean wind speed measurements. The comparison of the lidar measurements of the wind direction with that from wind vanes...

  19. Calibration of Ground -based Lidar instrument

    DEFF Research Database (Denmark)

    Villanueva, Héctor; Georgieva Yankova, Ginka

    This report presents the result of the lidar calibration performed for the given Ground-based Lidar at DTU’s test site for large wind turbines at Høvsøre, Denmark. Calibration is here understood as the establishment of a relation between the reference wind speed measurements with measurement...... uncertainties provided by measurement standard and corresponding lidar wind speed indications with associated measurement uncertainties. The lidar calibration concerns the 10 minute mean wind speed measurements. The comparison of the lidar measurements of the wind direction with that from wind vanes...

  20. Measurements of radar ground returns

    NARCIS (Netherlands)

    Loor, G.P. de

    1974-01-01

    The ground based measurement techniques for the determination of the radar back-scatter of vegetation and soils as used in The Netherlands will be described. Two techniques are employed: one covering a large sample area (> 1000 m2) but working at low grazing angels only and one (short range) coverin

  1. Lightning-produced NO2 observed by two ground-based UV-visible spectrometers at Vanscoy, Saskatchewan in August 2004

    Directory of Open Access Journals (Sweden)

    A. Fraser

    2007-01-01

    Full Text Available Ground-based measurements of ozone and NO2 differential slant columns by the SAOZ (Système d'Analyse par Observations Zénithales and UT-GBS (University of Toronto Ground-Based Spectrometer instruments during the MANTRA 2004 field campaign are presented herein. During the afternoon of 28 August, a thunderstorm passed over the instruments, which were installed at Vanscoy, Saskatchewan (52° N, 107° W. Enhanced differential slant columns of ozone and NO2 were observed by both instruments during the storm, with maximum values of two and 25 times the expected clear sky columns, respectively. The enhanced ozone differential slant columns are primarily due to the longer path traversed by the solar radiation caused by multiple scattering inside the thick cloud layer associated with the thunderstorm. The enhanced NO2 columns are partly attributed to NOx production by lightning. Two new methods are used to separate the NO2 enhancements into contributions from the longer path length and production by lightning. Combining the observed excess NO2 with lightning flash data from the Canadian Lightning Detection Network and Environment Canada Doppler radar measurements, the production of NO2 molecules per lightning flash is determined. Using these two methods, the best estimate of the production rate is found to be (7.88±2.52×1026 molecules NO2/flash from the UT-GBS and (6.81±2.17×1026 molecules NO2/flash from SAOZ. These results are consistent with the range of previous estimates reported in the literature.

  2. The Cloud Radar System

    Science.gov (United States)

    Racette, Paul; Heymsfield, Gerald; Li, Lihua; Tian, Lin; Zenker, Ed

    2003-01-01

    Improvement in our understanding of the radiative impact of clouds on the climate system requires a comprehensive view of clouds including their physical dimensions, dynamical generation processes, and detailed microphysical properties. To this end, millimeter vave radar is a powerful tool by which clouds can be remotely sensed. The NASA Goddard Space Flight Center has developed the Cloud Radar System (CRS). CRS is a highly sensitive 94 GHz (W-band) pulsed-Doppler polarimetric radar that is designed to fly on board the NASA high-altitude ER-2 aircraft. The instrument is currently the only millimeter wave radar capable of cloud and precipitation measurements from above most all clouds. Because it operates from high-altitude, the CRS provides a unique measurement perspective for cirrus cloud studies. The CRS emulates a satellite view of clouds and precipitation systems thus providing valuable measurements for the implementation and algorithm validation for the upcoming NASA CloudSat mission that is designed to measure ice cloud distributions on the global scale using a spaceborne 94 GHz radar. This paper describes the CRS instrument and preliminary data from the recent Cirrus Regional Study of Tropical Anvils and Cirrus Layers - Florida Area Cirrus Experiment (CRYSTAL-FACE). The radar design is discussed. Characteristics of the radar are given. A block diagram illustrating functional components of the radar is shown. The performance of the CRS during the CRYSTAL-FACE campaign is discussed.

  3. Multi-beam raindrop size distributions retrievals on the Doppler spectra: Influence of averaging and mean horizontal wind correction

    NARCIS (Netherlands)

    Unal, C.M.H.

    2012-01-01

    Acquiring the raindrop size distribution (DSD) from radar data is still a challenge. For profiling radar, this distribution can be estimated from the Doppler spectra. However the Doppler spectrum is not a direct measure of the DSD. The radial component of the wind shifts the Doppler spectrum related

  4. Focus-before-detection Methods for Radar Detection of Near Space High-maneuvering Aircrafts

    Directory of Open Access Journals (Sweden)

    Xu Jia

    2017-06-01

    Full Text Available Recently emerging, high maneuvering near space targets have many characteristics that differ from conventional targets, like ultra-high speed, high-maneuverability, ultra-far range, low Radar Cross Section (RCS, plasma sheath, ionosphere layer pollution, and cosmic ray interference. Based on general signal modeling for near space targets of ground-based, airborne, and spaceborne radars, this paper proposes novel focus-before-detection methods with respect to a distributed radar network, multi-dimensions, multiple targets, micro motion, varied model, and non-parametric processing. The proposed FBD based methods can effectively suppress the strong ionosphere layer pollution and active jamming, as well as problems like the scaled effect of echoes, arbitrary motion, aperture fill time, sparse sub-band frequency synthesis, across range cell, across Doppler cell, and across beam width. The proposed Focus-Before-Detection (FBD based methods can remarkably improve the signal processing performance on target detection, parameter estimation, maneuver tracking, high-resolution imaging, feature extraction, and target recognition. Additionally, they are suitable for both high maneuvering near space targets and conventional targets, and can be applied for both new-generation radars and conventional targets. Therefore, the proposed FBD based methods for high maneuvering near space target detection have both important academic research value and impact a wide variety of applications.

  5. Super-cooled liquid water topped sub-arctic clouds and precipitation - investigation based on combination of ground-based in-situ and remote-sensing observations

    Science.gov (United States)

    Hirsikko, Anne; Brus, David; O'Connor, Ewan J.; Filioglou, Maria; Komppula, Mika; Romakkaniemi, Sami

    2017-04-01

    In the high and mid latitudes super-cooled liquid water layers are frequently observed on top of clouds. These layers are difficult to forecast with numerical weather prediction models, even though, they have strong influence on atmospheric radiative properties, cloud microphysical properties, and subsequently, precipitation. This work investigates properties of super-cooled liquid water layer topped sub-arctic clouds and precipitation observed with ground-based in-situ (cloud probes) and remote-sensing (a cloud radar, Doppler and multi-wavelength lidars) instrumentation during two-month long Pallas Cloud Experiment (PaCE 2015) in autumn 2015. Analysis is based on standard Cloudnet scheme supplemented with new retrieval products of the specific clouds and their properties. Combination of two scales of observation provides new information on properties of clouds and precipitation in the sub-arctic Pallas region. Current status of results will be presented during the conference. The authors acknowledge financial support by the Academy of Finland (Centre of Excellence Programme, grant no 272041; and ICINA project, grant no 285068), the ACTRIS2 - European Union's Horizon 2020 research and innovation programme under grant agreement No 654109, the KONE foundation, and the EU FP7 project BACCHUS (grant no 603445).

  6. Laser doppler and radar interferometer for contactless measurements on unaccessible tie-rods on monumental buildings: Santa Maria della Consolazione Temple in Todi

    Science.gov (United States)

    Gioffré, M.; Cavalagli, N.; Pepi, C.; Trequattrini, M.

    2017-01-01

    Non-contact measurements can be effectively used in civil engineering to assess the variation of structural performance with time. In the last decades this approach has received considerable interests from researchers working in the field of structural health monitoring (SHM). Indeed, non-contact measurements are very attractive because it is possible to perform non intrusive and non destructive investigations even being at a significant distance from the targets. Within this context, contactless measurements of the tie-rod vibrations in the Santa Maria della Consolazione Temple in Todi (Italy) are presented in this paper. In particular, laser vibrometer and radar interferometer measurements are used to estimate natural frequencies and mode shapes. This information is crucial to obtain the tensile axial force in the tie-rods, which can be used as an indicator of structural integrity or possible failure. Furthermore, a novel approach is proposed where drones (Unmanned Aerial Vehicles) can be successfully used to improve the effectiveness and the accuracy of the experimental activities.

  7. Navigator alignment using radar scan

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin W.; Marquette, Brandeis

    2016-04-05

    The various technologies presented herein relate to the determination of and correction of heading error of platform. Knowledge of at least one of a maximum Doppler frequency or a minimum Doppler bandwidth pertaining to a plurality of radar echoes can be utilized to facilitate correction of the heading error. Heading error can occur as a result of component drift. In an ideal situation, a boresight direction of an antenna or the front of an aircraft will have associated therewith at least one of a maximum Doppler frequency or a minimum Doppler bandwidth. As the boresight direction of the antenna strays from a direction of travel at least one of the maximum Doppler frequency or a minimum Doppler bandwidth will shift away, either left or right, from the ideal situation.

  8. ESTIMATION OF DOPPLER CENTROID FREQUENCY IN SPACEBORNE SCANSAR

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Doppler centroid frequency is an essential parameter in the imaging processing of the Scanning mode Synthetic Aperture Radar(ScanSAR).Inaccurate Doppler centroid frequency will result in ghost images in imaging result.In this letter,the principle and algorithms of Doppler centroid frequency estimation are introduced.Then the echo data of ScanSAR system is analyzed.Based on the algorithms of energy balancing and correlation Doppler estimator in the estimation of Doppler centroid fequency in strip mode SAR,an improved method for Doppler centroid frequency estimation in ScanSAR is proposed.The method has improved the accuracy of Doppler centroid fequency estimation in ScanSAR by zero padding between burst data.Finally,the proposed method is validated with the processing of ENVironment SATellite Advanced Synthetic Aperture Radar(ENVISAT ASAR)wide swath raw data.

  9. Large phased-array radars

    Science.gov (United States)

    Brookner, Eli, Dr.

    1988-12-01

    Large phased-array radars can play a very important part in arms control. They can be used to determine the number of RVs being deployed, the type of targeting of the RVs (the same or different targets), the shape of the deployed objects, and possibly the weight and yields of the deployed RVs. They can provide this information at night as well as during the day and during rain and cloud covered conditions. The radar can be on the ground, on a ship, in an airplane, or space-borne. Airborne and space-borne radars can provide high resolution map images of the ground for reconnaissance, of anti-ballistic missile (ABM) ground radar installations, missile launch sites, and tactical targets such as trucks and tanks. The large ground based radars can have microwave carrier frequencies or be at HF (high frequency). For a ground-based HF radar the signal is reflected off the ionosphere so as to provide over-the-horizon (OTH) viewing of targets. OTH radars can potentially be used to monitor stealth targets and missile traffic.

  10. Lunar topography - Global determination by radar.

    Science.gov (United States)

    Shapiro, I. I.; Zisk, S. H.; Rogers, A. E. E.; Slade, M. A.; Thompson, T. W.

    1972-01-01

    Previous methods used for two-dimensional radar mapping of the moon are contrasted with new techniques that add altitude information to the radar map. Delay-Doppler stereoscopy and delay-Doppler interferometry are shown to provide surface-height variations with higher accuracy and better global fidelity than has been possible previously. Sample results are presented for altitude contours on the moon as obtained with the Haystack and Westford radar systems of the Massachusetts Institute of Technology. An appendix describes the mathematical principles of delay-Doppler interferometry in determining the position of an arbitrary reflecting region of the lunar surface from measurements of the time delay, Doppler shift, and fringe phase of radar echoes from that region.

  11. Ground Based Retrievals of Small Ice Crystals and Water Phase in Arctic Cirrus

    Science.gov (United States)

    Mishra, Subhashree; Mitchell, David L.; DeSlover, Daniel

    2009-03-01

    The microphysical properties of cirrus clouds are uncertain due to the problem of ice particles shattering at the probe inlet upon sampling. To facilitate better estimation of small ice crystal concentrations in cirrus clouds, a new ground-based remote sensing technique has been used in combination with in situ aircraft measurements. Data from the Mixed-Phase Arctic Cloud Experiment (M-PACE), conducted at the north slope of Alaska (winter 2004), have been used to test a new method for retrieving the liquid water path (LWP) and ice water path (IWP) in mixed phase clouds. The framework of the retrieval algorithm consists of the modified anomalous diffraction approximation or MADA (for mixed phase cloud optical properties), a radar reflectivity-ice microphysics relationship and a temperature-dependent ice particle size distribution (PSD) scheme. Cloud thermal emission measurements made by the ground-based Atmospheric Emitted Radiance Interferometer (AERI) yield information on the total water path (TWP) while reflectivity measurements from the Millimeter Cloud Radar (MMCR) are used to derive the IWP. The AERI is also used to indicate the concentration of small ice crystals (DBeer's law absorption. While this is still a work in progress, the anticipated products from this AERI-radar retrieval scheme are the IWP, LWP, small-to-large ice crystal number concentration ratio and effective diameter for cirrus, as well as the ice particle number concentration for a given ice water content (IWC).

  12. Proceedings of the COST 75 final seminar on advanced weather radar systems; Beitraege des Instituts zum COST 75 final seminar on advanced weather radar systems

    Energy Technology Data Exchange (ETDEWEB)

    Baumann, R.; Flender, F.; Hagen, M.; Hoeller, H.; Keil, C.; Meischner, P.

    1998-07-01

    Across Europe more than 110 weather radars are in operation. More than 60 of them are Doppler radars and this number is increasing steadily. Doppler systems are becoming an operational standard. Most systems operate in C-band, with the exception of the Spanish radar network which is composed of S-band Doppler radars. Radar product composites are available for Scandinavia and Central Europe. National networks exist for the UK, France and Spain. Europe further is fortunate to have 8 polarimetric Doppler radars used mainly for research. In Italy some of those systems are used also for operational nowcasting applications for dedicated customers. The Chilbolton multiparameter Doppler radar operates at S-band. (orig.)

  13. Analysis of physical parameter field and echo characteristics of Doppler radar in a thunderstorm process%一次雷暴大风的物理环境场和多普勒雷达回波特征

    Institute of Scientific and Technical Information of China (English)

    阎访; 陈静; 卞韬; 廖颖慧; 张翠华

    2013-01-01

    A thunderstorm disaster appeared in Shijiazhuang region from 15:00 to 18:00 on August 27,2009. The mesoscale synoptic systems of this process such as gust front, squall line and mesocyclone and so on were detected by a Doppler radar at Xinle county of Shijiazhuang. The characteristics of physical parameter field of this process and Doppler radar product were analyzed. The results show that unstable stratification of temperature inversion in the low level and vertical wind shear in the middle and low levels provide favorable conditions for strong convec-tive development. Gust front has feedback action on the development of convective storm intensity. When gust front is moving away from the convective storm,the convective storm weakens or even dies out; when both are gradually close to each other,the convective storm strengthens or even develops into a supercell convective storm. Multiple single convective storm belt arrangement constitutes a squall line system, which brings wind speed spurt, wind zag,pressure upwelling and temperature falling. The supercell convective storm has the typical features of echoes with a "hook" shape,a "herringbone" shape,a "bow" shape,and deep lasting mesocyclone. The ground destructive wind is mainly brought by supercell convective storms.%2009年8月27日15-18时,石家庄地区出现雷暴大风灾害性强对流天气过程,石家庄北部新乐县多普勒雷达探测到了完整的阵风锋、飑线和中气旋等中尺度天气系统,对此次雷暴大风的环境场和多普勒雷达产品进行分析.结果表明:低层逆温、中低层垂直风切变较强的不稳定层结为强对流天气的发生发展提供了有利环境条件.阵风锋对对流风暴发展强度具有反馈作用,当二者逐渐远离时,对流风暴强度减弱甚至消亡;当二者逐渐靠近时,对流风暴发展加强,甚至发展为超级单体对流风暴.多单体对流风暴带状排列构成飑线系统,所经测站出现风速突增、风

  14. STMAS中雷达反射率数据三维变分同化方案%3D Variational assimilation schemes of Doppler radar reflectivity data in STMAS

    Institute of Scientific and Technical Information of China (English)

    刘淑媛; 王奇; 刘海霞; 朱晓林

    2013-01-01

    介绍了在时空多尺度分析系统(STMAS)中以雨水含量作为控制变量,利用Z-qr关系,实现对区域中多部雷达回波强度资料三维变分同化方案,和水汽惩罚项模块方案.方案避免了利用Z-qr关系直接以回波强度或雨水混合比为控制变量会造成一阶导数不连续的问题.实例分析同化后初始场表明,从同化后的雨水混合比反算出来的回波强度与观测结果保持了较好的一致性.以2009年8月的MORA-KOT台风个例为例,设计实验来分析本文提出的雷达回波强度资料同化和水汽惩罚项方案效果.结果表明:雷达回波强度资料的同化方案(STMAS方案),提高了降水位置和强度预报的准确性;加入惩罚项和对雷达回波强度资料的同化模块后(HYDRO方案),削弱了水汽影响并加强了其他物理量的变化,相对STMAS方案,台风总降水增强了,但在强降水区域的降水强度减弱;相对控制试验,2种方案均改善了降水位置和强度的预报.%The schemes of Doppler radar reflectivity data 3D variational assimilation and hydrostatic balance in STMAS were introduced.The hydrostatic balance code was added into the STMAS cost function.The test shows that the reflectivity retrieved from the analysis field of STMAS is quite similar to that observed by doppler radar.Experiments using data from a typhoon case were conducted for comparing the different assimilation schemes.According to the experiments,the conclusions could be made that assimilating the reflectivity (STMAS scheme,test1)can result in a good performance,with the forecast of the rainfall area and cumulative precipitation improved,that adding hydrostatic balance penalty term and assimilating the reflectivity scheme together (HYDRO scheme,test1) can enhanced the total precipitation,but the maximal precipitation became smaller than sensitivity test 1,and that the forcast rainfall area and precipitation in HYDRO scheme and STMAS scheme were Improvement

  15. Radar channel balancing with commutation

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin Walter

    2014-02-01

    When multiple channels are employed in a pulse-Doppler radar, achieving and maintaining balance between the channels is problematic. In some circumstances the channels may be commutated to achieve adequate balance. Commutation is the switching, trading, toggling, or multiplexing of the channels between signal paths. Commutation allows modulating the imbalance energy away from the balanced energy in Doppler, where it can be mitigated with filtering.

  16. Meteor radar measurements of MLT winds near the equatorial electro jet region over Thumba (8.5° N, 77° E: comparison with TIDI observations

    Directory of Open Access Journals (Sweden)

    S. R. John

    2011-07-01

    Full Text Available The All-Sky interferometric meteor (SKYiMET radar (MR derived winds in the vicinity of the equatorial electrojet (EEJ are discussed. As Thumba (8.5° N, 77° E; dip lat. 0.5° N is under the EEJ belt, there has been some debate on the reliability of the meteor radar derived winds near the EEJ height region. In this regard, the composite diurnal variations of zonal wind profiles in the mesosphere-lower thermosphere (MLT region derived from TIMED Doppler Interferometer (TIDI and ground based meteor radar at Thumba are compared. In this study, emphasis is given to verify the meteor radar observations at 98 km height region, especially during the EEJ peaking time (11:00 to 14:00 LT. The composite diurnal cycles of zonal winds over Thumba are constructed during four seasons of the year 2006 using TIDI and meteor radar observations, which showed good agreement especially during the peak EEJ hours, thus assuring the reliability of meteor radar measurements of neutral winds close to the EEJ height region. It is evident from the present study that on seasonal scales, the radar measurements are not biased by the EEJ. The day-time variations of HF radar measured E-region drifts at the EEJ region are also compared with MR measurements to show there are large differences between ionospheric drifts and MR measurements. The significance of the present study lies in validating the meteor radar technique over Thumba located at magnetic equator by comparing with other than the radio technique for the first time.

  17. Comparative rainfall data analysis from two vertically pointing radars, an optical disdrometer, and a rain gauge

    Directory of Open Access Journals (Sweden)

    E. I. Nikolopoulos

    2008-12-01

    Full Text Available The authors present results of a comparative analysis of rainfall data from several ground-based instruments. The instruments include two vertically pointing Doppler radars, S-band and X-band, an optical disdrometer, and a tipping-bucket rain gauge. All instruments were collocated at the Iowa City Municipal Airport in Iowa City, Iowa, for a period of several months. The authors used the rainfall data derived from the four instruments to first study the temporal variability and scaling characteristics of rainfall and subsequently assess the instrumental effects on these derived properties. The results revealed obvious correspondence between the ground and remote sensors, which indicates the significance of the instrumental effect on the derived properties.

  18. Doppler Tomography

    CERN Document Server

    Marsh, T R

    2000-01-01

    I review the method of Doppler tomography which translates binary-star line profiles taken at a series of orbital phases into a distribution of emission over the binary. I begin with a discussion of the basic principles behind Doppler tomography, including a comparison of the relative merits of maximum entropy regularisation versus filtered back-projection for implementing the inversion. Following this I discuss the issue of noise in Doppler images and possible methods for coping with it. Then I move on to look at the results of Doppler Tomography applied to cataclysmic variable stars. Outstanding successes to date are the discovery of two-arm spiral shocks in cataclysmic variable accretion discs and the probing of the stream/magnetospheric interaction in magnetic cataclysmic variable stars. Doppler tomography has also told us much about the stream/disc interaction in non-magnetic systems and the irradiation of the secondary star in all systems. The latter indirectly reveals such effects as shadowing by the a...

  19. Radar activities of the DFVLR Institute for Radio Frequency Technology

    Science.gov (United States)

    Keydel, W.

    1983-01-01

    Aerospace research and the respective applications microwave tasks with respect to remote sensing, position finding and communication are discussed. The radar activities are directed at point targets, area targets and volume targets; they center around signature research for earth and ocean remote sensing, target recognition, reconnaissance and camouflage and imaging and area observation radar techniques (SAR and SLAR). The radar activities cover a frequency range from 1 GHz up to 94 GHz. The radar program is oriented to four possible application levels: ground, air, shuttle orbits and satellite orbits. Ground based studies and measurements, airborne scatterometers and imaging radars, a space shuttle radar, the MRSE, and follow on experiments are considered.

  20. Radar activities of the DFVLR Institute for Radio Frequency Technology

    Science.gov (United States)

    Keydel, W.

    1983-01-01

    Aerospace research and the respective applications microwave tasks with respect to remote sensing, position finding and communication are discussed. The radar activities are directed at point targets, area targets and volume targets; they center around signature research for earth and ocean remote sensing, target recognition, reconnaissance and camouflage and imaging and area observation radar techniques (SAR and SLAR). The radar activities cover a frequency range from 1 GHz up to 94 GHz. The radar program is oriented to four possible application levels: ground, air, shuttle orbits and satellite orbits. Ground based studies and measurements, airborne scatterometers and imaging radars, a space shuttle radar, the MRSE, and follow on experiments are considered.

  1. Estimation of rain rate by microwave radiometry and active radar during CLEOPATRA `92

    Energy Technology Data Exchange (ETDEWEB)

    Smirnov, M.T. [Inst. of Radioengineering and Electronics, RAS, Moscow (Russian Federation); Hagen, M. [Inst. fuer Physik der Atmosphaere, DLR Oberpfaffenhofen, Wessling (Germany); Evtushenko, A.V. [Inst. of Radioengineering and Electronics, RAS, Moscow (Russian Federation); Kutuza, B.G. [Inst. of Radioengineering and Electronics, RAS, Moscow (Russian Federation); Meischner, P.F. [Inst. fuer Physik der Atmosphaere, DLR Oberpfaffenhofen, Wessling (Germany); Petrenko, B.Z. [Inst. of Radioengineering and Electronics, RAS, Moscow (Russian Federation)

    1994-11-01

    Microwave radiometers operating at wavelengths 0.3, 0.8, 1.35 and 2.25 cm were used to estimate rain rates from ground during CLEOPATRA (Meischner et al., 1993). The systems were similar to those planned for the forthcoming PRIRODA mission. They were mainly operated looking at a fixed elevation of 75 . A model for estimation of the microwave emission of a rain layer taking into account polarization effects is briefly described. Originally designed for the evaluation of space borne measurements it was modified for ground based measurements and used to retrieve different rain parameters of interest. Intercomparisons with simultaneous measurements by the polarimetric Doppler radar POLDIRAD of DLR (Deutsche Forschungsanstalt fuer Luft- und Raumfahrt) and rain gauges provided the base for validation of the algorithm for rain rate estimations. Agreement strongly depends on the type of rain event characterized by the homogeneity of the rain clouds and by different drop size distributions influencing especially the radar measurements. Passive microwave radiometer measurements and active polarimetric radar measurements ideally complement each other in rain rate estimations from space as well as from ground. Ground based active radar is of importance in estimating small scale structures in time and space, such reducing possible errors of the radiometer measurements and for the selection of appropriate parameters for the rain model. (orig.) [Deutsch] Ein Mikrowellenradiometersystem mit den Wellenlaengen 0,3; 0,8; 1,35 und 2,25 cm wurde eingesetzt, um Regenraten am Grund waehrend CLEOPATRA (Meischner et al., 1993) zu messen. Das System entspricht einer Konfiguration, die mit der zukuenftigen PRIRODA Mission auf der russischen Raumstation MIR fliegen soll. Die Messungen wurden weitgehend unter einem festen Elevationswinkel von 75 durchgefuehrt. Ein Modell zur Bestimmung der emittierten Mikrowellenstrahlung unter Beruecksichtigung polarimetrischer Effekte wird kurz beschrieben

  2. Autonomous landing of a helicopter UAV with a ground-based multisensory fusion system

    Science.gov (United States)

    Zhou, Dianle; Zhong, Zhiwei; Zhang, Daibing; Shen, Lincheng; Yan, Chengping

    2015-02-01

    In this study, this paper focus on the vision-based autonomous helicopter unmanned aerial vehicle (UAV) landing problems. This paper proposed a multisensory fusion to autonomous landing of an UAV. The systems include an infrared camera, an Ultra-wideband radar that measure distance between UAV and Ground-Based system, an PAN-Tilt Unit (PTU). In order to identify all weather UAV targets, we use infrared cameras. To reduce the complexity of the stereovision or one-cameral calculating the target of three-dimensional coordinates, using the ultra-wideband radar distance module provides visual depth information, real-time Image-PTU tracking UAV and calculate the UAV threedimensional coordinates. Compared to the DGPS, the test results show that the paper is effectiveness and robustness.

  3. Radar clutter classification

    Science.gov (United States)

    Stehwien, Wolfgang

    1989-11-01

    The problem of classifying radar clutter as found on air traffic control radar systems is studied. An algorithm based on Bayes decision theory and the parametric maximum a posteriori probability classifier is developed to perform this classification automatically. This classifier employs a quadratic discriminant function and is optimum for feature vectors that are distributed according to the multivariate normal density. Separable clutter classes are most likely to arise from the analysis of the Doppler spectrum. Specifically, a feature set based on the complex reflection coefficients of the lattice prediction error filter is proposed. The classifier is tested using data recorded from L-band air traffic control radars. The Doppler spectra of these data are examined; the properties of the feature set computed using these data are studied in terms of both the marginal and multivariate statistics. Several strategies involving different numbers of features, class assignments, and data set pretesting according to Doppler frequency and signal to noise ratio were evaluated before settling on a workable algorithm. Final results are presented in terms of experimental misclassification rates and simulated and classified plane position indicator displays.

  4. Quality assessment of weather radar wind profiles during bird migration

    NARCIS (Netherlands)

    Holleman, I.; van Gasteren, H.; Bouten, W.

    2008-01-01

    Wind profiles from an operational C-band Doppler radar have been combined with data from a bird tracking radar to assess the wind profile quality during bird migration. The weather radar wind profiles (WRWPs) are retrieved using the well-known volume velocity processing (VVP) technique. The X-band

  5. Radar Observations of Asteroids

    Science.gov (United States)

    Ostro, S. J.

    2003-05-01

    During the past 25 years, radar investigations have provided otherwise unavailable information about the physical and dynamical properties of more than 200 asteroids. Measurements of the distribution of echo power in time delay and Doppler frequency provide two-dimensional images with spatial resolution as fine as a decameter. Sequences of delay-Doppler images can be used to produce geologically detailed three-dimensional models, to define the rotation state precisely, to constrain the internal density distribution, and to estimate the trajectory of the object's center of mass. Radar wavelengths (4 to 13 cm) and the observer's control of transmitted and received polarizations make the observations sensitive to near-surface bulk density and macroscopic structure. Since delay-Doppler positional measurements are orthogonal to optical angle measurements and typically have much finer fractional precision, they are powerful for refining orbits and prediction ephemerides. Radar astrometry can add decades or centuries to the interval over which an asteroid's close Earth approaches can accurately be predicted and can significantly refine collision probability estimates based on optical astrometry alone. In the highly unlikely case that a small body is on course for an Earth collision in this century, radar reconnaissance would almost immediately distinguish between an impact trajectory and a near miss and would dramatically reduce the difficulty and cost of any effort to prevent the collision. The sizes and rotation periods of radar-detected asteroids span more than four orders of magnitude. These observations have revealed both stony and metallic objects, elongated and nonconvex shapes as well as nearly featureless spheroids, small-scale morphology ranging from smoother than the lunar regolith to rougher than the rockiest terrain on Mars, craters and diverse linear structures, non-principal-axis spin states, contact binaries, and binary systems.

  6. High Ice Water Content at Low Radar Reflectivity near Deep Convection. Part I ; Consistency of In Situ and Remote-Sensing Observations with Stratiform Rain Column Simulations

    Science.gov (United States)

    Fridlind, A. M.; Ackerman, A. S.; Grandin, A.; Dezitter, F.; Weber, M.; Strapp, J. W.; Korolev, A. V.; Williams, C. R.

    2015-01-01

    Occurrences of jet engine power loss and damage have been associated with flight through fully glaciated deep convection at -10 to -50 degrees Centigrade. Power loss events commonly occur during flight through radar reflectivity (Zeta (sub e)) less than 20-30 decibels relative to Zeta (dBZ - radar returns) and no more than moderate turbulence, often overlying moderate to heavy rain near the surface. During 2010-2012, Airbus carried out flight tests seeking to characterize the highest ice water content (IWC) in such low-radar-reflectivity regions of large, cold-topped storm systems in the vicinity of Cayenne, Darwin, and Santiago. Within the highest IWC regions encountered, at typical sampling elevations (circa 11 kilometers), the measured ice size distributions exhibit a notably narrow concentration of mass over area-equivalent diameters of 100-500 micrometers. Given substantial and poorly quantified measurement uncertainties, here we evaluate the consistency of the Airbus in situ measurements with ground-based profiling radar observations obtained under quasi-steady, heavy stratiform rain conditions in one of the Airbus-sampled locations. We find that profiler-observed radar reflectivities and mean Doppler velocities at Airbus sampling temperatures are generally consistent with those calculated from in situ size-distribution measurements. We also find that column simulations using the in situ size distributions as an upper boundary condition are generally consistent with observed profiles of radar reflectivity (Ze), mean Doppler velocity (MDV), and retrieved rain rate. The results of these consistency checks motivate an examination of the microphysical pathways that could be responsible for the observed size-distribution features in Ackerman et al. (2015).

  7. Estimating the Doppler centroid of SAR data

    DEFF Research Database (Denmark)

    Madsen, Søren Nørvang

    1989-01-01

    After reviewing frequency-domain techniques for estimating the Doppler centroid of synthetic-aperture radar (SAR) data, the author describes a time-domain method and highlights its advantages. In particular, a nonlinear time-domain algorithm called the sign-Doppler estimator (SDE) is shown to have...... attractive properties. An evaluation based on an existing SEASAT processor is reported. The time-domain algorithms are shown to be extremely efficient with respect to requirements on calculations and memory, and hence they are well suited to real-time systems where the Doppler estimation is based on raw SAR...... data. For offline processors where the Doppler estimation is performed on processed data, which removes the problem of partial coverage of bright targets, the ΔE estimator and the CDE (correlation Doppler estimator) algorithm give similar performance. However, for nonhomogeneous scenes it is found...

  8. Compressive sensing for high resolution profiles with enhanced Doppler performance

    NARCIS (Netherlands)

    Anitori, L.; Hoogeboom, P.; Chevalier, F. Le; Otten, M.P.G.

    2012-01-01

    In this paper we demonstrate how Compressive Sensing (CS) can be used in pulse-Doppler radars to improve the Doppler performance while preserving range resolution. We investigate here two types of stepped frequency waveforms, the coherent frequency bursts and successive frequency ramps, which can be

  9. Doppler imaging

    Energy Technology Data Exchange (ETDEWEB)

    Piskunov, N [Department of Physics and Astronomy, Uppsala University, Box 515, S-75120 Uppsala (Sweden)], E-mail: piskunov@fysast.uu.se

    2008-12-15

    In this paper, I present a short review of the history and modern status of Doppler imaging techniques, highlighting their dependence on the knowledge of the fundamental stellar parameters, the quality of stellar atmospheric models and the accuracy of spectral synthesis.

  10. Space noise synthetic aperture radar

    Science.gov (United States)

    Kulpa, Krzysztof S.

    2006-03-01

    The paper presents limitations of space borne synthetic aperture radars, caused by range and Doppler velocity ambiguities, and the concept of usage of the noise radar technology for creation of high-resolution space SAR images. The noise SAR is free from limitation caused by the periodicity of pulse waveform ambiguity function, and therefore this technology can be used in the future space missions. The basic concept of noise SAR image formation is also presented. The image formation algorithm has been verified using the simulated data produced by Raw Radar Data Simulator.

  11. Classification of Small UAVs and Birds by Micro-Doppler Signatures

    NARCIS (Netherlands)

    Molchanov, P.; Egiazarian, K.; Astola, J.; Harmanny, R.I.A.; Wit, J.J.M. de

    2013-01-01

    The problem of unmanned aerial vehicles classification using continuous wave radar is considered in this paper. Classification features are extracted from micro-Doppler signature. Before the classification, the micro-Doppler signature is filtered and aligned to compensate the Doppler shift caused by

  12. Ground-based observations of Kepler asteroseismic targets

    DEFF Research Database (Denmark)

    Uyttterhoeven , K.; Karoff, Christoffer

    2010-01-01

    We present the ground-based activities within the different working groups of the Kepler Asteroseismic Science Consortium (KASC). The activities aim at the systematic characterization of the 5000+ KASC targets, and at the collection of ground-based follow-up time-series data of selected promising...

  13. Ocean wave parameters and spectrum estimated from single and dual high-frequency radar systems

    Science.gov (United States)

    Hisaki, Yukiharu

    2016-09-01

    The high-frequency (HF) radar inversion algorithm for spectrum estimation (HIAS) can estimate ocean wave directional spectra from both dual and single radar. Wave data from a dual radar and two single radars are compared with in situ observations. The agreement of the wave parameters estimated from the dual radar with those from in situ observations is the best of the three. In contrast, the agreement of the wave parameters estimated from the single radar in which no Doppler spectra are observed in the cell closest to the in situ observation point is the worst among the three. Wave data from the dual radar and the two single radars are compared. The comparison of the wave heights estimated from the single and dual radars shows that the area sampled by the Doppler spectra for the single radar is more critical than the number of Doppler spectra in terms of agreement with the dual-radar-estimated wave heights. In contrast, the comparison of the wave periods demonstrates that the number of Doppler spectra observed by the single radar is more critical for agreement of the wave periods than the area of the Doppler spectra. There is a bias directed to the radar position in the single radar estimated wave direction.

  14. Detection of small UAV helicopters using micro-Doppler

    Science.gov (United States)

    Tahmoush, David

    2014-05-01

    The detection of small unmanned aerial vehicles (UAVs) using radar can be challenging due to the small radar cross section and the presence of false targets such as birds. We present the initial results of micro-Doppler radar data collected on a small helicopter at G-band and compare the results to previously measured birds. The resulting signature differences can be used to help discriminate small UAVs from naturally occurring moving clutter such as birds.

  15. Movable Ground Based Recovery System for Reuseable Space Flight Hardware

    Science.gov (United States)

    Sarver, George L. (Inventor)

    2013-01-01

    A reusable space flight launch system is configured to eliminate complex descent and landing systems from the space flight hardware and move them to maneuverable ground based systems. Precision landing of the reusable space flight hardware is enabled using a simple, light weight aerodynamic device on board the flight hardware such as a parachute, and one or more translating ground based vehicles such as a hovercraft that include active speed, orientation and directional control. The ground based vehicle maneuvers itself into position beneath the descending flight hardware, matching its speed and direction and captures the flight hardware. The ground based vehicle will contain propulsion, command and GN&C functionality as well as space flight hardware landing cushioning and retaining hardware. The ground based vehicle propulsion system enables longitudinal and transverse maneuverability independent of its physical heading.

  16. MIMO Radar Using Compressive Sampling

    CERN Document Server

    Yu, Yao; Poor, H Vincent

    2009-01-01

    A MIMO radar system is proposed for obtaining angle and Doppler information on potential targets. Transmitters and receivers are nodes of a small scale wireless network and are assumed to be randomly scattered on a disk. The transmit nodes transmit uncorrelated waveforms. Each receive node applies compressive sampling to the received signal to obtain a small number of samples, which the node subsequently forwards to a fusion center. Assuming that the targets are sparsely located in the angle- Doppler space, based on the samples forwarded by the receive nodes the fusion center formulates an l1-optimization problem, the solution of which yields target angle and Doppler information. The proposed approach achieves the superior resolution of MIMO radar with far fewer samples than required by other approaches. This implies power savings during the communication phase between the receive nodes and the fusion center. Performance in the presence of a jammer is analyzed for the case of slowly moving targets. Issues rel...

  17. Multi-variable X-band radar observation and tracking of ash plume from Mt. Etna volcano on November 23, 2013 event

    Science.gov (United States)

    Montopoli, Mario; Vulpiani, Gianfranco; Riccci, Matteo; Corradini, Stefano; Merucci, Luca; Marzano, Frank S.

    2015-04-01

    Ground based weather radar observations of volcanic ash clouds are gaining momentum after recent works which demonstrated their potential use either as stand alone tool or in combination with satellite retrievals. From an operational standpoint, radar data have been mainly exploited to derive the height of ash plume and its temporal-spatial development, taking into account the radar limitation of detecting coarse ash particles (from approximately 20 microns to 10 millimeters and above in terms of particle's radius). More sophisticated radar retrievals can include airborne ash concentration, ash fall rate and out-flux rate. Marzano et al. developed several volcanic ash radar retrieval (VARR) schemes, even though their practical use is still subject to a robust validation activity. The latter is made particularly difficult due to the lack of field campaigns with multiple observations and the scarce repetition of volcanic events. The radar variable, often used to infer the physical features of actual ash clouds, is the radar reflectivity named ZHH. It is related to ash particle size distribution and it shows a nice power law relationship with ash concentration. This makes ZHH largely used in radar-volcanology studies. However, weather radars are often able to detect Doppler frequency shifts and, more and more, they have a polarization-diversity capability. The former means that wind speed spectrum of the ash cloud is potentially inferable, whereas the latter implies that variables other than ZHH are available. Theoretically, these additional radar variables are linked to the degree of eccentricity of ash particles, their orientation and density as well as the presence of strong turbulence effects. Thus, the opportunity to refine the ash radar estimates so far developed can benefit from the thorough analysis of radar Doppler and polarization diversity. In this work we show a detailed analysis of Doppler shifts and polarization variables measured by the X band radar

  18. Radar Investigations of Asteroids

    Science.gov (United States)

    Ostro, S.

    2004-05-01

    Radar investigations have provided otherwise unavailable information about the physical and dynamical properties of about 230 asteroids. Measurements of the distribution of echo power in time delay (range) and Doppler frequency (line-of-sight velocity) provide two-dimensional images with spatial resolution as fine as a decameter. Sequences of delay-Doppler images can be used to produce geologically detailed three-dimensional models, to define the rotation state precisely, to constrain the internal density distribution, and to estimate the trajectory of the object's center of mass. Radar wavelengths (4 to 13 cm) and the observer's control of transmitted and received polarizations make the observations sensitive to near-surface bulk density and macroscopic structure. Since delay-Doppler measurements are orthogonal to optical angle measurements and typically have much finer fractional precision, they are powerful for refining orbits and prediction ephemerides. Such astrometric measurements can add decades or centuries to the interval over which an asteroid's close Earth approaches can accurately be predicted and can significantly refine collision probability estimates based on optical astrometry alone. In the highly unlikely case that a small body is on course for an Earth collision in this century, radar reconnaissance would almost immediately distinguish between an impact trajectory and a near miss and would dramatically reduce the difficulty and cost of any effort to prevent the collision. The sizes and rotation periods of radar-detected asteroids span more than four orders of magnitude. The observations have revealed both stony and metallic objects, elongated and nonconvex shapes as well as nearly featureless spheroids, small-scale morphology ranging from smoother than the lunar regolith to rougher than the rockiest terrain on Mars, craters and diverse linear structures, non-principal-axis spin states, contact binaries, and binary systems.

  19. A Doppler RADAR sensor for trampoline jumping

    DEFF Research Database (Denmark)

    2013-01-01

    Patentansøgning på en sensor, samt signalbehandling, til at måle brugerens højde over trampolindug......Patentansøgning på en sensor, samt signalbehandling, til at måle brugerens højde over trampolindug...

  20. Prospects for Geostationary Doppler Weather Radar

    Science.gov (United States)

    Tanelli, Simone; Fang, Houfei; Durden, Stephen L.; Im, Eastwood; Rhamat-Samii, Yahya

    2009-01-01

    A novel mission concept, namely NEXRAD in Space (NIS), was developed for detailed monitoring of hurricanes, cyclones, and severe storms from a geostationary orbit. This mission concept requires a space deployable 35-m diameter reflector that operates at 35-GHz with a surface figure accuracy requirement of 0.21 mm RMS. This reflector is well beyond the current state-of-the-art. To implement this mission concept, several potential technologies associated with large, lightweight, spaceborne reflectors have been investigated by this study. These spaceborne reflector technologies include mesh reflector technology, inflatable membrane reflector technology and Shape Memory Polymer reflector technology.

  1. Micro-range micro-doppler for dismount classification

    Science.gov (United States)

    Tahmoush, Dave

    2013-05-01

    This paper presents a processing technique that can be used to detect and classify pedestrians group based on the micro- Doppler signature gathered with a millimeter wave radar. The evaluation of the number of pedestrians moving in a group can be a difficult task using a traditional micro-Doppler spectrogram because of a tendency for people to partially synchronize their steps when walking together. The new approach, based on multi-range variation as well as the micro-Doppler variations, provides promising results. The range-spectrogram processing technique was developed and tested using a database composed of hundreds of pedestrian and vehicle signatures gathered in an urban test site over a two year period in a variety of weather conditions. We associate image detections with radar detections through motion extracted from both radar and imagery. We also explain how radar and video together can produce an inexpensive alternative to 3-D imaging.

  2. Clutter attenuation using the Doppler effect in standoff electromagnetic quantum sensing

    Science.gov (United States)

    Lanzagorta, Marco; Jitrik, Oliverio; Uhlmann, Jeffrey; Venegas, Salvador

    2016-05-01

    In the context of traditional radar systems, the Doppler effect is crucial to detect and track moving targets in the presence of clutter. In the quantum radar context, however, most theoretical performance analyses to date have assumed static targets. In this paper we consider the Doppler effect at the single photon level. In particular, we describe how the Doppler effect produced by clutter and moving targets modifies the quantum distinguishability and the quantum radar error detection probability equations. Furthermore, we show that Doppler-based delayline cancelers can reduce the effects of clutter in the context of quantum radar, but only in the low-brightness regime. Thus, quantum radar may prove to be an important technology if the electronic battlefield requires stealthy tracking and detection of moving targets in the presence of clutter.

  3. Development of Integrated Monitoring Platform for the New Generation Doppler Weather Radar-SA%新一代天气雷达集成监控平台开发

    Institute of Scientific and Technical Information of China (English)

    张骞; 陈海燕; 吕庆利; 杨传凤; 耿力

    2016-01-01

    The new generation weather radar is an important part of modern meteorological observation methods ,monitoring the run-ning status of the new generation weather radar is important for the normal operation of the radar .This paper introduces the compo-sition of radar system and classification of radar data ,and analyzes the characteristics and laws of the radar system when it is normal or abnormal .Using Macromedia Dreamweaver and PHP , the integrated monitoring platform for the new generation weather radar is developed .Using Web page to monitor the real-time radar system running status , the sound alarm will be triggered when the status is abnormal ,and radar power ,status parameters and other important performance indicators could also be monitored .%新一代天气雷达是现代气象观测手段中的重要组成部分,监控新一代天气雷达系统的运行状态对于雷达的正常运行有着重要意义。文中介绍了雷达系统的组成和雷达资料的分类,通过分析雷达系统运行正常与运行故障时的特征和规律,应用Macromedia Dreamweaver 和PHP开发新一代天气雷达集成监控平台,以Web网页形式实时监控雷达系统运行状态,既能在状态异常时触发声音报警,又能监控雷达功率、状态参数等重要性能指标。

  4. 2011年贵州两次降雪天气过程的多普勒雷达产品特征分析%Doppler radar analyses of twice snowing weather process in 2011 Guizhou

    Institute of Scientific and Technical Information of China (English)

    周治黔; 朱燕; 黄世芹; 罗乃兴; 田程

    2012-01-01

    利用常规观测和新一代多普勒天气雷达回波资料对2011年1月17日至20日贵州省出现的两次降雪天气进行详细的特征分析。结果表明:贵州降雪回波强度一般〈30dBz,中心强度普遍在30-40dBz之间,反射率因子的分布梯度不大;但降雪过程中夹杂冰粒的时候,回波中心强度能达到50dBz。降雪回波的顶高一般在7km以下,其中顶高5-7km的情况占到60%左右,发展旺盛时回波顶高可达到8km以上。降雪回波径向速度的等值线比较密集,沿径向梯度变化大。“牛眼”状回波是降雪回波的一个典型特征,“牛眼”状回波正负速度中心值的大小与降雪量存在一定的正比关系。风廓线产品的近地面层风向对于预报降水类型有明显的指示意义,当风廓线产品上近地面1.5km高度的风向由东偏南转为东偏北时,地面冷平流取代暖平流,雨夹雪向纯雪转换,反之,暖平流取代冷平流,则是纯雪向雨夹雪转换,或者降雪减弱消失。%Using conventional observation and a new generation Doppler radar data on January 17 2011 to 20, ana- lyzed the snowfall weather detailed features appeared twice in Guizhou. The results show that the snowfalls echoes generally are less than 30dbz, and center echoes intensity are between 30 to 40dbz, reflectivity factors distribution gradient is not big; but when the snowfall mingled with ice particles, center echoes intensity are 50dbz. The top highs of echoes of snowfall are under the 7kin, and the top high of 5 -7km accounted for about 60% , the most top high can be achieved 8kin when the echoes are most vigorous. The radial velocity isolines of snow echoes arc inten- sive, along the radial gradient changes are small. "Bull ' s - eye" shape echo is a typical features of snowfall echo, and it plus or minus speed central values with the amount of snow there exist certain proportional relations. Surface layer wind direction

  5. 一次强烈雹暴的多普勒天气雷达资料分析%Analysis of an intensive hailstorm with Doppler weather radar data

    Institute of Scientific and Technical Information of China (English)

    王丛梅; 景华; 王福侠; 王丽荣

    2011-01-01

    利用石家庄多普勒天气雷达资料和常规探测资料,对2008年5月17日发生在河北南部的强烈雹暴的生成环境和动力机制以及发展演变特征进行了分析.内蒙古东部冷涡后部的冷空气和低层暖湿气流在河北中南部交汇,导致这个地区上空的层结不稳定,低层的暖切变和地面的东风辐合线为触发系统.高低空急流、不稳定层结、强垂直风切变为强烈雹暴的发生提供了有利的环境条件.强烈雹暴的多普勒天气雷达观测特征表现为一个次超级单体的发展移动过程,呈现回波悬垂和弱回波区特征,强回波核区反射率因子达到73 dBz,三体散射现象明显,对应径向速度图表现为弱中气旋,旋转速度为15 m/s.次超级单体右移特征明显,沿承载层平均风方向偏右侧移动.风暴相对螺旋度(Srh)大值与强雹暴的产生密切相关,0.3~2.1 km的Srh正值出现以及2.1 ~6.1 km的Srh减小随后迅速增加对冰雹的预报有很好的指示意义.%By using Shijiazhuang Doppler weather radar data and routine observation data of an intensive hailstorm on May 17, 2008 in south of Hebei, analysis of its environmental conditions, dynamical mechanism and evolution characteristics were made. It was the cold air behind east-Mongolia cold eddy confluenced by moist-warm flow in low layer that the atmospheric stratification became instable. The trigger systems were low layer warm sheer and surface convergence line. Upper-low jet stream, instable stratification and strong vertical wind sheer were favourable environmental conditions. Typical hook echo, echo overhang and weak echo region ( WER) appeared. The maximum reflectivity value was 73 dBz. Three-body scattering phenomenon was obvious. Radial velocity maps show a weak mesocyclone with its velocity 15 m/s. Sub-supercell storm shifted to the right side of average bearing layer wind direction. The big value of storm relative helicity (Srh ) was closely related to

  6. Analysis on Doppler radar characteristic of grade F1 tornado in Haimen%海门一次F1级龙卷的多普勒天气雷达特征分析

    Institute of Scientific and Technical Information of China (English)

    林应; 陈铁; 张树民; 缪燕; 严晓庆

    2011-01-01

    By using the Doppler weather radar, routine and intensive observation data the process of a grade Fl tornado happened in Haimen of Jiangsu province was analyzed in detail. The results show that before the tornado there existed a long entrainment instability, a low LCL, a strong horizontal and vertical wind shear and a surface dry line which provides very good dynamic conditions for a convective system to develop a tornado. Bottom cool air intrusion and strong wind shear made a single convective cell easier to develop more rapidly. The downward strong echo center height, the descending VIL, the rapid development of the radial velocity of the wind field in cyclonic vortex are good indicators of early warning of tornado. Tornado in the development process, as a low mass center convective system, obviously differs from the hail, a high center of gravity convection system. Sudden downward of mesocyclone height and maximum wind shear height, a sharp contraction of cyclone size indicate that the tornado will occur soon.%用多普勒天气雷达、常规观测和地面加密观测资料对2011年7月13日发生在江苏南通海门市树勋镇的龙卷风过程进行了详细分析.得出:较长时间的不稳定层结的存在,较低的抬升凝结高度,较强的水平和垂直风切变以及地面干线的存在为龙卷风的发生发展提供很好的动力条件;底层冷空气的切入,较强的风切变易使单体发展更加旺盛.强回波中心高度和垂直积分液态含水量的下降,径向速度风场中气旋性涡旋的迅速发展是对龙卷风提前警戒的很好指标.龙卷风进行过程中,此系统为低位质心的对流系统,产生的天气是龙卷,伴随大风,与冰雹的高位质心对流系统有明显的区别.中气旋高度,最大切变高度的骤降,中气旋尺度的急剧收缩预示着龙卷的发生,为我们今后的龙卷风预警提供有利的参考.

  7. Quantum radar

    CERN Document Server

    Lanzagorta, Marco

    2011-01-01

    This book offers a concise review of quantum radar theory. Our approach is pedagogical, making emphasis on the physics behind the operation of a hypothetical quantum radar. We concentrate our discussion on the two major models proposed to date: interferometric quantum radar and quantum illumination. In addition, this book offers some new results, including an analytical study of quantum interferometry in the X-band radar region with a variety of atmospheric conditions, a derivation of a quantum radar equation, and a discussion of quantum radar jamming.This book assumes the reader is familiar w

  8. CSSF MIMO RADAR: Low-Complexity Compressive Sensing Based MIMO Radar That Uses Step Frequency

    CERN Document Server

    Yu, Yao; Poor, H Vincent

    2011-01-01

    A new approach is proposed, namely CSSF MIMO radar, which applies the technique of step frequency (SF) to compressive sensing (CS) based multi-input multi-output (MIMO) radar. The proposed approach enables high resolution range, angle and Doppler estimation, while transmitting narrowband pulses. The problem of joint angle-Doppler-range estimation is first formulated to fit the CS framework, i.e., as an L1 optimization problem. Direct solution of this problem entails high complexity as it employs a basis matrix whose construction requires discretization of the angle-Doppler-range space. Since high resolution requires fine space discretization, the complexity of joint range, angle and Doppler estimation can be prohibitively high. For the case of slowly moving targets, a technique is proposed that achieves significant complexity reduction by successively estimating angle-range and Doppler in a decoupled fashion and by employing initial estimates obtained via matched filtering to further reduce the space that nee...

  9. Finding extraterrestrial life using ground-based high-resolution spectroscopy

    CERN Document Server

    Snellen, Ignas; Poole, Rudolf Le; Brogi, Matteo; Birkby, Jayne

    2013-01-01

    Exoplanet observations promise one day to unveil the presence of extraterrestrial life. Atmospheric compounds in strong chemical disequilibrium would point to large-scale biological activity just as oxygen and methane do in the Earth's atmosphere. The cancellation of both the Terrestrial Planet Finder and Darwin missions means that it is unlikely that a dedicated space telescope to search for biomarker gases in exoplanet atmospheres will be launched within the next 25 years. Here we show that ground-based telescopes provide a strong alternative for finding biomarkers in exoplanet atmospheres through transit observations. Recent results on hot Jupiters show the enormous potential of high-dispersion spectroscopy to separate the extraterrestrial and telluric signals making use of the Doppler shift of the planet. The transmission signal of oxygen from an Earth-twin orbiting a small red dwarf star is only a factor 3 smaller than that of carbon monoxide recently detected in the hot Jupiter tau Bootis b, albeit such...

  10. Seismo-traveling ionospheric disturbances of earthquake and tsunami waves observed by space- and ground-based GPS receivers

    Science.gov (United States)

    Liu, J. Y. G.; Chen, C. Y.; Lin, C. H.

    2015-12-01

    FORMOSAT-3/COSMIC (F3/C) is a constellation of six microsatellites launched on April 15, 2006 and has been orbiting with 72° inclination at 700 to 800 km above the earth since December 2007. The main payload of the F3/C is the GPS Occultation eXperiment (GOX) which carries out probing the radio occultation (RO) total electron content between GPS satellite and F3/C. Therefore, F3/C provides us an excellent opportunity to vertically scan ionospheric electron density from 100 up to 800 km altitude. On the other hand, worldwide ground-based GPS receivers can be employed to observe traveling ionospheric disturbances of the TEC. Here, we present the ionosphere response to seismic and tsunami waves by means of F3/C RO TEC and worldwide ground-based GPS TEC as well as existing data of infrasondes, magnetometers, and Doppler sounding systems during the 11 March 2011 M9.0 Tohoku earthquake.

  11. Radar fall detectors: a comparison

    Science.gov (United States)

    Erol, Baris; Amin, Moeness; Ahmad, Fauzia; Boashash, Boualem

    2016-05-01

    Falls are a major cause of accidents in elderly people. Even simple falls can lead to severe injuries, and sometimes result in death. Doppler fall detection has drawn much attention in recent years. Micro-Doppler signatures play an important role for the Doppler-based radar systems. Numerous studies have demonstrated the offerings of micro-Doppler characteristics for fall detection. In this respect, a plethora of micro-Doppler signature features have been proposed, including those stemming from speech recognition and wavelet decomposition. In this work, we consider four different sets of features for fall detection. These can be categorized as spectrogram based features, wavelet based features, mel-frequency cepstrum coefficients, and power burst curve features. Support vector machine is employed as the classifier. Performance of the respective fall detectors is investigated using real data obtained with the same radar operating resources and under identical sensing conditions. For the considered data, the spectrogram based feature set is shown to provide superior fall detection performance.

  12. The doppler ultrasound. La ecografia Doppler

    Energy Technology Data Exchange (ETDEWEB)

    Contreras Cecilia, E.; Lozano Setien, E.; Hernandez Montero, J.; Ganado Diaz, T.; Jorquera Moya, M.; Blasco Pascual, E. (Hospital Universitario San Carlos. Madrid (Spain))

    1994-01-01

    The discovery and development of Doppler ultrasound has had a great influence on Medical practice since it allows the noninvasive study of vascular pathology, both arterial and venous, as well as the flow patterns of the different parenchyma. This article deals with the principles, limitations and interpretation of the Doppler signal, as well as the different Doppler ultrasound systems routinely employed in Medicine.

  13. Radar Chart

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Radar Chart collection is an archived product of summarized radar data. The geographic coverage is the 48 contiguous states of the United States. These hourly...

  14. Weather Radar Technology Development

    Science.gov (United States)

    1990-08-15

    Preparation). MISCELLANEOUS Donaldson Jr, R.J., 1987: "Significance of the 40th Anniversary Conference." Address at the Battan Memorial and 40th Anni - versary...Bergen and Albers (1987). They have achieved -37 -29 -25 -6 4 7 magnificent results for reducing general -35 -28 -19 -7 -3 4 ambiguity. 283 284 285 3.2... Albers , 1988: Two- and the National Severe Storms Laboratory S-band three-dimensional de-aliasing of Doppler radar in Norman, Oklahoma. For three

  15. Multiple frequency atmospheric radar techniques

    Science.gov (United States)

    Stitt, Gary Richard

    The use of multiple frequency coding to improve the vertical resolution of pulsed-Doppler very high frequency atmospheric radars, especially with regards to the two-frequency techniques known as frequency domain interferometry (FDI), is presented. This technique consists of transmitting alternate pulses on two distinct carrier frequencies. The two resulting time series are used to evaluate the normalized cross-correlation function, whose magnitude and phase are related to the thickness and position of a scattering layer. These same time series are also used to evaluate cross-spectra, which yield magnitude and phase values for each Doppler frequency component of the return signal.

  16. Planetary Doppler Imaging

    Science.gov (United States)

    Murphy, N.; Jefferies, S.; Hart, M.; Hubbard, W. B.; Showman, A. P.; Hernandez, G.; Rudd, L.

    2014-12-01

    from space, however, much can be learned about Jupiter and Saturn using ground-based measurements. We will present the first results from a ground-based observing campaign of Jupiter and Saturn, made from the Bok 90" telescope on Kitt Peak, intended to validate the work of Gaulme et al, and extend such observations to Saturn.

  17. Cloud Base Height and Effective Cloud Emissivity Retrieval with Ground-Based Infrared Interferometer

    Institute of Scientific and Technical Information of China (English)

    PAN Lin-Jun; LU Da-Ren

    2012-01-01

    Based on ground-based Atmospheric Emitted Radiance Interferometer (AERI) observations in Shouxian, Anhui province, China, the authors retrieve the cloud base height (CBH) and effective cloud emissivity by using the minimum root-mean-square difference method. This method was originally developed for satellite remote sensing. The high-temporal-resolution retrieval results can depict the trivial variations of the zenith clouds continu- ously. The retrieval results are evaluated by comparing them with observations by the cloud radar. The compari- son shows that the retrieval bias is smaller for the middle and low cloud, especially for the opaque cloud. When two layers of clouds exist, the retrieval results reflect the weighting radiative contribution of the multi-layer cloud. The retrieval accuracy is affected by uncertainties of the AERI radiances and sounding profiles, in which the role of uncertainty in the temperature profile is dominant.

  18. Imaging synthetic aperture radar

    Science.gov (United States)

    Burns, Bryan L.; Cordaro, J. Thomas

    1997-01-01

    A linear-FM SAR imaging radar method and apparatus to produce a real-time image by first arranging the returned signals into a plurality of subaperture arrays, the columns of each subaperture array having samples of dechirped baseband pulses, and further including a processing of each subaperture array to obtain coarse-resolution in azimuth, then fine-resolution in range, and lastly, to combine the processed subapertures to obtain the final fine-resolution in azimuth. Greater efficiency is achieved because both the transmitted signal and a local oscillator signal mixed with the returned signal can be varied on a pulse-to-pulse basis as a function of radar motion. Moreover, a novel circuit can adjust the sampling location and the A/D sample rate of the combined dechirped baseband signal which greatly reduces processing time and hardware. The processing steps include implementing a window function, stabilizing either a central reference point and/or all other points of a subaperture with respect to doppler frequency and/or range as a function of radar motion, sorting and compressing the signals using a standard fourier transforms. The stabilization of each processing part is accomplished with vector multiplication using waveforms generated as a function of radar motion wherein these waveforms may be synthesized in integrated circuits. Stabilization of range migration as a function of doppler frequency by simple vector multiplication is a particularly useful feature of the invention; as is stabilization of azimuth migration by correcting for spatially varying phase errors prior to the application of an autofocus process.

  19. Plans of a test bed for ionospheric modelling based on Fennoscandian ground-based instrumentation

    Science.gov (United States)

    Kauristie, Kirsti; Kero, Antti; Verronen, Pekka T.; Aikio, Anita; Vierinen, Juha; Lehtinen, Markku; Turunen, Esa; Pulkkinen, Tuija; Virtanen, Ilkka; Norberg, Johannes; Vanhamäki, Heikki; Kallio, Esa; Kestilä, Antti; Partamies, Noora; Syrjäsuo, Mikko

    2016-07-01

    One of the recommendations for teaming among research groups in the COSPAR/ILWS roadmap is about building test beds in which coordinated observing supports model development. In the presentation we will describe a test bed initiative supporting research on ionosphere-thermosphere-magnetosphere interactions. The EISCAT incoherent scatter radars with their future extension, EISCAT3D, form the backbone of the proposed system. The EISCAT radars are surrounded by versatile and dense arrays of ground-based instrumentation: magnetometers and auroral cameras (the MIRACLE and IMAGE networks), ionospheric tomography receivers (the TomoScand network) and other novel technology for upper atmospheric probing with radio waves (e.g. the KAIRA facility, riometers and the ionosonde maintained by the Sodankylä Geophysical Observatory). As a new opening, close coordination with the Finnish national cubesat program is planned. We will investigate opportunities to establish a cost efficient nanosatellite program which would support the ground-based observations in a systematic and persistent manner. First experiences will be gathered with the Aalto-1 and Aalto-2 satellites, latter of which will be the Finnish contribution to the international QB50 mission. We envisage close collaboration also in the development of data analysis tools with the goal to integrate routines and models from different research groups to one system, where the different elements support each other. In the longer run we are aiming for a modelling framework with observational guidance which gives a holistic description on ionosphere-thermosphere processes and this way enables reliable forecasts on upper atmospheric space weather activity.

  20. Microwave signatures of ice hydrometeors from ground-based observations above Summit, Greenland

    Directory of Open Access Journals (Sweden)

    C. Pettersen

    2015-12-01

    Full Text Available Multi-instrument, ground-based measurements provide unique and comprehensive datasets of the atmosphere for a specific location over long periods of time and resulting data compliments past and existing global satellite observations. This paper explores the effect of ice hydrometeors on ground-based, high frequency passive microwave measurements and attempts to isolate an ice signature for summer seasons at Summit, Greenland from 2010–2013. Data from a combination of passive microwave, cloud radar, radiosonde, and ceilometer were examined to isolate the ice signature at microwave wavelengths. By limiting the study to a cloud liquid water path of 40 g m−2 or less, the cloud radar can identify cases where the precipitation was dominated by ice. These cases were examined using liquid water and gas microwave absorption models, and brightness temperatures were calculated for the high frequency microwave channels: 90, 150, and 225 GHz. By comparing the measured brightness temperatures from the microwave radiometers and the calculated brightness temperature using only gas and liquid contributions, any residual brightness temperature difference is due to emission and scattering of microwave radiation from the ice hydrometeors in the column. The ice signature in the 90, 150, and 225 GHz channels for the Summit Station summer months was isolated. This measured ice signature was then compared to an equivalent brightness temperature difference calculated with a radiative transfer model including microwave single scattering properties for several ice habits. Initial model results compare well against the four years of summer season isolated ice signature in the high-frequency microwave channels.

  1. CRRES/Ground-based multi-instrument observations of an interval of substorm activity

    Directory of Open Access Journals (Sweden)

    T. K. Yeoman

    Full Text Available Observations are presented of data taken during a 3-h interval in which five clear substorm onsets/intensifications took place. During this interval ground-based data from the EISCAT incoherent scatter radar, a digital CCD all sky camera, and an extensive array of magnetometers were recorded. In addition data from the CRRES and DMSP spacecraft, whose footprints passed over Scandinavia very close to most of the ground-based instrumentation, are available. The locations and movements of the substorm current system in latitude and longitude, determined from ground and spacecraft magnetic field data, have been correlated with the locations and propagation of increased particle precipitation in the E-region at EISCAT, increased particle fluxes measured by CRRES and DMSP, with auroral luminosity and with ionospheric convection velocities. The onsets and propagation of the injection of magnetospheric particle populations and auroral luminosity have been compared. CRRES was within or very close to the substorm expansion phase onset sector during the interval. The onset region was observed at low latitudes on the ground, and has been confirmed to map back to within L=7 in the magnetotail. The active region was then observed to propagate tailward and poleward. Delays between the magnetic signature of the substorm field aligned currents and field dipolarisation have been measured. The observations support a near-Earth plasma instability mechanism for substorm expansion phase onset.

  2. Determining the Best Method for Estimating the Observed Level of Maximum Detrainment Based on Radar Reflectivity

    Energy Technology Data Exchange (ETDEWEB)

    Carletta, Nicholas D.; Mullendore, Gretchen L.; Starzec, Mariusz; Xi, Baike; Feng, Zhe; Dong, Xiquan

    2016-08-01

    Convective mass transport is the transport of mass from near the surface up to the upper troposphere and lower stratosphere (UTLS) by a deep convective updraft. This transport can alter the chemical makeup and water vapor balance of the UTLS, which affects cloud formation and the radiative properties of the atmosphere. It is therefore important to understand the exact altitudes at which mass is detrained from convection. The purpose of this study was to improve upon previously published methodologies for estimating the level of maximum detrainment (LMD) within convection using data from a single ground-based radar. Four methods were used to identify the LMD and validated against dual-Doppler derived vertical mass divergence fields for six cases with a variety of storm types. The best method for locating the LMD was determined to be the method that used a reflectivity texture technique to determine convective cores and a multi-layer echo identification to determine anvil locations. Although an improvement over previously published methods, the new methodology still produced unreliable results in certain regimes. The methodology worked best when applied to mature updrafts, as the anvil needs time to grow to a detectable size. Thus, radar reflectivity is found to be valuable in estimating the LMD, but storm maturity must also be considered for best results.

  3. Radar Fundamentals, Presentation

    OpenAIRE

    Jenn, David

    2008-01-01

    Topics include: introduction, radar functions, antennas basics, radar range equation, system parameters, electromagnetic waves, scattering mechanisms, radar cross section and stealth, and sample radar systems.

  4. Radar Fundamentals, Presentation

    OpenAIRE

    Jenn, David

    2008-01-01

    Topics include: introduction, radar functions, antennas basics, radar range equation, system parameters, electromagnetic waves, scattering mechanisms, radar cross section and stealth, and sample radar systems.

  5. Extracting and analyzing micro-Doppler from ladar signatures

    Science.gov (United States)

    Tahmoush, Dave

    2015-05-01

    Ladar and other 3D imaging modalities have the capability of creating 3D micro-Doppler to analyze the micro-motions of human subjects. An additional capability to the recognition of micro-motion is the recognition of the moving part, such as the hand or arm. Combined with measured RCS values of the body, ladar imaging can be used to ground-truth the more sensitive radar micro-Doppler measurements and associate the moving part of the subject with the measured Doppler and RCS from the radar system. The 3D ladar signatures can also be used to classify activities and actions on their own, achieving an 86% accuracy using a micro-Doppler based classification strategy.

  6. Doppler Compensation by using of Segmented Match Filter

    Directory of Open Access Journals (Sweden)

    Nader Ghadimi

    2008-09-01

    Full Text Available Match filter is one of the important parts of radar receiver. By using of Match Filter, the signal to noise ratio can be maximized so that the probability of detection is increased. Match Filter can be used as a pulse compression filter in radar receiver. Binary phase code is one of the pulse compression methods that, the compression can be down with a Match Filter in the receiver. Doppler effect is one of the problems that degrade the performance of Match Filter. In this paper, two methods “Mixer Array” and “Segmented Match Filter” are proposed for Doppler compensation. The operation of these two methods as Doppler compensation techniques are considered theoretically. The simulation is used to demonstrate the Doppler compensation performance of new techniques compared to conventional methods.

  7. An MSK Radar Waveform

    Science.gov (United States)

    Quirk, Kevin J.; Srinivasan, Meera

    2012-01-01

    The minimum-shift-keying (MSK) radar waveform is formed by periodically extending a waveform that separately modulates the in-phase and quadrature- phase components of the carrier with offset pulse-shaped pseudo noise (PN) sequences. To generate this waveform, a pair of periodic PN sequences is each passed through a pulse-shaping filter with a half sinusoid impulse response. These shaped PN waveforms are then offset by half a chip time and are separately modulated on the in-phase and quadrature phase components of an RF carrier. This new radar waveform allows an increase in radar resolution without the need for additional spectrum. In addition, it provides self-interference suppression and configurable peak sidelobes. Compared strictly on the basis of the expressions for delay resolution, main-lobe bandwidth, effective Doppler bandwidth, and peak ambiguity sidelobe, it appears that bi-phase coded (BPC) outperforms the new MSK waveform. However, a radar waveform must meet certain constraints imposed by the transmission and reception of the modulation, as well as criteria dictated by the observation. In particular, the phase discontinuity of the BPC waveform presents a significant impediment to the achievement of finer resolutions in radar measurements a limitation that is overcome by using the continuous phase MSK waveform. The phase continuity, and the lower fractional out-of-band power of MSK, increases the allowable bandwidth compared with BPC, resulting in a factor of two increase in the range resolution of the radar. The MSK waveform also has been demonstrated to have an ambiguity sidelobe structure very similar to BPC, where the sidelobe levels can be decreased by increasing the length of the m-sequence used in its generation. This ability to set the peak sidelobe level is advantageous as it allows the system to be configured to a variety of targets, including those with a larger dynamic range. Other conventionally used waveforms that possess an even greater

  8. Orbit Determination Using a Decametric Line-of-Sight Radar

    Science.gov (United States)

    Frazer, G.; Meehan, D.; Rutten, M.; Gordon, N.

    2013-09-01

    The paper investigates the effectiveness of a ground-based bistatic decametric line-of-sight radar for orbit determination of low Earth orbit satellites. Radar observations of the Hubble Space Telescope are used to demonstrate our approach. We present methods for initial orbit determination and for the case of improving an a-priori established orbit descriptor. We discuss the suitability of this class of radar for wide-field space situational awareness and consider a SSA architecture that uses this class of radar to cue high-accuracy narrow field-of-view optical sensors as part of a wide-field high-accuracy system for SSA.

  9. Radar equations for modern radar

    CERN Document Server

    Barton, David K

    2012-01-01

    Based on the classic Radar Range-Performance Analysis from 1980, this practical volume extends that work to ensure applicability of radar equations to the design and analysis of modern radars. This unique book helps you identify what information on the radar and its environment is needed to predict detection range. Moreover, it provides equations and data to improve the accuracy of range calculations. You find detailed information on propagation effects, methods of range calculation in environments that include clutter, jamming and thermal noise, as well as loss factors that reduce radar perfo

  10. Radar Control Optimal Resource Allocation

    Science.gov (United States)

    2015-07-13

    Campaign as shown in Figure 7. This radar is an experimental frequency agile, high-resolution originally developed for the purpose of iceberg detection...Information Theory , Under Review 2015. [24] A. Pezeshki, A. Calderbank, W. Moran, and S. Howard, “Doppler resilient golay complemn- tary waveforms...IEEE Transactions on Information Theory , vol. 54, no. 9, pp. 4254–4266, 2008. [25] W. Dang, A. Pezeshki, S. Howard, B. Moran, and R. Calderbank

  11. Quantitative precipitation estimation in complex orography using quasi-vertical profiles of dual polarization radar variables

    Science.gov (United States)

    Montopoli, Mario; Roberto, Nicoletta; Adirosi, Elisa; Gorgucci, Eugenio; Baldini, Luca

    2017-04-01

    Weather radars are nowadays a unique tool to estimate quantitatively the rain precipitation near the surface. This is an important task for a plenty of applications. For example, to feed hydrological models, mitigate the impact of severe storms at the ground using radar information in modern warning tools as well as aid the validation studies of satellite-based rain products. With respect to the latter application, several ground validation studies of the Global Precipitation Mission (GPM) products have recently highlighted the importance of accurate QPE from ground-based weather radars. To date, a plenty of works analyzed the performance of various QPE algorithms making use of actual and synthetic experiments, possibly trained by measurement of particle size distributions and electromagnetic models. Most of these studies support the use of dual polarization variables not only to ensure a good level of radar data quality but also as a direct input in the rain estimation equations. Among others, one of the most important limiting factors in radar QPE accuracy is the vertical variability of particle size distribution that affects at different levels, all the radar variables acquired as well as rain rates. This is particularly impactful in mountainous areas where the altitudes of the radar sampling is likely several hundred of meters above the surface. In this work, we analyze the impact of the vertical profile variations of rain precipitation on several dual polarization radar QPE algorithms when they are tested a in complex orography scenario. So far, in weather radar studies, more emphasis has been given to the extrapolation strategies that make use of the signature of the vertical profiles in terms of radar co-polar reflectivity. This may limit the use of the radar vertical profiles when dual polarization QPE algorithms are considered because in that case all the radar variables used in the rain estimation process should be consistently extrapolated at the surface

  12. Soil moisture retrieval using ground based bistatic scatterometer data at X-band

    Science.gov (United States)

    Gupta, Dileep Kumar; Prasad, Rajendra; Kumar, Pradeep; Vishwakarma, Ajeet Kumar

    2017-02-01

    Several hydrological phenomenon and applications need high quality soil moisture information of the top Earth surface. The advent of technologies like bistatic scatterometer can retrieve soil moisture information with high accuracy and hence used in present study. The radar data is acquired by specially designed ground based bistatic scatterometer system in the specular direction of 20-70° incidence angles at steps of 5° for HH and VV polarizations. This study provides first time comprehensive evaluation of different machine learning algorithms for the retrieval of soil moisture using the X-band bistatic scatterometer measurements. The comparison of different artificial neural network (ANN) models such as back propagation artificial neural network (BPANN), radial basis function artificial neural network (RBFANN), generalized regression artificial neural network (GRANN) along with linear regression model (LRM) are used to estimate the soil moisture. The performance indices such as %Bias, Root Mean Squared Error (RMSE) and Nash-Sutcliffe Efficiency (NSE) are used to evaluate the performances of the machine learning techniques. Among different models employed in this study, the BPANN is found to have marginally higher performance in case of HH polarization while RBFANN is found suitable with VV polarization followed by GRANN and LRM. The results obtained are of considerable scientific and practical value to the wider scientific community for the number of practical applications and research studies in which radar datasets are used.

  13. Ground-based Optical Observations of Geophysical Phenomena: Aurora Borealis and Meteors

    Science.gov (United States)

    Samara, Marilia

    2010-10-01

    Advances in low-light level imaging technology have enabled significant improvements in the ground based study of geophysical phenomena. In this talk we focus on two such phenomena that occur in the Earth's ionosphere: aurorae and meteors. Imaging the aurora which is created by the interplay of the Earth's magnetosphere, ionosphere and atmosphere, provides a tool for remote sensing physical processes that are otherwise very difficult to study. By quantifying the intensities, scale sizes and lifetimes of auroral structures, we can gain significant insight into the physics behind the generation of the aurora and the interaction of the magnetosphere with the solar wind. Additionally, the combination of imaging with radars provides complimentary data and therefore more information than either method on its own. Meteor observations are a perfect example of this because the radar can accurately determine only the line-of-sight component of velocity, while imaging provides the direction of motion, the perpendicular velocity and brightness (a proxy for mass), therefore enabling a much more accurate determination of the full velocity vector and mass.

  14. Coupling Fine-Scale Root and Canopy Structure Using Ground-Based Remote Sensing

    Directory of Open Access Journals (Sweden)

    Brady S. Hardiman

    2017-02-01

    Full Text Available Ecosystem physical structure, defined by the quantity and spatial distribution of biomass, influences a range of ecosystem functions. Remote sensing tools permit the non-destructive characterization of canopy and root features, potentially providing opportunities to link above- and belowground structure at fine spatial resolution in functionally meaningful ways. To test this possibility, we employed ground-based portable canopy LiDAR (PCL and ground penetrating radar (GPR along co-located transects in forested sites spanning multiple stages of ecosystem development and, consequently, of structural complexity. We examined canopy and root structural data for coherence (i.e., correlation in the frequency of spatial variation at multiple spatial scales ≤10 m within each site using wavelet analysis. Forest sites varied substantially in vertical canopy and root structure, with leaf area index and root mass more becoming even vertically as forests aged. In all sites, above- and belowground structure, characterized as mean maximum canopy height and root mass, exhibited significant coherence at a scale of 3.5–4 m, and results suggest that the scale of coherence may increase with stand age. Our findings demonstrate that canopy and root structure are linked at characteristic spatial scales, which provides the basis to optimize scales of observation. Our study highlights the potential, and limitations, for fusing LiDAR and radar technologies to quantitatively couple above- and belowground ecosystem structure.

  15. GLAST and Ground-Based Gamma-Ray Astronomy

    Science.gov (United States)

    McEnery, Julie

    2008-01-01

    The launch of the Gamma-ray Large Area Space Telescope together with the advent of a new generation of ground-based gamma-ray detectors such as VERITAS, HESS, MAGIC and CANGAROO, will usher in a new era of high-energy gamma-ray astrophysics. GLAST and the ground based gamma-ray observatories will provide highly complementary capabilities for spectral, temporal and spatial studies of high energy gamma-ray sources. Joint observations will cover a huge energy range, from 20 MeV to over 20 TeV. The LAT will survey the entire sky every three hours, allowing it both to perform uniform, long-term monitoring of variable sources and to detect flaring sources promptly. Both functions complement the high-sensitivity pointed observations provided by ground-based detectors. Finally, the large field of view of GLAST will allow a study of gamma-ray emission on large angular scales and identify interesting regions of the sky for deeper studies at higher energies. In this poster, we will discuss the science returns that might result from joint GLAST/ground-based gamma-ray observations and illustrate them with detailed source simulations.

  16. GLAST and Ground-Based Gamma-Ray Astronomy

    Science.gov (United States)

    McEnery, Julie

    2008-01-01

    The launch of the Gamma-ray Large Area Space Telescope together with the advent of a new generation of ground-based gamma-ray detectors such as VERITAS, HESS, MAGIC and CANGAROO, will usher in a new era of high-energy gamma-ray astrophysics. GLAST and the ground based gamma-ray observatories will provide highly complementary capabilities for spectral, temporal and spatial studies of high energy gamma-ray sources. Joint observations will cover a huge energy range, from 20 MeV to over 20 TeV. The LAT will survey the entire sky every three hours, allowing it both to perform uniform, long-term monitoring of variable sources and to detect flaring sources promptly. Both functions complement the high-sensitivity pointed observations provided by ground-based detectors. Finally, the large field of view of GLAST will allow a study of gamma-ray emission on large angular scales and identify interesting regions of the sky for deeper studies at higher energies. In this poster, we will discuss the science returns that might result from joint GLAST/ground-based gamma-ray observations and illustrate them with detailed source simulations.

  17. Coordinated ground-based, low altitude satellite and Cluster observations on global and local scales during a transient post-noon sector excursion of the magnetospheric cusp

    DEFF Research Database (Denmark)

    Opgenoorth, H.J.; Lockwood, M.; Alcayde, D.

    2001-01-01

    in Canada, Greenland and Scandinavia. After an initial eastward and later poleward expansion of the flow-channel between 13:20 and 13:40 UT, the four Cluster spacecraft, and the field line footprints covered by the eastward looking scan cycle of the Sondre Stromfjord incoherent scatter radar were engulfed...... formed to the west and north of the radar. From a detailed analysis of the coordinated Cluster and ground-based data, it was found that this extraordinary transient convection pattern, indeed, had moved the cusp precipitation from its former pre-noon position into the late post-noon sector, allowing...

  18. Characterizing Olive Grove Canopies by Means of Ground-Based Hemispherical Photography and Spaceborne RADAR Data

    Directory of Open Access Journals (Sweden)

    Carmen Morillo

    2011-07-01

    Full Text Available One of the main strengths of active microwave remote sensing, in relation to frequency, is its capacity to penetrate vegetation canopies and reach the ground surface, so that information can be drawn about the vegetation and hydrological properties of the soil surface. All this information is gathered in the so called backscattering coefficient (s0. The subject of this research have been olive groves canopies, where which types of canopy biophysical variables can be derived by a specific optical sensor and then integrated into microwave scattering models has been investigated. This has been undertaken by means of hemispherical photographs and gap fraction procedures. Then, variables such as effective and true Leaf Area Indices have been estimated. Then, in order to characterize this kind of vegetation canopy, two models based on Radiative Transfer theory have been applied and analyzed. First, a generalized two layer geometry model made up of homogeneous layers of soil and vegetation has been considered. Then, a modified version of the Xu and Steven Water Cloud Model has been assessed integrating the canopy biophysical variables derived by the suggested optical procedure. The backscattering coefficients at various polarized channels have been acquired from RADARSAT 2 (C-band, with 38.5° incidence angle at the scene center. For the soil simulation, the best results have been reached using a Dubois scattering model and the VV polarized channel (r2 = 0.88. In turn, when effective LAI (LAIeff has been taken into account, the parameters of the scattering canopy model are better estimated (r2 = 0.89. Additionally, an inversion procedure of the vegetation microwave model with the adjusted parameters has been undertaken, where the biophysical values of the canopy retrieved by this methodology fit properly with field measured values.

  19. Tentative detection of clear-air turbulence using a ground-based Rayleigh lidar.

    Science.gov (United States)

    Hauchecorne, Alain; Cot, Charles; Dalaudier, Francis; Porteneuve, Jacques; Gaudo, Thierry; Wilson, Richard; Cénac, Claire; Laqui, Christian; Keckhut, Philippe; Perrin, Jean-Marie; Dolfi, Agnès; Cézard, Nicolas; Lombard, Laurent; Besson, Claudine

    2016-05-01

    Atmospheric gravity waves and turbulence generate small-scale fluctuations of wind, pressure, density, and temperature in the atmosphere. These fluctuations represent a real hazard for commercial aircraft and are known by the generic name of clear-air turbulence (CAT). Numerical weather prediction models do not resolve CAT and therefore provide only a probability of occurrence. A ground-based Rayleigh lidar was designed and implemented to remotely detect and characterize the atmospheric variability induced by turbulence in vertical scales between 40 m and a few hundred meters. Field measurements were performed at Observatoire de Haute-Provence (OHP, France) on 8 December 2008 and 23 June 2009. The estimate of the mean squared amplitude of bidimensional fluctuations of lidar signal showed excess compared to the estimated contribution of the instrumental noise. This excess can be attributed to atmospheric turbulence with a 95% confidence level. During the first night, data from collocated stratosphere-troposphere (ST) radar were available. Altitudes of the turbulent layers detected by the lidar were roughly consistent with those of layers with enhanced radar echo. The derived values of turbulence parameters Cn2 or CT2 were in the range of those published in the literature using ST radar data. However, the detection was at the limit of the instrumental noise and additional measurement campaigns are highly desirable to confirm these initial results. This is to our knowledge the first successful attempt to detect CAT in the free troposphere using an incoherent Rayleigh lidar system. The built lidar device may serve as a test bed for the definition of embarked CAT detection lidar systems aboard airliners.

  20. New-Measurement Techniques to Diagnose Charged Dust and Plasma Layers in the Near-Earth Space Environment Using Ground-Based Ionospheric Heating Facilities

    OpenAIRE

    Mahmoudian, Alireza

    2013-01-01

    Recently, experimental observations have shown that radar echoes from the irregularitysource region associated with mesospheric dusty space plasmas may be modulated by radio wave heating with ground-based ionospheric heating facilities. These experiments show great promise as a diagnostic for the associated dusty plasma in the Near-Earth Space Environment which is believed to have links to global change. This provides an alternative to more complicated and costly space-based observational app...

  1. Planetary Radar

    Science.gov (United States)

    Neish, Catherine D.; Carter, Lynn M.

    2015-01-01

    This chapter describes the principles of planetary radar, and the primary scientific discoveries that have been made using this technique. The chapter starts by describing the different types of radar systems and how they are used to acquire images and accurate topography of planetary surfaces and probe their subsurface structure. It then explains how these products can be used to understand the properties of the target being investigated. Several examples of discoveries made with planetary radar are then summarized, covering solar system objects from Mercury to Saturn. Finally, opportunities for future discoveries in planetary radar are outlined and discussed.

  2. Coded continuous wave meteor radar

    Science.gov (United States)

    Vierinen, Juha; Chau, Jorge L.; Pfeffer, Nico; Clahsen, Matthias; Stober, Gunter

    2016-03-01

    The concept of a coded continuous wave specular meteor radar (SMR) is described. The radar uses a continuously transmitted pseudorandom phase-modulated waveform, which has several advantages compared to conventional pulsed SMRs. The coding avoids range and Doppler aliasing, which are in some cases problematic with pulsed radars. Continuous transmissions maximize pulse compression gain, allowing operation at lower peak power than a pulsed system. With continuous coding, the temporal and spectral resolution are not dependent on the transmit waveform and they can be fairly flexibly changed after performing a measurement. The low signal-to-noise ratio before pulse compression, combined with independent pseudorandom transmit waveforms, allows multiple geographically separated transmitters to be used in the same frequency band simultaneously without significantly interfering with each other. Because the same frequency band can be used by multiple transmitters, the same interferometric receiver antennas can be used to receive multiple transmitters at the same time. The principles of the signal processing are discussed, in addition to discussion of several practical ways to increase computation speed, and how to optimally detect meteor echoes. Measurements from a campaign performed with a coded continuous wave SMR are shown and compared with two standard pulsed SMR measurements. The type of meteor radar described in this paper would be suited for use in a large-scale multi-static network of meteor radar transmitters and receivers. Such a system would be useful for increasing the number of meteor detections to obtain improved meteor radar data products.

  3. Scanning ARM Cloud Radar Handbook

    Energy Technology Data Exchange (ETDEWEB)

    Widener, K; Bharadwaj, N; Johnson, K

    2012-06-18

    The scanning ARM cloud radar (SACR) is a polarimetric Doppler radar consisting of three different radar designs based on operating frequency. These are designated as follows: (1) X-band SACR (X-SACR); (2) Ka-band SACR (Ka-SACR); and (3) W-band SACR (W-SACR). There are two SACRs on a single pedestal at each site where SACRs are deployed. The selection of the operating frequencies at each deployed site is predominantly determined by atmospheric attenuation at the site. Because RF attenuation increases with atmospheric water vapor content, ARM's Tropical Western Pacific (TWP) sites use the X-/Ka-band frequency pair. The Southern Great Plains (SGP) and North Slope of Alaska (NSA) sites field the Ka-/W-band frequency pair. One ARM Mobile Facility (AMF1) has a Ka/W-SACR and the other (AMF2) has a X/Ka-SACR.

  4. Pedestrian recognition using automotive radar sensors

    Science.gov (United States)

    Bartsch, A.; Fitzek, F.; Rasshofer, R. H.

    2012-09-01

    The application of modern series production automotive radar sensors to pedestrian recognition is an important topic in research on future driver assistance systems. The aim of this paper is to understand the potential and limits of such sensors in pedestrian recognition. This knowledge could be used to develop next generation radar sensors with improved pedestrian recognition capabilities. A new raw radar data signal processing algorithm is proposed that allows deep insights into the object classification process. The impact of raw radar data properties can be directly observed in every layer of the classification system by avoiding machine learning and tracking. This gives information on the limiting factors of raw radar data in terms of classification decision making. To accomplish the very challenging distinction between pedestrians and static objects, five significant and stable object features from the spatial distribution and Doppler information are found. Experimental results with data from a 77 GHz automotive radar sensor show that over 95% of pedestrians can be classified correctly under optimal conditions, which is compareable to modern machine learning systems. The impact of the pedestrian's direction of movement, occlusion, antenna beam elevation angle, linear vehicle movement, and other factors are investigated and discussed. The results show that under real life conditions, radar only based pedestrian recognition is limited due to insufficient Doppler frequency and spatial resolution as well as antenna side lobe effects.

  5. Realizing Tunable Inverse and Normal Doppler Shifts in Reconfigurable RF Metamaterials

    Science.gov (United States)

    Ran, Jia; Zhang, Yewen; Chen, Xiaodong; Fang, Kai; Zhao, Junfei; Sun, Yong; Chen, Hong

    2015-06-01

    The Doppler effect has well-established applications in astronomy, medicine, radar and metrology. Recently, a number of experimental demonstrations of the inverse Doppler effect have begun to appear. However, the inverse Doppler effect has never been observed on an electronically reconfigurable system with an external electromagnetic wave source at radio frequencies (RF) in experiment. Here we demonstrate an experimental observation of the inverse Doppler shift on an electronically reconfigurable RF metamaterial structure, which can exhibit anomalous dispersion, normal dispersion or a stop band, depending on an applied bias voltage. Either inverse or normal Doppler shift is realized by injecting an external RF signal into the electronically reconfigurable metamaterial, on which an electronically controllable moving reflective boundary is formed. The effective velocity of this boundary and the resulting frequency shift can be tuned over a wide range by a digital switching circuit. This work is expected to open up possibilities in applying the inverse Doppler effect in wireless communications, radar and satellite navigation.

  6. Multiple hypothesis clustering in radar plot extraction

    NARCIS (Netherlands)

    Huizing, A.G.; Theil, A.; Dorp, Ph. van; Ligthart, L.P.

    1995-01-01

    False plots and plots with inaccurate range and Doppler estimates may severely degrade the performance of tracking algorithms in radar systems. This paper describes how a multiple hypothesis clustering technique can be applied to mitigate the problems involved in plot extraction. The measures of

  7. Multiple hypothesis clustering in radar plot extraction

    NARCIS (Netherlands)

    Huizing, A.G.; Theil, A.; Dorp, Ph. van; Ligthart, L.P.

    1995-01-01

    False plots and plots with inaccurate range and Doppler estimates may severely degrade the performance of tracking algorithms in radar systems. This paper describes how a multiple hypothesis clustering technique can be applied to mitigate the problems involved in plot extraction. The measures of con

  8. Airborne Field Campaign Results of Ka-band Precipitation Measuring Radar in China%我国Ka频段降水测量雷达机载校飞试验结果

    Institute of Scientific and Technical Information of China (English)

    商建; 郭杨; 吴琼; 杨虎; 尹红刚

    2011-01-01

    conditions, observe simultaneously with ground-based radar and microwave radiometer and compare satellite-airplane-ground observation data, validate the functionality and performance of precipitation measuring radar, and explore data processing and retrieval algorithms of precipitation measuring radar. Numerous data are obtained from various instruments in the field campaign, including airborne precipitation measuring radar, ground-based weather radar, ground-based multi-channel microwave radiometer, GPS radiosonde, 10 GHz and 37 GHz radiometer, portable wind measuring device, and temperature measuring device. Initial analysis is accomplished with observation data obtained from BH-RM 2010. Observation results of Ka-band precipitation measuring radar working in pulse compression mode and short pulse mode are presented, which show clearly the vertical and horizontal structure of rainfall. Due to the radar different scan modes, resolutions, frequencies, and dynamic range, it's difficult to compare airborne radar data and ground-based radar data accurately, and the unstable attitude of the airplane makes the comparison more difficult. Spatial matching of Ka-band airborne radar data and Tianjin S-band ground-based Doppler radar data is carried out and detailed procedures are introduced. Quantitative indexes are further computed to indicate the observation consistency statistically. In rain retrieval algorithms, attenuation correction is a critical step. Using GPS radiosonde data, ground-based multi-channel microwave radiometer data and microwave radiative transfer model, the integrated attenuation of Ka-band radar is computed and attenuation correction is accomplished. The result is reasonable, which lays a basis for future rain retrieval. Data obtained by various instruments in the field campaign will be analyzed thoroughly, propelling development and rain rate retrieval of our spaceborne precipitation measuring radar.

  9. A Potential Integrated Multiwavelength Radar System at the Medicina Radiotelescopes

    Science.gov (United States)

    Montebugnoli, S.; Salerno, E.; Pupillo, G.; Pluchino, S.

    2009-03-01

    Ground-based radars provide a powerful tool for detection, tracking and identification of the space debris fragments orbiting around Earth at different altitudes. The Medicina Radioastronomical Station is an Italian radio observation facility that is here proposed as receiving part of a bistatic radar system for detecting and tracking space debris at different orbital regions (from Low Earth Orbits up to Geostationary Earth Orbits).

  10. Comparing Aerosol Retrievals from Ground-Based Instruments at the Impact-Pm Field Campaign

    Science.gov (United States)

    Kupinski, M.; Bradley, C. L.; Kalashnikova, O. V.; Xu, F.; Diner, D. J.; Clements, C. B.; Camacho, C.

    2016-12-01

    Detection of aerosol types, components having different size and chemical composition, over urban areas is important for understanding their impact on health and climate. In particular, sustained contact with size-differentiated airborne particulate matter: PM10 and PM2.5 can lead to adverse health effects such as asthma attacks, heart and lung diseases, and premature mortality. Multi-angular polarimetric measurements have been advocated in recent years as an additional tool to better understand and retrieve the aerosol properties needed for improved predictions of aerosol impart on air quality and climate. We deployed the ground-based Multiangle SpectroPolarimetric Imager (GroundMSPI) for accurate spectropolarimetric and radiance measurements co-located with the AERONET CIMEL sun photometer and a Halo Doppler 18 m resolution lidar from San José State University at the Garland-Fresno Air Quality supersite in Fresno, CA on July 7 during the Imaging Polarimetric Assessment and Characterization of Tropospheric Particulate Matter (ImPACT-PM) field experiment. GroundMSPI sampled the atmospheric scattering phase function in and 90 degrees out of the principal plane every 15 minutes in an automated manner, utilizing the 2-axis gimbal mount in elevation and azimuth. The goal of this work is verify atmospheric measurement of GroundMSPI with the coincident CIMEL sun photometer and ground-based lidar. Diffuse-sky radiance measurements of GroundMSPI are compared with the CIMEL sun photometer throughout the day. AERONET aerosol parameters such as size, shape, and index of refraction as well as lidar aerosol extinction profiles will be used in a forward radiative transfer model to compare with GroundMSPI observations and optimize these parameters to best match GroundMSPI data.

  11. Ground-based observations of Kepler asteroseismic targets

    CERN Document Server

    Uytterhoeven, K; Southworth, J; Randall, S; Ostensen, R; Molenda-Zakowicz, J; Marconi, M; Kurtz, D W; Kiss, L; Gutierrez-Soto, J; Frandsen, S; De Cat, P; Bruntt, H; Briquet, M; Zhang, X B; Telting, J H; Steslicki, M; Ripepi, V; Pigulski, A; Paparo, M; Oreiro, R; Choong, Ngeow Chow; Niemczura, E; Nemec, J; Narwid, A; Mathias, P; Martin-Ruiz, S; Lehman, H; Kopacki, G; Karoff, C; Jackiewicz, J; Henden, A A; Handler, G; Grigachene, A; Green, E M; Garrido, R; Machado, L Fox; Debosscher, J; Creevey, O L; Catanzaro, G; Bognar, Z; Biazzo, K; Bernabei, S

    2010-01-01

    We present the ground-based activities within the different working groups of the Kepler Asteroseismic Science Consortium (KASC). The activities aim at the systematic characterization of the 5000+ KASC targets, and at the collection of ground-based follow-up time-series data of selected promising Kepler pulsators. So far, 35 different instruments at 30 telescopes on 22 different observatories in 12 countries are in use, and a total of more than 530 observing nights has been awarded. (Based on observations made with the Isaac Newton Telescope, William Herschel Telescope, Nordic Optical Telescope, Telescopio Nazionale Galileo, Mercator Telescope (La Palma, Spain), and IAC-80 (Tenerife, Spain). Also based on observations taken at the observatories of Sierra Nevada, San Pedro Martir, Vienna, Xinglong, Apache Point, Lulin, Tautenburg, Loiano, Serra la Nave, Asiago, McDonald, Skinakas, Pic du Midi, Mauna Kea, Steward Observatory, Bialkow Observatory of the Wroclaw University, Piszkesteto Mountain Station, Observato...

  12. Ground-based Nuclear Detonation Detection (GNDD) Technology Roadmap

    Energy Technology Data Exchange (ETDEWEB)

    Casey, Leslie A.

    2014-01-13

    This GNDD Technology Roadmap is intended to provide guidance to potential researchers and help management define research priorities to achieve technology advancements for ground-based nuclear explosion monitoring science being pursued by the Ground-based Nuclear Detonation Detection (GNDD) Team within the Office of Nuclear Detonation Detection in the National Nuclear Security Administration (NNSA) of the U.S. Department of Energy (DOE). Four science-based elements were selected to encompass the entire scope of nuclear monitoring research and development (R&D) necessary to facilitate breakthrough scientific results, as well as deliver impactful products. Promising future R&D is delineated including dual use associated with the Comprehensive Nuclear-Test-Ban Treaty (CTBT). Important research themes as well as associated metrics are identified along with a progression of accomplishments, represented by a selected bibliography, that are precursors to major improvements to nuclear explosion monitoring.

  13. Open-loop GPS signal tracking at low elevation angles from a ground-based observation site

    Science.gov (United States)

    Beyerle, Georg; Zus, Florian

    2017-01-01

    A 1-year data set of ground-based GPS signal observations aiming at geometric elevation angles below +2° is analysed. Within the "GLESER" measurement campaign about 2600 validated setting events were recorded by the "OpenGPS" open-loop tracking receiver at an observation site located at 52.3808° N, 13.0642° E between January and December 2014. The measurements confirm the feasibility of open-loop signal tracking down to geometric elevation angles of -1 to -1.5° extending the corresponding closed-loop tracking range by up to 1°. The study is based on the premise that observations of low-elevation events by a ground-based receiver may serve as test cases for space-based radio occultation measurements, even if the latter proceed at a significantly faster temporal scale. The results support the conclusion that the open-loop Doppler model has negligible influence on the derived carrier frequency profile for strong signal-to-noise density ratios above about 30 dB Hz. At lower signal levels, however, the OpenGPS receiver's dual-channel design, which tracks the same signal using two Doppler models differing by 10 Hz, uncovers a notable bias. The repeat patterns of the GPS orbit traces in terms of azimuth angle reveal characteristic signatures in both signal amplitude and Doppler frequency with respect to the topography close to the observation site. Mean vertical refractivity gradients, extracted from ECMWF meteorological fields, correlate weakly to moderately with observed signal amplitude fluctuations at geometric elevation angles between +1 and +2°. Results from multiple phase screen simulations support the interpretation that these fluctuations are at least partly produced by atmospheric multipath; at negative elevation angles diffraction at the ground surface seems to contribute.

  14. Investigating mixed phase clouds using a synergy of ground based remote sensing measurements

    Science.gov (United States)

    Gierens, Rosa; Kneifel, Stefan; Löhnert, Ulrich

    2017-04-01

    Low level mixed phase clouds occur frequently in the Arctic, and can persist from hours to several days. However, the processes that lead to the commonality and persistence of these clouds are not well understood. The aim of our work is to get a more detailed understanding of the dynamics of and the processes in Arctic mixed phase clouds using a combination of instruments operating at the AWIPEV station in Svalbard. In addition, an aircraft campaign collecting in situ measurements inside mixed phase clouds above the station is planned for May-June 2017. The in situ data will be used for developing and validating retrievals for microphysical properties from Doppler cloud radar measurements. Once observational data for cloud properties is obtained, it can be used for evaluating model performance, for studies combining modeling and observational approaches, and eventually lead to developing model parameterizations of mixed phase microphysics. To describe the low-level mixed phase clouds, and the atmospheric conditions in which they occur, we present a case study of a persistent mixed phase cloud observed above the AWIPEV station. In the frame of the Arctic Amplification: Climate Relevant Atmospheric and Surface Processes and Feedback Mechanisms ((AC)3) -project, a millimeter wavelength cloud radar was installed at the site in June 2016. The high vertical (4 m in the lowest layer) and temporal (2.5 sec) resolution allows for a detailed description of the structure of the cloud. In addition to radar reflectivity and mean vertical velocity, we also utilize the higher moments of the Doppler spectra, such as skewness and kurtosis. To supplement the radar measurements, a ceilometer is used to detect liquid layers inside the cloud. Liquid water path and integrated water vapor are estimated using a microwave radiometer, which together with soundings can also provide temperature and humidity profiles in the lower troposphere. Moreover, a three-dimensional wind field is be

  15. Ground-Based Calibration Of A Microwave Landing System

    Science.gov (United States)

    Kiriazes, John J.; Scott, Marshall M., Jr.; Willis, Alfred D.; Erdogan, Temel; Reyes, Rolando

    1996-01-01

    System of microwave instrumentation and data-processing equipment developed to enable ground-based calibration of microwave scanning-beam landing system (MSBLS) at distances of about 500 to 1,000 ft from MSBLS transmitting antenna. Ensures accuracy of MSBLS near touchdown point, without having to resort to expense and complex logistics of aircraft-based testing. Modified versions prove useful in calibrating aircraft instrument landing systems.

  16. Coded continuous wave meteor radar

    Science.gov (United States)

    Chau, J. L.; Vierinen, J.; Pfeffer, N.; Clahsen, M.; Stober, G.

    2016-12-01

    The concept of a coded continuous wave specular meteor radar (SMR) is described. The radar uses a continuously transmitted pseudorandom phase-modulated waveform, which has several advantages compared to conventional pulsed SMRs. The coding avoids range and Doppler aliasing, which are in some cases problematic with pulsed radars. Continuous transmissions maximize pulse compression gain, allowing operation at lower peak power than a pulsed system. With continuous coding, the temporal and spectral resolution are not dependent on the transmit waveform and they can be fairly flexibly changed after performing a measurement. The low signal-to-noise ratio before pulse compression, combined with independent pseudorandom transmit waveforms, allows multiple geographically separated transmitters to be used in the same frequency band simultaneously without significantly interfering with each other. Because the same frequency band can be used by multiple transmitters, the same interferometric receiver antennas can be used to receive multiple transmitters at the same time. The principles of the signal processing are discussed, in addition to discussion of several practical ways to increase computation speed, and how to optimally detect meteor echoes. Measurements from a campaign performed with a coded continuous wave SMR are shown and compared with two standard pulsed SMR measurements. The type of meteor radar described in this paper would be suited for use in a large-scale multi-static network of meteor radar transmitters and receivers. Such a system would be useful for increasing the number of meteor detections to obtain improved meteor radar data products, such as wind fields. This type of a radar would also be useful for over-the-horizon radar, ionosondes, and observations of field-aligned-irregularities.

  17. Ground-Based Lidar for Atmospheric Boundary Layer Ozone Measurements

    Science.gov (United States)

    Kuang, Shi; Newchurch, Michael J.; Burris, John; Liu, Xiong

    2013-01-01

    Ground-based lidars are suitable for long-term ozone monitoring as a complement to satellite and ozonesonde measurements. However, current ground-based lidars are unable to consistently measure ozone below 500 m above ground level (AGL) due to both engineering issues and high retrieval sensitivity to various measurement errors. In this paper, we present our instrument design, retrieval techniques, and preliminary results that focus on the high-temporal profiling of ozone within the atmospheric boundary layer (ABL) achieved by the addition of an inexpensive and compact mini-receiver to the previous system. For the first time, to the best of our knowledge, the lowest, consistently achievable observation height has been extended down to 125 m AGL for a ground-based ozone lidar system. Both the analysis and preliminary measurements demonstrate that this lidar measures ozone with a precision generally better than 10% at a temporal resolution of 10 min and a vertical resolution from 150 m at the bottom of the ABL to 550 m at the top. A measurement example from summertime shows that inhomogeneous ozone aloft was affected by both surface emissions and the evolution of ABL structures.

  18. Ground-based lidar for atmospheric boundary layer ozone measurements.

    Science.gov (United States)

    Kuang, Shi; Newchurch, Michael J; Burris, John; Liu, Xiong

    2013-05-20

    Ground-based lidars are suitable for long-term ozone monitoring as a complement to satellite and ozonesonde measurements. However, current ground-based lidars are unable to consistently measure ozone below 500 m above ground level (AGL) due to both engineering issues and high retrieval sensitivity to various measurement errors. In this paper, we present our instrument design, retrieval techniques, and preliminary results that focus on the high-temporal profiling of ozone within the atmospheric boundary layer (ABL) achieved by the addition of an inexpensive and compact mini-receiver to the previous system. For the first time, to the best of our knowledge, the lowest, consistently achievable observation height has been extended down to 125 m AGL for a ground-based ozone lidar system. Both the analysis and preliminary measurements demonstrate that this lidar measures ozone with a precision generally better than ±10% at a temporal resolution of 10 min and a vertical resolution from 150 m at the bottom of the ABL to 550 m at the top. A measurement example from summertime shows that inhomogeneous ozone aloft was affected by both surface emissions and the evolution of ABL structures.

  19. Overview and Initial Results from the DEEPWAVE Airborne and Ground-Based Measurement Program

    Science.gov (United States)

    Fritts, D. C.

    2015-12-01

    The deep-propagating gravity wave experiment (DEEPWAVE) was performed on and over New Zealand, the Tasman Sea, and the Southern Ocean with core airborne measurements extending from 5 June to 21 July 2014 and supporting ground-based measurements spanning a longer interval. The NSF/NCAR GV employed standard flight-level measurements and new airborne lidar and imaging measurements of gravity waves (GWs) from sources at lower altitudes throughout the stratosphere and into the mesosphere and lower thermosphere (MLT). The new GV lidars included a Rayleigh lidar measuring atmospheric density and temperature from ~20-60 km and a sodium resonance lidar measuring sodium density and temperature at ~75-105 km. An airborne Advanced Mesosphere Temperature Mapper (AMTM) and two IR "wing" cameras imaged the OH airglow temperature and/or intensity fields extending ~900 km across the GV flight track. The DLR Falcon was equipped with its standard flight-level instruments and an aerosol Doppler lidar measuring radial winds below the Falcon. DEEPWAVE also included extensive ground-based measurements in New Zealand, Tasmania, and Southern Ocean Islands. DEEPWAVE performed 26 GV flights and 13 Falcon flights, and ground-based measurements occurred whether or not the aircraft were flying. Collectively, many diverse cases of GW forcing, propagation, refraction, and dissipation spanning altitudes of 0-100 km were observed. Examples include strong mountain wave (MW) forcing and breaking in the lower and middle stratosphere, weak MW forcing yielding MW penetration into the MLT having very large amplitudes and momentum fluxes, MW scales at higher altitudes ranging from ~10-250 km, large-scale trailing waves from orography refracting into the polar vortex and extending to high altitudes, GW generation by deep convection, large-scale GWs arising from jet stream sources, and strong MWs in the MLT arising from strong surface flow over a small island. DEEPWAVE yielded a number of surprises, among

  20. A range-rate extraction unit for determining Doppler effect

    Science.gov (United States)

    1970-01-01

    Active ranging technique devised for VHF or S-band radar systems divides target Doppler frequency by counter-generated number that is proportional to transmitting frequency, thus producing target velocity data in terms of speed and distance relative to target transponder.

  1. On polarimetric radar signatures of deep convection for model evaluation: columns of specific differential phase observed during MC3E

    Energy Technology Data Exchange (ETDEWEB)

    van Lier-Walqui, Marcus; Fridlind, Ann; Ackerman, Andrew S; Collis, Scott; Helmus, Jonathan; MacGorman, Donald R; North, Kirk; Kollias, Pavlos; Posselt, Derek J

    2016-02-01

    The representation of deep convection in general circulation models is in part informed by cloud-resolving models (CRMs) that function at higher spatial and temporal resolution; however, recent studies have shown that CRMs often fail at capturing the details of deep convection updrafts. With the goal of providing constraint on CRM simulation of deep convection updrafts, ground-based remote sensing observations are analyzed and statistically correlated for four deep convection events observed during the Midlatitude Continental Convective Clouds Experiment (MC3E). Since positive values of specific differential phase observed above the melting level are associated with deep convection updraft cells, so-called columns are analyzed using two scanning polarimetric radars in Oklahoma: the National Weather Service Vance WSR-88D (KVNX) and the Department of Energy C-band Scanning Atmospheric Radiation Measurement (ARM) Precipitation Radar (C-SAPR). KVNX and C-SAPR volumes and columns are then statistically correlated with vertical winds retrieved via multi-Doppler wind analysis, lightning flash activity derived from the Oklahoma Lightning Mapping Array, and KVNX differential reflectivity . Results indicate strong correlations of volume above the melting level with updraft mass flux, lightning flash activity, and intense rainfall. Analysis of columns reveals signatures of changing updraft properties from one storm event to another as well as during event evolution. Comparison of to shows commonalities in information content of each, as well as potential problems with associated with observational artifacts.

  2. RADAR CLIMATOLOGY OF HAIL IN THE APUSENI MOUNTAINS

    Directory of Open Access Journals (Sweden)

    N. MAIER

    2011-03-01

    Full Text Available Radar Climatology of hail in the Apuseni Mountains A newmethod for the assessment of large areas with frequent occurrence of hail in a finespatial resolution and its application for the Apuseni Mountains and their adjacentareas is presented. Due to the fine tempo-spatial resolution of the radar detection,the creation of radar climatology of the areas where the hail production conditionsare determined is imposed. With the help of two Doppler radars at Oradea andBobohalma, the area of interest is examined and spatial maps of the relativefrequency of hail contained in the clouds are made. Composite maps are made (bysuperimposing the two Doppler radar images from Oradea and Bobohalma of theareas in which clouds with hail of different sizes occur.

  3. Assessing collision risk for birds and bats : radar survey

    Energy Technology Data Exchange (ETDEWEB)

    Brunet, R. [Genivar SEC, Sherbrooke, PQ (Canada)

    2010-07-01

    This PowerPoint presentation described some of the inventories and instrumentation available for monitoring winged fauna in and around wind farms. In addition to visual observations, bird calls and songs can be recorded to determine the amount and different types of birds located at wind farm sites. Radio-telemetry devices are also used to evaluate bird activities, and nest searches are conducted to determine the amount of eggs or young birds that will soon add to the bird population. Between 90 and 100 percent of birds and bats migrate at night. Acoustic radar, Doppler radar, and maritime surveillance radar instruments are used to monitor night-time activities in wind farm locations. Doppler radar is also used to detect bird and bat migration corridors. Screen-shots of various radar interfaces were presented. tabs., figs.

  4. System-level view of geospace dynamics: Challenges for high-latitude ground-based observations

    Science.gov (United States)

    Donovan, E.

    2014-12-01

    Increasingly, research programs including GEM, CEDAR, GEMSIS, GO Canada, and others are focusing on how geospace works as a system. Coupling sits at the heart of system level dynamics. In all cases, coupling is accomplished via fundamental processes such as reconnection and plasma waves, and can be between regions, energy ranges, species, scales, and energy reservoirs. Three views of geospace are required to attack system level questions. First, we must observe the fundamental processes that accomplish the coupling. This "observatory view" requires in situ measurements by satellite-borne instruments or remote sensing from powerful well-instrumented ground-based observatories organized around, for example, Incoherent Scatter Radars. Second, we need to see how this coupling is controlled and what it accomplishes. This demands quantitative observations of the system elements that are being coupled. This "multi-scale view" is accomplished by networks of ground-based instruments, and by global imaging from space. Third, if we take geospace as a whole, the system is too complicated, so at the top level we need time series of simple quantities such as indices that capture important aspects of the system level dynamics. This requires a "key parameter view" that is typically provided through indices such as AE and DsT. With the launch of MMS, and ongoing missions such as THEMIS, Cluster, Swarm, RBSP, and ePOP, we are entering a-once-in-a-lifetime epoch with a remarkable fleet of satellites probing processes at key regions throughout geospace, so the observatory view is secure. With a few exceptions, our key parameter view provides what we need. The multi-scale view, however, is compromised by space/time scales that are important but under-sampled, combined extent of coverage and resolution that falls short of what we need, and inadequate conjugate observations. In this talk, I present an overview of what we need for taking system level research to its next level, and how

  5. Parametric Sparse Representation and Its Applications to Radar Sensing

    Directory of Open Access Journals (Sweden)

    Li Gang

    2016-02-01

    Full Text Available Sparse signal processing has been utilized to the area of radar sensing. Due to the presence of unknown factors such as the motion of the targets of interest and the error of the radar trajectory, a predesigned dictionary cannot provide the optimally spare representation of the actual radar signals. This paper will introduce a method called parametric sparse representation, which is a special case of dictionary learning and can dynamically learn the unknown factors during the radar sensing and achieve the optimally sparse representation of radar signals. This paper will also introduce the applications of parametric sparse representation to Inverse Synthetic Aperture Radar imaging (ISAR imaging, Synthetic Aperture Radar imaging (SAR autofocusing and target recognition based on micro-Doppler effect.

  6. Radar reconnaissance of near-Earth asteroids

    Science.gov (United States)

    Ostro, Steven J.; Giorgini, Jon D.; Benner, Lance A. M.

    2007-05-01

    Radar is a uniquely powerful source of information about near-Earth asteroid (NEA) physical properties and orbits. Measurements of the distribution of echo power in time delay (range) and Doppler frequency (radial velocity) constitute two-dimensional images that can provide spatial resolution finer than a decameter. The best radar images reveal geologic details, including craters and blocks. Radar wavelengths (13 cm at Arecibo, 3.5 cm at Goldstone) are sensitive to the bulk density (a joint function of mineralogy and porosity) and the degree of decimeter-scale structural complexity of the uppermost meter or so of the surface. Radar can determine the masses of binary NEAs via Kepler's third law and of solitary NEAs via measurement of the Yarkovsky acceleration. With adequate orientational coverage, a sequence of images can be used to construct a three-dimensional model, to define the rotation state, to determine the distribution of radar surface properties, and to constrain the internal density distribution. As of mid 2006, radar has detected echoes from 193 NEAs, of which 107 are designated Potentially Hazardous Asteroids. Radar has revealed both stony and metallic objects, principal-axis and non-principal-axis rotators, smooth and extremely rough surfaces, objects that appear to be monolithic fragments and objects likely to be nearly strengthless gravitational aggregates, spheroids and highly elongated shapes, contact-binary shapes, and binary systems. Radar can add centuries to the interval over which close Earth approaches can accurately be predicted, significantly refining collision probability estimates compared to those based on optical astrometry alone. If a small body is on course for a collision with Earth in this century, delay-Doppler radar echoes could almost immediately let us recognize this by distinguishing between an impact trajectory and a near miss, and would dramatically reduce the difficulty and cost of any effort to prevent the collision.

  7. 新型多普勒成像激光雷达原理设计与仿真%Schematic design and simulation of new Doppler imaging laser radar

    Institute of Scientific and Technical Information of China (English)

    姜成昊; 杨进华; 张丽娟; 李祥

    2014-01-01

    采用相干多普勒测量手段获取目标面型变化信息具有明显的优势。基于激光多普勒效应,设计一套多普勒成像激光雷达实验系统,同时引入APFFT全相位测相处理思路对外差信号进行时频分析,抑制频谱泄露,减小噪声对测量结果的影响,获取高测量精度信号时频曲线。在MATLAB软件simulink交互式仿真集成环境中进行过程仿真,证明其可以实现对扫描空间高分辨率、高精度的成像。实验结果表明:该系统能够较好还原被测目标表面特性,为激光雷达实现对目标高分辨率与高灵敏度成像提出新的解决思路。%The means of coherent Doppler has obvious advantages to obtain the target range change. Based on laser Doppler effect, designed a set of imaging Doppler lidar experimental system. Introduction all phase measurement phase treatment consideration to do time-frequency analysis for heterodyne signal, restraining spectral leakage and reducing the impact of noise on the measurement results, a high measurement accuracy signal frequency curve will be acquired. The process simulation in the simulink interactive simulation integration environment which comes with MATLAB software, to prove it can achieve higher resolution, high precision imaging for scan space. The experimental results show that the system was able to restore the surface of target feature preferably. It plays a promoting role in high-resolution and high-sensitivity imaging of the target for lidar.

  8. Augmenting WFIRST Microlensing with a Ground-Based Telescope Network

    Science.gov (United States)

    Zhu, Wei; Gould, Andrew

    2016-06-01

    Augmenting the Wide Field Infrared Survey Telescope (WFIRST) microlensing campaigns with intensive observations from a ground-based network of wide-field survey telescopes would have several major advantages. First, it would enable full two-dimensional (2-D) vector microlens parallax measurements for a substantial fraction of low-mass lenses as well as planetary and binary events that show caustic crossing features. For a significant fraction of the free-floating planet (FFP) events and all caustic-crossing planetary/binary events, these 2-D parallax measurements directly lead to complete solutions (mass, distance, transverse velocity) of the lens object (or lens system). For even more events, the complementary ground-based observations will yield 1-D parallax measurements. Together with the 1-D parallaxes from WFIRST alone, they can probe the entire mass range M > M_Earth. For luminous lenses, such 1-D parallax measurements can be promoted to complete solutions (mass, distance, transverse velocity) by high-resolution imaging. This would provide crucial information not only about the hosts of planets and other lenses, but also enable a much more precise Galactic model. Other benefits of such a survey include improved understanding of binaries (particularly with low mass primaries), and sensitivity to distant ice-giant and gas-giant companions of WFIRST lenses that cannot be detected by WFIRST itself due to its restricted observing windows. Existing ground-based microlensing surveys can be employed if WFIRST is pointed at lower-extinction fields than is currently envisaged. This would come at some cost to the event rate. Therefore the benefits of improved characterization of lenses must be weighed against these costs.

  9. Moving target detection for frequency agility radar by sparse reconstruction

    Science.gov (United States)

    Quan, Yinghui; Li, YaChao; Wu, Yaojun; Ran, Lei; Xing, Mengdao; Liu, Mengqi

    2016-09-01

    Frequency agility radar, with randomly varied carrier frequency from pulse to pulse, exhibits superior performance compared to the conventional fixed carrier frequency pulse-Doppler radar against the electromagnetic interference. A novel moving target detection (MTD) method is proposed for the estimation of the target's velocity of frequency agility radar based on pulses within a coherent processing interval by using sparse reconstruction. Hardware implementation of orthogonal matching pursuit algorithm is executed on Xilinx Virtex-7 Field Programmable Gata Array (FPGA) to perform sparse optimization. Finally, a series of experiments are performed to evaluate the performance of proposed MTD method for frequency agility radar systems.

  10. Standardization to Boost the Sustainable Development of MetstarWeather Radar

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The standardization of China's New Generation of Doppler Weather Radar (hereinafter referred to as CINRAD radar) is an important technical support for the development of CINRAD radar and also an important indicator of the industry development level.Beijing Metstar Radar Co.,Ltd.(hereinafter refened to as Metstar),as a navigator of CINRAD radar,has,for a long time,attached great importance to standardization to enhance the enterprise's operation & management level,improve the quality of products,cultivate the image of brand,train the backbone personnel and facilitate the sustainable development of weather radar.

  11. Architectural design of a ground-based deep-space optical reception antenna

    Science.gov (United States)

    Kerr, E. L.

    1989-01-01

    An architectural design of a ground-based antenna (telescope) for receiving optical communications from deep space is presented. Physical and optical parameters, and their effect on the performance and cost considerations, are described. The channel capacity of the antenna is 100 kbits/s from Saturn and 5 Mbits/s from Mars. A novel sunshade is designed to permit optical communication even when the deep-space laser source is as close to the sun as 12 deg. Inserts in the tubes of the sunshade permit operations at solar elongations as small as 6 or 3 deg. The Nd:YAG source laser and the Fraunhofer filter (a narrow-band predetection optical filter) are tuned to match the Doppler shifts of the source and background. A typical Saturn-to-earth data link can reduce its source power requirement from 8.2 W to 2 W of laser output by employing a Fraunhofer filter instead of a conventional multilayer dielectric filter.

  12. FINDING EXTRATERRESTRIAL LIFE USING GROUND-BASED HIGH-DISPERSION SPECTROSCOPY

    Energy Technology Data Exchange (ETDEWEB)

    Snellen, I. A. G.; Le Poole, R.; Brogi, M.; Birkby, J. [Leiden Observatory, Leiden University, Postbus 9513, 2300-RA Leiden (Netherlands); De Kok, R. J. [SRON, Sorbonnelaan 2, 3584-CA Utrecht (Netherlands)

    2013-02-20

    Exoplanet observations promise one day to unveil the presence of extraterrestrial life. Atmospheric compounds in strong chemical disequilibrium would point to large-scale biological activity just as oxygen and methane do in the Earth's atmosphere. The cancellation of both the Terrestrial Planet Finder and Darwin missions means that it is unlikely that a dedicated space telescope to search for biomarker gases in exoplanet atmospheres will be launched within the next 25 years. Here we show that ground-based telescopes provide a strong alternative for finding biomarkers in exoplanet atmospheres through transit observations. Recent results on hot Jupiters show the enormous potential of high-dispersion spectroscopy to separate the extraterrestrial and telluric signals, making use of the Doppler shift of the planet. The transmission signal of oxygen from an Earth-twin orbiting a small red dwarf star is only a factor of three smaller than that of carbon monoxide recently detected in the hot Jupiter {tau} Booetis b, albeit such a star will be orders of magnitude fainter. We show that if Earth-like planets are common, the planned extremely large telescopes can detect oxygen within a few dozen transits. Ultimately, large arrays of dedicated flux-collector telescopes equipped with high-dispersion spectrographs can provide the large collecting area needed to perform a statistical study of life-bearing planets in the solar neighborhood.

  13. A ground-based measurement of the relativistic beaming effect in a detached double WD binary

    CERN Document Server

    Shporer, Avi; Steinfadt, Justin D R; Bildsten, Lars; Howell, Steve B; Mazeh, Tsevi

    2010-01-01

    We report on the first ground-based measurement of the relativistic beaming effect (aka Doppler boosting). We observed the beaming effect in the detached, non-interacting eclipsing double white dwarf (WD) binary NLTT 11748. Our observations were motivated by the system's high mass ratio and low luminosity ratio, leading to a large beaming-induced variability amplitude at the orbital period of 5.6 hr. We observed the system during 3 nights at the 2.0m Faulkes Telescope North with the SDSS-g' filter, and fitted the data simultaneously for the beaming, ellipsoidal and reflection effects. Our fitted relative beaming amplitude is (3.0 +/- 0.4) x 10^(-3), consistent with the expected amplitude from a blackbody spectrum given the photometric primary radial velocity amplitude and effective temperature. This result is a first step in testing the relation between the photometric beaming amplitude and the spectroscopic radial velocity amplitude in NLTT 11748 and similar systems. We did not identify any variability due t...

  14. Architectural design of a ground-based deep-space optical reception antenna

    Science.gov (United States)

    Kerr, E. L.

    1989-01-01

    An architectural design of a ground-based antenna (telescope) for receiving optical communications from deep space is presented. Physical and optical parameters, and their effect on the performance and cost considerations, are described. The channel capacity of the antenna is 100 kbits/s from Saturn and 5 Mbits/s from Mars. A novel sunshade is designed to permit optical communication even when the deep-space laser source is as close to the sun as 12 deg. Inserts in the tubes of the sunshade permit operations at solar elongations as small as 6 or 3 deg. The Nd:YAG source laser and the Fraunhofer filter (a narrow-band predetection optical filter) are tuned to match the Doppler shifts of the source and background. A typical Saturn-to-earth data link can reduce its source power requirement from 8.2 W to 2 W of laser output by employing a Fraunhofer filter instead of a conventional multilayer dielectric filter.

  15. Quantifying the effect of riming on snowfall using ground-based observations

    Science.gov (United States)

    Moisseev, Dmitri; von Lerber, Annakaisa; Tiira, Jussi

    2017-04-01

    Ground-based observations of ice particle size distribution and ensemble mean density are used to quantify the effect of riming on snowfall. The rime mass fraction is derived from these measurements by following the approach that is used in a single ice-phase category microphysical scheme proposed for the use in numerical weather prediction models. One of the characteristics of the proposed scheme is that the prefactor of a power law relation that links mass and size of ice particles is determined by the rime mass fraction, while the exponent does not change. To derive the rime mass fraction, a mass-dimensional relation representative of unrimed snow is also determined. To check the validity of the proposed retrieval method, the derived rime mass fraction is converted to the effective liquid water path that is compared to microwave radiometer observations. Since dual-polarization radar observations are often used to detect riming, the impact of riming on dual-polarization radar variables is studied for differential reflectivity measurements. It is shown that the relation between rime mass fraction and differential reflectivity is ambiguous, other factors such as change in median volume diameter need also be considered. Given the current interest on sensitivity of precipitation to aerosol pollution, which could inhibit riming, the importance of riming for surface snow accumulation is investigated. It is found that riming is responsible for 5% to 40% of snowfall mass. The study is based on data collected at the University of Helsinki field station in Hyytiälä during U.S. Department of Energy Biogenic Aerosols Effects on Clouds and Climate (BAECC) field campaign and the winter 2014/2015. In total 22 winter storms were analyzed, and detailed analysis of two events is presented to illustrate the study.

  16. The STACEE-32 Ground Based Gamma-ray Detector

    CERN Document Server

    Hanna, D S; Boone, L M; Chantell, M C; Conner, Z; Covault, C E; Dragovan, M; Fortin, P; Gregorich, D T; Hinton, J A; Mukherjee, R; Ong, R A; Oser, S; Ragan, K; Scalzo, R A; Schütte, D R; Theoret, C G; Tümer, T O; Williams, D A; Zweerink, J A

    2002-01-01

    We describe the design and performance of the Solar Tower Atmospheric Cherenkov Effect Experiment detector in its initial configuration (STACEE-32). STACEE is a new ground-based gamma ray detector using the atmospheric Cherenkov technique. In STACEE, the heliostats of a solar energy research array are used to collect and focus the Cherenkov photons produced in gamma-ray induced air showers. The large Cherenkov photon collection area of STACEE results in a gamma-ray energy threshold below that of previous detectors.

  17. The STACEE Ground-Based Gamma-Ray Detector

    CERN Document Server

    Gingrich, D M; Bramel, D; Carson, J; Covault, C E; Fortin, P; Hanna, D S; Hinton, J A; Jarvis, A; Kildea, J; Lindner, T; Müller, C; Mukherjee, R; Ong, R A; Ragan, K; Scalzo, R A; Theoret, C G; Williams, D A; Zweerink, J A

    2005-01-01

    We describe the design and performance of the Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE) in its complete configuration. STACEE uses the heliostats of a solar energy research facility to collect and focus the Cherenkov photons produced in gamma-ray induced air showers. The light is concentrated onto an array of photomultiplier tubes located near the top of a tower. The large Cherenkov photon collection area of STACEE results in a gamma-ray energy threshold below that of previous ground-based detectors. STACEE is being used to observe pulsars, supernova remnants, active galactic nuclei, and gamma-ray bursts.

  18. Research on target accuracy for ground-based lidar

    Science.gov (United States)

    Zhu, Ling; Shi, Ruoming

    2009-05-01

    In ground based Lidar system, the targets are used in the process of registration, georeferencing for point cloud, and also can be used as check points. Generally, the accuracy of capturing the flat target center is influenced by scanning range and scanning angle. In this research, the experiments are designed to extract accuracy index of the target center with 0-90°scan angles and 100-195 meter scan ranges using a Leica HDS3000 laser scanner. The data of the experiments are listed in detail and the related results are analyzed.

  19. Basics and first experiments demonstrating isolation improvements in the agile polarimetric FM-CW radar – PARSAX

    NARCIS (Netherlands)

    Krasnov, O.A.; Babur, G.P.; Wang, Z.; Ligthart, L.P.; Van der Zwan, F.

    2010-01-01

    The article describes the IRCTR PARSAX radar system, the S-band high-resolution Doppler polarimetric frequency modulated continuous wave (FM-CW) radar with dual-orthogonal sounding signals, which has the possibility to measure all elements of the radar target polarization scattering matrix

  20. MSFC Doppler Lidar Science experiments and operations plans for 1981 airborne test flight

    Science.gov (United States)

    Fichtl, G. H.; Bilbro, J. W.; Kaufman, J. W.

    1981-01-01

    The flight experiment and operations plans for the Doppler Lidar System (DLS) are provided. Application of DLS to the study of severe storms and local weather penomena is addressed. Test plans involve 66 hours of flight time. Plans also include ground based severe storm and local weather data acquisition.

  1. Ground-Based Global Positioning System (GPS) Meteorology Integrated Precipitable Water Vapor (IPW)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Ground-Based Global Positioning System (GPS) Meteorology Integrated Precipitable Water Vapor (IPW) data set measures atmospheric water vapor using ground-based...

  2. Statistical Studies of Ground-Based Optical Lightning Signatures

    Science.gov (United States)

    Hunt, C. R.; Nemzek, R. J.; Suszcynsky, D. M.

    2005-12-01

    Most extensive optical studies of lightning have been conducted from orbit, and the statistics of events collected from earth are relatively poorly documented. The time signatures of optical power measured in the presence of clouds are inevitably affected by scattering,which can distort the signatures by extending and delaying the amplitude profile in time. We have deployed two all-sky photodiode detectors, one in New Mexico and one in Oklahoma, which are gathering data alongside electric field change monitors as part of the LANL EDOTX Great Plains Array. Preliminary results show that the photodiode is sensitive to approximately 50% or more of RF events detected at ranges of up to 30 km, and still has some sensitivity at ranges in excess of 60 km (distances determined by the EDOTX field-change array). The shapes of events within this range were assessed, with focus on rise time, width, peak power, and their correlation to corresponding electric field signatures, and these are being compared with published on-orbit and ground-based data. Initial findings suggest a mean characteristic width (ratio of total detected optical energy to peak power) of 291 +/- 12 microseconds and a mean delay between the RF signal peak and optical peak of 121 +/- 17 microseconds. These values fall between prior ground-based measurements of direct return stroke emissions, and scattering-dominated on-orbit measurements. This work will promote better understanding of the correspondence between radio and optical measurements of lightning.

  3. Micro-Doppler Ambiguity Resolution Based on Short-Time Compressed Sensing

    Directory of Open Access Journals (Sweden)

    Jing-bo Zhuang

    2015-01-01

    Full Text Available When using a long range radar (LRR to track a target with micromotion, the micro-Doppler embodied in the radar echoes may suffer from ambiguity problem. In this paper, we propose a novel method based on compressed sensing (CS to solve micro-Doppler ambiguity. According to the RIP requirement, a sparse probing pulse train with its transmitting time random is designed. After matched filtering, the slow-time echo signals of the micromotion target can be viewed as randomly sparse sampling of Doppler spectrum. Select several successive pulses to form a short-time window and the CS sensing matrix can be built according to the time stamps of these pulses. Then performing Orthogonal Matching Pursuit (OMP, the unambiguous micro-Doppler spectrum can be obtained. The proposed algorithm is verified using the echo signals generated according to the theoretical model and the signals with micro-Doppler signature produced using the commercial electromagnetic simulation software FEKO.

  4. Project ORION: Orbital Debris Removal Using Ground-Based Sensors and Lasers

    Science.gov (United States)

    Campbell, J. W.

    1996-01-01

    About 100,000 pieces of 1 to 10-cm debris in low-Earth orbit are too small to track reliably but large enough to cripple or destroy spacecraft. The ORION team studied the feasibility of removing the debris with ground-based laser impulses. Photoablation experiments were surveyed and applied to likely debris materials. Laser intensities needed for debris orbit modification call for pulses on the order of lOkJ or continuous wave lasers on the order of 1 MW. Adaptive optics are necessary to correct for atmospheric turbulence. Wavelength and pulse duration windows were found that limit beam degradation due to nonlinear atmospheric processes. Debris can be detected and located to within about 10 microrads with existing radar and passive optical technology. Fine targeting would be accomplished with laser illumination, which might also be used for detection. Bistatic detection with communications satellites may also be possible. We recommend that existing technology be used to demonstrate the concept at a loss of about $20 million. We calculate that an installation to clear altitudes up to 800 km of 1 to 10-cm debris over 2 years of operation would cost about $80 million. Clearing altitudes up to 1,500 km would take about 3 years and cost about $160 million.

  5. Ground-based remote sensing scheme for monitoring aerosol–cloud interactions

    Directory of Open Access Journals (Sweden)

    K. Sarna

    2015-11-01

    Full Text Available A method for continuous observation of aerosol–cloud interactions with ground-based remote sensing instruments is presented. The main goal of this method is to enable the monitoring of cloud microphysical changes due to the changing aerosol concentration. We use high resolution measurements from lidar, radar and radiometer which allow to collect and compare data continuously. This method is based on a standardised data format from Cloudnet and can be implemented at any observatory where the Cloudnet data set is available. Two example study cases were chosen from the Atmospheric Radiation Measurement (ARM Program deployment at Graciosa Island, Azores, Portugal in 2009 to present the method. We show the Pearson Product–Moment Correlation Coefficient, r, and the Coefficient of Determination, r2 for data divided into bins of LWP, each of 10 g m−2. We explain why the commonly used way of quantity aerosol cloud interactions by use of an ACI index (ACIr,τ = dln re,τ/dlnα is not the best way of quantifying aerosol–cloud interactions.

  6. Evidence of rock slope breathing using ground-based InSAR

    Science.gov (United States)

    Rouyet, Line; Kristensen, Lene; Derron, Marc-Henri; Michoud, Clément; Blikra, Lars Harald; Jaboyedoff, Michel; Lauknes, Tom Rune

    2017-07-01

    Ground-Based Interferometric Synthetic Aperture Radar (GB-InSAR) campaigns were performed in summer 2011 and 2012 in the Romsdalen valley (Møre & Romsdal county, western Norway) in order to assess displacements on Mannen/Børa rock slope. Located 1 km northwest, a second GB-InSAR system continuously monitors the large Mannen rockslide. The availability of two GB-InSAR positions creates a wide coverage of the rock slope, including a slight dataset overlap valuable for validation. A phenomenon of rock slope breathing is detected in a remote and hard-to-access area in mid-slope. Millimetric upward displacements are recorded in August 2011. Analysis of 2012 GB-InSAR campaign, combined with the large dataset from the continuous station, shows that the slope is affected by inflation/deflation phenomenon between 5 and 10 mm along the line-of-sight. The pattern is not homogenous in time and inversions of movement have a seasonal recurrence. These seasonal changes are confirmed by satellite InSAR observations and can possibly be caused by hydrogeological variations. In addition, combination of GB-InSAR results, in situ measurements and satellite InSAR analyses contributes to a better overview of movement distribution over the whole area.

  7. Differential doppler heterodyning technique

    DEFF Research Database (Denmark)

    Lading, Lars

    1971-01-01

    Measuring velocity without disturbing the moving object is possible by use of the laser doppler heterodyning technique. Theoretical considerations on the doppler shift show that the antenna property of the photodetector can solve an apparent conflict between two different ways of calculating...... the detected doppler frequency. It is found that the doppler frequency for this particular setup is independent of the direction of detection. Investigations of the signal-to-noise ratio (SNR) show that the maximum SNR-considering the optical setup-is obtained by measuring the frequency difference between two...

  8. Doppler Lidar for Wind Measurements on Venus

    Science.gov (United States)

    Singh, Upendra N.; Emmitt, George D.; Yu, Jirong; Kavaya, Michael J.

    2010-01-01

    NASA Langley Research Center has a long history of developing 2-micron laser transmitter for wind sensing. With support from NASA Laser Risk Reduction Program (LRRP) and Instrument Incubator Program (IIP), NASA Langley Research Center has developed a state-of-the-art compact lidar transceiver for a pulsed coherent Doppler lidar system for wind measurement. The transmitter portion of the transceiver employs the high-pulse-energy, Ho:Tm:LuLiF, partially conductively cooled laser technology developed at NASA Langley. The transceiver is capable of 250 mJ pulses at 10 Hz. It is very similar to the technology envisioned for coherent Doppler lidar wind measurements from Earth and Mars orbit. The transceiver is coupled to the large optics and data acquisition system in the NASA Langley VALIDAR mobile trailer. The large optics consists of a 15-cm off-axis beam expanding telescope, and a full-hemispheric scanner. Vertical and horizontal vector winds are measured, as well as relative backscatter. The data acquisition system employs frequency domain velocity estimation and pulse accumulation. It permits real-time display of the processed winds and archival of all data. This lidar system was recently deployed at Howard University facility in Beltsville, Mary-land, along with other wind lidar systems. Coherent Doppler wind lidar ground-based wind measurements and comparisons with other sensors will be presented. A simulation and data product for wind measurement at Venus will be presented.

  9. Estimates of the Planet Yield from Ground-Based High-Contrast Imaging Observations as a Function of Stellar Mass

    CERN Document Server

    Crepp, Justin R

    2011-01-01

    We use Monte Carlo simulations to estimate the number of extrasolar planets that are directly detectable in the solar-neighborhood using current and forthcoming high-contrast imaging instruments. Our calculations take into account the important factors that govern the likelihood for imaging a planet, including the statistical properties of nearby stars, correlations between star and planet properties, observational effects, and selection criteria. We consider several different ground-based surveys and express the resulting yields as a function of stellar mass. Selecting targets based on their youth and visual brightness, we find that strong correlations between star mass and planet properties are required to reproduce high-contrast imaging results to date. Using the most recent empirical findings for the occurrence rate of planets from RV surveys, our simulations indicate that extrapolation of the Doppler planet population to separations accessible to high-contrast instruments provides excellent agreement bet...

  10. Low-Frequency Gravitational Wave Searches Using Spacecraft Doppler Tracking

    Directory of Open Access Journals (Sweden)

    Armstrong J. W.

    2006-01-01

    Full Text Available This paper discusses spacecraft Doppler tracking, the current-generation detector technology used in the low-frequency (~millihertz gravitational wave band. In the Doppler method the earth and a distant spacecraft act as free test masses with a ground-based precision Doppler tracking system continuously monitoring the earth-spacecraft relative dimensionless velocity $2 Delta v/c = Delta u/ u_0$, where $Delta u$ is the Doppler shift and $ u_0$ is the radio link carrier frequency. A gravitational wave having strain amplitude $h$ incident on the earth-spacecraft system causes perturbations of order $h$ in the time series of $Delta u/ u_0$. Unlike other detectors, the ~1-10 AU earth-spacecraft separation makes the detector large compared with millihertz-band gravitational wavelengths, and thus times-of-flight of signals and radio waves through the apparatus are important. A burst signal, for example, is time-resolved into a characteristic signature: three discrete events in the Doppler time series. I discuss here the principles of operation of this detector (emphasizing transfer functions of gravitational wave signals and the principal noises to the Doppler time series, some data analysis techniques, experiments to date, and illustrations of sensitivity and current detector performance. I conclude with a discussion of how gravitational wave sensitivity can be improved in the low-frequency band.

  11. Doppler Ambiguity Resolution Based on Random Sparse Probing Pulses

    Directory of Open Access Journals (Sweden)

    Yunjian Zhang

    2015-01-01

    Full Text Available A novel method for solving Doppler ambiguous problem based on compressed sensing (CS theory is proposed in this paper. A pulse train with the random and sparse transmitting time is transmitted. The received signals after matched filtering can be viewed as randomly sparse sampling from the traditional fixed-pulse repetition frequency (PRF echo signals. The whole target echo could be reconstructed via CS recovery algorithms. Through refining the sensing matrix, which is equivalent to increase the sampling frequency of target characteristic, the Doppler unambiguous range is enlarged. In particular, Complex Approximate Message Passing (CAMP algorithm is developed to estimate the unambiguity Doppler frequency. Cramer-Rao lower bound expressions are derived for the frequency. Numerical simulations validate the effectiveness of the proposed method. Finally, compared with traditional methods, the proposed method only requires transmitting a few sparse probing pulses to achieve a larger Doppler frequency unambiguous range and can also reduce the consumption of the radar time resources.

  12. Ground Based GPS Phase Measurements for Atmospheric Sounding

    Science.gov (United States)

    2016-06-14

    based GPS observations for the correction of radar observations. 6 REFERENCES Alber, C., R. Ware, C. Rocken, and J. Braun, A new method for sensing ...rocken@ucar.edu Award #: N00014-97-1-0258 LONG-TERM GOAL The goal is to develop GPS remote sensing techniques to determine atmospheric signal delay and...agrees best with the observations in a least squares sense is selected. The corresponding refractivity profile is then selected. • We tested this

  13. Coordinated ground-based, low altitude satellite and Cluster observations on global and local scales during a transient post-noon sector excursion of the magnetospheric cusp

    Directory of Open Access Journals (Sweden)

    H. J. Opgenoorth

    Full Text Available On 14 January 2001, the four Cluster spacecraft passed through the northern magnetospheric mantle in close conjunction to the EISCAT Svalbard Radar (ESR and approached the post-noon dayside magnetopause over Green-land between 13:00 and 14:00 UT. During that interval, a sudden reorganisation of the high-latitude dayside convection pattern occurred after 13:20 UT, most likely caused by a direction change of the Solar wind magnetic field. The result was an eastward and poleward directed flow-channel, as monitored by the SuperDARN radar network and also by arrays of ground-based magnetometers in Canada, Greenland and Scandinavia. After an initial eastward and later poleward expansion of the flow-channel between 13:20 and 13:40 UT, the four Cluster spacecraft, and the field line footprints covered by the eastward looking scan cycle of the Söndre Strömfjord incoherent scatter radar were engulfed by cusp-like precipitation with transient magnetic and electric field signatures. In addition, the EISCAT Svalbard Radar detected strong transient effects of the convection reorganisation, a poleward moving precipitation, and a fast ion flow-channel in association with the auroral structures that suddenly formed to the west and north of the radar. From a detailed analysis of the coordinated Cluster and ground-based data, it was found that this extraordinary transient convection pattern, indeed, had moved the cusp precipitation from its former pre-noon position into the late post-noon sector, allowing for the first and quite unexpected encounter of the cusp by the Cluster spacecraft. Our findings illustrate the large amplitude of cusp dynamics even in response to moderate solar wind forcing. The global ground-based data proves to be an invaluable tool to monitor the dynamics and width of the affected magnetospheric regions.

    Key words. Magnetospheric cusp, ionosphere, reconnection, convection flow-channel, Cluster, ground-based observations

  14. The STACEE Ground-Based Gamma-ray Observatory

    Science.gov (United States)

    Ragan, Ken

    2002-04-01

    The Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE) is a ground-based instrument designed to study astrophysical sources of gamma rays in the energy range from 50 to 500 GeV using an array of heliostat mirrors at the National Solar Thermal Test Facility in New Mexico. The mirrors collect Cherenkov light generated by gamma-ray air showers and concentrate it onto cameras composed of photomultiplier tubes. The STACEE instrument is now complete, and uses a total of 64 heliostats. Prototype instruments, using smaller numbers of heliostats, have previously detected gamma emission from both the Crab Nebula and the Active Galactic Nucleus Mrk421. The complete instrument has a lower threshold -- approximately 50 GeV -- than those prototypes due to superior triggering and electronics, including flash ADCs for every channel.We will discuss the performance of the complete instrument in its first full season of operation, and present preliminary results of selected observations.

  15. Atmospheric contamination for CMB ground-based observations

    CERN Document Server

    Errard, J; Akiba, Y; Arnold, K; Atlas, M; Baccigalupi, C; Barron, D; Boettger, D; Borrill, J; Chapman, S; Chinone, Y; Cukierman, A; Delabrouille, J; Dobbs, M; Ducout, A; Elleflot, T; Fabbian, G; Feng, C; Feeney, S; Gilbert, A; Goeckner-Wald, N; Halverson, N W; Hasegawa, M; Hattori, K; Hazumi, M; Hill, C; Holzapfel, W L; Hori, Y; Inoue, Y; Jaehnig, G C; Jaffe, A H; Jeong, O; Katayama, N; Kaufman, J; Keating, B; Kermish, Z; Keskitalo, R; Kisner, T; Jeune, M Le; Lee, A T; Leitch, E M; Leon, D; Linder, E; Matsuda, F; Matsumura, T; Miller, N J; Myers, M J; Navaroli, M; Nishino, H; Okamura, T; Paar, H; Peloton, J; Poletti, D; Puglisi, G; Rebeiz, G; Reichardt, C L; Richards, P L; Ross, C; Rotermund, K M; Schenck, D E; Sherwin, B D; Siritanasak, P; Smecher, G; Stebor, N; Steinbach, B; Stompor, R; Suzuki, A; Tajima, O; Takakura, S; Tikhomirov, A; Tomaru, T; Whitehorn, N; Wilson, B; Yadav, A; Zahn, O

    2015-01-01

    Atmosphere is one of the most important noise sources for ground-based Cosmic Microwave Background (CMB) experiments. By increasing optical loading on the detectors, it amplifies their effective noise, while its fluctuations introduce spatial and temporal correlations between detected signals. We present a physically motivated 3d-model of the atmosphere total intensity emission in the millimeter and sub-millimeter wavelengths. We derive an analytical estimate for the correlation between detectors time-ordered data as a function of the instrument and survey design, as well as several atmospheric parameters such as wind, relative humidity, temperature and turbulence characteristics. Using numerical computation, we examine the effect of each physical parameter on the correlations in the time series of a given experiment. We then use a parametric-likelihood approach to validate the modeling and estimate atmosphere parameters from the POLARBEAR-I project first season data set. We compare our results to previous st...

  16. Observational Selection Effects with Ground-based Gravitational Wave Detectors

    CERN Document Server

    Chen, Hsin-Yu; Vitale, Salvatore; Holz, Daniel E; Katsavounidis, Erik

    2016-01-01

    Ground-based interferometers are not perfectly all-sky instruments, and it is important to account for their behavior when considering the distribution of detected events. In particular, the LIGO detectors are most sensitive to sources above North America and the Indian Ocean and, as the Earth rotates, the sensitive regions are swept across the sky. However, because the detectors do not acquire data uniformly over time, there is a net bias on detectable sources' right ascensions. Both LIGO detectors preferentially collect data during their local night; it is more than twice as likely to be local midnight than noon when both detectors are operating. We discuss these selection effects and how they impact LIGO's observations and electromagnetic follow-up. Beyond galactic foregrounds associated with seasonal variations, we find that equatorial observatories can access over $80\\%$ of the localization probability, while mid-latitudes will access closer to $70\\%$. Facilities located near the two LIGO sites can obser...

  17. Progress in the ULTRA 1-m ground-based telescope

    Science.gov (United States)

    Romeo, Robert C.; Martin, Robert N.; Twarog, Bruce; Anthony-Twarog, Barbara; Taghavi, Ray; Hale, Rick; Etzel, Paul; Fesen, Rob; Shawl, Steve

    2006-06-01

    We present the technical status of the Ultra Lightweight Telescope for Research in Astronomy (ULTRA) program. The program is a 3-year Major Research Instrumentation (MRI) program funded by NSF. The MRI is a collaborative effort involving Composite Mirror Applications, Inc. (CMA), University of Kansas, San Diego State University and Dartmouth College. Objectives are to demonstrate the feasibility of carbon fiber reinforced plastic (CFRP) composite mirror technology for ground-based optical telescopes. CMA is spearheading the development of surface replication techniques to produce the optics, fabricating the 1m glass mandrel, and constructing the optical tube assembly (OTA). Presented will be an overview and status of the 1-m mandrel fabrication, optics development, telescope design and CFRP telescope fabrication by CMA for the ULTRA Telescope.

  18. Identification of rainy periods from ground based microwave radiometry

    Directory of Open Access Journals (Sweden)

    Ada Vittoria Bosisio

    2012-03-01

    Full Text Available In this paper the authors present the results of a study aiming at detecting rainy data in measurements collected by a dual band ground-based radiometer. The proposed criterion is based on the ratio of the brightness temperatures observed in the 20-30 GHz band without need of any ancillary information. A major result obtained from the probability density of the ratio computed over one month of data is the identification of threshold values between clear sky, cloudy sky and rainy sky, respectively. A linear fit performed by using radiometric data and concurrent rain gauge measurements shows a correlation coefficient equal to 0.56 between the temperature ratio and the observed precipitation.

  19. Optical vortex coronagraphs on ground-based telescopes

    CERN Document Server

    Jenkins, Charles

    2007-01-01

    The optical vortex coronagraph is potentially a remarkably effective device, at least for an ideal unobstructed telescope. Most ground-based telescopes however suffer from central obscuration and also have to operate through the aberrations of the turbulent atmosphere. This note analyzes the performance of the optical vortex in these circumstances and compares to some other designs, showing that it performs similarly in this situation. There is a large class of coronagraphs of this general type, and choosing between them in particular applications depends on details of performance at small off-axis distances and uniformity of response in the focal plane. Issues of manufacturability to the necessary tolerances are also likely to be important.

  20. Observational Selection Effects with Ground-based Gravitational Wave Detectors

    Science.gov (United States)

    Chen, Hsin-Yu; Essick, Reed; Vitale, Salvatore; Holz, Daniel; Katsavounidis, Erik

    2017-01-01

    Ground-based interferometers are not perfectly all-sky instruments, and it is important to account for their behavior when considering the distribution of detected events. In particular, the LIGO detectors are most sensitive to sources above North America and the Indian Ocean and, as the Earth rotates, the sensitive regions are swept across the sky. However, because the detectors do not acquire data uniformly over time, there is a net bias on detectable sources' right ascensions. Both LIGO detectors preferentially collect data during their local night; it is more than twice as likely to be local midnight than noon when both detectors are operating. We discuss these selection effects and how they impact LIGO's observations and electromagnetic follow-up. These effects can inform electromagnetic follow-up activities and optimization, including the possibility of directing observations even before gravitational-wave events occur.

  1. Unique cell culture systems for ground based research

    Science.gov (United States)

    Lewis, Marian L.

    1990-01-01

    The horizontally rotating fluid-filled, membrane oxygenated bioreactors developed at NASA Johnson for spacecraft applications provide a powerful tool for ground-based research. Three-dimensional aggregates formed by cells cultured on microcarrier beads are useful for study of cell-cell interactions and tissue development. By comparing electron micrographs of plant seedlings germinated during Shuttle flight 61-C and in an earth-based rotating bioreactor it is shown that some effects of microgravity are mimicked. Bioreactors used in the UAH Bioreactor Laboratory will make it possible to determine some of the effects of altered gravity at the cellular level. Bioreactors can be valuable for performing critical, preliminary-to-spaceflight experiments as well as medical investigations such as in vitro tumor cell growth and chemotherapeutic drug response; the enrichment of stem cells from bone marrow; and the effect of altered gravity on bone and muscle cell growth and function and immune response depression.

  2. Spatial-angular modeling of ground-based biaxial lidar

    Science.gov (United States)

    Agishev, Ravil R.

    1997-10-01

    Results of spatial-angular LIDAR modeling based on an efficiency criterion introduced are represented. Their analysis shows that a low spatial-angular efficiency of traditional VIS and NIR systems is a main cause of a low S/BR ratio at the photodetector input. It determines the considerable measurements errors and the following low accuracy of atmospheric optical parameters retrieval. As we have shown, the most effective protection against intensive sky background radiation for ground-based biaxial LIDAR's consist in forming of their angular field according to spatial-angular efficiency criterion G. Some effective approaches to high G-parameter value achievement to achieve the receiving system optimization are discussed.

  3. Tendinopathy and Doppler activity

    DEFF Research Database (Denmark)

    Boesen, M I; Koenig, M J; Torp-Pedersen, S

    2006-01-01

    Intratendinous Doppler activity has been interpreted as an equivalent of neovessels in the Achilles tendon and as a sign of tendinosis (AT).......Intratendinous Doppler activity has been interpreted as an equivalent of neovessels in the Achilles tendon and as a sign of tendinosis (AT)....

  4. Ultrasonic colour Doppler imaging

    DEFF Research Database (Denmark)

    Evans, David H.; Jensen, Jørgen Arendt; Nielsen, Michael Bachmann

    2011-01-01

    Ultrasonic colour Doppler is an imaging technique that combines anatomical information derived using ultrasonic pulse-echo techniques with velocity information derived using ultrasonic Doppler techniques to generate colour-coded maps of tissue velocity superimposed on grey-scale images of tissue ...

  5. Radar based autonomous sensor module

    Science.gov (United States)

    Styles, Tim

    2016-10-01

    Most surveillance systems combine camera sensors with other detection sensors that trigger an alert to a human operator when an object is detected. The detection sensors typically require careful installation and configuration for each application and there is a significant burden on the operator to react to each alert by viewing camera video feeds. A demonstration system known as Sensing for Asset Protection with Integrated Electronic Networked Technology (SAPIENT) has been developed to address these issues using Autonomous Sensor Modules (ASM) and a central High Level Decision Making Module (HLDMM) that can fuse the detections from multiple sensors. This paper describes the 24 GHz radar based ASM, which provides an all-weather, low power and license exempt solution to the problem of wide area surveillance. The radar module autonomously configures itself in response to tasks provided by the HLDMM, steering the transmit beam and setting range resolution and power levels for optimum performance. The results show the detection and classification performance for pedestrians and vehicles in an area of interest, which can be modified by the HLDMM without physical adjustment. The module uses range-Doppler processing for reliable detection of moving objects and combines Radar Cross Section and micro-Doppler characteristics for object classification. Objects are classified as pedestrian or vehicle, with vehicle sub classes based on size. Detections are reported only if the object is detected in a task coverage area and it is classified as an object of interest. The system was shown in a perimeter protection scenario using multiple radar ASMs, laser scanners, thermal cameras and visible band cameras. This combination of sensors enabled the HLDMM to generate reliable alerts with improved discrimination of objects and behaviours of interest.

  6. Ultrasonic colour Doppler imaging

    DEFF Research Database (Denmark)

    Evans, David H; Jensen, Jørgen Arendt; Nielsen, Michael Bachmann

    2011-01-01

    anatomy. The most common use of the technique is to image the movement of blood through the heart, arteries and veins, but it may also be used to image the motion of solid tissues such as the heart walls. Colour Doppler imaging is now provided on almost all commercial ultrasound machines, and has been......Ultrasonic colour Doppler is an imaging technique that combines anatomical information derived using ultrasonic pulse-echo techniques with velocity information derived using ultrasonic Doppler techniques to generate colour-coded maps of tissue velocity superimposed on grey-scale images of tissue...... vectors. This review briefly introduces the principles behind colour Doppler imaging and describes some clinical applications. It then describes the basic components of conventional colour Doppler systems and the methods used to derive velocity information from the ultrasound signal. Next, a number of new...

  7. An Observational Study of a Prefrontal Convective Rainband Using Tamex Single-and Dual-Doppler Data

    Science.gov (United States)

    1991-01-01

    integration from the surface. Other Doppler studies, e.g., Chong and Testud (1983), Lin et al. 37 (1986), etc, also showed similiar results. 4.3 Variational...Atmos. Sci., 39, 258- 279. Chong, M., and J. Testud , 1983: Three-Dimensional Wind Field Analysis from Dual-Doppler Radar Data. Part III: The Boundary

  8. Phase correlator reduces mm-wave radar cost

    Science.gov (United States)

    Weiss, R., Sr.; Hobbs, P.; Locatelli, J.

    1986-03-01

    A technique involving the IC storage of magnetron phase for reference has been developed to make possible the use of the low-cost efficient magnetron in obtaining phase coherent signals for pulse Doppler radar. In the new external coherence method, the recorded random midpulse-region phase is compared with the frequency of the echo allowing Doppler information, free of phase noise, to be extracted. The gated magnetron was tested at Ka-band in a 35-GHz radar, and good agreement with the CP-4 5.5 GHz radar was shown. With good accuracy down to 10 cm/s, the present system, especially in the mm-wave region, has important applications to meteorological and military radar.

  9. Sentinel-1 and ground-based sensors for a continuous monitoring of the Corvara landslide kinematic (South Tirol, Italy)

    Science.gov (United States)

    Schlögel, Romy; Darvishi, Mehdi; Cuozzo, Giovanni; Kofler, Christian; Rutzinger, Martin; Zieher, Thomas; Toschi, Isabella; Remondino, Fabio

    2017-04-01

    Sentinel-1 mission allows us to have Synthetic Aperture Radar (SAR) acquisitions over large areas every 6 days with spatial resolution of 20 m. This new open-source generation of satellites has enhanced the capabilities for continuously studying earth surface changes. Over the past two decades, several studies have demonstrated the potential of Differential Synthetic Aperture Radar Interferometry (DInSAR) for detecting and quantifying land surface deformation. DInSAR limitations and challenges are linked to the SAR properties and the field conditions (especially in Alpine environments) leading to spatial and temporal decorrelation of the SAR signal. High temporal decorrelation can be caused by changes in vegetation (particularly in non-urban areas), atmospheric conditions or high ground surface velocity. In this study, kinematics of the complex and vegetated Corvara landslide, situated in Val Badia (South Tirol, Italy), are monitored by a network of 3 permanent and 13 monthly Differential Global Positioning System (DGPS) stations. The slope displacement rates are found to be highly unsteady and reach several meters a year. This analysis focuses on evaluating the limitations of Sentinel-1 imagery processed with Small Baseline Subset (SBAS) technique in comparison to ground-based measurements for assessing the landslide kinematic linked to meteorological conditions. Selecting some particular acquisitions, coherence thresholds and unwrapping processes gives various results in terms of reliability and accuracy supporting the understanding of the landslide velocity field. The evolution of the coherence and phase signals are studied according to the changing field conditions and the monitored ground-based displacements. DInSAR deformation maps and residual topographic heights are finally compared with difference of high resolution Digital Elevation Models at local scale. This research is conducted within the project LEMONADE (http://lemonade.mountainresearch.at) funded

  10. The interdependence of continental warm cloud properties derived from unexploited solar background signal in ground-based lidar measurements

    Directory of Open Access Journals (Sweden)

    J. C. Chiu

    2014-04-01

    Full Text Available We have extensively analysed the interdependence between cloud optical depth, droplet effective radius, liquid water path (LWP and geometric thickness for stratiform warm clouds using ground-based observations. In particular, this analysis uses cloud optical depths retrieved from untapped solar background signal that is previously unwanted and needs to be removed in most lidar applications. Combining these new optical depth retrievals with radar and microwave observations at the Atmospheric Radiation Measurement (ARM Climate Research Facility in Oklahoma during 2005–2007, we have found that LWP and geometric thickness increase and follow a power-law relationship with cloud optical depth regardless of the presence of drizzle; LWP and geometric thickness in drizzling clouds can be generally 20–40% and at least 10% higher than those in non-drizzling clouds, respectively. In contrast, droplet effective radius shows a negative correlation with optical depth in drizzling clouds, while it increases with optical depth and reaches an asymptote of 10 μm in non-drizzling clouds. This asymptotic behaviour in non-drizzling clouds is found in both droplet effective radius and optical depth, making it possible to use simple thresholds of optical depth, droplet size, or a combination of these two variables for drizzle delineation. This paper demonstrates a new way to enhance ground-based cloud observations and drizzle delineations using existing lidar networks.

  11. Radar detection

    CERN Document Server

    DiFranco, Julius

    2004-01-01

    This book presents a comprehensive tutorial exposition of radar detection using the methods and techniques of mathematical statistics. The material presented is as current and useful to today's engineers as when the book was first published by Prentice-Hall in 1968 and then republished by Artech House in 1980. The book is divided into six parts.

  12. ACCELERATION AMBIGUITY FUNCTION OF RADAR SIGNALS AND ITS APPLICATION

    Institute of Scientific and Technical Information of China (English)

    Zhao Hongzhong; Zhou Jianxiong; Li Weimin; Fu Qiang

    2003-01-01

    High acceleration of radar targets is analyzed using Acceleration Ambiguity Function (AAF). The acceleration resolution based on AAF is defined. The AAF and acceleration resolution of rectangle pulse signal are derivated and the conclusion that its acceleration resolution is in inverse proportion with the square of its duration is drawn. In the end, these conclusions are applied to the parameter designing and performance evaluation for a certain type of pulse Doppler radar.

  13. Reconciling Ground-Based and Space-Based Estimates of the Frequency of Occurrence and Radiative Effect of Clouds around Darwin, Australia

    Energy Technology Data Exchange (ETDEWEB)

    Protat, Alain; Young, Stuart; McFarlane, Sally A.; L' Ecuyer, Tristan; Mace, Gerald G.; Comstock, Jennifer M.; Long, Charles N.; Berry, Elizabeth; Delanoe, Julien

    2014-02-01

    The objective of this paper is to investigate whether estimates of the cloud frequency of occurrence and associated cloud radiative forcing as derived from ground-based and satellite active remote sensing and radiative transfer calculations can be reconciled over a well instrumented active remote sensing site located in Darwin, Australia, despite the very different viewing geometry and instrument characteristics. It is found that the ground-based radar-lidar combination at Darwin does not detect most of the cirrus clouds above 10 km (due to limited lidar detection capability and signal obscuration by low-level clouds) and that the CloudSat radar - Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) combination underreports the hydrometeor frequency of occurrence below 2 km height, due to instrument limitations at these heights. The radiative impact associated with these differences in cloud frequency of occurrence is large on the surface downwelling shortwave fluxes (ground and satellite) and the top-of atmosphere upwelling shortwave and longwave fluxes (ground). Good agreement is found for other radiative fluxes. Large differences in radiative heating rate as derived from ground and satellite radar-lidar instruments and RT calculations are also found above 10 km (up to 0.35 Kday-1 for the shortwave and 0.8 Kday-1 for the longwave). Given that the ground-based and satellite estimates of cloud frequency of occurrence and radiative impact cannot be fully reconciled over Darwin, caution should be exercised when evaluating the representation of clouds and cloud-radiation interactions in large-scale models and limitations of each set of instrumentation should be considered when interpreting model-observations differences.

  14. Emulation of Forward-looking Radar Technology for Threat Detection in Rough Terrain Environments: A Scattering and Imaging Study

    Science.gov (United States)

    2012-12-01

    ground -based, ultra-wideband (UWB) radars with the capability to simultaneously penetrate the ground , and image concealed landmines and improvised...electromagnetic, ground - penetrating radar , rough terrain, target detection, time-reversal imaging 16. SECURITY CLASSIFICATION OF: 17. LIMITATION...developed at the U.S. Army Research Laboratory (ARL)—is the low-frequency, UWB synchronous impulse reconstruction (SIRE), imaging ground - penetrating radar

  15. Probing Pluto's Atmosphere Using Ground-Based Stellar Occultations

    Science.gov (United States)

    Sicardy, Bruno; Rio de Janeiro Occultation Team, Granada Team, International Occultation and Timing Association, Royal Astronomical Society New Zealand Occultation Section, Lucky Star associated Teams

    2016-10-01

    Over the last three decades, some twenty stellar occultations by Pluto have been monitored from Earth. They occur when the dwarf planet blocks the light from a star for a few minutes as it moves on the sky. Such events led to the hint of a Pluto's atmosphere in 1985, that was fully confirmed during another occultation in 1988, but it was only in 2002 that a new occultation could be recorded. From then on, the dwarf planet started to move in front of the galactic center, which amplified by a large factor the number of events observable per year.Pluto occultations are essentially refractive events during which the stellar rays are bent by the tenuous atmosphere, causing a gradual dimming of the star. This provides the density, pressure and temperature profiles of the atmosphere from a few kilometers above the surface up to about 250 km altitude, corresponding respectively to pressure levels of about 10 and 0.1 μbar. Moreover, the extremely fine spatial resolution (a few km) obtained through this technique allows the detection of atmospheric gravity waves, and permits in principle the detection of hazes, if present.Several aspects make Pluto stellar occultations quite special: first, they are the only way to probe Pluto's atmosphere in detail, as the dwarf planet is far too small on the sky and the atmosphere is far too tenuous to be directly imaged from Earth. Second, they are an excellent example of participative science, as many amateurs have been able to record those events worldwide with valuable scientific returns, in collaboration with professional astronomers. Third, they reveal Pluto's climatic changes on decade-scales and constrain the various seasonal models currently explored.Finally, those observations are fully complementary to space exploration, in particular with the New Horizons (NH) mission. I will show how ground-based occultations helped to better calibrate some NH profiles, and conversely, how NH results provide some key boundary conditions

  16. Independet Component Analyses of Ground-based Exoplanetary Transits

    Science.gov (United States)

    Silva Martins-Filho, Walter; Griffith, Caitlin Ann; Pearson, Kyle; Waldmann, Ingo; Biddle, Lauren; Zellem, Robert Thomas; Alvarez-Candal, Alvaro

    2016-10-01

    Most observations of exoplanetary atmospheres are conducted when a "Hot Jupiter" exoplanet transits in front of its host star. These Jovian-sized planets have small orbital periods, on the order of days, and therefore a short transit time, making them more ameanable to observations. Measurements of Hot Jupiter transits must achieve a 10-4 level of accuracy in the flux to determine the spectral modulations of the exoplanetary atmosphere. In order to accomplish this level of precision, we need to extract systematic errors, and, for ground-based measurements, the effects of Earth's atmosphere, from the signal due to the exoplanet, which is several orders of magnitudes smaller. Currently, the effects of the terrestrial atmosphere and the some of the time-dependent systematic errors are treated by dividing the host star by a reference star at each wavelength and time step of the transit. More recently, Independent Component Analyses (ICA) have been used to remove systematic effects from the raw data of space-based observations (Waldmann 2014,2012; Morello et al.,2015,2016). ICA is a statistical method born from the ideas of the blind-source separation studies, which can be used to de-trend several independent source signals of a data set (Hyvarinen and Oja, 2000). One strength of this method is that it requires no additional prior knowledge of the system. Here, we present a study of the application of ICA to ground-based transit observations of extrasolar planets, which are affected by Earth's atmosphere. We analyze photometric data of two extrasolar planets, WASP-1b and GJ3470b, recorded by the 61" Kuiper Telescope at Stewart Observatory using the Harris B and U filters. The presentation will compare the light curve depths and their dispersions as derived from the ICA analysis to those derived by analyses that ratio of the host star to nearby reference stars.References: Waldmann, I.P. 2012 ApJ, 747, 12, Waldamann, I. P. 2014 ApJ, 780, 23; Morello G. 2015 ApJ, 806

  17. Improving the atmospheric wind speed measured accuracy by the ground-based airglow imaging interferometer

    Science.gov (United States)

    Tang, Yuanhe; Yang, Rui; Gao, Haiyang; Zhai, Fengtao; Yu, Yang; Cui, Jin

    2017-02-01

    A prototype ground based airglow imaging interferometer (GBAII) has been constructed to observe the upper atmospheric wind velocity and temperature at an altitude of 90-100 km, but the GBAII's wind speed accuracy was found to be unsatisfactory with a value of 21.0 m/s. Three theoretical aspects have been investigated to improve the accuracy, with the following finding: 1) By replacing the surface coatings of the GBAII's 6 lenses and Michelson interferometer (MI) with a new wind-speed infrared film rather than the original visible light film, the accuracy can be increased by 3.0 m/s. 2) By replacing the original charge-coupled device (CCD) with a quantum efficiency (QE) of 0.38 at the wavelength of approximately 866 nm by an electron multiplying CCD (EMCCD) with QE of 0.95, the accuracy can be increased by 6.7 m/s. By adding all the factors that improve the accuracy of the GBAII, it can be improved by 15.0 m/s, which realizes the original aim of wind speed accuracy of 6.0 m/s. Experimental results have been obtained for two aspects: 1) By replacing the surface film on the GBAII's 6 lenses and MI interface, the wind speed accuracy has been increased by 3.8 m/s. 2) A new GBAII temperature controller has been constructed to control the environmental temperature in 0.2 K steps. The results obtained by the GBAII on Dec. 6, 2013 show an average atmospheric temperature of 206.5 K, zonal wind speed of -26.8 m/s and meridional wind speed of 28.1 m/s. These results are close to those of the TIMED (Thermosphere Ionosphere Mesosphere Energetics and Dynamics) satellite Doppler interferometer (TIDI) data collected at almost the same time.

  18. Radar tracking and classification of littoral targets

    Science.gov (United States)

    Silvious, Jerry; Tahmoush, Dave

    2012-06-01

    Radar can provide inexpensive wide-area surveillance of river and port traffic for both security and emergency response. We demonstrate the tracking of multiple vessels as well as the micro-Doppler signatures of different classes of small vessels, including kayaks and zodiacs. The pattern of life of a river is analyzed over several days and can be used to easily identify suspicious or unusual cases.

  19. Scanning Radar Investigations to Characterize Cloud and Precipitation Processes for ASR

    Energy Technology Data Exchange (ETDEWEB)

    Venkatachalam, Chandrasekar [Colorado State Univ., Fort Collins, CO (United States). Dept. of Electrical and Computer Engineering. Cooperative Inst. for Research in the Atmosphere (CIRA)

    2016-12-17

    The project conducted investigations in the following areas related to scanning radar retrievals: a) Development for Cloud drizzle separation studies for the ENA site based on Doppler Spectra b) Advanced radar retrieval for the SGP site c) Characterizing falling snow using multifrequency dual-polarization measurements d) BAECC field experiment. More details about these investigations can be found within each subtopic within the report.

  20. Experimental 0.22 THz Stepped Frequency Radar System for ISAR Imaging

    Science.gov (United States)

    Liang, Mei Yan; Zhang, Cun Lin; Zhao, Ran; Zhao, Yue Jin

    2014-09-01

    High resolution inverse synthetic aperture radar (ISAR) imaging is demonstrated by using a 0.22 THz stepped-frequency (SF) imaging radar system. The synthesis bandwidth of the terahertz (THz) SF radar is 12 GHz, which are beneficial for high resolution imaging. The resolution of ISAR image can reach centimeter-scale with the use of Range-Doppler algorithm (RDA). Results indicate that high resolution ISAR imaging is realized by using 0.22THz SF radar coupled with turntable scanning, which can provide foundations for further research on high-resolution radar image in the THz band.