WorldWideScience

Sample records for hybrid doppler lidar

  1. Lab Demonstration of the Hybrid Doppler Wind Lidar (HDWL) Transceiver

    Science.gov (United States)

    Marx, Catherine T.; Gentry, Bruce; Jordan, Patrick; Dogoda, Peter; Faust, Ed; Kavaya, Michael

    2013-01-01

    The recommended design approach for the 3D Tropospheric Winds mission is a hybrid Doppler lidar which combines the best elements of both a coherent aerosol Doppler lidar operating at 2 microns and a direct detection molecular Doppler lidar operating at 0.355 microns. In support of the mission, we built a novel, compact, light-weighted multi-field of view transceiver where multiple telescopes are used to cover the required four fields of view. A small mechanism sequentially selects both the "transmit" and "receive" fields of view. The four fields are combined to stimulate both the 0.355 micron receiver and the 2 micron receiver. This version is scaled (0.2 m diameter aperture) from the space-based version but still demonstrates the feasibility of the hybrid approach. The primary mirrors were conventionally light-weighted and coated with dielectric, high reflectivity coatings with high laser damage thresholds at both 2 microns and 0.355 microns. The mechanical structure and mounts were fabricated from composites to achieve dimensional stability while significantly reducing the mass. In the laboratory, we demonstrated the system level functionality at 0.355 microns and at 2 microns, raising the Technology Readiness Level (TRL) from 2 to 4.

  2. High Throughput Direct Detection Doppler Lidar Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Lite Cycles, Inc. (LCI) proposes to develop a direct-detection Doppler lidar (D3L) technology called ELITE that improves the system optical throughput by more than...

  3. 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.

  4. Calibration of a cw infrared Doppler lidar.

    Science.gov (United States)

    Schwiesow, R L; Cupp, R E

    1980-09-15

    A moving scattering target used as a transfer standard allows absolute calibration of the response of a cw Doppler lidar to an atmospheric target. The lidar in this study operated at a 10.6-microm wavelength. Consideration of the distribution of radiant energy density near the focus of the lidar transceiver permits measurement of a backscatter coefficient from a distributed array of scatterers, such as atmospheric aerosols, based on the diffuse reflectance of the surface of the transfer standard. The minimum detectable signal for our system with a 5-sec averaging time corresponds to a backscatter coefficient of 2.4 x 10(-12) m (-1) sr (-1) +/- 2.5 dB, which is ~ 9 dB greater than the theoretical threshold. Calibration shows that the lidar response is 5+/-1 dB less than the ideal limit for signal powers well above the minimum detectable signal.

  5. Doppler Lidar Wind Value-Added Product

    Energy Technology Data Exchange (ETDEWEB)

    Newsom, R. K. [DOE ARM Climate Research Facility, Washington, DC (United States); Sivaraman, C. [DOE ARM Climate Research Facility, Washington, DC (United States); Shippert, T. R. [DOE ARM Climate Research Facility, Washington, DC (United States); Riihimaki, L. D. [DOE ARM Climate Research Facility, Washington, DC (United States)

    2015-07-01

    Wind speed and direction, together with pressure, temperature, and relative humidity, are the most fundamental atmospheric state parameters. Accurate measurement of these parameters is crucial for numerical weather prediction. Vertically resolved wind measurements in the atmospheric boundary layer are particularly important for modeling pollutant and aerosol transport. Raw data from a scanning coherent Doppler lidar system can be processed to generate accurate height-resolved measurements of wind speed and direction in the atmospheric boundary layer.

  6. Augmented Reality Based Doppler Lidar Data Visualization: Promises and Challenges

    Directory of Open Access Journals (Sweden)

    Cherukuru N. W.

    2016-01-01

    As a proof of concept, we used the lidar data from a recent field campaign and developed a smartphone application to view the lidar scan in augmented reality. In this paper, we give a brief methodology of this feasibility study, present the challenges and promises of using AR technology in conjunction with Doppler wind lidars.

  7. Advanced Digital Signal Processing for Hybrid Lidar

    Science.gov (United States)

    2014-10-30

    Technical 4. TITLE AND SUBTITLE Advance Digital Signal Processing for Hybrid Lidar 6. AUTHOR(S) William D. Jemison 7. PERFORMING ORGANIZATION NAME(S...development of signed processing algorithms for hybrid lidar - radar designed to improve detection performance. 15. SUBJECT TERMS Hybrid Lidar - Radar 16...Award Number N000141110371 Title of Research Advanced Digital Signal Processing for Hybrid Lidar Principal Investigator William D. Jemison

  8. Methodology for obtaining wind gusts using Doppler lidar

    DEFF Research Database (Denmark)

    Suomi, Irene; Gryning, Sven-Erik; O'Connor, Ewan J.

    2017-01-01

    . This novel method also provides estimates for wind gusts at arbitrary gust durations, including those shorter than the temporal resolution of the Doppler lidar measurements. The input parameters for the scaling method are the measured wind-gust speed as well as the mean and standard deviation...... of the horizontal wind speed. The method was tested using WindCube V2 Doppler lidar measurements taken next to a 100 m high meteorological mast. It is shown that the method can provide realistic Doppler lidar estimates of the gust factor, i.e. the ratio of the wind-gust speed to the mean wind speed. The method...... speed. To assure the data quality in this study, we applied a filtering technique based on spike detection to remove possible outliers in the Doppler lidar data. We found that the spike detection-removal method clearly improved the wind-gust measurements, both with and without the scaling method. Spike...

  9. Airborne Wind Profiling Algorithm for Doppler Wind LIDAR

    Science.gov (United States)

    Beyon, Jeffrey Y. (Inventor); Koch, Grady J. (Inventor); Kavaya, Michael J. (Inventor)

    2015-01-01

    Systems, methods, and devices of the present invention enable airborne Doppler Wind LIDAR system measurements and INS/GPS measurements to be combined to estimate wind parameters and compensate for instrument misalignment. In a further embodiment, the wind speed and wind direction may be computed based on two orthogonal line-of-sight LIDAR returns.

  10. High-Energy 2-Micrometers Doppler Lidar for Wind Measurements

    Science.gov (United States)

    Koch, Grady J.; Beyon, Jeffrey Y.; Barnes, Bruce W.; Petros, Mulugeta; Yu, Jirong; Amzajerdian, Farzin; Kavaya, Michael J.; Singh, Upendra N.

    2006-01-01

    High-energy 2-micrometer wavelength lasers have been incorporated in a prototype coherent Doppler lidar to test component technologies and explore applications for remote sensing of the atmosphere. Design of the lidar is presented including aspects in the laser transmitter, receiver, photodetector, and signal processing. Calibration tests and sample atmospheric data are presented on wind and aerosol profiling.

  11. Validar: a testbed for advanced 2-micron Doppler lidar

    Science.gov (United States)

    Koch, Grady J.; Petros, Mulugeta; Barnes, Bruce W.; Beyon, Jeffrey Y.; Amzajerdian, Farzin; Yu, Jirong; Kavaya, Michael J.; Singh, Upendra N.

    2004-09-01

    High-energy 2-micron lasers have been incorporated in a breadboard coherent Doppler lidar to test component technologies and explore applications for remote sensing of the atmosphere. Design of the lidar is presented including aspects in the laser transmitter, receiver, photodetector, and signal processing. Sample data is presented on wind profiling and CO2 concentration measurements.

  12. Augmented Reality Based Doppler Lidar Data Visualization: Promises and Challenges

    Science.gov (United States)

    Cherukuru, N. W.; Calhoun, R.

    2016-06-01

    Augmented reality (AR) is a technology in which the enables the user to view virtual content as if it existed in real world. We are exploring the possibility of using this technology to view radial velocities or processed wind vectors from a Doppler wind lidar, thus giving the user an ability to see the wind in a literal sense. This approach could find possible applications in aviation safety, atmospheric data visualization as well as in weather education and public outreach. As a proof of concept, we used the lidar data from a recent field campaign and developed a smartphone application to view the lidar scan in augmented reality. In this paper, we give a brief methodology of this feasibility study, present the challenges and promises of using AR technology in conjunction with Doppler wind lidars.

  13. Doppler Lidar in the Wind Forecast Improvement Projects

    Directory of Open Access Journals (Sweden)

    Pichugina Yelena

    2016-01-01

    Full Text Available This paper will provide an overview of some projects in support of Wind Energy development involving Doppler lidar measurement of wind flow profiles. The high temporal and vertical resolution of these profiles allows the uncertainty of Numerical Weather Prediction models to be evaluated in forecasting dynamic processes and wind flow phenomena in the layer of rotor-blade operation.

  14. Doppler Lidar in the Wind Forecast Improvement Projects

    Science.gov (United States)

    Pichugina, Yelena; Banta, Robert; Brewer, Alan; Choukulkar, Aditya; Marquis, Melinda; Olson, Joe; Hardesty, Mike

    2016-06-01

    This paper will provide an overview of some projects in support of Wind Energy development involving Doppler lidar measurement of wind flow profiles. The high temporal and vertical resolution of these profiles allows the uncertainty of Numerical Weather Prediction models to be evaluated in forecasting dynamic processes and wind flow phenomena in the layer of rotor-blade operation.

  15. Aircraft Wake Vortex Measurement with Coherent Doppler Lidar

    Science.gov (United States)

    Wu, Songhua; Liu, Bingyi; Liu, Jintao

    2016-06-01

    Aircraft vortices are generated by the lift-producing surfaces of the aircraft. The variability of near-surface conditions can change the drop rate and cause the cell of the wake vortex to twist and contort unpredictably. The pulsed Coherent Doppler Lidar Detection and Ranging is an indispensable access to real aircraft vortices behavior which transmitting a laser beam and detecting the radiation backscattered by atmospheric aerosol particles. Experiments for Coherent Doppler Lidar measurement of aircraft wake vortices has been successfully carried out at the Beijing Capital International Airport (BCIA). In this paper, the authors discuss the Lidar system, the observation modes carried out in the measurements at BCIA and the characteristics of vortices.

  16. Aircraft Wake Vortex Measurement with Coherent Doppler Lidar

    Directory of Open Access Journals (Sweden)

    Wu Songhua

    2016-01-01

    Full Text Available Aircraft vortices are generated by the lift-producing surfaces of the aircraft. The variability of near-surface conditions can change the drop rate and cause the cell of the wake vortex to twist and contort unpredictably. The pulsed Coherent Doppler Lidar Detection and Ranging is an indispensable access to real aircraft vortices behavior which transmitting a laser beam and detecting the radiation backscattered by atmospheric aerosol particles. Experiments for Coherent Doppler Lidar measurement of aircraft wake vortices has been successfully carried out at the Beijing Capital International Airport (BCIA. In this paper, the authors discuss the Lidar system, the observation modes carried out in the measurements at BCIA and the characteristics of vortices.

  17. Monostatic Doppler lidar using an Nd:YAG laser for wind-velocity measurement

    Science.gov (United States)

    Bersenev, V. I.; Kaptsov, L. N.; Priezzhev, A. V.

    1987-10-01

    A monostatic Doppler lidar using a CW Nd:YAG laser has been developed for measurements of wind velocity. A series of atmospheric measurements using this lidar was carried out. At medium turbulence levels, the limiting lidar range is 200 m. As compared with a CO2 Doppler lidar, the Nd:YAG lidar has a better spatial resolution, is more convenient to use, and does not require a cooled photodetector.

  18. Potential scientific research which will benefit from an airborne Doppler lidar measurement system

    Science.gov (United States)

    Frost, W.

    1980-01-01

    Areas of research which can be significantly aided by the Doppler lidar airborne system are described. The need for systematic development of the airborne Doppler lidar is discussed. The technology development associated with the systematic development of the system will have direct application to satellite systems for which the lidar also promises to be an effective instrument for atmospheric research.

  19. Doppler Lidar Vertical Velocity Statistics Value-Added Product

    Energy Technology Data Exchange (ETDEWEB)

    Newsom, R. K. [DOE ARM Climate Research Facility, Washington, DC (United States); Sivaraman, C. [DOE ARM Climate Research Facility, Washington, DC (United States); Shippert, T. R. [DOE ARM Climate Research Facility, Washington, DC (United States); Riihimaki, L. D. [DOE ARM Climate Research Facility, Washington, DC (United States)

    2015-07-01

    Accurate height-resolved measurements of higher-order statistical moments of vertical velocity fluctuations are crucial for improved understanding of turbulent mixing and diffusion, convective initiation, and cloud life cycles. The Atmospheric Radiation Measurement (ARM) Climate Research Facility operates coherent Doppler lidar systems at several sites around the globe. These instruments provide measurements of clear-air vertical velocity profiles in the lower troposphere with a nominal temporal resolution of 1 sec and height resolution of 30 m. The purpose of the Doppler lidar vertical velocity statistics (DLWSTATS) value-added product (VAP) is to produce height- and time-resolved estimates of vertical velocity variance, skewness, and kurtosis from these raw measurements. The VAP also produces estimates of cloud properties, including cloud-base height (CBH), cloud frequency, cloud-base vertical velocity, and cloud-base updraft fraction.

  20. Rayleigh Doppler Lidar for Higher Tropospheric and Stratospheric Wind Observation

    Institute of Scientific and Technical Information of China (English)

    TANG Lei; WANG Cong-Rong; WU Hai-Bin; DONG Ji-Hui

    2012-01-01

    A mobile molecular Doppler wind lidar (DWL) based on the double-edge technique is described for wind measurement from 10 km to 40 km altitude.Two edge filters located in the wings of the thermally broadened molecular backscattered signal spectrum at 355 nm are employed as a frequency discriminator to determine the Doppler shift proportional to the wind velocity.The lidar operates at 355 nm with a 45 cm aperture telescope and a matching azimuth-over-elevation scanner that can provide full hemispherical pointing.Intercomparison experiments of the lidar wind profile measurement are performed with collocated pilot balloon.The results show that the standard deviation of wind speed and direction are less than l0m/s and 30° in the 5-40 km altitude range,respectively.The small mean difference and normal distribution between DWL and pilot balloon data and the transient eddy of the west-wind jet observed demonstrate that the DWL consistently measures the wind with acceptable random errors.%A mobile molecular Doppler wind lidar (DWL) based on the double-edge technique is described for wind measurement from 10 km to 40 km altitude. Two edge filters located in the wings of the thermally broadened molecular backscattered signal spectrum at 355 nm are employed as a frequency discriminator to determine the Doppler shift proportional to the wind velocity. The lidar operates at 355 nm with a 45 cm aperture telescope and a matching azimuth-over-elevation scanner that can provide full hemispherical pointing. Intercomparison experiments of the lidar wind profile measurement are performed with collocated pilot balloon. The results show that the standard deviation of wind speed and direction are less than 10m/s and 30° in the 5-40 km altitude range, respectively. The small mean difference and normal distribution between DWL and pilot balloon data and the transient eddy of the west-wind jet observed demonstrate that the DWL consistently measures the wind with acceptable random errors.

  1. Design and performance simulation of a molecular Doppler wind lidar

    Institute of Scientific and Technical Information of China (English)

    Fahua Shen; Hyunki Cha; Jihui Dong; Dukhyeon Kim; Dongsong Sun; Sung Ok Kwon

    2009-01-01

    A mobile molecular Doppler wind lidar at an eye-safe wavelength of 355 nm based on double-edge technique is being built in Hefei (China) for wind measurement from 10-to 40-km altitude. The structure of this lidar system is described. A triple Fabry-Perot etalon is employed as a frequency discriminator whose parameters are optimized. The receiver system is designed to achieve compactness and stability by putting in a standard 19-inch socket bench. Simulation results show that within the wind speed dynamic range of ±100 m/s, the horizontal wind errors due to noise are less than 1 m/s below 20-km altitude for 100-m vertical resolution, and less than 5.5 m/s from 20 km up to 40 km for 500-m vertical resolution with 400-mJ laser energy, 30-min temporal resolution, and a 45-cm aperture telescope.

  2. Observing crosswind over urban terrain using scintillometer and Doppler lidar

    Directory of Open Access Journals (Sweden)

    D. van Dinther

    2014-07-01

    Full Text Available In this study, the crosswind (wind component perpendicular to a path, U⊥ is measured by a scintillometer and Doppler lidar above the urban environment of Helsinki, Finland, for 3 weeks. The scintillometer allows acquisition of a path-averaged value of U⊥ (U⊥, while the Doppler lidar allows acquisition of path-resolved U⊥ (U⊥ (x, where x is the position along the path. The goal of this study is to evaluate the applicability of scintillometer U⊥-measurements for conditions where U⊥ (x is variable. If the scintillometer is applicable in such variable-wind conditions, it can also be used in the urban environment. Two methods were applied to obtain U⊥ from the scintillometer signal; the cumulative spectrum method (relies on scintillation spectra, and the lookup table method (relies on time-lagged correlation functions. Both methods compared reasonably well with the Doppler lidar measurements, especially considering the challenging urban environment in which they were measuring; with RMSE of 0.71 and 0.73 m s−1. This indicates that both measurement technologies are able to obtain U⊥ in the complex urban environment. The in detail investigation of four cases indicate that the cumulative spectrum method is less susceptible to a variable U⊥ (x than the lookup table method. However, the lookup table method can be adjusted to improve its capabilities to obtain U⊥ for conditions where U⊥ (x is variable.

  3. Advanced Digital Signal Processing for Hybrid Lidar FY 2014

    Science.gov (United States)

    2014-10-30

    Report 3. DATES COVERED (Frorr) - To) 6/2011 to 9/2014 4. TITLE AND SUBTITLE Advance Digital Signal Processing for Hybrid Lidar 5a. CONTRACT NUMBER...report describes the technical progress towards the development of signed processing algorithms for hybrid lidar - radar designed to improve...detection performance. 15. SUBJECT TERMS Hybrid Lidar

  4. Incoherent pulse Doppler lidar as the velocimeter system

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    This note reports a new type of incoherent pulse laser Doppler lidar velocimeter with iodine molecular filter as a frequency discriminator. Its transmitter subsystem applies a Nd:YAG pulse laser which is injected with a single longitudinal-mode diode pumped continuous seeder laser.The field experiment proved that this velocimeter measurement results are consistent with those measured by photoelectric velocimeter. Measurements of eight different velocities show that the standard deviation is 0.56 m/s, the range resolution is 3.75 m.

  5. Study on characteristics of chirp about Doppler wind lidar system

    Science.gov (United States)

    Du, Li-fang; Yang, Guo-tao; Wang, Ji-hong; Yue, Chuan; Chen, Lin-xiang

    2016-11-01

    In the doppler wind lidar, usually every 4MHz frequency error will produce wind error of 1m/s of 532nm laser. In the Doppler lidar system, frequency stabilization was achieved through absorption of iodine molecules. Commands that control the instrumental system were based on the PID algorithm and coded using VB language. The frequency of the seed laser was locked to iodine molecular absorption line 1109 which is close to the upper edge of the absorption range, with long-time (>4h) frequency-locking accuracy being≤0.5MHz and long-time frequency stability being 10-9 . The experimental result indicated that the seed frequency and the pulse laser frequency have a deviation, which effect is called the laser chirp characteristics. Finally chirp test system was constructed and tested the frequency offset in time. And such frequency deviation is known as Chirp of the laser pulse. The real-time measured frequency difference of the continuous and pulsed lights was about 10MHz, long-time stability deviation was around 5MHz. After experimental testing technology mature, which can monitoring the signal at long-term with corrected the wind speed.

  6. Wind turbine wake visualization and characteristics analysis by Doppler lidar.

    Science.gov (United States)

    Wu, Songhua; Liu, Bingyi; Liu, Jintao; Zhai, Xiaochun; Feng, Changzhong; Wang, Guining; Zhang, Hongwei; Yin, Jiaping; Wang, Xitao; Li, Rongzhong; Gallacher, Daniel

    2016-05-16

    Wind power generation is growing fast as one of the most promising renewable energy sources that can serve as an alternative to fossil fuel-generated electricity. When the wind turbine generator (WTG) extracts power from the wind, the wake evolves and leads to a considerable reduction in the efficiency of the actual power generation. Furthermore, the wake effect can lead to the increase of turbulence induced fatigue loads that reduce the life time of WTGs. In this work, a pulsed coherent Doppler lidar (PCDL) has been developed and deployed to visualize wind turbine wakes and to characterize the geometry and dynamics of wakes. As compared with the commercial off-the-shelf coherent lidars, the PCDL in this work has higher updating rate of 4 Hz and variable physical spatial resolution from 15 to 60 m, which improves its capability to observation the instantaneous turbulent wind field. The wind speed estimation method from the arc scan technique was evaluated in comparison with wind mast measurements. Field experiments were performed to study the turbulent wind field in the vicinity of operating WTGs in the onshore and offshore wind parks from 2013 to 2015. Techniques based on a single and a dual Doppler lidar were employed for elucidating main features of turbine wakes, including wind velocity deficit, wake dimension, velocity profile, 2D wind vector with resolution of 10 m, turbulence dissipation rate and turbulence intensity under different conditions of surface roughness. The paper shows that the PCDL is a practical tool for wind energy research and will provide a significant basis for wind farm site selection, design and optimization.

  7. GroundWinds 2000 field campaign: demonstration of new Doppler lidar technology and wind lidar data intercomparison

    Science.gov (United States)

    Yoe, James G.; Varma Raja, M. K. Rama; Hardesty, R. Michael; Brewer, W. Alan; Moore, Berrien, III; Ryan, James M.; Hays, Paul B.; Nardell, Carl A.; Gentry, Bruce M.; Day, Michelle; Rancourt, Kenneth

    2003-03-01

    A field campaign featuring three collocated Doppler wind lidars was conducted over ten days during September 2000 at the GroundWinds Observatory in New Hampshire. The lidars were dissimilar in wavelength and Doppler detection method. The GroundWinds lidar operated at 532 nm and used fringe-imaging direct detection, while the Goddard Lidar Observatory for Winds (GLOW) ran at 355 nm and employed double-edge filter direct detection, and the NOAA mini-MOPA operated at 10 microns and used heterodyne detection. The objectives of the campaign were (1) to demonstrate the capability of the GroundWinds lidar to measure winds while employing several novel components, and (2) to compare directly the radial wind velocities measured by the three lidars for as wide a variety of conditions as possible. Baseline wind profiles and ancillary meteorological data (temperature and humidity profiles) were obtained by launching GPS radiosondes from the observatory as frequently as every 90 minutes. During the final week of the campaign the lidars collected data along common lines-of-sight for several extended periods. The wind speed varied from light to jet stream values, and sky conditions ranged from clear to thick clouds. Intercomparisons of overlapping lidar and radiosonde observations show that all three lidars were able to measure wind given sufficient backscatter. At ranged volumes containing thicker clouds, and those beyond, the wind sensing capability of the direct detection lidars was adversely affected.

  8. Time series analysis of continuous-wave coherent Doppler Lidar wind measurements

    DEFF Research Database (Denmark)

    Sjöholm, Mikael; Mikkelsen, Torben; Mann, Jakob

    2008-01-01

    The influence of spatial volume averaging of a focused 1.55 mu m continuous-wave coherent Doppler Lidar on observed wind turbulence measured in the atmospheric surface layer over homogeneous terrain is described and analysed. Comparison of Lidar-measured turbulent spectra with spectra simultaneou......The influence of spatial volume averaging of a focused 1.55 mu m continuous-wave coherent Doppler Lidar on observed wind turbulence measured in the atmospheric surface layer over homogeneous terrain is described and analysed. Comparison of Lidar-measured turbulent spectra with spectra...

  9. 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

  10. Development of all-solid coherent Doppler wind lidar

    Institute of Scientific and Technical Information of China (English)

    Xiaopeng Zhu; Jiqiao Liu; Decang Bi; Jun Zhou; Weifeng Diao; Weibiao Chen

    2012-01-01

    A 1064-nm pulsed coherent Doppler lidar (CDL) prototype is developed to measure short range wind speed in the lower altitude troposphere layer The CDL system adopts an injection seeded Nd:YAG laser with the pulse duration of 80 ns,single pulse energy of 0.5 m J,and pulse repetition rate of 200 Hz.Speed calibration experiments are implemented to obtain a speed accuracy of 0.3 m/s using a hard target.Data analysis results show that the CDL system can obtain a line-of-sight wind velocity at a range of 30 to 500m with the range resolution of 40 m and 38 pulses accumulation.

  11. Application of fiber interferometer in coherent Doppler lidar

    Institute of Scientific and Technical Information of China (English)

    Zongfeng Ma; Chunxi Zhang; Pan Ou; Guangming Luo; Zhaoyang Zhang

    2008-01-01

    @@ A novel coherent Doppler lidar (CDL) system based on single-mode fiber (SMF) components and instruments is presented to measure the speed of target. A fiber interferometer used in CDL system is reported.This fiber mixer is employed as a coherent receiver to resolve the shifts of signal-to-noise ratio (SNR) and mixing efficiency induced by backscattered field's wavefront error. For a certain wavelength, the maximum coupling efficiency between signal and SMF is determined by the ratio of pupil diameter to focal length of the coupling lens. The legible interference patterns and spectrum signals show that fiber interferometer is suitable to compensate for amplitude and phase vibrations. This robust coherent receiver can achieve improved CDL system performance with less transmitter power.

  12. A Doppler lidar with CO2-laser intracavity detection

    Science.gov (United States)

    Godlevskii, A. P.; Gordov, E. P.; Zhiliba, A. I.; Sharin, P. P.

    A version of a high-sensitive Doppler lidar, based on intracavity coherent laser detection is described. The device consists of a CO2 laser, transmitting-receiving optical system, and signal-processing unit. Laser-intensity stabilization is achieved by decreasing the mechanical disturbance of the laser resonator, and the optical tract is formed by a Cassegrain telescope. A portion of the laser beam reflected back by a Breuster window of the gas discharge tube is focused by a spherical mirror onto a photodetector. Results of laboratory and real-atmosphere experiments are reported, and it is shown that vibrations of a retroreflector with an amplitude of 50 micron are detected at distances up to 500 m.

  13. Doppler lidar wind measurement with the edge technique

    Science.gov (United States)

    Korb, C. Laurence; Gentry, Bruce M.

    1992-01-01

    The edge technique is a new and powerful method for measuring small frequency shifts. Range resolved lidar measurements of winds can be made with high accuracy and high vertical resolution using the edge technique to measure the Doppler shift of an atmospheric backscattered signal from a pulsed laser. The edge technique can be used at near-infrared or visible wavelengths using well developed solid state lasers and detectors with various edge filters. In the edge technique, the laser frequency is located on the steep slope of the spectral response function of a high resolution optical filter. Due to the steep slope of the edge, very small frequency shifts cause large changes in measured signal. The frequency of the outgoing laser pulse is determined by measuring its location on the edge of the filter. This is accomplished by sending a small portion of the beam to the edge detection setup where the incoming light is split into two channels - an edge filter and an energy monitor channel. The energy monitor signal is used to normalize the edge filter signal for magnitude. The laser return backscattered from the atmosphere is collected by a telescope and directed through the edge detection setup to determine its frequency (location on the edge) in a similar manner for each range element. The Doppler shift, and thus the wind, is determined from a differential measurement of the frequency of the outgoing laser pulse and the frequency of the laser return backscattered from the atmosphere. We have conducted simulations of the performance of an edge lidar system using an injection seeded pulsed Nd:YAG laser at 1.06 microns. The central fringe of a Fabry-Perot etalon is used as a high resolution edge filter to measure the shift of the aerosol return.

  14. Design and Development of a Scanning Airborne Direct Detection Doppler Lidar System

    Science.gov (United States)

    Gentry, Bruce; McGill, Matthew; Schwemmer, Geary; Hardesty, Michael; Brewer, Alan; Wilkerson, Thomas; Atlas, Robert; Sirota, Marcos; Lindemann, Scott

    2006-01-01

    In the fall of 2005 we began developing an airborne scanning direct detection molecular Doppler lidar. The instrument is being built as part of the Tropospheric Wind Lidar Technology Experiment (TWiLiTE), a three year project selected by the NASA Earth Sun Technology Office under the Instrument Incubator Program. The TWiLiTE project is a collaboration involving scientists and engineers from NASA Goddard Space Flight Center, NOAA ESRL, Utah State University Space Dynamics Lab, Michigan Aerospace Corporation and Sigma Space Corporation. The TWiLiTE instrument will leverage significant research and development investments made by NASA Goddard and it's partners in the past several years in key lidar technologies and sub-systems (lasers, telescopes, scanning systems, detectors and receivers) required to enable spaceborne global wind lidar measurement. These sub-systems will be integrated into a complete molecular direct detection Doppler wind lidar system designed for autonomous operation on a high altitude aircraft, such as the NASA WB57. The WB57 flies at an altitude of 18 km and from this vantage point the nadir viewing Doppler lidar will be able to profile winds through the full troposphere. The TWiLiTE integrated airborne Doppler lidar instrument will be the first demonstration of a airborne scanning direct detection Doppler lidar and will serve as a critical milestone on the path to a future spaceborne tropospheric wind system. In addition to being a technology testbed for space based tropospheric wind lidar, when completed the TWiLiTE high altitude airborne lidar will be used for studying mesoscale dynamics and storm research (e.g. winter storms, hurricanes) and could be used for calibration and validation of satellite based wind systems such as ESA's Aeolus Atmospheric Dynamics Mission. The TWiLiTE Doppler lidar will have the capability to profile winds in clear air from the aircraft altitude of 18 km to the surface with 250 m vertical resolution and < 2mls

  15. Development of Navigation Doppler Lidar for Future Landing Mission

    Science.gov (United States)

    Amzajerdian, Farzin; Hines, Glenn D.; Petway, Larry B.; Barnes, Bruce W.; Pierrottet, Diego F.; Carson, John M., III

    2016-01-01

    A coherent Navigation Doppler Lidar (NDL) sensor has been developed under the Autonomous precision Landing and Hazard Avoidance Technology (ALHAT) project to support future NASA missions to planetary bodies. This lidar sensor provides accurate surface-relative altitude and vector velocity data during the descent phase that can be used by an autonomous Guidance, Navigation, and Control (GN&C) system to precisely navigate the vehicle from a few kilometers above the ground to a designated location and execute a controlled soft touchdown. The operation and performance of the NDL was demonstrated through closed-loop flights onboard the rocket-propelled Morpheus vehicle in 2014. In Morpheus flights, conducted at the NASA Kennedy Space Center, the NDL data was used by an autonomous GN&C system to navigate and land the vehicle precisely at the selected location surrounded by hazardous rocks and craters. Since then, development efforts for the NDL have shifted toward enhancing performance, optimizing design, and addressing spaceflight size and mass constraints and environmental and reliability requirements. The next generation NDL, with expanded operational envelope and significantly reduced size, will be demonstrated in 2017 through a new flight test campaign onboard a commercial rocketpropelled test vehicle.

  16. Fiber-Based Doppler Lidar for Vector Velocity and Altitude Measurements

    Science.gov (United States)

    Amzajerdian, Farzin; Pierrottet, Diego; Hines, Glenn; Petway, Larry; Barnes, Bruce

    2015-01-01

    A coherent Doppler lidar capable of providing accurate velocity and altitude data has been developed and demonstrated for future NASA missions to the solar system bodies requiring precision navigation and controlled soft landing.

  17. Remote Sensing of Complex Flows by Doppler Wind Lidar: Issues and Preliminary Recommendations

    Energy Technology Data Exchange (ETDEWEB)

    Clifton, Andrew [National Renewable Energy Lab. (NREL), Golden, CO (United States); Boquet, Matthieu [Leosphere, Orsay (France); Burin Des Roziers, Edward [UL International Gmbh, Freemont, CA (United States); Westerhellweg, Annette [UL International Gmbh, Freemont, CA (United States); Hofsass, Martin [Univ. of Stuttgart (Germany). Stuttgart Wind Energy; Klaas, Tobias [Fraunhofer Inst. for Wind Energy and Energy System Technology, Freiburg (Germany); Vogstad, Klaus [Meventus, Hamburg (Germany); Clive, Peter [Sgurr Energy, Glasgow (United Kingdom); Harris, Mike [ZephIR Limited, Kirkcudbrightshire (United Kingdom); Wylie, Scott [ZephIR Limited, Kirkcudbrightshire (United Kingdom); Osler, Evan [Renewable NRG Systems, Hinesburg, VT (United States); Banta, Bob [National Oceanic and Atmospheric Administration (NOAA), Boulder, CO (United States); Choukulkar, Aditya [National Oceanic and Atmospheric Administration (NOAA), Boulder, CO (United States); Lundquist, Julie [Univ. of Colorado, Boulder, CO (United States); Aitken, Matthew [Univ. of Colorado, Boulder, CO (United States)

    2015-12-01

    Remote sensing of winds using lidar has become popular and useful in the wind energy industry. Extensive experience has been gained with using lidar for applications including land-based and offshore resource assessment, plant operations, and turbine control. Prepared by members of International Energy Agency Task 32, this report describes the state of the art in the use of Doppler wind lidar for resource assessment in complex flows. The report will be used as input for future recommended practices on this topic.

  18. Aircraft Wake Vortex Parametrization Based on 1.5-μm Coherent Doppler Lidar Data

    Directory of Open Access Journals (Sweden)

    Banakh V.A.

    2016-01-01

    Full Text Available A strategy of measurement by a 1.5-μm pulsed coherent Doppler lidar “Stream Line” has been developed, and a method for estimation of aircraft wake vortices from the lidar data has been proposed. The principal possibility of obtaining the information about the vortex situation over an airport airfield with the Stream Line lidar has been demonstrated.

  19. High-efficiency receiver architecture for resonance-fluorescence and Doppler lidars.

    Science.gov (United States)

    Smith, John A; Chu, Xinzhao

    2015-04-10

    A high-efficiency lidar receiver architecture that emphasizes boosting the receiver collection efficiency of resonance-fluorescence and Doppler lidars has opened up new avenues of study for the mesosphere and lower thermosphere-extended (MLT-X) at sites in Boulder, Colorado, USA, and Cerro Pachón, Chile. Described in this work are in-depth considerations in the design, construction, and alignment of Na Doppler lidar receivers that have yielded signal levels typically 5-10 times higher per power-aperture product than any demonstrated in the literature, to these authors' knowledge, making studies of fine-scale MLT turbulence and tenuous thermospheric layers in Na possible with temperature and vertical wind capability for the first time. A lowering of the detection threshold by higher receiver collection efficiency at Cerro Pachón has enabled this Na Doppler lidar to extend its measurement range far higher into the thermosphere, to regions with Na density less than 3  cm(-3). With renewed interest in the MLT-X region prompted by recent lidar discoveries of Fe in the thermosphere reaching 170 km at McMurdo, Antarctica, the receiver optimizations we have made now enable addressing an important need in the community. In addition, the higher spatial and temporal resolutions afforded by high signal-to-noise ratio, down to resolutions of ∼20  s and ∼20  m, promise to make the first direct measurements of eddy flux in the mesopause region possible. Results from deployment of optimized receivers at the Table Mountain Lidar Observatory in Boulder, the Andes Lidar Observatory at Cerro Pachón, and the Arecibo Observatory in Puerto Rico are presented to demonstrate the power and portability of our methods that are readily applicable to other lidar varieties, including, but not limited to, the newly developed Fe Doppler lidar and recently upgraded K Doppler lidar.

  20. Doppler lidar power, aperture diameter, and FFT size trade-off study

    Science.gov (United States)

    Chester, David B.; Budge, Scott E.

    2017-05-01

    In the design or selection of a Doppler lidar instrument for a spacecraft landing system, it is important to evaluate the balance between performance requirements and cost, weight, and power consumption. Leveraging the capability of LadarSIM, a trade-off study was performed to evaluate the interaction between the laser transmission power, aperture diameter, and FFT size in a Doppler lidar system. For this study the probabilities of detection and false alarm were calculated using LadarSIM to simulate FMCW lidar systems with varying power, aperture diameter, and FFT size. This paper reports the results of this trade-off study.

  1. Noise reduction in LOS wind velocity of Doppler lidar using discrete wavelet analysis

    Science.gov (United States)

    Wu, Songhua; Liu, Zhishen; Sun, Dapeng

    2003-12-01

    The line of sight (LOS) wind velocity can be determined from the incoherent Doppler lidar backscattering signals. Noise and interference in the measurement greatly degrade the inversion accuracy. In this paper, we apply the discrete wavelet denoising method by using biorthogonal wavelets and adopt a distancedependent thresholds algorithm to improve the accuracy of wind velocity measurement by incoherent Doppler lidar. The noisy simulation data are processed and compared with the true LOS wind velocity. The results are compared by the evaluation of both the standard deviation and correlation coefficient.The results suggest that wavelet denoising with distance-dependent thresholds can considerably reduce the noise and interfering turbulence for wind lidar measurement.

  2. Airborne Doppler Wind Lidar Post Data Processing Software DAPS-LV

    Science.gov (United States)

    Beyon, Jeffrey Y. (Inventor); Koch, Grady J. (Inventor); Kavaya, Michael J. (Inventor)

    2015-01-01

    Systems, methods, and devices of the present invention enable post processing of airborne Doppler wind LIDAR data. In an embodiment, airborne Doppler wind LIDAR data software written in LabVIEW may be provided and may run two versions of different airborne wind profiling algorithms. A first algorithm may be the Airborne Wind Profiling Algorithm for Doppler Wind LIDAR ("APOLO") using airborne wind LIDAR data from two orthogonal directions to estimate wind parameters, and a second algorithm may be a five direction based method using pseudo inverse functions to estimate wind parameters. The various embodiments may enable wind profiles to be compared using different algorithms, may enable wind profile data for long haul color displays to be generated, may display long haul color displays, and/or may enable archiving of data at user-selectable altitudes over a long observation period for data distribution and population.

  3. All-fiber pulse coherent Doppler LIDAR and its validations

    Science.gov (United States)

    Bu, Lingbing; Qiu, Zujing; Gao, Haiyang; Zhu, Xiaopeng; Liu, Jiqiao

    2015-12-01

    An all-fiber pulsed coherent Doppler LIDAR (CDL) system is described. It uses a fiber laser as a light source at a 1.54-μm wavelength, producing 200 μJ pulses at 10 kHz. The local oscillator signal is mixed with the backscattered light (of different frequency) in the fiber. The atmospheric wind speed is determined through the fast Fourier transform applied to the difference frequency signal acquired by an analog-to-digital converter card. This system was used to measure the atmospheric wind above the upper-air meteorological observatory in Rongcheng (37.10°N, 122.25°E) of China between January 7 and 19, 2015. The CDL data are compared with sounding- and pilot-balloon measurements to assess the CDL performance. The results show that the correlation coefficient of the different wind-speed measurements is 0.93 and their discrepancy 0.64 m/s; the correlation coefficient for wind-direction values is 0.92 and their discrepancy 5.8 deg. A time serial of the wind field, which benefits the understanding of atmospheric dynamics, is presented after the comparisons between data from CDL and balloons. The CDL system has a compact structure and demonstrates good stability, reliability, and a potential for application to wind-field measurements in the atmospheric boundary layer.

  4. Nature of Streaky Structures Observed with a Doppler Lidar

    Science.gov (United States)

    Yagi, Ayako; Inagaki, Atsushi; Kanda, Manabu; Fujiwara, Chusei; Fujiyoshi, Yasushi

    2017-04-01

    Observations using a three-dimensional scanning coherent Doppler lidar in an urban area revealed the characteristics of streaky structures above a rough, inhomogeneous surface for a high-Reynolds-number flow. The study focused on two points: (1) the frequency of occurrence and conditions required for the presence of streaky structures, and (2) the universal scaling of the spacing of streaky structures (λ ). The horizontal snapshots of the radial velocity were visually classified into six groups: Streak, Mixed, Fishnet, No streak, Front, and Others. The Streak category accounted for more than 50% of all possible flows and occurred when the horizontal wind speed was large and the atmospheric stratification was near-neutral. The spacing (λ ) was estimated from the power spectral density of the streamwise velocity fluctuations along the spanwise direction. The spacing λ decreased with an increase in the local velocity gradient. Furthermore, it was revealed that the local velocity gradient normalized by the friction velocity and the boundary-layer height (z_i ) comprehensively predicts λ /z_i under various experimental and environmental conditions, in terms of the scale of motion (i.e., indoor and outdoor scales), thermal stratification (i.e., from weakly unstable to stable stratification), and surface roughness (i.e., from flat to very rough surfaces).

  5. Nature of Streaky Structures Observed with a Doppler Lidar

    Science.gov (United States)

    Yagi, Ayako; Inagaki, Atsushi; Kanda, Manabu; Fujiwara, Chusei; Fujiyoshi, Yasushi

    2016-12-01

    Observations using a three-dimensional scanning coherent Doppler lidar in an urban area revealed the characteristics of streaky structures above a rough, inhomogeneous surface for a high-Reynolds-number flow. The study focused on two points: (1) the frequency of occurrence and conditions required for the presence of streaky structures, and (2) the universal scaling of the spacing of streaky structures (λ ) . The horizontal snapshots of the radial velocity were visually classified into six groups: Streak, Mixed, Fishnet, No streak, Front, and Others. The Streak category accounted for more than 50% of all possible flows and occurred when the horizontal wind speed was large and the atmospheric stratification was near-neutral. The spacing (λ ) was estimated from the power spectral density of the streamwise velocity fluctuations along the spanwise direction. The spacing λ decreased with an increase in the local velocity gradient. Furthermore, it was revealed that the local velocity gradient normalized by the friction velocity and the boundary-layer height (z_i ) comprehensively predicts λ /z_i under various experimental and environmental conditions, in terms of the scale of motion (i.e., indoor and outdoor scales), thermal stratification (i.e., from weakly unstable to stable stratification), and surface roughness (i.e., from flat to very rough surfaces).

  6. Mie-Rayleigh Doppler Wind Lidar with Two Double-edge Interferometers

    Institute of Scientific and Technical Information of China (English)

    孙东松

    2002-01-01

    The Mie-Rayleigh direct detection Doppler lidar (DDDL) with two double-edge etalons is presented. Fabry-Perot (F-P) etalon is used as the spectral analyzer for Doppler measurement formthe aerosol and molecule backscattered signals. The aerosol and molecular backscattering signals are separated by a polarization isolator with less signal decrement, so this system has about same accuracy as individual Rayleigh Doppler lidar or Mie Doppler lidar system. The simulation on a proposed ground-based DDDL at 532 nm shows that the velocity error is less than 2 m/s below 8 km for a 100 m vertical resolution by Mie channel and 2m/s up to 20 km by Rayleigh channel, respectively.

  7. Wind Profiling from a New Compact, Pulsed, 2-Micron, Coherent-Detection Doppler Lidar Transceiver during Wind Measurement Intercomparison

    Science.gov (United States)

    Singh, Upendra N.; Koch, Grady J.; Kavaya, Michael J.; Yu, Jirong; Beyon, Jeffrey Y.; Demoz, B.; Veneable, D.

    2009-01-01

    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. This lidar system was recently deployed at Howard University facility in Beltsville, Maryland, along with other wind lidar systems. Coherent Doppler wind lidar ground-based wind measurements and comparisons with other lidars and other sensors will be presented.

  8. The Tropospheric Wind Lidar Technology Experiment (TWiLiTE): An Airborne Direct Detection Doppler Lidar Instrument Development Program

    Science.gov (United States)

    Gentry, Bruce; McGill, Matthew; Schwemmer, Geary; Hardesty, Michael; Brewer, Alan; Wilkerson, Thomas; Atlas, Robert; Sirota, Marcos; Lindemann, Scott

    2006-01-01

    Global measurement of tropospheric winds is a key measurement for understanding atmospheric dynamics and improving numerical weather prediction. Global wind profiles remain a high priority for the operational weather community and also for a variety of research applications including studies of the global hydrologic cycle and transport studies of aerosols and trace species. In addition to space based winds, a high altitude airborne system flown on UAV or other advanced platforms would be of great interest for studying mesoscale dynamics and hurricanes. The Tropospheric Wind Lidar Technology Experiment (TWiLiTE) project was selected in 2005 by the NASA Earth Sun Technology Office as part of the Instrument Incubator Program. TWiLiTE will leverage significant research and development investments in key technologies made in the past several years. The primary focus will be on integrating these sub-systems into a complete molecular direct detection Doppler wind lidar system designed for autonomous operation on a high altitude aircraft, such as the NASA WB57, so that the nadir viewing lidar will be able to profile winds through the full troposphere. TWiLiTE is a collaboration involving scientists and technologists from NASA Goddard, NOAA ESRL, Utah State University Space Dynamics Lab and industry partners Michigan Aerospace Corporation and Sigma Space Corporation. NASA Goddard and it's partners have been at the forefront in the development of key lidar technologies (lasers, telescopes, scanning systems, detectors and receivers) required to enable spaceborne global wind lidar measurement. The TWiLiTE integrated airborne Doppler lidar instrument will be the first demonstration of a airborne scanning direct detection Doppler lidar and will serve as a critical milestone on the path to a fixture spaceborne tropospheric wind system. The completed system will have the capability to profile winds in clear air from the aircraft altitude of 18 h to the surface with 250 m vertical

  9. Doppler Lidar Vector Retrievals and Atmospheric Data Visualization in Mixed/Augmented Reality

    Science.gov (United States)

    Cherukuru, Nihanth Wagmi

    Environmental remote sensing has seen rapid growth in the recent years and Doppler wind lidars have gained popularity primarily due to their non-intrusive, high spatial and temporal measurement capabilities. While lidar applications early on, relied on the radial velocity measurements alone, most of the practical applications in wind farm control and short term wind prediction require knowledge of the vector wind field. Over the past couple of years, multiple works on lidars have explored three primary methods of retrieving wind vectors viz., using homogeneous windfield assumption, computationally extensive variational methods and the use of multiple Doppler lidars. Building on prior research, the current three-part study, first demonstrates the capabilities of single and dual Doppler lidar retrievals in capturing downslope windstorm-type flows occurring at Arizona's Barringer Meteor Crater as a part of the METCRAX II field experiment. Next, to address the need for a reliable and computationally efficient vector retrieval for adaptive wind farm control applications, a novel 2D vector retrieval based on a variational formulation was developed and applied on lidar scans from an offshore wind farm and validated with data from a cup and vane anemometer installed on a nearby research platform. Finally, a novel data visualization technique using Mixed Reality (MR)/ Augmented Reality (AR) technology is presented to visualize data from atmospheric sensors. MR is an environment in which the user's visual perception of the real world is enhanced with live, interactive, computer generated sensory input (in this case, data from atmospheric sensors like Doppler lidars). A methodology using modern game development platforms is presented and demonstrated with lidar retrieved wind fields. In the current study, the possibility of using this technology to visualize data from atmospheric sensors in mixed reality is explored and demonstrated with lidar retrieved wind fields as well as

  10. Short-Term Wind Power Forecasts using Doppler Lidar

    Science.gov (United States)

    Magerman, Beth

    With a ground-based Doppler lidar on the upwind side of a wind farm in the Tehachapi Pass of California, radial wind velocity measurements were collected for repeating sector sweeps, scanning up to 10 kilometers away. This region consisted of complex terrain, with the scans made between mountains. The dataset was utilized for techniques being studied for short-term forecasting of wind power by correlating changes in energy content and of turbulence intensity by tracking spatial variance, in the wind ahead of a wind farm. A ramp event was also captured and its propagation was tracked. Orthogonal horizontal wind vectors were retrieved from the radial velocity using a sector Velocity Azimuth Display method. Streamlines were plotted to determine the potential sites for a correlation of upstream wind speed with wind speed at downstream locations near the wind farm. A "virtual wind turbine" was "placed" in locations along the streamline by using the time-series velocity data at the location as the input to a modeled wind turbine, to determine the extractable energy content at that location. The relationship between this time-dependent energy content upstream and near the wind farm was studied. By correlating the energy content with each upstream location based on a time shift estimated according to advection at the mean wind speed, several fits were evaluated. A prediction of the downstream energy content was produced by shifting the power output in time and applying the best-fit function. This method made predictions of the power near the wind farm several minutes in advance. Predictions were also made up to an hour in advance for a large ramp event. The Magnitude Absolute Error and Standard Deviation are presented for the predictions based on each selected upstream location.

  11. Performance Assessment of Mobile Rayleigh Doppler Lidars for Middle Atmosphere Research

    Directory of Open Access Journals (Sweden)

    Han Yuli

    2016-01-01

    Full Text Available Recently, two sets of mobile Rayleigh Doppler lidars were implemented in University of Science and Technology of China (USTC for atmospheric gravity waves research. One of them works in a step stare scanning mode with azimuths corresponding to four cardinal points, while the other one consists of three fixed subassemblies: one points to the zenith and the two others are titled at 30° from the zenith with east and north pointings, respectively. They both operate at eye-safe wavelength 354.7 nm and adopt a triple Fabry-Perot interferometer (FPI as frequency discriminator. In order to assess the performance of the Doppler lidars, comparison experiments were performed between them. Perhaps, it is the first time to make direct comparison between scanning and non-scanning Rayleigh Doppler lidars.

  12. Doppler wind lidar using a MOPA semiconductor laser at stable single-frequency operation

    DEFF Research Database (Denmark)

    Rodrigo, Peter John; Pedersen, Christian

    2009-01-01

    A compact master-oscillator power-amplifier semiconductor laser (MOPA-SL) is a good candidate for a coherent light source (operating at 1550 nm) in a Doppler wind Lidar. The MOPA-SL requires two injection currents: Idfb for the distributed-feedback (DFB) laser section (master oscillator) and Iamp...... to the laser. This was done by observing the spectral characteristic of the laser using an optical spectrum at different drive current combinations. When using the laser for a Doppler wind Lidar application, a combination of (Idfb, Iamp) which is close to the center of an identified stable single......-frequency regime is used. The current settings for the laser result in a highly stable Lidar as shown by a 5-day long continuous measurement of the Doppler shift produced by a constantly rotating diffusely reflecting target....

  13. Observations and Analysis of Turbulent Wake of Wind Turbine by Coherent Doppler Lidar

    Directory of Open Access Journals (Sweden)

    Wu Songhua

    2016-01-01

    Full Text Available Turbulent wake of wind turbine will reduce the power output of wind farm. The access to real turbulent wake of wind turbine blades with different spatial and temporal scales is provided by the pulsed Coherent Doppler Lidar (CDL which operates by transmitting a laser beam and detecting the radiation backscattered by atmospheric aerosol particles. In this paper, the authors discuss the possibility of using lidar measurements to characterize the complicated wind field, specifically wind velocity deficit by the turbine wake.

  14. Development and Potential of Space-Borne Doppler Wind Lidar

    Institute of Scientific and Technical Information of China (English)

    LIU Zhishen; SUN Dapeng; WU Dong; Juergen Streicher; Ines Leike

    2003-01-01

    The advantage of lidar over other wind sensors is presented in this paper. With more than 20 years research, the development of the space-borne wind lidar is reviewed. Longer-term investigation has made many technologies suitable for the wind lidar measurement from an orbital platform become mature. However, there are still some problems to be solved. In order to obtain the optimal performance in wind detection, great importance is being attached to the simulation of a virtual space-borne wind lidar system on computer as developed by NASA and ESA.

  15. Simulation of a Doppler lidar system for autonomous navigation and hazard avoidance during planetary landing

    Science.gov (United States)

    Budge, Scott E.; Chester, David B.

    2016-05-01

    The latest mission proposals for exploration of solar system bodies require accurate position and velocity data during the descent phase in order to ensure safe, soft landing at the pre-designated sites. During landing maneuvers, the accuracy of the on-board inertial measurement unit (IMU) may not be reliable due to drift over extended travel times to destinations. NASA has proposed an advanced Doppler lidar system with multiple beams that can be used to accurately determine attitude and position of the landing vehicle during descent, and to detect hazards that might exist in the landing area. In order to assess the effectiveness of such a Doppler lidar landing system, it is valuable to simulate the system with different beam numbers and configurations. In addition, the effectiveness of the system to detect and map potential landing hazards must be understood. This paper reports the simulated system performance for a proposed multi-beam Doppler lidar using the LadarSIM system simulation software. Details of the simulation methods are given, as well as lidar performance parameters such as range and velocity accuracy, detection and false alarm rates, and examples of the Doppler lidars ability to detect and characterize simulated hazards in the landing site. The simulation includes modulated pulse generation and coherent detection methods, beam footprint simulation, beam scanning, and interaction with terrain.

  16. Estimation of aircraft wake vortex parameters from data measured with a 1.5-μm coherent Doppler lidar.

    Science.gov (United States)

    Smalikho, I N; Banakh, V A

    2015-07-15

    A strategy of measurement by a 1.5-μm pulsed coherent Doppler lidar "Stream Line" has been developed, and a method for estimation of aircraft wake vortices from the lidar data has been proposed. The principal possibility of obtaining the information about the vortex situation over an airport airfield with the Stream-Line lidar has been demonstrated.

  17. 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.

  18. Doppler lidar atmospheric wind sensors - A comparative performance evaluation for global measurement applications from earth orbit

    Science.gov (United States)

    Menzies, R. T.

    1986-01-01

    A comparison is made of four prominent Doppler lidar systems, ranging in wavelength from the near UV to the middle IR, which are presently being studied for their potential in an earth-orbiting global tropospheric wind field measurement application. The comparison is restricted to relative photon efficiencies, i.e., the required number of transmitted photons per pulse is calculated for each system for midtropospheric velocity estimate uncertainties ranging from + or - 1 to + or - 4 m/s. The results are converted to laser transmitter pulse energy and power requirements. The analysis indicates that a coherent CO2 Doppler lidar operating at 9.11-micron wavelength is the most efficient.

  19. Fine-measuring technique and application for sea surface wind by mobile Doppler wind lidar

    Science.gov (United States)

    Liu, Zhishen; Wang, Zhangjun; Wu, Songhua; Liu, Bingyi; Li, Zhigang; Zhang, Xin; Bi, Decang; Chen, Yubao; Li, Rongzhong; Yang, Yuqiang

    2009-06-01

    The Key Laboratory of Ocean Remote Sensing of the Ministry of Education of China, Ocean University of China, has developed the first mobile Doppler wind lidar in China. As an important component of meteorological services for the Good Luck Beijing 2007 Qingdao International Regatta, the mobile Doppler wind lidar was used to measure the sea surface wind (SSW) with 100 m*100 m spatial and 10-min temporal resolution in Qingdao from 15 to 23 August 2007. We present the results from two aspects of this campaign. First, the lidar was operated in the fixed-direction mode and compared to SSW simultaneously measured by a collocated buoy. Second, we present lidar wind measurements throughout the regatta and show good agreement with the match situation of the International Regatta. In addition, we present a case study, accounting for the observation of sailboats stopped by the headwind. With considerable data accumulated, we have shown that the mobile Doppler wind lidar can indeed provide near real-time SSW in support of the sailing games. The lidar has also provided meteorological services for the 2008 Olympic sailing games from 8 to 22 August and Paralympics Sailing Games from 8 to 13 September 2008 in Qingdao.

  20. Instrument configuration for dual-Doppler lidar coplanar scans: METCRAX II

    Science.gov (United States)

    Cherukuru, Nihanth Wagmi; Calhoun, Ronald; Lehner, Manuela; Hoch, Sebastian W.; Whiteman, C. David

    2015-01-01

    The second Meteor Crater Experiment (METCRAX II) was designed to study downslope-windstorm-type flows occurring at the Barringer Meteorite Crater in Arizona. Two Doppler wind lidars were deployed to perform a coplanar dual-Doppler lidar analysis to capture the two-dimensional (2-D) vertical structure of these flows in the crater basin. This type of analysis allows the flow to be resolved on a 2-D Cartesian grid constructed in the range height indicator scan overlap region. Previous studies have shown that the dominant error in the coplanar dual-Doppler analysis mentioned above is due to the under sampling of radial velocities. Hence, it is necessary to optimize the setup and choose a scan strategy that minimizes the under sampling of radial velocities and provides a good spatial as well as temporal coverage of these short-lived events. A lidar simulator was developed using a large Eddy simulation wind field to optimize the lidar parameters for METCRAX II field experiment. A retrieval technique based on the weighted least squares technique with weights calculated based on the relative location of the lidar range gate centers to the grid intersection point was developed. The instrument configuration was determined by comparing the simulator retrievals to the background wind field and taking into account the limitations of commercially available lidars.

  1. Wind gust measurements using pulsed Doppler wind-lidar: comparison of direct and indirect techniques

    DEFF Research Database (Denmark)

    model, driven by the Doppler lidar measurements, which uses a non-linear particle filter to estimate the small-scale turbulent fluctuations. The first results show that the reconstruction method can reproduce the wind speed maxima measured by the sonic anemometer if a low-pass filter with a cut......-off frequency similar to the lidar measurement frequency is applied to the sonic data. These results from the reconstructed wind are better than the maxima derived directly from the wind lidar measurements. However, the maxima of the raw sonic anemometer signal are still higher than the maxima...

  2. Coherent Doppler Lidar for Measuring Velocity and Altitude of Space and Arial Vehicles

    Science.gov (United States)

    Amzajerdian, Farzin; Pierrottet, Diego; Hines, Glenn D.; Petway, Larry; Barnes, Bruce W.

    2016-01-01

    A coherent Doppler lidar has been developed to support future NASA missions to planetary bodies. The lidar transmits three laser beams and measures line-of-sight range and velocity along each beam using a frequency modulated continuous wave (FMCW) technique. Accurate altitude and velocity vector data, derived from the line-of-sight measurements, enables the landing vehicle to precisely navigate from several kilometers above the ground to the designated location and execute a gentle touchdown. The same lidar sensor can also benefit terrestrial applications that cannot rely on GPS or require surface-relative altitude and velocity data.

  3. Wind turbine wake characterization using long-range Doppler lidar

    Science.gov (United States)

    Aitken, M.; Lundquist, J. K.; Hestmark, K.; Banta, R. M.; Pichugina, Y.; Brewer, A.

    2012-12-01

    Wind turbines extract energy from the freestream flow, resulting in a waked region behind the rotor which is characterized by reduced wind speed and increased turbulence. The velocity deficit in the wake diminishes with distance, as faster-moving air outside is gradually entrained. In a concentrated group of turbines, then, downwind machines experience very different inflow conditions compared to those in the front row. As utility-scale turbines rarely exist in isolation, detailed knowledge of the mean flow and turbulence structure inside wakes is needed to correctly model both power production and turbine loading at modern wind farms. To this end, the Turbine Wake and Inflow Characterization Study (TWICS) was conducted in the spring of 2011 to determine the reduction in wind speeds downstream from a multi-MW turbine located at the National Renewable Energy Laboratory's National Wind Technology Center (NWTC) near Boulder, Colorado. Full-scale measurements of wake dynamics are hardly practical or even possible with conventional sensors, such as cup anemometers mounted on meteorological (met) masts. Accordingly, the High Resolution Doppler Lidar (HRDL) developed by the National Oceanic and Atmospheric Administration's Earth System Research Laboratory was employed to investigate the formation and propagation of wakes under varying levels of ambient wind speed, shear, atmospheric stability, and turbulence. HRDL remotely senses line-of-sight wind velocities and has been used in several previous studies of boundary layer aerodynamics. With a fully steerable beam and a maximum range up to about 5 km, depending on atmospheric conditions, HRDL performed a comprehensive survey of the wind flow in front of and behind the turbine to study the shape, meandering, and attenuation of wakes. Due in large part to limited experimental data availability, wind farm wake modeling is still subject to an unacceptable amount of uncertainty, particularly in complex terrain. Here, analytical

  4. Pulse-Shape Control in an All Fiber Multi-Wavelength Doppler Lidar

    Directory of Open Access Journals (Sweden)

    Töws Albert

    2016-01-01

    Full Text Available Pulse distortion during amplification in fiber amplifiers due to gain saturation and cross talk in a multi-wavelength Doppler lidar are discussed. We present a feedback control technique which is capable of adjusting any predefined pulse shape and show some examples of feedback controlled pulse shapes.

  5. Comparative study of the performance of semiconductor laser based coherent Doppler lidars

    DEFF Research Database (Denmark)

    Rodrigo, Peter John; Pedersen, Christian

    2012-01-01

    Coherent Doppler Lidars (CDLs), operating at an eye-safe 1.5-micron wavelength, have found promising applications in the optimization of wind-power production. To meet the wind-energy sector's impending demand for more cost-efficient industrial sensors, we have focused on the development...

  6. Measurement of wind profiles by motion-stabilised ship-borne Doppler lidar

    Science.gov (United States)

    Achtert, P.; Brooks, I. M.; Brooks, B. J.; Moat, B. I.; Prytherch, J.; Persson, P. O. G.; Tjernström, M.

    2015-11-01

    Three months of Doppler lidar wind measurements were obtained during the Arctic Cloud Summer Experiment on the icebreaker Oden during the summer of 2014. Such ship-borne Doppler measurements require active stabilisation to remove the effects of ship motion. We demonstrate that the combination of a commercial Doppler lidar with a custom-made motion-stabilisation platform enables the retrieval of wind profiles in the Arctic atmospheric boundary layer during both cruising and ice-breaking with statistical uncertainties comparable to land-based measurements. This held true particularly within the atmospheric boundary layer even though the overall aerosol load was very low. Motion stabilisation was successful for high wind speeds in open water and the resulting wave conditions. It allows for the retrieval of vertical winds with a random error below 0.2 m s-1. The comparison of lidar-measured wind and radio soundings gives a mean bias of 0.3 m s-1 (2°) and a mean standard deviation of 1.1 m s-1 (12°) for wind speed (wind direction). The agreement for wind direction degrades with height. The combination of a motion-stabilised platform with a low-maintenance autonomous Doppler lidar has the potential to enable continuous long-term high-resolution ship-based wind profile measurements over the oceans.

  7. Improvement of vertical velocity statistics measured by a Doppler lidar through comparison with sonic anemometer observations

    Science.gov (United States)

    Bonin, Timothy A.; Newman, Jennifer F.; Klein, Petra M.; Chilson, Phillip B.; Wharton, Sonia

    2016-12-01

    Since turbulence measurements from Doppler lidars are being increasingly used within wind energy and boundary-layer meteorology, it is important to assess and improve the accuracy of these observations. While turbulent quantities are measured by Doppler lidars in several different ways, the simplest and most frequently used statistic is vertical velocity variance (w'2) from zenith stares. However, the competing effects of signal noise and resolution volume limitations, which respectively increase and decrease w'2, reduce the accuracy of these measurements. Herein, an established method that utilises the autocovariance of the signal to remove noise is evaluated and its skill in correcting for volume-averaging effects in the calculation of w'2 is also assessed. Additionally, this autocovariance technique is further refined by defining the amount of lag time to use for the most accurate estimates of w'2. Through comparison of observations from two Doppler lidars and sonic anemometers on a 300 m tower, the autocovariance technique is shown to generally improve estimates of w'2. After the autocovariance technique is applied, values of w'2 from the Doppler lidars are generally in close agreement (R2 ≈ 0.95 - 0.98) with those calculated from sonic anemometer measurements.

  8. Measurement of wind profiles by motion-stabilised ship-borne Doppler lidar

    Directory of Open Access Journals (Sweden)

    P. Achtert

    2015-11-01

    Full Text Available Three months of Doppler lidar wind measurements were obtained during the Arctic Cloud Summer Experiment on the icebreaker Oden during the summer of 2014. Such ship-borne Doppler measurements require active stabilisation to remove the effects of ship motion. We demonstrate that the combination of a commercial Doppler lidar with a custom-made motion-stabilisation platform enables the retrieval of wind profiles in the Arctic atmospheric boundary layer during both cruising and ice-breaking with statistical uncertainties comparable to land-based measurements. This held true particularly within the atmospheric boundary layer even though the overall aerosol load was very low. Motion stabilisation was successful for high wind speeds in open water and the resulting wave conditions. It allows for the retrieval of vertical winds with a random error below 0.2 m s−1. The comparison of lidar-measured wind and radio soundings gives a mean bias of 0.3 m s−1 (2° and a mean standard deviation of 1.1 m s−1 (12° for wind speed (wind direction. The agreement for wind direction degrades with height. The combination of a motion-stabilised platform with a low-maintenance autonomous Doppler lidar has the potential to enable continuous long-term high-resolution ship-based wind profile measurements over the oceans.

  9. Performance evaluation of an all-fiber image-reject homodyne coherent Doppler wind lidar

    DEFF Research Database (Denmark)

    Abari, Cyrus F.; Pedersen, Anders Tegtmeier; Dellwik, Ebba

    2015-01-01

    The main purpose of this study is to evaluate the near-zero wind velocity measurement performance of two separate 1.5 µm all-fiber coherent Doppler lidars (CDLs). The performance characterization is carried out through the presentation of the results from two separate atmospheric field campaigns...

  10. 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.

  11. Noise reduction in LOS wind velocity of Doppler lidar using discrete wavelet analysis

    Institute of Scientific and Technical Information of China (English)

    Songhua Wu(吴松华); Zhishen Liu(刘智深); Dapeng Sun(孙大鹏)

    2003-01-01

    The line of sight (LOS) wind velocity can be determined from the incoherent Doppler lidar backscattering signals. Noise and interference in the measurement greatly degrade the inversion accuracy. In this paper,we apply the discrete wavelet denoising method by using biorthogonal wavelets and adopt a distancedependent thresholds algorithm to improve the accuracy of wind velocity measurement by incoherent Doppler lidar. The noisy simulation data are processed and compared with the true LOS wind velocity.The results are compared by the evaluation of both the standard deviation and correlation coefficient.The results suggest that wavelet denoising with distance-dependent thresholds can considerably reduce the noise and interfering turbulence for wind lidar measurement.

  12. All-Fiber Airborne Coherent Doppler Lidar to Measure Wind Profiles

    Directory of Open Access Journals (Sweden)

    Liu Jiqiao

    2016-01-01

    Full Text Available An all-fiber airborne pulsed coherent Doppler lidar (CDL prototype at 1.54μm is developed to measure wind profiles in the lower troposphere layer. The all-fiber single frequency pulsed laser is operated with pulse energy of 300μJ, pulse width of 400ns and pulse repetition rate of 10kHz. To the best of our knowledge, it is the highest pulse energy of all-fiber eye-safe single frequency laser that is used in airborne coherent wind lidar. The telescope optical diameter of monostatic lidar is 100 mm. Velocity-Azimuth-Display (VAD scanning is implemented with 20 degrees elevation angle in 8 different azimuths. Real-time signal processing board is developed to acquire and process the heterodyne mixing signal with 10000 pulses spectra accumulated every second. Wind profiles are obtained every 20 seconds. Several experiments are implemented to evaluate the performance of the lidar. We have carried out airborne wind lidar experiments successfully, and the wind profiles are compared with aerological theodolite and ground based wind lidar. Wind speed standard error of less than 0.4m/s is shown between airborne wind lidar and balloon aerological theodolite.

  13. Development of semiconductor laser based Doppler lidars for wind-sensing applications

    DEFF Research Database (Denmark)

    Rodrigo, Peter John; Hu, Qi; Pedersen, Christian

    2015-01-01

    We summarize the progress we have made in the development of semiconductor laser (SL) based Doppler lidar systems for remote wind speed and direction measurements. The SL emitter used in our wind-sensing lidar is an integrated diode laser with a tapered (semiconductor) amplifier. The laser source...... based wind sensors have a strong potential in a number of applications such as wind turbine control, wind resource assessment, and micrometeorology (e.g. as alternative to the construction of meteorological towers with anemometers and wind vanes)....

  14. Compact, High Energy 2-micron Coherent Doppler Wind Lidar Development for NASA's Future 3-D Winds Measurement from Space

    Science.gov (United States)

    Singh, Upendra N.; Koch, Grady; Yu, Jirong; Petros, Mulugeta; Beyon, Jeffrey; Kavaya, Michael J.; Trieu, Bo; Chen, Songsheng; Bai, Yingxin; Petzar, paul; Modlin, Edward A.; Barnes, Bruce W.; Demoz, Belay B.

    2010-01-01

    This paper presents an overview of 2-micron laser transmitter development at NASA Langley Research Center for coherent-detection lidar profiling of winds. The novel high-energy, 2-micron, Ho:Tm:LuLiF laser technology developed at NASA Langley was employed to study laser technology currently envisioned by NASA for future global coherent Doppler lidar winds measurement. The 250 mJ, 10 Hz laser was designed as an integral part of a compact lidar transceiver developed for future aircraft flight. Ground-based wind profiles made with this transceiver will be presented. NASA Langley is currently funded to build complete Doppler lidar systems using this transceiver for the DC-8 aircraft in autonomous operation. Recently, LaRC 2-micron coherent Doppler wind lidar system was selected to contribute to the NASA Science Mission Directorate (SMD) Earth Science Division (ESD) hurricane field experiment in 2010 titled Genesis and Rapid Intensification Processes (GRIP). The Doppler lidar system will measure vertical profiles of horizontal vector winds from the DC-8 aircraft using NASA Langley s existing 2-micron, pulsed, coherent detection, Doppler wind lidar system that is ready for DC-8 integration. The measurements will typically extend from the DC-8 to the earth s surface. They will be highly accurate in both wind magnitude and direction. Displays of the data will be provided in real time on the DC-8. The pulsed Doppler wind lidar of NASA Langley Research Center is much more powerful than past Doppler lidars. The operating range, accuracy, range resolution, and time resolution will be unprecedented. We expect the data to play a key role, combined with the other sensors, in improving understanding and predictive algorithms for hurricane strength and track. 1

  15. Analysis of the Uncertainty in Wind Measurements from the Atmospheric Radiation Measurement Doppler Lidar during XPIA: Field Campaign Report

    Energy Technology Data Exchange (ETDEWEB)

    Newsom, Rob [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2016-03-01

    In March and April of 2015, the ARM Doppler lidar that was formerly operated at the Tropical Western Pacific site in Darwin, Australia (S/N 0710-08) was deployed to the Boulder Atmospheric Observatory (BAO) for the eXperimental Planetary boundary-layer Instrument Assessment (XPIA) field campaign. The goal of the XPIA field campaign was to investigate methods of using multiple Doppler lidars to obtain high-resolution three-dimensional measurements of winds and turbulence in the atmospheric boundary layer, and to characterize the uncertainties in these measurements. The ARM Doppler lidar was one of many Doppler lidar systems that participated in this study. During XPIA the 300-m tower at the BAO site was instrumented with well-calibrated sonic anemometers at six levels. These sonic anemometers provided highly accurate reference measurements against which the lidars could be compared. Thus, the deployment of the ARM Doppler lidar during XPIA offered a rare opportunity for the ARM program to characterize the uncertainties in their lidar wind measurements. Results of the lidar-tower comparison indicate that the lidar wind speed measurements are essentially unbiased (~1cm s-1), with a random error of approximately 50 cm s-1. Two methods of uncertainty estimation were tested. The first method was found to produce uncertainties that were too low. The second method produced estimates that were more accurate and better indicators of data quality. As of December 2015, the first method is being used by the ARM Doppler lidar wind value-added product (VAP). One outcome of this work will be to update this VAP to use the second method for uncertainty estimation.

  16. 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.

  17. An all-fiber image-reject homodyne coherent Doppler wind lidar

    DEFF Research Database (Denmark)

    Foroughi Abari, Farzad; Pedersen, Anders Tegtmeier; Mann, Jakob

    2014-01-01

    In this paper, we present an alternative approach to the down-conversion (translation) of the received optical signals collected by the antenna of an all-fiber coherent Doppler lidar (CDL). The proposed method, widely known as image-reject, quadrature detection, or in-phase/quadrature-phase detec......In this paper, we present an alternative approach to the down-conversion (translation) of the received optical signals collected by the antenna of an all-fiber coherent Doppler lidar (CDL). The proposed method, widely known as image-reject, quadrature detection, or in......-phase/quadrature-phase detection, utilizes the advances in fiber optic communications such that the received signal can be optically down-converted into baseband where not only the radial velocity but also the direction of the movement can be inferred. In addition, we show that by performing a cross-spectral analysis, enabled...

  18. 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.

  19. 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.

  20. Current Applications of Scanning Coherent Doppler Lidar in Wind Energy Industry

    Directory of Open Access Journals (Sweden)

    Krishnamurthy R

    2016-01-01

    Full Text Available Scanning Doppler Lidars have become more prominent in the wind energy industry for a variety of applications. Scanning Lidar’s provide spatial variation of winds and direction over a large area, which can be used to assess the spatial uncertainty of winds and analyze complex flows. Due to the recent growth in wind energy, wind farms are being built in complex terrain areas and fine tuning of the existing wind farms for optimized performance have gained significant interest. Scanning Lidar is an ideal tool for improved assessment of flow over complex terrains and wake characterization of large wind farms. In this article, the various applications of Lidar in the wind industry are discussed and results from several campaigns conducted in US and Europe is presented. The conglomeration of results provided in this article would assist wind energy developers and researchers in making improved decisions about their wind farm operations and pre-construction analysis using scanning Lidar’s.

  1. Measurement of wind profiles by motion-stabilised ship-borne Doppler lidar

    Directory of Open Access Journals (Sweden)

    P. Achtert

    2015-09-01

    Full Text Available Three months of Doppler lidar wind measurements were obtained during the Arctic Cloud Summer Experiment on the icebreaker Oden during the summer of 2014. Such ship-borne measurements require active stabilisation to remove the effects of ship motion. We demonstrate that the combination of a commercial Doppler lidar with a custom-made motion-stabilisation platform enables the retrieval of wind profiles in the Arctic boundary layer during both cruising and ice-breaking with statistical uncertainties comparable to land-based measurements. This holds particularly within the planetary boundary layer even though the overall aerosol load was very low. Motion stabilisation was successful for high wind speeds in open water and the resulting wave conditions. It allows for the retrieval of winds with a random error below 0.2 m s−1, comparable to the measurement error of standard radiosondes. The combination of a motion-stabilised platform with a low-maintenance autonomous Doppler lidar has the potential to enable continuous long-term high-resolution ship-based wind profile measurements over the oceans.

  2. The Athena-OAWL Doppler Wind Lidar Mission

    Science.gov (United States)

    Tucker, Sara C.; Weimer, Carl; Hardesty, R. Michael

    2016-06-01

    With the objective of providing tropospheric wind profile data over the mid-latitude oceans and tropics for data-starved weather forecast models, the Earth Venture Instrument (EV-I) Mission concept "Atmospheric Transport, Hurricanes, and Extratropical Numerical weAther prediction with the Optical Autocovariance Wind Lidar" (ATHENA-OAWL) was proposed in November 2013. The mission concept is described here along with a brief history of the OAWL system development and current development of an ATHENA-OAWL airborne demonstrator under NASA's Venture Technology development.

  3. Rlationship between the aerosol scattering ratio and temperature of atmosphere and the sensitivity of a Doppler wind lidar with iodine filter

    Institute of Scientific and Technical Information of China (English)

    Jinshan Zhu; Yubao Chen; Zhaoai Yan; Songhua Wu; Zhishen Liu

    2008-01-01

    The sensitivity of Doppler wind lidar is an important parameter which affects the performance of Doppler wind lidar. Aerosol scattering ratio, atmospheric temperature, and wind speed obviously affect the mea- surement of Doppler wind lidar with iodine filter. We discuss about the relationship between the measurement sensitivity and the above atmospheric parameters. The numerical relationship between them is given through the theoretical simulation and calculation.

  4. Theoretical description of improving measurement accuracy for incoherence Mie Doppler wind lidar

    Institute of Scientific and Technical Information of China (English)

    Du Jun; Ren De-Ming; Zhao Wei-Jiang; Qu Yan-Chen; Chen Zhen-Lei; Geng Li-Jie

    2013-01-01

    For the nonlinearity of Fabry-Perot interferometer (FPI) transmission spectrum,the measurement uncertainty of incoherent Mie Doppler wind lidar based on it increases evidently with the increase of backscattering signal Doppler shift.A method of repeating the use of the approximate linear part of FPI transmission spectra for reducing the high uncertainty of a big Doppler shift is proposed.One of the ways of realizing this method is discussed in detail,in which the characteristics of FPI transmission spectrum changing with thickness and incident angle are utilized simultaneously.Under different atmosphere conditions,it has been proved theoretically that the range of measurement uncertainty drops to one-sixth while its minimum has no serious change.This method can be used not only to guide the new system design,but also as a new working way for the fabricated system.

  5. Challenges in noise removal from Doppler spectra acquired by a continuous-wave lidar

    DEFF Research Database (Denmark)

    Angelou, Nikolas; Foroughi Abari, Farzad; Mann, Jakob;

    2012-01-01

    This paper is focused on the required post processing of Doppler spectra, acquired from a continuous-wave coherent lidar at high sampling rates (400 Hz) and under rapid scanning of the laser beam. In particular, the necessary steps followed for extracting the wind speed from such Doppler spectra...... are presented. A method for determining the background noise spectrum without interrupting the transmission of the laser beam is described. Moreover, the dependency between the determination of the threshold of a Doppler spectrum with low signal-to-noise ratios and the characteristics of the wind flow...... are investigated and a systematic approach for removing the noise is outlined. The suggested post processing procedures are applied to two sample time series acquired by a short-range WindScanner during one second each....

  6. A comparison of Doppler lidar wind sensors for Earth-orbit global measurement applications

    Science.gov (United States)

    Menzies, Robert T.

    1985-01-01

    Now, there are four Doppler lidar configurations which are being promoted for the measurement of tropospheric winds: (1) the coherent CO2 Lidar, operating in the 9 micrometer region using a pulsed, atmospheric pressure CO2 gas discharge laser transmitter, and heterodyne detection; (2) the coherent Neodymium doped YAG or Glass Lidar, operating at 1.06 micrometers, using flashlamp or diode laser optical pumping of the solid state laser medium, and heterodyne detection; (3) the Neodymium doped YAG/Glass Lidar, operating at the doubled frequency (at 530 nm wavelength), again using flashlamp or diode laser pumping of the laser transmitter, and using a high resolution tandem Fabry-Perot filter and direct detection; and (4) the Raman shifted Xenon Chloride Lidar, operating at 350 nm wavelength, using a pulsed, atmospheric pressure XeCl gas discharge laser transmitter at 308 nm, Raman shifted in a high pressure hydrogen cell to 350 nm in order to avoid strong stratospheric ozone absorption, also using a high resolution tandem Fabry-Perot filter and direct detection. Comparisons of these four systems can include many factors and tradeoffs. The major portion of this comparison is devoted to efficiency. Efficiency comparisons are made by estimating the number of transmitted photons required for a single pulse wind velocity estimate of + or - 1 m/s accuracy in the middle troposphere, from an altitude of 800 km, which is assured to be reasonable for a polar orbiting platform.

  7. Estimate of Boundary-Layer Depth Over Beijing, China, Using Doppler Lidar Data During SURF-2015

    Science.gov (United States)

    Huang, Meng; Gao, Zhiqiu; Miao, Shiguang; Chen, Fei; LeMone, Margaret A.; Li, Ju; Hu, Fei; Wang, Linlin

    2016-09-01

    Planetary boundary-layer (PBL) structure was investigated using observations from a Doppler lidar and the 325-m Institute of Atmospheric Physics (IAP) meteorological tower in the centre of Beijing during the summer 2015 Study of Urban-impacts on Rainfall and Fog/haze (SURF-2015) field campaign. Using six fair-weather days of lidar and tower data under clear to cloudy skies, we evaluate the ability of the Doppler lidar to probe the urban boundary-layer structure, and then propose a composite method for estimating the diurnal cycle of the PBL depth using the Doppler lidar. For the convective boundary layer (CBL), a threshold method using vertical velocity variance (σ _w^2 >0.1 m2s^{-2}) is used, since it provides more reliable CBL depths than a conventional maximum wind-shear method. The nocturnal boundary-layer (NBL) depth is defined as the height at which σ _w^2 decreases to 10 % of its near-surface maximum minus a background variance. The PBL depths determined by combining these methods have average values ranging from ≈ 270 to ≈ 1500 m for the six days, with the greatest maximum depths associated with clear skies. Release of stored and anthropogenic heat contributes to the maintenance of turbulence until late evening, keeping the NBL near-neutral and deeper at night than would be expected over a natural surface. The NBL typically becomes more shallow with time, but grows in the presence of low-level nocturnal jets. While current results are promising, data over a broader range of conditions are needed to fully develop our PBL-depth algorithms.

  8. Estimate of Boundary-Layer Depth Over Beijing, China, Using Doppler Lidar Data During SURF-2015

    Science.gov (United States)

    Huang, Meng; Gao, Zhiqiu; Miao, Shiguang; Chen, Fei; LeMone, Margaret A.; Li, Ju; Hu, Fei; Wang, Linlin

    2017-03-01

    Planetary boundary-layer (PBL) structure was investigated using observations from a Doppler lidar and the 325-m Institute of Atmospheric Physics (IAP) meteorological tower in the centre of Beijing during the summer 2015 Study of Urban-impacts on Rainfall and Fog/haze (SURF-2015) field campaign. Using six fair-weather days of lidar and tower data under clear to cloudy skies, we evaluate the ability of the Doppler lidar to probe the urban boundary-layer structure, and then propose a composite method for estimating the diurnal cycle of the PBL depth using the Doppler lidar. For the convective boundary layer (CBL), a threshold method using vertical velocity variance (σ _w^2 >0.1 m2s^{-2}) is used, since it provides more reliable CBL depths than a conventional maximum wind-shear method. The nocturnal boundary-layer (NBL) depth is defined as the height at which σ _w^2 decreases to 10 % of its near-surface maximum minus a background variance. The PBL depths determined by combining these methods have average values ranging from ≈ 270 to ≈ 1500 m for the six days, with the greatest maximum depths associated with clear skies. Release of stored and anthropogenic heat contributes to the maintenance of turbulence until late evening, keeping the NBL near-neutral and deeper at night than would be expected over a natural surface. The NBL typically becomes more shallow with time, but grows in the presence of low-level nocturnal jets. While current results are promising, data over a broader range of conditions are needed to fully develop our PBL-depth algorithms.

  9. Exploration of Whole Atmosphere Lidar: Mach-zehnder Receiver to Extend Fe Doppler Lidar Wind Measurements from the Thermosphere to the Ground

    Science.gov (United States)

    Smith, John A.; Chu, Xinzhao

    2016-06-01

    A receiver employing a field-widened Mach-Zehnder interferometer (MZI) is investigated for extending the wind measurement range of a narrowband Fe Doppler (372 nm) lidar from its existing measurement range in the mesosphere and lower thermosphere (MLT) down to the ground. This design uses the multiple transmitted frequencies available from the base Fe Doppler lidar in combination with an MZI receiver to make a measurement of the Doppler shift from Rayleigh-Mie scattering that is independent of aerosol backscatter ratio, temperature and pressure of the lidar volume and also independent of geometric overlap, the chopper function and any other factor affecting the signal in both MZI channels equally. A ratio is constructed from the three frequencies and two channels of the interferometer that exhibits a measurement performance of 1.75 times the Cramer-Rao lower bound, which is comparable to the dual MZI (DMZ) while preserving the insensitivity to backscatter spectrum of the quad MZI (QMZ). Using actual data obtained recently from the Fe Doppler lidar, we show the expected measurement performance of this whole atmosphere lidar instrument concept.

  10. Three Dimensional Measurements of Boundary Layer Statistics using Scanning Doppler Lidar

    Science.gov (United States)

    Frehlich, R.

    2008-12-01

    Accurate measurements and modeling of the boundary layer is challenging, especially for the stable night time boundary layer, the highly turbulent boundary layer, and the early morning transition to convection. High quality profiles of mean and turbulent statistics of the night time boundary layer are logistically difficult using instrumented towers or instrumented research aircraft. One of the fundamental limits to the accuracy of atmospheric estimates of mean and turbulent quantities is the number of independent samples of the relevant processes. Traditional measurements from towers, sodars, radar profilers, and instrumented aircraft essentially produce a spatial sample of the atmosphere along a line defined by the mean wind (or aircraft trajectory). Advanced three dimensional measurements of the boundary layer provides the highest statistical accuracy which is essential to understand complex rapidly changing processes. The development of eye-safe scanning Doppler lidars and processing algorithms to correct for the spatial filtering by the laser pulse smoothing and the contribution from estimation error have produced profiles of the mean velocity and key turbulence statistics (the energy dissipation rate, velocity variance, and turbulence length scale) for two orthogonal horizontal velocity components. This requires accurate information about the sensing volume of the lidar measurements as well as the statistical properties of the estimation error. The various processing techniques and fundamental assumptions for the analysis of scanning Doppler lidar data will be presented for various atmospheric conditions. Unresolved issues for future work will also be outlined.

  11. Gravity waves observation of wind field in stratosphere based on a Rayleigh Doppler lidar.

    Science.gov (United States)

    Zhao, Ruocan; Dou, Xiankang; Sun, Dongsong; Xue, Xianghui; Zheng, Jun; Han, Yuli; Chen, Tingdi; Wang, Guocheng; Zhou, Yingjie

    2016-03-21

    Simultaneous wind and temperature measurements in stratosphere with high time-spatial resolution for gravity waves study are scarce. In this paper we perform wind field gravity waves cases in the stratosphere observed by a mobile Rayleigh Doppler lidar. This lidar system with both wind and temperature measurements were implemented for atmosphere gravity waves research in the altitude region 15-60 km. Observations were carried out for two periods of time: 3 months started from November 4, 2014 in Xinzhou, China (38.425°N,112.729°E) and 2 months started from October 7, 2015 in Jiuquan, China (39.741°N, 98.495°E) . The mesoscale fluctuations of the horizontal wind velocity and the two dimensional spectra analysis of these fluctuations show the presence of dominant oscillatory modes with wavelength of 4-14 km and period of around 10 hours in several cases. The simultaneous temperature observations make it possible to identify gravity wave cases from the relationships between different variables: temperature and horizontal wind. The observed cases demonstrate the Rayleigh Doppler Lidar's capacity to study gravity waves.

  12. Doppler lidar sensor for precision navigation in GPS-deprived environment

    Science.gov (United States)

    Amzajerdian, F.; Pierrottet, D. F.; Hines, G. D.; Petway, L. B.; Barnes, B. W.

    2013-05-01

    Landing mission concepts that are being developed for exploration of solar system bodies are increasingly ambitious in their implementations and objectives. Most of these missions require accurate position and velocity data during their descent phase in order to ensure safe, soft landing at the pre-designated sites. Data from the vehicle's Inertial Measurement Unit will not be sufficient due to significant drift error after extended travel time in space. Therefore, an onboard sensor is required to provide the necessary data for landing in the GPS-deprived environment of space. For this reason, NASA Langley Research Center has been developing an advanced Doppler lidar sensor capable of providing accurate and reliable data suitable for operation in the highly constrained environment of space. The Doppler lidar transmits three laser beams in different directions toward the ground. The signal from each beam provides the platform velocity and range to the ground along the laser line-of-sight (LOS). The six LOS measurements are then combined in order to determine the three components of the vehicle velocity vector, and to accurately measure altitude and attitude angles relative to the local ground. These measurements are used by an autonomous Guidance, Navigation, and Control system to accurately navigate the vehicle from a few kilometers above the ground to the designated location and to execute a gentle touchdown. A prototype version of our lidar sensor has been completed for a closed-loop demonstration onboard a rocket-powered terrestrial free-flyer vehicle.

  13. Multiscale modeling to evaluate proposed space-based Doppler lidar sampling strategies

    Science.gov (United States)

    Emmitt, G. D.

    1985-01-01

    A proposal has been made to place a pulsed Doppler lidar on a space platform (Huffaker, et al., 1980; Emmitt, 1982) in a low earth orbit (200 to 800 km) to measure the atmospheric winds with a spatial resolution commensurate with the current continental rawinsonde network density - i.e., 300 to 500 km resolution. In the case of the space-based doppler lidar, the full range of space scales applies. Single shot pulses with dimensions of 10 x 1000 meters are used to sample areas 100,000 x 100,000 meters to resolved mass flow structure with wavelength of 1 million meters. Simulation studies, therefore, require an equally broad range of atmospheric models. A general circulation model is appropriate to answer questions regarding the impact of a global wind measuring system upon synoptic forecasts. Since the nominal resolution of the spacebased system is expected to be a few 100's of kilometers, then a numerical model with mesoscale dynamics is required. The meaning of an average Doppler shift within a laser pulse volume must be evaluated with models of turbulent/convective scale motions and aerosol gradients. Examples of how models on all these scales have been applied in an ongoing simulation study are presented. In particular, the uncertainties in a mesoscale wind estimate are separated into those arising from pulse scale variances and those due to sample distribution within a prescribed resolution volume. Trade-offs between accuracy and representativeness are discussed in terms of the model results.

  14. Retrieval of aerosol backscatter and extinction from airborne coherent Doppler wind lidar measurements

    Directory of Open Access Journals (Sweden)

    F. Chouza

    2015-02-01

    Full Text Available A novel method for calibration and quantitative aerosol optical properties retrieval from Doppler wind lidars (DWL is presented in this work. Due to the strong wavelength dependence of the atmospheric molecular backscatter and the low sensitivity of the coherent detection to spectrally broad signals, calibration methods for aerosol lidars cannot be applied to a coherent DWLs usually operating at wavelengths between 1.5–2 μm. Instead, concurrent measurements of an airborne DWL at 2 μm and the POLIS ground-based aerosol lidar at 532 nm are used in this work, in combination with sun photometer measurements, for the calibration and retrieval of aerosol backscatter and extinction profiles. The proposed method was applied to measurements from the SALTRACE experiment in June–July 2013, which aimed at quantifying the aerosol transport and change in aerosol properties from the Sahara desert to the Caribbean. The retrieved backscatter and extinction coefficient profiles from the airborne DWL are within 20% of POLIS aerosol lidar and CALIPSO satellite measurements. Thus the proposed method extends the capabilities of coherent DWL to measure profiles of the horizontal and vertical wind towards aerosol backscatter and extinction profiles, which is of high benefit for aerosol transport studies.

  15. Dynamic Data Filtering of Long-Range Doppler LiDAR Wind Speed Measurements

    Directory of Open Access Journals (Sweden)

    Hauke Beck

    2017-06-01

    Full Text Available Doppler LiDARs have become flexible and versatile remote sensing devices for wind energy applications. The possibility to measure radial wind speed components contemporaneously at multiple distances is an advantage with respect to meteorological masts. However, these measurements must be filtered due to the measurement geometry, hard targets and atmospheric conditions. To ensure a maximum data availability while producing low measurement errors, we introduce a dynamic data filter approach that conditionally decouples the dependency of data availability with increasing range. The new filter approach is based on the assumption of self-similarity, that has not been used so far for LiDAR data filtering. We tested the accuracy of the dynamic data filter approach together with other commonly used filter approaches, from research and industry applications. This has been done with data from a long-range pulsed LiDAR installed at the offshore wind farm ‘alpha ventus’. There, an ultrasonic anemometer located approximately 2.8 km from the LiDAR was used as reference. The analysis of around 1.5 weeks of data shows, that the error of mean radial velocity can be minimised for wake and free stream conditions.

  16. Improving Maryland's Offshore Wind Energy Resource Estimate Using Doppler Wind Lidar Technology to Assess Microtmeteorology Controls

    Science.gov (United States)

    St. Pé, Alexandra; Wesloh, Daniel; Antoszewski, Graham; Daham, Farrah; Goudarzi, Navid; Rabenhorst, Scott; Delgado, Ruben

    2016-06-01

    There is enormous potential to harness the kinetic energy of offshore wind and produce power. However significant uncertainties are introduced in the offshore wind resource assessment process, due in part to limited observational networks and a poor understanding of the marine atmosphere's complexity. Given the cubic relationship between a turbine's power output and wind speed, a relatively small error in the wind speed estimate translates to a significant error in expected power production. The University of Maryland Baltimore County (UMBC) collected in-situ measurements offshore, within Maryland's Wind Energy Area (WEA) from July-August 2013. This research demonstrates the ability of Doppler wind lidar technology to reduce uncertainty in estimating an offshore wind resource, compared to traditional resource assessment techniques, by providing a more accurate representation of the wind profile and associated hub-height wind speed variability. The second objective of this research is to elucidate the impact of offshore micrometeorology controls (stability, wind shear, turbulence) on a turbine's ability to produce power. Compared to lidar measurements, power law extrapolation estimates and operational National Weather Service models underestimated hub-height wind speeds in the WEA. In addition, lidar observations suggest the frequent development of a low-level wind maximum (LLWM), with high turbinelayer wind shear and low turbulence intensity within a turbine's rotor layer (40m-160m). Results elucidate the advantages of using Doppler wind lidar technology to improve offshore wind resource estimates and its ability to monitor under-sampled offshore meteorological controls impact on a potential turbine's ability to produce power.

  17. Three-Dimensional Wind Profiling of Offshore Wind Energy Areas With Airborne Doppler Lidar

    Science.gov (United States)

    Koch, Grady J.; Beyon, Jeffrey Y.; Cowen, Larry J.; Kavaya, Michael J.; Grant, Michael S.

    2014-01-01

    A technique has been developed for imaging the wind field over offshore areas being considered for wind farming. This is accomplished with an eye-safe 2-micrometer wavelength coherent Doppler lidar installed in an aircraft. By raster scanning the aircraft over the wind energy area (WEA), a three-dimensional map of the wind vector can be made. This technique was evaluated in 11 flights over the Virginia and Maryland offshore WEAs. Heights above the ocean surface planned for wind turbines are shown to be within the marine boundary layer, and the wind vector is seen to show variation across the geographical area of interest at turbine heights.

  18. Three-dimensional wind profiling of offshore wind energy areas with airborne Doppler lidar

    Science.gov (United States)

    Koch, Grady J.; Beyon, Jeffrey Y.; Cowen, Larry J.; Kavaya, Michael J.; Grant, Michael S.

    2014-01-01

    A technique has been developed for imaging the wind field over offshore areas being considered for wind farming. This is accomplished with an eye-safe 2-μm wavelength coherent Doppler lidar installed in an aircraft. By raster scanning the aircraft over the wind energy area (WEA), a three-dimensional map of the wind vector can be made. This technique was evaluated in 11 flights over the Virginia and Maryland offshore WEAs. Heights above the ocean surface planned for wind turbines are shown to be within the marine boundary layer, and the wind vector is seen to show variation across the geographical area of interest at turbine heights.

  19. Airborne wind profiling algorithms for the pulsed 2-micron coherent doppler Lidar at NASA Langley Research Center

    Science.gov (United States)

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

    2013-05-01

    Two versions of airborne wind profiling algorithms for the pulsed 2-micron coherent Doppler lidar system at NASA Langley Research Center in Virginia are presented. Each algorithm utilizes different number of line-of-sight (LOS) lidar returns while compensating the adverse effects of different coordinate systems between the aircraft and the Earth. One of the two algorithms APOLO (Airborne Wind Profiling Algorithm for Doppler Wind Lidar) estimates wind products using two LOSs. The other algorithm utilizes five LOSs. The airborne lidar data were acquired during the NASA's Genesis and Rapid Intensification Processes (GRIP) campaign in 2010. The wind profile products from the two algorithms are compared with the dropsonde data to validate their results.

  20. Comparing Pulsed Doppler LIDAR with SODAR and Direct Measurements for Wind Assessment

    Energy Technology Data Exchange (ETDEWEB)

    Kelley, N. D.; Jonkman, B. J.; Scott, G. N.; Pichugina, Y. L.

    2007-07-01

    There is a pressing need for good wind-speed measurements at greater and greater heights to assess the availability of the resource in terms of power production and to identify any frequently occurring atmospheric structural characteristics that may create turbulence that impacts the operational reliability and lifetime of wind turbines and their components. In this paper, we summarize the results of a short study that compares the relative accuracies of wind speeds derived from a high-resolution pulsed Doppler LIDAR operated by the National Oceanic and Atmospheric Administration (NOAA) and a midrange Doppler SODAR with wind speeds measured by four levels of tower-based sonic anemometry up to a height of 116 m.

  1. Note: A sub-sampling technique for frequency locking in Doppler wind lidar.

    Science.gov (United States)

    Yao, Yuan; Li, Feng; Chen, Lian; Jin, Ge

    2016-05-01

    Double-edge technique is employed in Doppler wind lidar for detecting the Doppler frequency shift. A dedicated locking channel, employing one channel of a triple Fabry-Perot etalon, is designed to compensate for the effects caused by the frequency drift of outgoing laser. Agilent Oscilloscopes, with a sampling rate of 2.5 GSPS, are employed to obtain accurate amplitudes of the narrow pulses in existing experiments. In order to achieve the requirement of real-time ability and integration, a sub-sampling technique based on the theory of statistics is presented. With the technique, the drift can be acquired at a sub-sampling rate, 250 MSPS. A prototype is designed and the test results show that the prototype, providing real-time ability and better integration, has a comparable performance as the oscilloscope for frequency locking.

  2. Phase noise in pulsed Doppler lidar and limitations on achievable single-shot velocity accuracy

    Science.gov (United States)

    Mcnicholl, P.; Alejandro, S.

    1992-01-01

    The smaller sampling volumes afforded by Doppler lidars compared to radars allows for spatial resolutions at and below some sheer and turbulence wind structure scale sizes. This has brought new emphasis on achieving the optimum product of wind velocity and range resolutions. Several recent studies have considered the effects of amplitude noise, reduction algorithms, and possible hardware related signal artifacts on obtainable velocity accuracy. We discuss here the limitation on this accuracy resulting from the incoherent nature and finite temporal extent of backscatter from aerosols. For a lidar return from a hard (or slab) target, the phase of the intermediate frequency (IF) signal is random and the total return energy fluctuates from shot to shot due to speckle; however, the offset from the transmitted frequency is determinable with an accuracy subject only to instrumental effects and the signal to noise ratio (SNR), the noise being determined by the LO power in the shot noise limited regime. This is not the case for a return from a media extending over a range on the order of or greater than the spatial extent of the transmitted pulse, such as from atmospheric aerosols. In this case, the phase of the IF signal will exhibit a temporal random walk like behavior. It will be uncorrelated over times greater than the pulse duration as the transmitted pulse samples non-overlapping volumes of scattering centers. Frequency analysis of the IF signal in a window similar to the transmitted pulse envelope will therefore show shot-to-shot frequency deviations on the order of the inverse pulse duration reflecting the random phase rate variations. Like speckle, these deviations arise from the incoherent nature of the scattering process and diminish if the IF signal is averaged over times greater than a single range resolution cell (here the pulse duration). Apart from limiting the high SNR performance of a Doppler lidar, this shot-to-shot variance in velocity estimates has a

  3. Stratospheric temperature measurement with scanning Fabry-Perot interferometer for wind retrieval from mobile Rayleigh Doppler lidar.

    Science.gov (United States)

    Xia, Haiyun; Dou, Xiankang; Shangguan, Mingjia; Zhao, Ruocan; Sun, Dongsong; Wang, Chong; Qiu, Jiawei; Shu, Zhifeng; Xue, Xianghui; Han, Yuli; Han, Yan

    2014-09-08

    Temperature detection remains challenging in the low stratosphere, where the Rayleigh integration lidar is perturbed by aerosol contamination and ozone absorption while the rotational Raman lidar is suffered from its low scattering cross section. To correct the impacts of temperature on the Rayleigh Doppler lidar, a high spectral resolution lidar (HSRL) based on cavity scanning Fabry-Perot Interferometer (FPI) is developed. By considering the effect of the laser spectral width, Doppler broadening of the molecular backscatter, divergence of the light beam and mirror defects of the FPI, a well-behaved transmission function is proved to show the principle of HSRL in detail. Analysis of the statistical error of the HSRL is carried out in the data processing. A temperature lidar using both HSRL and Rayleigh integration techniques is incorporated into the Rayleigh Doppler wind lidar. Simultaneous wind and temperature detection is carried out based on the combined system at Delhi (37.371°N, 97.374°E; 2850 m above the sea level) in Qinghai province, China. Lower Stratosphere temperature has been measured using HSRL between 18 and 50 km with temporal resolution of 2000 seconds. The statistical error of the derived temperatures is between 0.2 and 9.2 K. The temperature profile retrieved from the HSRL and wind profile from the Rayleigh Doppler lidar show good agreement with the radiosonde data. Specifically, the max temperature deviation between the HSRL and radiosonde is 4.7 K from 18 km to 36 km, and it is 2.7 K between the HSRL and Rayleigh integration lidar from 27 km to 34 km.

  4. Assessment of measurement error due to sampling perspective in the space-based Doppler lidar wind profiler

    Science.gov (United States)

    Houston, S. H.; Emmitt, G. D.

    1986-01-01

    A Multipair Algorithm (MPA) has been developed to minimize the contribution of the sampling error in the simulated Doppler lidar wind profiler measurements (due to angular and spatial separation between shots in a shot pair) to the total measurement uncertainty. Idealized wind fields are used as input to the profiling model, and radial wind estimates are passed through the MPA to yield a wind measurement for 300 x 300 sq km areas. The derived divergence fields illustrate the gradient patterns that are particular to the Doppler lidar sampling strategy and perspective.

  5. Method of radial velocities for the estimation of aircraft wake vortex parameters from data measured by coherent Doppler lidar.

    Science.gov (United States)

    Smalikho, I N; Banakh, V A; Holzäpfel, F; Rahm, S

    2015-09-21

    The method of radial velocities (RV) is applied to estimate aircraft wake vortex parameters from measurements conducted with pulsed coherent Doppler lidar (PCDL). Operations of the Stream Line lidar and the 2-µm PCDL are simulated numerically to analyze the accuracy of the estimated wake vortex parameters with the RV method. The RV method is also used to estimate wake vortex trajectories and circulation from lidar measurements at Tomsk and Munich airports. The method of velocity envelopes and the RV method are compared employing data gathered with the 2-µm PCDL. The domain of applicability of the RV method is determined.

  6. Improving Maryland’s Offshore Wind Energy Resource Estimate Using Doppler Wind Lidar Technology to Assess Microtmeteorology Controls

    Directory of Open Access Journals (Sweden)

    Pé Alexandra St.

    2016-01-01

    Compared to lidar measurements, power law extrapolation estimates and operational National Weather Service models underestimated hub-height wind speeds in the WEA. In addition, lidar observations suggest the frequent development of a low-level wind maximum (LLWM, with high turbinelayer wind shear and low turbulence intensity within a turbine’s rotor layer (40m-160m. Results elucidate the advantages of using Doppler wind lidar technology to improve offshore wind resource estimates and its ability to monitor under-sampled offshore meteorological controls impact on a potential turbine’s ability to produce power.

  7. Analysis of Detectors and Transmission Curve Correction of Mobile Rayleigh Doppler Wind Lidar

    Institute of Scientific and Technical Information of China (English)

    TANG Lei; SUN Dong-Song; CHA Hyunki; WANG Yong-Tao; SHU Zhi-Feng; DONG Ji-Hui; WANG Guo-Cheng; XU Wen-Jing; HU Dong-Dong; CHEN Ting-Di; DOU Xian-Kang

    2010-01-01

    @@ A mobile molecular Doppler wind lidar (DWL) based on double-edge technique is presented for wind measurement at altitudes from 10 km to 40 km.A triple Fabry-Perot etalon is employed as a frequency discriminator to determine the Doppler shift proportional to the wind velocity.The lidar operates at 355 nm with a 45-cm aperture telescope and a matching azimuth-over-elevation scanner that can provide full hemispherical pointing.In order to guarantee the wind accuracy,different forms of calibration function of detectors in different count rates response range would be especially valuable.The accuracy of wind velocity iteration is improved greatly because of application of the calibration function of linearity at the ultra low light intensity especially at altitudes from 10 km to 40 km.The calibration functions of nonlinearity make the transmission of edge channel 1 and edge channel 2 increase 38.9% and 27.7% at about 1M count rates,respectively.The dynamic range of wind field measurement may also be extended because of consideration of the response function of detectors in their all possible operating range.

  8. Hybrid lidar radar receiver for underwater imaging applications

    Science.gov (United States)

    Seetamraju, Madhavi; Gurjar, Rajan; Squillante, Michael; Derderian, Jeffrey P.

    2009-05-01

    In this work, we present research performed to improve the receiver characteristics for underwater imaging applications using the hybrid lidar-radar detection technique. We report the development of the next-generation coherent heterodyne receiver using modulation of the optical receiver's amplifier gain. Significant advantages in the receiver specifications are achieved using a large-area, high gain, low-noise silicon avalanche photodiode (APD) as the photodetector cum frequency mixer-demodulator. We demonstrate that heterodyne detection by gain modulation of APD can be used to increase the signal-to-noise ratio, detection sensitivity and bandwidth for the hybrid receiver system.

  9. Assessment of a multibeam Fizeau wedge interferometer for Doppler wind lidar.

    Science.gov (United States)

    McKay, Jack A

    2002-03-20

    The Fabry-Perot interferometer is the standard instrument for the direct detection Doppler lidar measurement of atmospheric wind speeds. The multibeam Fizeau wedge has some practical advantages over the Fabry-Perot, such as the linear fringe pattern, and is evaluated for this application. The optimal Fizeau must have a resolving power of 10(6) or more. As the multibeam Fizeau wedge is pushed to such high resolving power, the interference fringes of the device become complicated by asymmetry and secondary maxima. A simple condition for the interferometer plate reflectance, optical gap, and wedge angle reveals whether a set of parameters will yield simple, Airy-like fringes or complex Fizeau fringes. Tilting of the Fizeau wedge improves the fringe shape and permits an extension of the regime of Airy-like fringes to higher resolving power. Sufficient resolving power for the wind lidar application is shown to be possible with a large-gap, low-finesse multibeam Fizeau wedge. Liabilities of the multibeam Fizeau wedge in the wind lidar application include a smaller acceptance solid angle and calibration sensitivity to localized deviations of the plates from the ideal.

  10. Eye-safe diode laser Doppler lidar with a MEMS beam-scanner.

    Science.gov (United States)

    Hu, Qi; Pedersen, Christian; Rodrigo, Peter John

    2016-02-08

    We present a novel Doppler lidar that employs a cw diode laser operating at 1.5 μm and a micro-electro-mechanical-system scanning mirror (MEMS-SM). In this work, two functionalities of the lidar system are demonstrated. Firstly, we describe the capability to effectively steer the lidar probe beam to multiple optical transceivers along separate lines-of-sight. The beam steering functionality is demonstrated using four lines-of-sight--each at an angle of 18° with respect to their symmetry axis. Secondly, we demonstrate the ability to spatially dither the beam focus to reduce the mean irradiance at the probing distance (R = 60 m) of each line-of-sight--elevant for meeting eye-safety requirements. The switching time of the MEMS-SM is measured to be in the order of a few milliseconds. Time-shared (0.25 s per line-of-sight) radial wind speed measurements at 50 Hz data rate are experimentally demonstrated. Spatial dithering of the beam focus is also implemented using a spiral scan trajectory resulting in a 16 dB reduction of beam focus mean irradiance.

  11. Development of a mobile Doppler lidar system for wind and temperature measurements at 30-70 km

    Science.gov (United States)

    Yan, Zhaoai; Hu, Xiong; Guo, Wenjie; Guo, Shangyong; Cheng, Yongqiang; Gong, Jiancun; Yue, Jia

    2017-02-01

    A mobile Doppler lidar system has been developed to simultaneously measure zonal and meridional winds and temperature from 30 to 70 km. Each of the two zonal and meridional wind subsystems employs a 15 W power, 532 nm laser and a 1 m diameter telescope. Iodine vapor filters are used to stabilize laser frequency and to detect the Doppler shift of backscattered signal. The integration method is used for temperature measurement. Experiments were carried out using the mobile Doppler lidar in August 2014 at Qinghai, China (91°E, 38°N). The zonal wind was measured from 20 to 70 km at a 3 km spatial resolution and 2 h temporal resolution. The measurement error is about 0.5 m/s at 30 km, and 10 m/s at 70 km. In addition, the temperature was measured from 30 to 70 km at 1 km spatial resolution and 1 h temporal resolution. The temperature measurement error is about 0.4 K at 30 km, and 8.0 K at 70 km. Comparison of the lidar results with the temperature of the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER), the zonal wind of the Modern-Era Retrospective Analysis for Re-search and Applications (MERRA), and radiosonde zonal wind shows good agreement, indicating that the Doppler lidar results are reliable.

  12. A time-space synchronization of coherent Doppler scanning lidars for 3D measurements of wind fields

    DEFF Research Database (Denmark)

    Vasiljevic, Nikola

    This thesis consists of the results of a Ph.D. study that was focused on the development of the system of three time-space synchronized pulsed coherent Doppler scanning lidars, which are coordinated by a remote ’master computer’. This system has the unique capability to measure a complete three...... synchronization and time control of the emission, steering and acquisition were achieved, resulting that the complete lidar measurement process is controlled from the single hardware component. The system was formed using a novel approach, in which the master computer simultaneously coordinates the remote lidars...... through a UDP/IP and TCP/IP network by exchange of network packets. Since the size of the packets is roughly 1 kB, this approach allows an uninterrupted and fast coordination of the lidars, even in the case of mobile networks such as GSM. With this approach a maximum lag of 10 ms was observed in terms...

  13. Navigation Doppler Lidar Sensor for Precision Altitude and Vector Velocity Measurements Flight Test Results

    Science.gov (United States)

    Pierrottet, Diego F.; Lockhard, George; Amzajerdian, Farzin; Petway, Larry B.; Barnes, Bruce; Hines, Glenn D.

    2011-01-01

    An all fiber Navigation Doppler Lidar (NDL) system is under development at NASA Langley Research Center (LaRC) for precision descent and landing applications on planetary bodies. The sensor produces high resolution line of sight range, altitude above ground, ground relative attitude, and high precision velocity vector measurements. Previous helicopter flight test results demonstrated the NDL measurement concepts, including measurement precision, accuracies, and operational range. This paper discusses the results obtained from a recent campaign to test the improved sensor hardware, and various signal processing algorithms applicable to real-time processing. The NDL was mounted in an instrumentation pod aboard an Erickson Air-Crane helicopter and flown over vegetation free terrain. The sensor was one of several sensors tested in this field test by NASA?s Autonomous Landing and Hazard Avoidance Technology (ALHAT) project.

  14. Coherent Doppler Lidar for Measuring Altitude, Ground Velocity, and Air Velocity of Aircraft and Spaceborne Vehicles

    Science.gov (United States)

    Amzajerdian, Farzin (Inventor); Pierrottet, Diego F. (Inventor)

    2015-01-01

    A Doppler lidar sensor system includes a laser generator that produces a highly pure single frequency laser beam, and a frequency modulator that modulates the laser beam with a highly linear frequency waveform. A first portion of the frequency modulated laser beam is amplified, and parts thereof are transmitted through at least three separate transmit/receive lenses. A second portion of the laser beam is used as a local oscillator beam for optical heterodyne detection. Radiation from the parts of the laser beam transmitted via the transmit/receive lenses is received by the respective transmit/receive lenses that transmitted the respective part of the laser beam. The received reflected radiation is compared with the local oscillator beam to calculate the frequency difference there between to determine various navigational data.

  15. Doppler lidar investigation of wind turbine wake characteristics and atmospheric turbulence under different surface roughness.

    Science.gov (United States)

    Zhai, Xiaochun; Wu, Songhua; Liu, Bingyi

    2017-06-12

    Four field experiments based on Pulsed Coherent Doppler Lidar with different surface roughness have been carried out in 2013-2015 to study the turbulent wind field in the vicinity of operating wind turbine in the onshore and offshore wind parks. The turbulence characteristics in ambient atmosphere and wake area was analyzed using transverse structure function based on Plane Position Indicator scanning mode. An automatic wake processing procedure was developed to determine the wake velocity deficit by considering the effect of ambient velocity disturbance and wake meandering with the mean wind direction. It is found that the turbine wake obviously enhances the atmospheric turbulence mixing, and the difference in the correlation of turbulence parameters under different surface roughness is significant. The dependence of wake parameters including the wake velocity deficit and wake length on wind velocity and turbulence intensity are analyzed and compared with other studies, which validates the empirical model and simulation of a turbine wake for various atmosphere conditions.

  16. Measurement uncertainty analysis in incoherent Doppler lidars by a new scattering approach.

    Science.gov (United States)

    Belmonte, Aniceto; Lázaro, Antonio

    2006-08-21

    We need to examine the uncertainty added to the Doppler measurement process of atmospheric wind speeds of a practical incoherent detection lidar. For this application, the multibeam Fizeau wedge has the advantage over the Fabry-Perot interferometer of defining linear fringe patterns. Unfortunately, the convenience of using the transfer function for angular spectrum transmission has not been available because the nonparallel mirror geometry of Fizeau wedges. In this paper, we extent the spatial-frequency arguments used in Fabry-Perot etalons to the Fizeau geometry by using a generalized scattering matrix method based on the propagation of optical vortices. Our technique opens the door to consider complex, realistic configurations for any Fizeau-based instrument.

  17. Low-level mixing height detection in coastal locations with a scanning Doppler lidar

    Directory of Open Access Journals (Sweden)

    V. Vakkari

    2014-12-01

    Full Text Available Mixing height is one of the key parameters in describing lower tropospheric dynamics, and capturing the diurnal variability is crucial, especially in interpreting surface observations. In this paper we introduce a method for identifying mixing heights below the vertical minimum range of a scanning Doppler lidar. The method we propose is based on velocity variance in low elevation angle conical scanning, and is applied to measurements in two very different coastal environments: Limassol, Cyprus during summer; and Loviisa, Finland during winter. At both locations, the new method agrees well with mixing heights derived from turbulent kinetic energy dissipation rate profiles obtained from vertically-pointing measurements. The low-level scanning routine frequently indicated non-zero mixing heights less than 100 m above the surface. Such low mixing heights were more common at wintertime Loviisa on the Baltic Sea coast than during summertime in Mediterranean Limassol.

  18. Four-dimensional data assimilation with optimized viscosity using High Resolution Doppler Lidar observations

    Science.gov (United States)

    Chai, Tianfeng; Lin, Ching-Long

    2001-11-01

    We present a four-dimensional variational data assimilation (4D-Var) technique with optimized eddy viscosity for the retrieval of the detailed atmospheric boundary-layer structures from High-Resolution Doppler Lidar (HRDL) radial velocity observations. The 4D-Var is based on the calculus of variations and optimal control theory to recover complete and dynamically consistent data set by minimizing the difference between limited observations and corresponding model predictions. To reflect the nature of the atmospheric boundary layer under various stability conditions, eddy viscosity is treated as part of control variables to be optimized in the 4D-Var model. The mathematical formulation for optimizing eddy viscosity is presented. The model is validated by conducting numerical experiments that utilize synthetic observations. We then apply the 4D-Var to the HRDL data measured under convective and stable conditions.

  19. Performance evaluation of an all-fiber image-reject homodyne coherent Doppler wind lidar

    Directory of Open Access Journals (Sweden)

    C. F. Abari

    2015-04-01

    Full Text Available The main purpose of this study is to evaluate the near-zero wind velocity measurement performance of two separate 1.5 μm all-fiber coherent Doppler lidars (CDL. The performance characterization is performed through the presentation of the results from two separate atmospheric field campaigns. In one campaign, a recently developed continuous wave (CW CDL benefiting from an image-reject front-end was deployed. The other campaign utilized a different CW CDL, benefiting from a heterodyne receiver with intermediate frequency (IF sampling. In both field campaigns the results are compared against a sonic anemometer, as the reference instrument. The measurements clearly show that the image-reject architecture results in more accurate measurements of radial wind velocities close to zero. Close-to-zero velocities are usually associated with the vertical component of the wind and are important to characterize.

  20. Signal to Noise Ratio Characterization of Coherent Doppler Lidar Backscattered Signals

    Directory of Open Access Journals (Sweden)

    Abdelazim Sameh

    2016-01-01

    Full Text Available An eye-safe coherent Doppler Lidar (CDL system for wind measurement was developed and tested at the Remote Sensing Laboratory of the City College of New York (CCNY. The system employs a 1542 nm fiber laser to leverage components’ availability and affordability of the telecommunication industry. A balanced detector with a bandwidth extending from dc to 125 MHz is used to eliminate the common mode relative intensity noise (RIN. The system is shot noise limited i.e., the dominant component of received signals’ noise is the shot noise. Wind velocity can be measured under nominal aerosol loading and atmospheric turbulence conditions for ranges up to 3 km while pointing vertically with 0.08 m/s precision.

  1. Signal to Noise Ratio Characterization of Coherent Doppler Lidar Backscattered Signals

    Science.gov (United States)

    Abdelazim, Sameh; Santoro, David; Arend, Mark; Moshary, Fred; Ahmed, Sam

    2016-06-01

    An eye-safe coherent Doppler Lidar (CDL) system for wind measurement was developed and tested at the Remote Sensing Laboratory of the City College of New York (CCNY). The system employs a 1542 nm fiber laser to leverage components' availability and affordability of the telecommunication industry. A balanced detector with a bandwidth extending from dc to 125 MHz is used to eliminate the common mode relative intensity noise (RIN). The system is shot noise limited i.e., the dominant component of received signals' noise is the shot noise. Wind velocity can be measured under nominal aerosol loading and atmospheric turbulence conditions for ranges up to 3 km while pointing vertically with 0.08 m/s precision.

  2. Eye-safe,single-frequency pulsed all-fiber laser for Doppler wind lidar

    Institute of Scientific and Technical Information of China (English)

    Yuan Liu; Jiqiao Liu; Weibiao Chen

    2011-01-01

    @@ A single-frequency pulsed erbium-doped fiber(EDF)laser with master-oscillator Dower-amplifier comiguration at t bass nm is developed.A short-cavity,erbium-doped phosphate class fiber laser is utilized as a seeaer laser wntn a unewidtn of b khz and power of 40 mW.The seeder laser is modulated to be a pulse laser with a repetition rate of 10 kHz and pulse duration of 500 ns.The amplifier consists of two pre-amplifiers and one main amplifier.The detailed characteristics of the spectrum and linewidth of the amplifiers are presented.A pulse energy of 116 pJ and a linewidth of 1.1 MHz are obtained.This laser can be a candidate transmitter for an all-fiber Doppler wind lidar in the boundarv laver.%A single-frequency pulsed erbium-doped fiber (EDF) laser with master-oscillator power-amplifier configuration at 1533 nm is developed. A short-cavity, erbium-doped phosphate glass fiber laser is utilized as a seeder laser with a linewidth of 5 kHz and power of 40 mW. The seeder laser is modulated to be a pulse laser with a repetition rate of 10 kHz and pulse duration of 500 ns. The amplifier consists of two pre-amplifiers and one main amplifier. The detailed characteristics of the spectrum and linewidth of the amplifiers are presented. A pulse energy of 116 μJ and a linewidth of 1.1 MHz are obtained. This laser can be a candidate transmitter for an all-fiber Doppler wind lidar in the boundary layer.

  3. Micro-pulse upconversion Doppler lidar for wind and visibility detection in the atmospheric boundary layer

    CERN Document Server

    Xia, Haiyun; Wang, Chong; Shentu, Guoliang; Qiu, Jiawei; Zhang, Qiang; Dou, Xiankang; Pan, Jianwei

    2016-01-01

    For the first time, a versatile, eyesafe, compact and direct detection Doppler lidar is developed using upconversion single-photon detection method. An all-fiber and polarization maintaining architecture is realized to guarantee the high optical coupling efficiency and the system stability. Using integrated-optic components, the conservation of etendue of the optical receiver is achieved by manufacturing a fiber-coupled periodically poled Lithium niobate waveguide and an all-fiber Fabry-Perot interferometer (FPI). The so-called double-edge direct detection is implemented using a single-channel FPI and a single upconversion detector, incorporating time-division multiplexing method. The relative error of the system is lower than 0.1% over 9 weeks. To show the robust of the system, atmospheric wind and visibility over 48 hours are detected in the boundary layer. In the intercomparison experiments, lidar shows good agreement with the ultrasonic wind sensor (Vaisala windcap WMT52), with standard deviation of 1.04 ...

  4. Winds and temperatures in the stratosphere and mesosphere at ALOMAR derived by Doppler lidar

    Science.gov (United States)

    Hildebrand, Jens; Baumgarten, Gerd; Fiedler, Jens; Lübken, Franz-Josef

    2016-04-01

    Wind and temperature measurements in the middle atmosphere are crucial for a comprehensive understanding of atmospheric dynamics. Unfortunately, they are very challenging, especially with vertical and temporal resolutions reasonable for gravity-wave studies. The Doppler Rayleigh Iodine Spectrometer (DoRIS) of the Rayleigh/Mie/Raman lidar at the Arctic station ALOMAR in Northern Norway (69°N, 16°E) is the only remote sensing instrument that simultaneously derives temperatures and two wind components in the entire stratosphere and mesosphere, even under daylight conditions, necessarily for long-duration gravity-wave studies. The temporal and vertical resolutions are, typically, 1 h and 3 km, respectively. We are going to present case studies of middle atmospheric winds and temperatures, obtained during winter seasons 2010 - 2015. During a sounding rocket campaign in March 2015 an extensive salvo of meteorological rockets for in-situ wind measurements was launched at the Andøya Space Center close to ALOMAR. This gave the opportunity for a comprehensive comparison of winds derived by lidar and in-situ observations in the middle atmosphere, whose results we will present.

  5. Inertia gravity wave in the stratosphere and mesosphere observed by Doppler wind and temperature lidar

    Science.gov (United States)

    Baumgarten, G.; Fiedler, J.; Hildebrand, J.; Lübken, F.-J.

    2015-12-01

    We report on the first observation of persistent inertia gravity wave signatures in the horizontal wind and temperature by Doppler Rayleigh lidar in the middle atmosphere. The observations were performed at the Arctic Lidar Observatory for Middle Atmosphere Research station in northern Norway (69°N,16°E) between 21 and 23 January 2012. The measurements cover the altitude range from 20 km to about 80 km during nighttime and to about 70 km during daytime. We observe amplitudes of 5 to 25 m/s and 1 to 8 K in wind and temperature, respectively. The measured kinetic to potential energy density ratio is about 10, indicating that the majority of variability is due to waves with intrinsic frequencies close to the inertial frequency. The entire wavefield is mainly characterized by the presence of multiple waves; however, quasi-monochromatic waves could be identified at limited times around 60 km altitude with a mean momentum flux in direction of propagation of 3.8 m2/s2.

  6. Nocturnal Low-level Jet Evolution in a Broad Valley Observed by Dual Doppler Lidar

    Directory of Open Access Journals (Sweden)

    Thomas Damian

    2014-09-01

    Full Text Available The temporal evolution of a nocturnal low-level jet (LLJ in the 40km$40\\,\\text{km}$ broad Rhine Valley near Karlsruhe is studied, in the framework of a case study, with two heterodyne detection Doppler lidars using the new scan concept of “virtual towers”. For validation of this measuring technique, we performed comparative case studies with a tethered balloon and the highly instrumented 200m$200\\,\\text{m}$ KIT tower. The findings show capabilities of the virtual tower technique for wind measurements. Virtual towers can be placed at all locations within the range of Lidar measurements. Associated with nocturnal stable stratification, the LLJ, a wind speed maximum of about 9ms-1$9\\,\\text{m}\\,\\text{s}^{-1}$, develops at 100m$100\\,\\text{m}$ to 150m$150\\,\\text{m}$ agl, but the wind does not show the typical clockwise wind direction change that is reported in many other studies. This is attributed to the channeling effect occurring in broad valleys like the Rhine Valley when the boundary layer is stably stratified. Such channeling means a significant deviation of the wind direction from the Ekman spiral so that low-altitude winds turn into valley-parallel direction.

  7. Micro-pulse upconversion Doppler lidar for wind and visibility detection in the atmospheric boundary layer.

    Science.gov (United States)

    Xia, Haiyun; Shangguan, Mingjia; Wang, Chong; Shentu, Guoliang; Qiu, Jiawei; Zhang, Qiang; Dou, Xiankang; Pan, Jianwei

    2016-11-15

    For the first time, to the best of our knowledge, a compact, eye-safe, and versatile direct detection Doppler lidar is developed using an upconversion single-photon detection method at 1.5 μm. An all-fiber and polarization maintaining architecture is realized to guarantee the high optical coupling efficiency and the robust stability. Using integrated-optic components, the conservation of etendue of the optical receiver is achieved by manufacturing a fiber-coupled periodically poled lithium niobate waveguide and an all-fiber Fabry-Perot interferometer (FPI). The double-edge technique is implemented by using a convert single-channel FPI and a single upconversion detector, incorporating a time-division multiplexing method. The backscatter photons at 1548.1 nm are converted into 863 nm via mixing with a pump laser at 1950 nm. The relative error of the system is less than 0.1% over nine weeks. In experiments, atmospheric wind and visibility over 48 h are detected in the boundary layer. The lidar shows good agreement with the ultrasonic wind sensor, with a standard deviation of 1.04 m/s in speed and 12.3° in direction.

  8. Simultaneous Observations of Mesoscale Gravity Waves Over the Central US with CRRL Na Doppler Lidars and USU Temperature Mapper

    Science.gov (United States)

    Lu, Xian; Chen, Cao; Huang, Wentao; Smith, John A.; Zhao, Jian; Chu, Xinzhao; Yuan, Tao; Pautet, Pierre-Dominique; Taylor, Mike J.

    2016-06-01

    We present the first coordinated study of a 1-h mesoscale gravity wave event detected simultaneously by a Na Doppler lidar at Boulder, CO (40.1°N, 105.2°W), and a Na Doppler lidar and an airglow temperature mapper (AMTM) at Logan, UT (41.7°N, 111.8°W) in the mesopause region on 27 Nov. 2013. The vertical and horizontal wavelengths are ~16.0±0.3 and 342.0±10.4 km, corresponding to vertical and horizontal phase speeds of ~4.4±0.1 and 95.0±3.0 m/s, respectively. The wave propagates from Logan to Boulder with an azimuth angle of ~138.1±1.7° clockwise from North. A uniqueness of this study is that the 1-h wave amplitudes on vertical winds have been quantified for the first time by the STAR Na lidar at Boulder. The GW polarization relation between vertical wind and temperature is evaluated. The intrinsic period of the wave is Doppler shifted to ~100 min by a background wind of 40 m/s, which is confirmed by USU lidar wind observations. This study illustrates a great potential of combining multiple instruments to fully characterize mesoscale gravity waves and inspect their intrinsic properties

  9. Analysis of Doppler Lidar Data Acquired During the Pentagon Shield Field Campaign

    Energy Technology Data Exchange (ETDEWEB)

    Newsom, Rob K. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2011-04-14

    Observations from two coherent Doppler lidars deployed during the Pentagon Shield field campaign are analyzed in conjunction with other sensors to characterize the overall boundary-layer structure, and identify the dominant flow characteristics during the entire two-week field campaign. Convective boundary layer (CBL) heights and cloud base heights (CBH) are estimated from an analysis of the lidar signal-to-noise-ratio (SNR), and mean wind profiles are computed using a modified velocity-azimuth-display (VAD) algorithm. Three-dimensional wind field retrievals are computed from coordinated overlapping volume scans, and the results are analyzed by visualizing the flow in horizontal and vertical cross sections. The VAD winds show that southerly flows dominate during the two-week field campaign. Low-level jets (LLJ) were evident on all but two of the nights during the field campaign. The LLJs tended to form a couple hours after sunset and reach maximum strength between 03 and 07 UTC. The surface friction velocities show distinct local maxima during four nights when strong LLJs formed. Estimates of the convective boundary layer height and residual layer height are obtained through an analysis of the vertical gradient of the lidar signal-to-noise-ratio (SNR). Strong minimum in the SNR gradient often develops just above the surface after sunrise. This minimum is associated with the developing CBL, and increases rapidly during the early portion of the daytime period. On several days, this minimum continues to increase until about sunset. Secondary minima in the SNR gradient were also observed at higher altitudes, and are believed to be remnants of the CBL height from previous days, i.e. the residual layer height. The dual-Doppler analysis technique used in this study makes use of hourly averaged radial velocity data to produce three-dimensional grids of the horizontal velocity components, and the horizontal velocity variance. Visualization of horizontal and vertical cross

  10. Investigation of the Air-Wave-Sea Interaction Modes Using an Airborne Doppler Wind Lidar: Analyses of the HRDL Data Taken using DYNAMO

    Science.gov (United States)

    2013-10-07

    Interaction Modes Using an Airborne Doppler Wind Lidar: Analyses of the HRDL data taken using DYNAMO 5a. CONTRACT NUMBER N0001411C0464 5b. GRANT...efficiency of energy, mass and momentum exchange at the bottom and top of the ABL. 15. SUBJECT TERMS DYNAMO , ABL 16. SECURITY CLASSIFICATION OF: 17...Investigation of the Air-Wave-Sea Interaction Modes Using an Airborne Doppler Wind Lidar: Analyses of the HRDL data taken during DYNAMO George

  11. Doppler Rayleigh/Mie/Raman lidar for wind and temperature measurements in the middle atmosphere up to 80 km

    Directory of Open Access Journals (Sweden)

    G. Baumgarten

    2010-11-01

    Full Text Available A direct detection Doppler lidar for measuring wind speed in the middle atmosphere up to 80 km with 2 h resolution was implemented in the ALOMAR Rayleigh/Mie/Raman lidar (69° N, 16° E. The random error of the line of sight wind is about 0.6 m/s and 10 m/s at 49 km and 80 km, respectively. We use a Doppler Rayleigh Iodine Spectrometer (DoRIS at the iodine line 1109 (~532.260 nm. DoRIS uses two branches of intensity cascaded channels to cover the dynamic range from 10 to 100 km altitude. The wind detection system was designed to extend the existing multi-wavelength observations of aerosol and temperature performed at wavelengths of 355 nm, 532 nm and 1064 nm. The lidar uses two lasers with a mean power of 14 W at 532 nm each and two 1.8 m diameter tiltable telescopes. Below about 49 km altitude the accuracy and time resolution is limited by the maximum count rate of the detectors used and not by the number of photons available. We report about the first simultaneous Rayleigh temperature and wind measurements by lidar in the strato- and mesosphere on 17 and 23 January 2009.

  12. Coherent Doppler Lidar for Wind and Cloud Measurements on Venus from an Orbiting or Floating/Flying Platform

    Science.gov (United States)

    Singh, Upendra; Limaye, Sanjay; Emmitt, George; Kavaya, Michael; Yu, Jirong; Petros, Mulugeta

    Abstract Given the presence of clouds and haze in the upper portion of the Venus atmosphere, it is reasonable to consider a Doppler wind lidar (DWL) for making remote measurements of the 3D winds within the tops of clouds and the overlying haze layer. Assuming an orbit altitude of 250 km and cloud tops at 60km (within the “upper cloud layer”), an initial performance assessment of an orbiting DWL was made using a numerical instrument and atmospheres model developed for both Earth and Mars. The threshold aerosol backscatter for 2-micron was taken to be 1.0*10-6 msr-1. This backscatter value is between 1 and 2 orders of magnitude lower than that expected for clouds with optical depths greater than 2.0. Cloud composition was assumed to be mixture of dust, frozen CO2 and sulfuric acid. Based on the DWL assessment and simulation, it is reasonable to expect vertical profiles of the 3D wind speed with 1 km vertical resolution and horizontal spacing of 25 km to several 100 kms depending upon the desired integration times. These profiles would begin somewhere just below the tops of the highest clouds and extend into the overlying haze layer to some TBD height. Getting multiple layers of cloud returns is also possible with no negative impact on velocity measurement accuracy. With support from the 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 2-micron coherent Doppler lidar system for wind measurement in the Earth’s atmosphere [1-3]. The knowledge and expertise for developing coherent Doppler wind lidar technologies and techniques for Earth related mission at NASA LaRC is being leveraged to develop an appropriate system suitable for wind measurement around Venus. We are considering a fiber laser based lidar system of high efficiency and smaller size and advancing the technology level to meet the requirements for DWL system for Venus from

  13. A mobile incoherent Mie-Rayleigh Doppler wind lidar with a single frequency and tunable operation of an injection Nd︰YAG laser

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A mobile incoherent Doppler lidar system has been experimentally demonstrated to be able to transmit reliable single frequency operation laser pulse, even after truck transit and in very high vibration environments. The linewidth of the injection-seeded pulse Nd:YAG laser can be measured by means of an I2 molecular filter. And, lidar validation experiments demonstrated the feasibility and capability of measuring wind field by the Mie-Rayleigh Doppler wind lidar. The uncertainty of measured wind speed is 0.985m/s in the altitude range from 2 to 4 km.

  14. Doppler Lidar System Design via Interdisciplinary Design Concept at NASA Langley Research Center - Part III

    Science.gov (United States)

    Barnes, Bruce W.; Sessions, Alaric M.; Beyon, Jeffrey; Petway, Larry B.

    2014-01-01

    Optimized designs of the Navigation Doppler Lidar (NDL) instrument for Autonomous Landing Hazard Avoidance Technology (ALHAT) were accomplished via Interdisciplinary Design Concept (IDEC) at NASA Langley Research Center during the summer of 2013. Three branches in the Engineering Directorate and three students were involved in this joint task through the NASA Langley Aerospace Research Summer Scholars (LARSS) Program. The Laser Remote Sensing Branch (LRSB), Mechanical Systems Branch (MSB), and Structural and Thermal Systems Branch (STSB) were engaged to achieve optimal designs through iterative and interactive collaborative design processes. A preliminary design iteration was able to reduce the power consumption, mass, and footprint by removing redundant components and replacing inefficient components with more efficient ones. A second design iteration reduced volume and mass by replacing bulky components with excessive performance with smaller components custom-designed for the power system. The existing power system was analyzed to rank components in terms of inefficiency, power dissipation, footprint and mass. Design considerations and priorities are compared along with the results of each design iteration. Overall power system improvements are summarized for design implementations.

  15. Doppler Lidar System Design via Interdisciplinary Design Concept at NASA Langley Research Center - Part I

    Science.gov (United States)

    Boyer, Charles M.; Jackson, Trevor P.; Beyon, Jeffrey Y.; Petway, Larry B.

    2013-01-01

    Optimized designs of the Navigation Doppler Lidar (NDL) instrument for Autonomous Landing Hazard Avoidance Technology (ALHAT) were accomplished via Interdisciplinary Design Concept (IDEC) at NASA Langley Research Center during the summer of 2013. Three branches in the Engineering Directorate and three students were involved in this joint task through the NASA Langley Aerospace Research Summer Scholars (LARSS) Program. The Laser Remote Sensing Branch (LRSB), Mechanical Systems Branch (MSB), and Structural and Thermal Systems Branch (STSB) were engaged to achieve optimal designs through iterative and interactive collaborative design processes. A preliminary design iteration was able to reduce the power consumption, mass, and footprint by removing redundant components and replacing inefficient components with more efficient ones. A second design iteration reduced volume and mass by replacing bulky components with excessive performance with smaller components custom-designed for the power system. Mechanical placement collaboration reduced potential electromagnetic interference (EMI). Through application of newly selected electrical components and thermal analysis data, a total electronic chassis redesign was accomplished. Use of an innovative forced convection tunnel heat sink was employed to meet and exceed project requirements for cooling, mass reduction, and volume reduction. Functionality was a key concern to make efficient use of airflow, and accessibility was also imperative to allow for servicing of chassis internals. The collaborative process provided for accelerated design maturation with substantiated function.

  16. Doppler Lidar System Design via Interdisciplinary Design Concept at NASA Langley Research Center - Part II

    Science.gov (United States)

    Crasner, Aaron I.; Scola,Salvatore; Beyon, Jeffrey Y.; Petway, Larry B.

    2014-01-01

    Optimized designs of the Navigation Doppler Lidar (NDL) instrument for Autonomous Landing Hazard Avoidance Technology (ALHAT) were accomplished via Interdisciplinary Design Concept (IDEC) at NASA Langley Research Center during the summer of 2013. Three branches in the Engineering Directorate and three students were involved in this joint task through the NASA Langley Aerospace Research Summer Scholars (LARSS) Program. The Laser Remote Sensing Branch (LRSB), Mechanical Systems Branch (MSB), and Structural and Thermal Systems Branch (STSB) were engaged to achieve optimal designs through iterative and interactive collaborative design processes. A preliminary design iteration was able to reduce the power consumption, mass, and footprint by removing redundant components and replacing inefficient components with more efficient ones. A second design iteration reduced volume and mass by replacing bulky components with excessive performance with smaller components custom-designed for the power system. Thermal modeling software was used to run steady state thermal analyses, which were used to both validate the designs and recommend further changes. Analyses were run on each redesign, as well as the original system. Thermal Desktop was used to run trade studies to account for uncertainty and assumptions about fan performance and boundary conditions. The studies suggested that, even if the assumptions were significantly wrong, the redesigned systems would remain within operating temperature limits.

  17. Simultaneous wind and temperature measurements in the middle atmosphere with a twin Doppler lidar

    Science.gov (United States)

    Hildebrand, Jens; Baumgarten, Gerd; Fiedler, Jens; Lübken, Franz-Josef

    2016-04-01

    Winds play an important role for the filtering of gravity waves traveling from the ground to higher altitudes. They control the propagation of gravity waves and the amount of transported energy and momentum. The thermal structure of the atmosphere determines its stability, hence the buoyancy frequency. Therefore, knowing winds and temperatures in the middle atmosphere is crucial to study and interpret atmospheric dynamics comprehensively. Both temperature and wind affect the propagation of infrasound waves through the middle atmosphere. Observing winds and temperatures in the middle atmosphere on routine basis is challenging since a large part of this altitude range is not accessible by radars or satellites. Using the Doppler Rayleigh Iodine Spectrometer DoRIS, our Rayleigh/Mie/Raman lidar at the Arctic station ALOMAR in Northern Norway (69°N, 16°E) is capable to measure winds and temperatures simultaneously in the middle atmosphere between about 20 and 80 km altitude. Since two independently steerable telescopes are used, we can derive two wind components at once. Winds and temperatures are measured even under daylight conditions, yielding observations spanning multiple days, which is essential for, e.g., gravity-wave studies. We will present results from case studies and a larger data set covering winter situations between 2012 and 2015, including stratospheric warmings and periods of enhanced gravity wave activity.

  18. Gravity wave observations by Doppler wind and temperature lidar measurements in the strato- and mesosphere

    Science.gov (United States)

    Baumgarten, Gerd; Fiedler, Jens; Hildebrand, Jens; Lübken, Franz-Josef

    2016-04-01

    The observation of wind and temperature perturbations by gravity waves propagating throughout the strato- and mesosphere is a challenging task. Both the kinetic and potential energy density can be derived and yield information about ensemble mean properties of gravity waves. We measure temperatures and winds with the Doppler Rayleigh/Mie/Raman lidar at the ALOMAR research station in Northern Norway (69N, 16E). Using two independently steerable telescopes and lasers we are able to measure vertical profiles of two wind components and temperatures simultaneously. The observations can be performed even under sunlit conditions, which is essential for measuring atmospheric perturbations over several days and during summer at this location. We report on the first observation of persistent inertia gravity wave signatures in the horizontal wind and temperature. The measurements cover the altitude range from 20 km to about 80 km during night and to about 70 km during daytime. For one case with observations lasting more than 50 hours, we find amplitudes of 5 to 25 m/s and 1 to 8 K in wind and temperature, respectively. The measured kinetic to potential energy density ratio is about 10, indicating that the majority of variability is due to waves with intrinsic frequencies close to the inertial frequency. The entire wave field is mainly characterized by the presence of multiple waves, however quasi-monochromatic waves can be identified at limited times and allow a more detailed analysis of wave properties like propagation direction, amplitudes and the momentum flux.

  19. Applications of spectral analysis and filter design in laser frequency locking for Na Doppler lidars

    Science.gov (United States)

    Smith, John A.; Chu, Xinzhao; Huang, Wentao; Tan, Bo

    2009-10-01

    A dye ring laser is stabilized to a D2a Doppler-free feature of sodium vapor using a LabVIEW®-based, phase-sensitive servo. Locking precision and stability, at better than +/-1 MHz, are suitable for Na lidar applications. This performance was achieved with improved digital filtering and new approaches to the problem. The inverse (type II) Chebyshev discrete filter employed demonstrates superior filtering and computational efficiency plus improved flexibility. New approaches include the determination of optimum modulation frequency, laser-tuning sensitivity, and bandwidth requirements via spectral analyses of the noise spectrum, derivative scan, and modulated spectrum. This practice guides a user in selecting the system operation parameters and negotiating the trade-offs involved when expanding the filter's passband. Allan deviation plots provide a quantitative description of the short- and long-term frequency excursions. A comparison of Allan deviation plots before and after locking shows a substantial improvement in stability throughout time scales from 0.10 to 10 s.

  20. An all-fiber image-reject homodyne coherent Doppler wind lidar.

    Science.gov (United States)

    Abari, Cyrus F; Pedersen, Anders T; Mann, Jakob

    2014-10-20

    In this paper, we present an alternative approach to the down-conversion (translation) of the received optical signals collected by the antenna of an all-fiber coherent Doppler lidar (CDL). The proposed method, widely known as image-reject, quadrature detection, or in-phase/quadrature-phase detection, utilizes the advances in fiber optic communications such that the received signal can be optically down-converted into baseband where not only the radial velocity but also the direction of the movement can be inferred. In addition, we show that by performing a cross-spectral analysis, enabled by the presence of two independent signal observations with uncorrelated noise, various noise sources can be suppressed and a more simplified velocity estimation algorithm can be employed in the spectral domain. Other benefits of this architecture include, but are not limited to, a more reliable measurement of radial velocities close to zero and an improved bandwidth. The claims are verified through laboratory implementation of a continuous wave CDL, where measurements both on a hard and diffuse target have been performed and analyzed.

  1. Noise modeling by the trend of each range gate for coherent Doppler LIDAR

    Science.gov (United States)

    Bu, Zhichao; Zhang, Yinchao; Chen, Siying; Guo, Pan; Li, Lu; Chen, He

    2014-06-01

    A denoising method of all-fiber pulsed coherent Doppler LIDAR (CDL) is investigated. The goal is to enhance the signal-to-noise ratio (SNR) in the weak signal regime. Based on differential detection theory, the total noise expression of CDL with a dual-balanced detector is introduced and analyzed. The conclusion is drawn that the total noise can be acquired under the local oscillator laser exposure conditions by reasonable simplification. Using the actual measured data, the ratio of the standard deviation to the mean value of the total noise in each range gate is obtained and is up to approximately 11%. In order to suppress the jitter of the noise, an effective noise modeling by the trend of each range gate is developed. The feasibility of this method is verified by a long set of measured data. The spatial and temporal distribution of wind speed is illustrated with 400 pulses accumulation. Compared to the noise modeling of the tail, the detection range of wind speed using the proposed method can be improved by 35.3%.

  2. Ultrawideband coherent noise lidar range-Doppler imaging and signal processing by use of spatial-spectral holography in inhomogeneously broadened absorbers.

    Science.gov (United States)

    Li, Youzhi; Hoskins, Alan; Schlottau, Friso; Wagner, Kelvin H; Embry, Carl; Babbitt, William Randall

    2006-09-01

    We introduce a new approach to coherent lidar range-Doppler sensing by utilizing random-noise illuminating waveforms and a quantum-optical, parallel sensor based on spatial-spectral holography (SSH) in a cryogenically cooled inhomogeneously broadened absorber (IBA) crystal. Interference between a reference signal and the lidar return in the spectrally selective absorption band of the IBA is used to sense the lidar returns and perform the front-end range-correlation signal processing. Modulating the reference by an array of Doppler compensating frequency shifts enables multichannel Doppler filtering. This SSH sensor performs much of the postdetection signal processing, increases the lidar system sensitivity through range-correlation gain before detection, and is capable of not only Doppler processing but also parallel multibeam reception using the high-spatial resolution of the IBA crystals. This approach permits the use of ultrawideband, high-power, random-noise, cw lasers as ranging waveforms in lidar systems instead of highly stabilized, injection-seeded, and amplified pulsed or modulated laser sources as required by most conventional coherent lidar systems. The capabilities of the IBA media for many tens of gigahertz bandwidth and resolution in the 30-300 kHz regime, while using either a pseudo-noise-coded waveform or just a high-power, noisy laser with a broad linewidth (e.g., a truly random noise lidar) may enable a new generation of improved lidar sensors and processors. Preliminary experimental demonstrations of lidar ranging and simulation on range-Doppler processing are presented.

  3. Measurements of the Spatial Variability of Mean Wind Profiles Using Multiple Doppler Lidars over Distances less than 1 Km

    Science.gov (United States)

    Banta, R. M.; Choukulkar, A.; Brewer, A.; Lundquist, J. K.; Iungo, V.; Pichugina, Y. L.; Quelet, P. T.; Wolfe, D. E.; Oncley, S.; Sandberg, S.; Weickmann, A. M.; Delgado, R.; McCaffrey, K.

    2015-12-01

    Small differences in wind speed can translate to large differences in wind energy (WE) revenues, so WE decision making requires accurate measurements of wind profiles through the turbine rotor layer of the lower atmosphere. Advances in understanding and modeling of boundary-layer processes, also needed by WE, requires such measurements through an even deeper layer—at least the lowest few hundreds of meters. An important use for such accurate measured wind-profile data is in the initiation and verification of NWP models. This prospect raises several fundamental questions, such as, what does the modeled profile represent, how was the measured profile determined, and what if the profile had been measured from a different site within the grid cell? To address these questions, two experiments were conducted at the Boulder Atmospheric Observatory (BAO) in modestly complex terrain downwind of the mountains. The Lidar Uncertainty Measurement Experiment (LUMEX) in June-July 2014 featured 5 Doppler lidars (2 scanning), and XPIA in April-May 2015, 11 Doppler lidars, including 5 scanning systems. Two broad goals of these projects were to assess differences in scanning and other data acquisition procedures on the measurements, addressed in (Pichugina et al.) at this conference, and to evaluate the effects of varying spatial separations on differences in the measured winds, addressed in the present paper. Sonic anemometers every 50 m on the 300-m BAO tower were used as a reference for the wind calculations, as well as another profile location. Lidar scan data indicated terrain-related regions of stronger flow within the scan volume of more than 1 m/s that were at least semi-recurrent. This variability produced significant differences in mean rotor-level winds by 2 identical profiling lidars separated by 500 m. During XPIA, four of the scanning Doppler lidars performed intersecting elevation scans (vertical-slice or "RHI") to create 'virtual towers' at various separation

  4. Implementing a wind measurement Doppler Lidar based on a molecular iodine filter to monitor the atmospheric wind field over Beijing

    Science.gov (United States)

    Du, Li-fang; Yang, Guo-tao; Wang, Ji-hong; Yue, Chuan; Chen, Lin-xiang

    2017-02-01

    A wind measurement Doppler Lidar system was developed, in which injection seeded laser was used to generate narrow linewidth laser pulse. Frequency stabilization was achieved through absorption of iodine molecules. Commands that control the instrumental system were based on the PID algorithm and coded using VB language. The frequency of the seed laser was locked to iodine molecular absorption line 1109 which is close to the upper edge of the absorption range,with long-time (>4 h) frequency-locking accuracy being ≤0.5 MHz and long-time frequency stability being 3.55×10-9. Design the continuous light velocity measuring system, which concluded the cure about doppler frequency shift and actual speed of chopped wave plate, the velocity error is less than 0.4 m/s. The experiment showed that the stabilized frequency of the seed laser was different from the transmission frequency of the Lidar. And such frequency deviation is known as Chirp of the laser pulse. The real-time measured frequency difference of the continuous and pulsed lights was about 10 MHz, long-time stability deviation was around 5 MHz. When the temporal and spatial resolutions were respectively set to 100 s and 96 m, the wind velocity measurement error of the horizontal wind field at the attitude of 15-35 km was within ±5 m/s, the results showed that the wind measurement Doppler Lidar implemented in Yanqing, Beijing was capable of continuously detecting in the middle and low atmospheric wind field at nighttime. With further development of this technique, system measurement error could be lowered, and long-run routine observations are promising.

  5. Estimation of the mixing layer height over a high altitude site in Central Himalayan region by using Doppler lidar

    Energy Technology Data Exchange (ETDEWEB)

    Shukla, K. K.; Phanikumar, D. V.; Newsom, Rob K.; Kumar, Niranjan; Ratnam, Venkat; Naja, M.; Singh, Narendra

    2014-03-01

    A Doppler lidar was installed at Manora Peak, Nainital (29.4 N; 79.2 E, 1958 amsl) to estimate mixing layer height for the first time by using vertical velocity variance as basic measurement parameter for the period September-November 2011. Mixing layer height is found to be located ~0.57 +/- 0.1and 0.45 +/- 0.05km AGL during day and nighttime, respectively. The estimation of mixing layer height shows good correlation (R>0.8) between different instruments and with different methods. Our results show that wavelet co-variance transform is a robust method for mixing layer height estimation.

  6. Momentum and heat flux estimation in the planetary boundary layer (PBL) with a 10.6-micron Doppler lidar

    Science.gov (United States)

    Gal-Chen, Tzvi; Xu, Mei; Eberhard, Wynn

    1991-01-01

    The mean wind, its standard deviation, and the momentum fluxes in the PBL are estimated with a 10.6-micron Doppler lidar. Spectral analysis of the radial velocities was performed, from which, by examining the amplitude of the power spectrum at the inertial range, the kinetic energy dissipation was deduced. The statistical form of the Navier-Stokes equations was used to derive the surface heat flux as the residual balance between the vertical gradient of the third moment of the vertical velocity and the kinetic energy dissipation.

  7. Qualification Testing of Laser Diode Pump Arrays for a Space-Based 2-micron Coherent Doppler Lidar

    Science.gov (United States)

    Amzajerdian, Farzin; Meadows, Byron L.; Baker, Nathaniel R.; Barnes, Bruce W.; Singh, Upendra N.; Kavaya, Michael J.

    2007-01-01

    The 2-micron thulium and holmium-based lasers being considered as the transmitter source for space-based coherent Doppler lidar require high power laser diode pump arrays operating in a long pulse regime of about 1 msec. Operating laser diode arrays over such long pulses drastically impact their useful lifetime due to the excessive localized heating and substantial pulse-to-pulse thermal cycling of their active regions. This paper describes the long pulse performance of laser diode arrays and their critical thermal characteristics. A viable approach is then offered that allows for determining the optimum operational parameters leading to the maximum attainable lifetime.

  8. Calculation of aerosol backscatter from airborne continuous wave focused CO sub 2 Doppler lidar measurements. 1. Algorithm description

    Energy Technology Data Exchange (ETDEWEB)

    Rothermel, J. (NASA Marshall Space Flight Center, Huntsville, AL (USA)); Bowdle, D.A. (Univ. of Alabama, Huntsville (USA)); Vaughan, J.M.; Brown, D.W. (Royal Signals and Radar Establishment, Worcestershire (England)); Woodfield, A.A. (Royal Aircraft Establishment, Bedfordshire (England))

    1991-03-20

    Since 1981 the Royal Signals and Radar Establishment and the Royal Aircraft Establishment, United Kingdom, have made vertical and horizontal sounding measurements of aerosol backscatter coefficients at 10.6 {mu}m using an airborne continuous wave focused CO{sub 2} Doppler lidar, the Laser True Airspeed System (LATAS). The heterodyne signal from the LATAS detector is spectrally analyzed. Then, in conjunction with aircraft flight parameters, the data are processed in a six-stage computer algorithm: Set search window, search for peak signal, test peak signal, measure total signal, calculate signal-to-noise ratio (SNR), and calculate backscatter coefficient.

  9. Theoretical and experimental signal-to-noise ratio assessment in new direction sensing continuous-wave Doppler lidar

    DEFF Research Database (Denmark)

    Pedersen, Anders Tegtmeier; Foroughi Abari, Farzad; Mann, Jakob;

    2014-01-01

    A new direction sensing continuous-wave Doppler lidar based on an image-reject homodyne receiver has recently been demonstrated at DTU Wind Energy, Technical University of Denmark. In this contribution we analyse the signal-to-noise ratio resulting from two different data processing methods both...... leading to the direction sensing capability. It is found that using the auto spectrum of the complex signal to determine the wind speed leads to a signal-to-noise ratio equivalent to that of a standard self-heterodyne receiver. Using the imaginary part of the cross spectrum to estimate the Doppler shift...... has the benefit of a zero-mean background spectrum, but comes at the expense of a decrease in the signal-to noise ratio by a factor of √2....

  10. Theoretical and experimental signal-to-noise ratio assessment in new direction sensing continuous-wave Doppler lidar

    Science.gov (United States)

    Tegtmeier Pedersen, A.; Abari, C. F.; Mann, J.; Mikkelsen, T.

    2014-06-01

    A new direction sensing continuous-wave Doppler lidar based on an image-reject homodyne receiver has recently been demonstrated at DTU Wind Energy, Technical University of Denmark. In this contribution we analyse the signal-to-noise ratio resulting from two different data processing methods both leading to the direction sensing capability. It is found that using the auto spectrum of the complex signal to determine the wind speed leads to a signal-to-noise ratio equivalent to that of a standard self-heterodyne receiver. Using the imaginary part of the cross spectrum to estimate the Doppler shift has the benefit of a zero-mean background spectrum, but comes at the expense of a decrease in the signal-to noise ratio by a factor of √2.

  11. Reduction of phase-induced intensity noise in a fiber-based coherent Doppler lidar using polarization control

    DEFF Research Database (Denmark)

    Rodrigo, Peter John; Pedersen, Christian

    2010-01-01

    Optimization of signal-to-noise ratio is an important aspect in the design of optical heterodyne detection systems such as a coherent Doppler lidar (CDL). In a CDL, optimal performance is achieved when the noise in the detector signal is dominated by local oscillator shot-noise. Most modern CDL...... systems are built using rugged and cost-efficient fiber optic components. Unfortunately, leakage signals such as residual reflections inherent within fiber components (e.g. circulator) can introduce phaseinduced intensity noise (PIIN) to the Doppler spectrum in a CDL. Such excess noise may be a few orders...... of magnitude above the shot-noise level within the relevant CDL frequency bandwidth – corrupting the measurement of typically weak backscattered signals. In this study, observation of PIIN in a fiber-based CDL with a master-oscillator poweramplifier tapered semiconductor laser source is reported. Furthermore...

  12. Doppler lidar mounted on a wind turbine nacelle – UPWIND deliverable D6.7.1

    DEFF Research Database (Denmark)

    Angelou, Nikolas; Mann, Jakob; Courtney, Michael

    was the investigation of the turbulence attenuation induced in the lidar measurements. In this report are presented results from data analysis over a 21-hour period (2009-05-05 12:00 – 2009-05-06 09:00). During this period the wind turbine was not operating and the line-of-sight of the lidar was aligned with the wind...... measurements, was estimated by means of spectral analysis. An attempt to increase the resolution of the wind speed measurements of a cw lidar was performed, through the deconvolution of the lidar signal. A theoretical model of such a procedure is presented in this report. A simulation has validated...

  13. Doppler lidar mounted on a wind turbine nacelle - UPWIND deliverable D6.7.1

    Energy Technology Data Exchange (ETDEWEB)

    Angelou, N.; Mann, J.; Courtney, M.; Sjoeholm, M.

    2010-12-15

    A ZephIR prototype wind lidar manufactured by QinetiQ was mounted on the nacelle of a Vestas V27 wind turbine and measurements of the incoming wind flow towards the rotor of the wind turbine were acquired for approximately 3 months (April - June 2009). The objective of this experiment was the investigation of the turbulence attenuation induced in the lidar measurements. In this report are presented results from data analysis over a 21-hour period (2009-05-05 12:00 - 2009-05-06 09:00). During this period the wind turbine was not operating and the line-of-sight of the lidar was aligned with the wind direction. The analysis included a correlation study between the ZephIR lidar and a METEK sonic anemometer. The correlation analysis was performed using both 10 minutes and 10 Hz wind speed values. The spectral transfer function which describes the turbulence attenuation, which is induced in the lidar measurements, was estimated by means of spectral analysis. An attempt to increase the resolution of the wind speed measurements of a cw lidar was performed, through the deconvolution of the lidar signal. A theoretical model of such a procedure is presented in this report. A simulation has validated the capability of the algorithm to deconvolve and consequently increase the resolution of the lidar system. However the proposed method was not efficient when applied to real lidar wind speed measurements, probably due to the effect, that the wind direction fluctuations along the lidar's line-of-sight have, on the lidar measurements. (Author)

  14. Characterization of Turbulence in Wind Turbine Wakes under Different Stability Conditions from Static Doppler LiDAR Measurements

    Directory of Open Access Journals (Sweden)

    Valerie-Marie Kumer

    2017-03-01

    Full Text Available Wake characteristics are of great importance for wind park performance and turbine loads. While wind tunnel experiments provided a solid base for the basic understanding of the structure and dynamics of wind turbine wakes, the consequent step forward to characterize wakes is full-scale measurements in real atmospheric boundary layer conditions under different stability regimes. Scanning Doppler LiDAR measurements have proven to be a flexible and useful tool for such measurements. However, their advantage of measuring spatial fluctuation is accompanied by the limited temporal resolution of individual sampling volumes within the scanned area. This study presents results from LiDAR Doppler Beam Swing (DBS measurements and highlights the potential of information retrieved from a spectral analysis of wake measurements. Data originate from three Windcube v1 and sonic anemometers, collected during the Wind Turbine Wake Experiment–Wieringermeer. Despite the ongoing research on the reliability of turbulence retrievals based on DBS data, our results show wake peak frequencies consistent with sonic anemometer measurements. The energy spectra show rather distinct maxima during stable conditions, which broaden during unstable and neutral conditions. Investigations on the effect of blade pitch on downstream wind speed and turbulence intensity profiles indicate the potential for the development of stability-dependent wind farm control strategies.

  15. Turbulence in wind turbine wakes under different atmospheric conditions from static and scanning Doppler LiDARs

    Science.gov (United States)

    Kumer, Valerie; Reuder, Joachim

    2016-04-01

    Wake characteristics are of great importance for wind park performances and turbine loads. Wind tunnel experiments helped to validate wake model simulations under neutral atmospheric conditions. However, recent studies show strongest wake characteristics and power losses in stable atmospheric conditions. Considering all three occurring atmospheric conditions this study presents a turbulence analysis of wind turbine wake flows measured by static and scanning Doppler LiDARs at the coast of the Netherlands. We use data collected by three Windcubes v1, a scanning Windcube 100S and sonic anemometers during the Wind Turbine Wake Experiment - Wieringermeer (WINTWEX-W). Turbulence parameters such as Turbulence Intensity (TI) and turbulent kinetic energy (TKE) are retrieved from the collected raw data. Results show highest turbulence on the flanks of the wake where strong wind shear dominates. On average the spatial turbulence distribution becomes more homogeneous with conical areas of enhanced TI. Highest turbulence and strongest wind deficits occur during stable weather conditions. Despite the ongoing research on the reliability of turbulence retrievals of Doppler LiDAR data, the results are consistent with sonic anemometer measurements and show promising opportunities for a qualitative study of wake characteristics such as wake strength and wake peak frequencies.

  16. Design and experimental verification of a novel Mie Doppler wind lidar based on all-fiber Mach-Zehnder frequency discriminator

    Science.gov (United States)

    Wang, Li; Gao, Fei; Wang, Jun; Yan, Qing; Chang, Bo; Hua, Dengxin

    2017-04-01

    Spaceborne Doppler wind lidar is currently one of the hot spots on the lidar technology. The all-fiber Mach-Zehnder interferometer (FMZI) as a frequency discriminator of Doppler wind lidar is proposed for profiling the atmospheric wind velocity. The frequency discriminator system parameters are optimized, and the retrieval method of wind velocity based on FMZI is deduced. The arm length difference of FMZI for the aerosol backscattering signal is optimized to be 74.8 cm at the laser wavelength of 532 nm. The maximum system sensitivity for wind profiling can reach up to 2.62%/(m/s), and the dynamic range of wind velocity is ±18.2 m/s. The system simulation shows that the detection range is up to 6.7 km for 1 m/s wind velocity error at a wind velocity of 15 m/s with laser energy of 250 mJ and telescope diameter of 406 mm. A rotating disc experimental system is designed to simulate the atmospheric wind field for verifying the feasibility of the system, and the results show that there is good agreement between the retrieved wind velocity and simulated wind velocity. The simulation and experimental test results show that FMZI is feasible as a frequency discriminator and can be suitable for direct Mie Doppler lidar, especially for satellite-based platform lidar due to its desirable characteristics, including its small volume, light weight, good stability and compact structure.

  17. Windscanner: 3-D wind and turbulence measurements from three steerable doppler lidars

    Energy Technology Data Exchange (ETDEWEB)

    Mikkelsen, T; Mann, J; Courtney, M; Sjoeholm, M [Wind Energy Department, Risoe National Laboratory for Sustainable Energy, Technical University of Denmark, P.O. 49, DK-4000 Roskilde (Denmark)], E-mail: torben.mikkelsen@risoe.dk

    2008-05-01

    At RISOe DTU we has started to build a new-designed laser-based lidar scanning facility for detailed remote measurements of the wind fields engulfing the huge wind turbines of today. Our aim is to measure in real-time 3D wind vector data at several hundred points every second: 1) upstream of the turbine, 2) near the turbine, and 3) in the wakes of the turbine rotors. Our first proto-type Windscanner is now being built from three commercially available Continuous Wave (CW) wind lidars modified with fast adjustable focus length and equipped with 2-D prism-based scan heads, in conjunction with a commercially available pulsed wind lidar for extended vertical profiling range. Design, construction and initial testing of the new 3-D wind lidar scanning facility are described and the functionality of the Windscanner and its potential as a new research facility within the wind energy community is discussed.

  18. Direct Detection 1.6?m DIAL / Doppler Lidar for Measurements of CO2 Concentration and Wind Profiles (Invited)

    Science.gov (United States)

    Shibata, Y.; Nagasawa, C.; Abo, M.

    2013-12-01

    Knowledge of present carbon sources and sinks including their spatial distribution and their variation in time is one of the essential information for predicting future CO2 atmospheric concentration levels. Moreover, wind information is an important parameter for transport simulations and inverse estimation of surface CO2 flux. The differential absorption lidar (DIAL) and the Doppler wind lidar with the range resolution is expected to measure atmospheric CO2 profiles and wind profiles in the atmospheric boundary layer and lower troposphere from a ground platform. We have succeeded to develop a scanning 1.6 μm DIAL and incoherent Doppler lidar system for simultaneously measuring CO2 concentration and wind speed profiles. Our 1.6 μm DIAL system consists of the Optical Parametric Generator (OPG) transmitter that excited by the LD pumped Nd: YAG laser with high repetition rate (500 Hz) and the receiving optics that included the near-infrared photomultiplier tube with high quantum efficiency operating at the photon counting mode, a fiber Bragg grating (FBG) filter to detect a Doppler shift, and a 25 cm telescope [1] [2]. We had developed an optical parametric oscillator (OPO) system for 1.6 μm CO2 DIAL[3]. To achieve continuous tuning of the resonant OPO output without mode hopping, it is necessary to vary the OPO cavity length synchronously with the seed-frequency. On the other hand, the OPG does not require a cavity and instead rely on sufficient conversion efficiency to be obtained with a single pass through the crystal. The single-frequency oscillation of the OPG was achieved by injection seeding. The CO2-DIAL was operated with the range-height indicator (RHI) mode, and the 2-D measurement provided inhomogeneity in the boundary layer. Vertical CO2 concentration profiles and wind profiles were also measured simultaneously. The elevation angle was fixed at 52 deg and CO2 concentration profiles were obtained up to 1 km altitude with 200 m height resolution. Vertical

  19. Aerosol optical and microphysical retrievals from a hybrid multiwavelength lidar dataset – DISCOVER-AQ 2011

    Directory of Open Access Journals (Sweden)

    P. Sawamura

    2014-03-01

    Full Text Available Retrievals of aerosol microphysical properties (e.g. effective radius, volume and surface-area concentrations and aerosol optical properties (e.g. complex index of refraction and single scattering albedo were obtained from a hybrid multiwavelength lidar dataset for the first time. In July of 2011, in the Baltimore-Washington DC region, synergistic profiling of optical and microphysical properties of aerosols with both airborne in-situ and ground-based remote sensing systems was performed during the first deployment of DISCOVER-AQ. The hybrid multiwavelength lidar dataset combines elastic ground-based measurements at 355 nm with airborne High Spectral Resolution Lidar (HSRL measurements at 532 nm and elastic measurements at 1064 nm that were obtained less than 5 km apart of each other. This was the first study in which optical and microphysical retrievals from lidar were obtained during the day and directly compared to AERONET and in-situ measurements for 11 cases. Good agreement was observed between lidar and AERONET retrievals. Larger discrepancies were observed between lidar retrievals and in-situ measurements obtained by the aircraft and aerosol hygroscopic effects are believed to be the main factor of such discrepancies.

  20. 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.

  1. A Comparison of sector-scan and dual Doppler wind measurements at Høvsøre Test Station – one lidar or two?

    DEFF Research Database (Denmark)

    Simon, Elliot; Courtney, Michael

    .5m met-mast, which provided reference wind speed and direction values. The 10 minute reconstructed lidar measurements were in excellent agreement with the reference instrumentation. The dual Doppler results matched within 0.1% of the reference wind speed, with very low levels of unbiased scatter...... from the coast). Ground based remote sensing has numerous advantages over traditional in-situ (offshore met mast) and buoy based installations, mainly in terms or cost, complexity, and failure/delay risk. Since each lidar can only measure a portion of the wind vector, it is necessary to either deploy...... two devices in tandem (dual Doppler) or employ a single Doppler scanning strategy such as PPI (plan position indicator, or sector scan) which allows for estimation of the two component horizontal wind vector. In preparation for a six month long measurement campaign along the Danish North Sea, a one...

  2. Doppler lidar mounted on a wind turbine nacelle – UPWIND deliverable D6.7.1

    OpenAIRE

    Angelou, Nikolas; Mann, Jakob; Courtney, Michael; Sjöholm, Mikael

    2010-01-01

    A ZephIR prototype wind lidar manufactured by QinetiQ was mounted on the nacelle of a Vestas V27 wind turbine and measurements of the incoming wind flow towards the rotor of the wind turbine were acquired for approximately 3 months (April - June 2009). The objective of this experiment was the investigation of the turbulence attenuation induced in the lidar measurements. In this report are presented results from data analysis over a 21-hour period (2009-05-05 12:00 – 2009-05-06 09:00). During ...

  3. Retrieval of Micro-scale Flow Structures from High Resolution Doppler Lidar Data Using an Adjoint Model

    Science.gov (United States)

    Lin, Ching-Long; Chai, Tianfeng

    2001-06-01

    In the digital information era one of the challenges is to extract useful information from accessible data. In this paper, we will present a four-dimensional variational data assimilation (4DVAR) technique and apply it to retrieving micro-scale turbulent structures in a convective boundary layer from high-resolution Doppler lidar radial velocity data. The 4DVAR is based on the calculus of variations and optimal control theories to recover complete data by assimilating limited data into a dynamic model. Several features are implemented into the 4DVAR model, e.g. a surface flux model, a buffer zone and smoothness constraints. The surface flux model provides appropriate momentum and temperature fluxes to the 4DVAR. The buffer zone is found to improve retrieval quality by reducing the effect of lateral boundary conditions. A generic algorithm is proposed to estimate weights of the smoothness constraints. The approach of identical twin experiments is first used to assess the performance of the model and its sensitivity to observational errors. The 4DVAR is then applied to real lidar data and reveals a micro-front like structure passing through the boundary layer.

  4. Airborne Doppler lidar at 532nm based on a tunable dual-channel Fabry-Perot interferometer

    Science.gov (United States)

    Feng, Jian-mei; Xing, Ting-wen; Lin, Wi-mei

    2009-07-01

    The aim of this paper is to explore a high-precision, a wide range of a frequency discrimination technique, and to study the application of this technique in the optical air data system (MOADS). To overcome the traditional equipment's shortcomings of short velocity detecting range such as pilot static tubes and wind wane, this technique can provide precision aviation data for various aerocrafts , without influencing pneumatic shape and performance of aerocraft. A tunable dual channel Fabry-Perot interferometer is used as a frequency discriminator in an airborne wind lidar system. This new frequency discriminator has been proposed to overcome the exiting frequency discriminator shortcoming. By adjusting the cavity length of interferometer, the speed of aerocraft can be detected and cut into several dynamic range. By this way, the Doppler wind lidar system can detect atmospheric parameters at the meantime, such as speed of aerocraft and temperature of atmosphere around the aerocraft, by analyzing the information of Rayleigh backscattering light. There are three main contribution in this paper: the first is discussing the basic theory of MOADS, calculational method and mathematic model of relative wind velocity between aircraft and wind are put forward.; the second is the parameter optimization of the dual-channel Fabry-Perot interferometer and the structure design of the interferometer; the third is the simulation of the performance and the accuracy of this system. Theory analysis and simulation results show this method is reasonable and practical.

  5. Turbulent structure and scaling of the inertial subrange in a stratocumulus-topped boundary layer observed by a Doppler lidar

    Directory of Open Access Journals (Sweden)

    J. Tonttila

    2014-09-01

    Full Text Available The turbulent structure of a stratocumulus-topped marine boundary layer over a two-day period is observed with a Doppler lidar at Mace Head in Ireland. Using profiles of vertical velocity statistics, the bulk of the mixing is identified as cloud-driven. This is supported by the pertinent feature of negative vertical velocity skewness in the sub-cloud layer which extends, on occasion, almost to the surface. Both coupled and decoupled turbulence characteristics are observed. The length and time scales related to the cloud driven mixing are investigated, which are shown to provide additional information about the structure and the source of the mixing inside the boundary layer. They are also shown to place constraints on the length of the sampling periods used to derive products, such as the turbulent dissipation rate, from lidar measurements. For this, the upper cut-off wavelength of the inertial subrange is studied through spectral analysis of the vertical velocity. The bulk statistical profiles and the scaling of the inertial subrange show consistent behaviour as the boundary layer undergoes transitions between a coupled and decoupled stratocumulus layer. The cut-off wavelength of the inertial subrange does not appear to scale robustly with the relative depth of the local mixing regime at different altitudes during decoupled periods. Rather, the competition between surface-based and cloud-driven mixed layers suppresses the range of eddy sizes at all heights inside the boundary layer.

  6. 3D Wind Reconstruction and Turbulence Estimation in the Boundary Layer from Doppler Lidar Measurements using Particle Method

    Science.gov (United States)

    Rottner, L.; Baehr, C.

    2014-12-01

    Turbulent phenomena in the atmospheric boundary layer (ABL) are characterized by small spatial and temporal scales which make them difficult to observe and to model.New remote sensing instruments, like Doppler Lidar, give access to fine and high-frequency observations of wind in the ABL. This study suggests to use a method of nonlinear estimation based on these observations to reconstruct 3D wind in a hemispheric volume, and to estimate atmospheric turbulent parameters. The wind observations are associated to particle systems which are driven by a local turbulence model. The particles have both fluid and stochastic properties. Therefore, spatial averages and covariances may be deduced from the particles. Among the innovative aspects, we point out the absence of the common hypothesis of stationary-ergodic turbulence and the non-use of particle model closure hypothesis. Every time observations are available, 3D wind is reconstructed and turbulent parameters such as turbulent kinectic energy, dissipation rate, and Turbulent Intensity (TI) are provided. This study presents some results obtained using real wind measurements provided by a five lines of sight Lidar. Compared with classical methods (e.g. eddy covariance) our technic renders equivalent long time results. Moreover it provides finer and real time turbulence estimations. To assess this new method, we suggest computing independently TI using different observation types. First anemometer data are used to have TI reference.Then raw and filtered Lidar observations have also been compared. The TI obtained from raw data is significantly higher than the reference one, whereas the TI estimated with the new algorithm has the same order.In this study we have presented a new class of algorithm to reconstruct local random media. It offers a new way to understand turbulence in the ABL, in both stable or convective conditions. Later, it could be used to refine turbulence parametrization in meteorological meso-scale models.

  7. Application of short-range dual-Doppler lidars to evaluate the coherence of turbulence

    Science.gov (United States)

    Cheynet, Etienne; Jakobsen, Jasna Bogunović; Snæbjörnsson, Jónas; Mikkelsen, Torben; Sjöholm, Mikael; Mann, Jakob; Hansen, Per; Angelou, Nikolas; Svardal, Benny

    2016-12-01

    Two synchronized continuous wave scanning lidars are used to study the coherence of the along-wind and across-wind velocity components. The goal is to evaluate the potential of the lidar technology for application in wind engineering. The wind lidars were installed on the Lysefjord Bridge during four days in May 2014 to monitor the wind field in the horizontal plane upstream of the bridge deck. Wind records obtained by five sonic anemometers mounted on the West side of the bridge are used as reference data. Single- and two-point statistics of wind turbulence are studied, with special emphasis on the root-coherence and the co-coherence of turbulence. A four-parameter decaying exponential function has been fitted to the measured co-coherence, and a good agreement is observed between data obtained by the sonic anemometers and the lidars. The root-coherence of turbulence is compared to theoretical models. The analytical predictions agree rather well with the measured coherence for the along-wind component. For increasing wavenumbers, larger discrepancies are, however, noticeable between the measured coherence and the theoretical predictions. The WindScanners are observed to slightly overestimate the integral length scales, which could not be explained by the laser beam averaging effect alone. On the other hand, the spatial averaging effect does not seem to have any significant effect on the coherence.

  8. Reduction of phase-induced intensity noise in a fiber-based coherent Doppler lidar using polarization control.

    Science.gov (United States)

    Rodrigo, Peter John; Pedersen, Christian

    2010-03-01

    Optimization of signal-to-noise ratio is an important aspect in the design of optical heterodyne detection systems such as a coherent Doppler lidar (CDL). In a CDL, optimal performance is achieved when the noise in the detector signal is dominated by local oscillator shot-noise. Most modern CDL systems are built using rugged and cost-efficient fiber optic components. Unfortunately, leakage signals such as residual reflections inherent within fiber components (e.g. circulator) can introduce phase-induced intensity noise (PIIN) to the Doppler spectrum in a CDL. Such excess noise may be a few orders of magnitude above the shot-noise level within the relevant CDL frequency bandwidth--corrupting the measurement of typically weak backscattered signals. In this study, observation of PIIN in a fiber-based CDL with a master-oscillator power-amplifier tapered semiconductor laser source is reported. Furthermore, we experimentally demonstrate what we believe is a newly proposed method using a simple polarization scheme to reduce PIIN by more than an order of magnitude.

  9. Investigation of a field-widened Mach-Zehnder receiver to extend Fe Doppler lidar wind measurements from the thermosphere to the ground.

    Science.gov (United States)

    Smith, John A; Chu, Xinzhao

    2016-02-20

    A receiver employing a field-widened Mach-Zehnder interferometer (MZI) is investigated for extending the wind measurement range of a narrow-band Fe Doppler lidar operating at 372 nm from its existing measurement range in the mesosphere and lower thermosphere (MLT) down to near the ground. This design uses the multiple transmitted frequencies available from the base Fe Doppler lidar in combination with a novel MZI receiver to make a measurement of the Doppler shift that rejects the influence of atmospheric parameters such as the aerosol backscatter ratio, temperature, and pressure of the lidar volume and receiver parameters such as the geometric overlap, the chopper function, and any other factor affecting the proportion of the signal in both channels of the MZI equally. A ratio is constructed from the three frequencies and two channels of the interferometer that exhibits a measurement performance of 1.75 times the Cramer-Rao lower bound, which is comparable to the dual MZI (DMZ) while preserving the insensitivity to backscatter spectrum of the quad MZI (QMZ). In addition, we show how the use of multiple transmitted frequencies can yield a wind measurement wherein the accuracy is insensitive to the optical imperfection and misalignment of the MZI or any other factor that affects the contrast, though the precision is still impacted by the fringe contrast. Simply adding a second surface mirror of a particular thickness to the basic tilted MZI can allow the field of the MZI to be widened sufficiently for most resonance Doppler lidar receivers in operation today. Provided that the detection sensitivity in each channel is known, the original resonance fluorescence and Rayleigh scattering signals can be recovered by simply scaling and adding the contributions from both channels. Consequently, the wind and temperature from the MLT region and the temperature from the Rayleigh region can be derived alongside the Rayleigh Doppler wind measurement without compromising the

  10. Lidar

    Science.gov (United States)

    Collis, R. T. H.

    1969-01-01

    Lidar is an optical radar technique employing laser energy. Variations in signal intensity as a function of range provide information on atmospheric constituents, even when these are too tenuous to be normally visible. The theoretical and technical basis of the technique is described and typical values of the atmospheric optical parameters given. The significance of these parameters to atmospheric and meteorological problems is discussed. While the basic technique can provide valuable information about clouds and other material in the atmosphere, it is not possible to determine particle size and number concentrations precisely. There are also inherent difficulties in evaluating lidar observations. Nevertheless, lidar can provide much useful information as is shown by illustrations. These include lidar observations of: cirrus cloud, showing mountain wave motions; stratification in clear air due to the thermal profile near the ground; determinations of low cloud and visibility along an air-field approach path; and finally the motion and internal structure of clouds of tracer materials (insecticide spray and explosion-caused dust) which demonstrate the use of lidar for studying transport and diffusion processes.

  11. Stratospheric and mesospheric wind measurements from the new WIRA-C wind radiometer and comparison to the Doppler lidar on La Réunion island

    Science.gov (United States)

    Hagen, Jonas; Kämpfer, Niklaus; Khaykin, Sergey; Hauchecorne, Alain

    2017-04-01

    Measurements of wind speeds in altitudes between 30 and 70 km are surprisingly rare. Passive microwave radiometry and Doppler lidar techniques provide two methods for covering this gap region. With the Rayleigh-Mie Doppler wind lidar of CNRS/INSU (Guyancourt, France) and OSUR (La Réunion, France) and the passive microwave radiometer WIRA-C of the IAP (Bern, Switzerland) two such instruments are collocated in the Maïdo observatory on the tropical island La Réunion (21° South, France). Both instruments participate in the ARISE2 project that is funded by the European Commission Horizon 2020. The Rayleigh-Mie Doppler wind lidar is an active sounder, measuring the Doppler shift of backscattered visible light and can provide wind profiles from 5 up to 50 km with a vertical resolution of up to 100 m and an accuracy better than 1 m- s up to 30 km. On the other side, WIRA-C is a passive microwave radiometer that measures the Doppler shift of the ozone thermal emission line at 142 GHz. The radiometer has a high spectral resolution of 12.2 kHz and a band width of 200 MHz and can thus exploit the pressure broadening of the ozone line to retrieve an altitude resolved wind profile. The retrieval is based on a model of the atmosphere and optimal estimation techniques implemented by ARTS and Atmlab/Qpack, but in contrast to previous versions the atmospheric model is three-dimensional. Meaningful wind speeds can be retrieved for an altitude range of 30 to 70 km with a vertical resolution of up to 4 km. WIRA-C is able to measure continuously, independent of daylight and clouds. WIRA-C has been installed on the Maïdo observatory in August 2016 and has measured since then whenever the optical thickness of the atmosphere was low enough. The Doppler lidar at Maïdo was operated on a campaign basis since 2013 and routinely twice a week since September 2015. We present the WIRA-C instrument and its measurement results for the tropical summer 2016/17 and compare them to coincident

  12. Helicopter downwash measured by continuous-wave Doppler lidars with agile beam steering

    DEFF Research Database (Denmark)

    Sjöholm, Mikael; Angelou, Nikolas; Hansen, Per

    2012-01-01

    A ground-based remote sensing short-range WindScanner with agile beam steering based on a modified ZephIR continuous-wave wind lidar (LIght Detection And Ranging) and a double prism arrangement has recently been developed at the Department of Wind Energy at the DTU Risø campus. The WindScanner me......A ground-based remote sensing short-range WindScanner with agile beam steering based on a modified ZephIR continuous-wave wind lidar (LIght Detection And Ranging) and a double prism arrangement has recently been developed at the Department of Wind Energy at the DTU Risø campus. The Wind...

  13. Lidar

    Science.gov (United States)

    Sage, J.-P.; Aubry, Y.

    1981-09-01

    It is noted that a photodetector at the telescope focal plane of a lidar produces a signal which is processed, giving information on the concentration of the species being monitored. The delay between the emitted and return signals indicates the distance to the interacting volume. Because of the poor efficiency of the interaction processes, the main difficulty in developing a good lidar has to do with the availability of sufficiently efficient lasers. Certain laser characteristics are discussed, and a CNES program for the development of lasers for lidar techniques is presented, future space applications being considered as mid-term objectives. The various components of the laser system developed by CNES are described. These are a dual frequency tunable oscillator, the amplifier chain, the beam control unit and wavelength servo-system, and the harmonic conversion subsystem.

  14. Windscanner: 3-D wind and turbulence measurements from three steerable doppler lidars

    DEFF Research Database (Denmark)

    Mikkelsen, Torben; Mann, Jakob; Courtney, Michael

    2008-01-01

    At RISO DTU we has started to build a new-designed laser-based lidar scanning facility for detailed remote measurements of the wind fields engulfing the huge wind turbines of today. Our aim is to measure in real-time 3D wind vector data at several hundred points every second: 1) upstream of the t......At RISO DTU we has started to build a new-designed laser-based lidar scanning facility for detailed remote measurements of the wind fields engulfing the huge wind turbines of today. Our aim is to measure in real-time 3D wind vector data at several hundred points every second: 1) upstream...... of the turbine, 2) near the turbine, and 3) in the wakes of the turbine rotors. Our first proto-type Windscanner is now being built from three commercially available Continuous Wave (CW) wind lidars modified with fast adjustable focus length and equipped with 2-D prism-based scan heads, in conjunction...

  15. A coordinated study of 1 h mesoscale gravity waves propagating from Logan to Boulder with CRRL Na Doppler lidars and temperature mapper

    Science.gov (United States)

    Lu, Xian; Chen, Cao; Huang, Wentao; Smith, John A.; Chu, Xinzhao; Yuan, Tao; Pautet, Pierre-Dominique; Taylor, Mike J.; Gong, Jie; Cullens, Chihoko Y.

    2015-10-01

    We present the first coordinated study using two lidars at two separate locations to characterize a 1 h mesoscale gravity wave event in the mesopause region. The simultaneous observations were made with the Student Training and Atmospheric Research (STAR) Na Doppler lidar at Boulder, CO, and the Utah State University Na Doppler lidar and temperature mapper at Logan, UT, on 27 November 2013. The high precision possessed by the STAR lidar enabled these waves to be detected in vertical wind. The mean wave amplitudes are ~0.44 m/s in vertical wind and ~1% in relative temperature at altitudes of 82-107 km. Those in the zonal and meridional winds are 6.1 and 5.2 m/s averaged from 84 to 99 km. The horizontal and vertical wavelengths inferred from the mapper and lidars are ~219 ± 4 and 16.0 ± 0.3 km, respectively. The intrinsic period is ~1.3 h for the airglow layer, Doppler shifted by a mean wind of ~17 m/s. The wave packet propagates from Logan to Boulder with an azimuth angle of ~135° clockwise from north and an elevation angle of ~ 3° from the horizon. The observed phase difference between the two locations can be explained by the traveling time of the 1 h wave from Logan to Boulder, which is about ~2.4 h. The wave polarization relations are examined through the simultaneous quantifications of the three wind components and temperature. This study has developed a systematic methodology for fully characterizing mesoscale gravity waves, inspecting their intrinsic properties and validating the derivation of horizontal wave structures by applying multiple instruments from coordinated stations.

  16. Investigation of the Air-Wave-Sea Interaction Modes Using an Airborne Doppler Wind Lidar: Analyses of the HRDL Data Taken During DYNAMO

    Science.gov (United States)

    2012-09-30

    an Airborne Doppler Wind Lidar: Analyses of the HRDL data taken during DYNAMO George D. Emmitt Simpson Weather Associates, Inc. 809 E...the DYNAMO field campaign in order to make comparisons with existing airborne DWL measurements (TODWL) and to conduct investigations into the...data could be applied to the shipboard HRDL observations taken during DYNAMO . A second objective was to use the HRDL data and the W band radar data

  17. 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.

  18. Application of short-range dual-Doppler lidars to evaluate the coherence of turbulence

    DEFF Research Database (Denmark)

    Cheynet, Etienne; Jakobsen, Jasna Bogunović; Snæbjörnsson, Jónas

    2016-01-01

    four days in May 2014 to monitor the wind field in the horizontal plane upstream of the bridge deck. Wind records obtained by five sonic anemometers mounted on the West side of the bridge are used as reference data. Single- and two-point statistics of wind turbulence are studied, with special emphasis...... on the root-coherence and the co-coherence of turbulence. A four-parameter decaying exponential function has been fitted to the measured co-coherence, and a good agreement is observed between data obtained by the sonic anemometers and the lidars. The root-coherence of turbulence is compared to theoretical...

  19. Development of a solid-state sodium Doppler lidar using an all-fiber-coupled injection seeding unit for simultaneous temperature and wind measurements in the mesopause region

    Science.gov (United States)

    Yang, Guotao; Xia, Yuan; Cheng, Xuewu; Du, Lifang; Wang, Jihong; Xun, Yuchang

    2017-04-01

    We present a solid-state sodium (Na) Doppler lidar developed at YanQing Station, Beijing, China (40°N, 116°E) to achieve simultaneous wind and temperature measurements of mesopause region. The 589nm pulse laser is produced by two injection seeded 1064nm and 1319nm Nd:YAG pulse lasers using the sum-frequency generation (SFG) technique. An all-fiber-coupled seeding laser unit was designed to enable absolute laser frequency locking and cycling the measurements among three different operating frequencies. Experimental observations were carried out using this Na lidar system and the preliminary results were described and compared with the temperature of the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) and the horizontal wind of the meteor Radar, demonstrating the reliability and good performance of this lidar system. The all-fiber-coupled injection seeding configuration together with the solid-state Nd:YAG lasers make the Na Doppler lidar more compact and greatly reduce the system maintenance, which is conducive to transportable and unattended operation.

  20. First comparison of LES of an offshore wind turbine wake with dual-Doppler lidar measurement in the offshore wind farm "alpha ventus"

    Science.gov (United States)

    Vollmer, L.; Trabucchi, D.; Witha, B.; van Dooren, M.; Trujillo, J. J.; Schneemann, J.; Kühn, M.

    2014-12-01

    The planning of offshore wind farms is still tainted with high risks due to unknown power losses and a higher level of fatigue loads due to wake effects. Recently, Large Eddy Simulations (LES) are more and more used for simulating offshore wind turbine wakes as they resolve the atmospheric turbulence as well as the wake turbulence.However, for an application of LES wind fields to assess offshore wind farm flow a proper validation with measured data is necessary.Several methods have been investigated at the University of Oldenburg to compare LES wind fields and lidar measurements. In this study we apply one of these methods to validate wake simulations of a single wake of a 5MW wind turbine in the German offshore wind farm "alpha ventus" with processed dual-Doppler lidar measurements in the same wind farm.The simulations are performed with the LES model PALM, which has been enhanced by two different approaches of actuator models to simulate the wake of single wind turbines and the interaction of wakes in wind farms. Effects of tower and nacelle are regarded as well as simple turbine control mechanisms. The simulations are initialized with comparable atmospheric conditions as during the time of lidar operation by using measurements from the adjacent meteorological mast FINO 1.Plan Position Indicator (PPI) measurements have been performed with two long-range wind lidars installed at different opposing platforms at the border of the wind farm. A Cartesian grid was overlapped to the scanned region and a dual-Doppler algorithm was applied in order to estimate the horizontal stationary wind field on the grid nodes. To our knowledge, the presented study is one of the first validations of LES wake simulations with lidar measurements and first which validates offshore LES wake simulations with 2D lidar data.

  1. Year-Long Vertical Velocity Statistics Derived from Doppler Lidar Data for the Continental Convective Boundary Layer

    Energy Technology Data Exchange (ETDEWEB)

    Berg, Larry K. [Pacific Northwest National Laboratory, Richland, Washington; Newsom, Rob K. [Pacific Northwest National Laboratory, Richland, Washington; Turner, David D. [Global Systems Division, NOAA/Earth System Research Laboratory, Boulder, Colorado

    2017-09-01

    One year of Coherent Doppler Lidar (CDL) data collected at the U.S. Department of Energy’s Atmospheric Radiation Measurement (ARM) site in Oklahoma is analyzed to provide profiles of vertical velocity variance, skewness, and kurtosis for cases of cloud-free convective boundary layers. The variance was scaled by the Deardorff convective velocity scale, which was successful when the boundary layer depth was stationary but failed in situations when the layer was changing rapidly. In this study the data are sorted according to time of day, season, wind direction, surface shear stress, degree of instability, and wind shear across the boundary-layer top. The normalized variance was found to have its peak value near a normalized height of 0.25. The magnitude of the variance changes with season, shear stress, and degree of instability, but was not impacted by wind shear across the boundary-layer top. The skewness was largest in the top half of the boundary layer (with the exception of wintertime conditions). The skewness was found to be a function of the season, shear stress, wind shear across the boundary-layer top, with larger amounts of shear leading to smaller values. Like skewness, the vertical profile of kurtosis followed a consistent pattern, with peak values near the boundary-layer top (also with the exception of wintertime data). The altitude of the peak values of kurtosis was found to be lower when there was a large amount of wind shear at the boundary-layer top.

  2. Calculation of aerosol backscatter from airborne continuous wave focused CO sub 2 Doppler lidar measurements. 2. Algorithm performance

    Energy Technology Data Exchange (ETDEWEB)

    Rothermel, J. (NASA Marshall Space Flight Center, Huntsville, AL (USA)); Bowdle, D.A. (Univ. of Alabama, Huntsville (USA)); Vaughan, J.M. (Royal Signals and Radar Establishment, Worcestshire (England))

    1991-03-20

    The performance of an algorithm to calculate aerosol backscatter coefficients, from measurements with an airborne continuous wave focused CO{sub 2} Doppler lidar, is described relative to flight hardware settings and operating characteristics, and theoretical considerations. The algorithm (described in paper 1) is used to analyze measurements by the Laser True Airspeed System (LATAS), operated by the Royal Signals and Radar Establishment (RSRE) and Royal Aircraft Establishment (RAE), United Kingdom. Under optimum signal conditions, backscatter signals are located unambiguously and the backscatter coefficients are accurately determined. Under marginal or subthreshold conditions, with a degraded system sensitivity, false alarms (mistaking noise for signal) occur. Parametric studies show that the false alarm rate under these conditions depends on the search window size and the signal-to-noise ratio (SNR) threshold for valid signals. Carefully selected diagnostic parameters are used to estimate the combined sensitivity of the flight hardware system and algorithm. Less than 1% of backscatter measurements for flights over approximately 5 years have been found to be below the measurement sensitivity when the LATAS flight hardware controls were set for optimum sensitivity.

  3. Simulating Wake Vortex Detection with the Sensivu Doppler Wind Lidar Simulator

    Science.gov (United States)

    Ramsey, Dan; Nguyen, Chi

    2014-01-01

    In support of NASA's Atmospheric Environment Safety Technologies NRA research topic on Wake Vortex Hazard Investigation, Aerospace Innovations (AI) investigated a set of techniques for detecting wake vortex hazards from arbitrary viewing angles, including axial perspectives. This technical report describes an approach to this problem and presents results from its implementation in a virtual lidar simulator developed at AI. Threedimensional data volumes from NASA's Terminal Area Simulation System (TASS) containing strong turbulent vortices were used as the atmospheric domain for these studies, in addition to an analytical vortex model in 3-D space. By incorporating a third-party radiative transfer code (BACKSCAT 4), user-defined aerosol layers can be incorporated into atmospheric models, simulating attenuation and backscatter in different environmental conditions and altitudes. A hazard detection algorithm is described that uses a twocomponent spectral model to identify vortex signatures observable from arbitrary angles.

  4. Spatial-temporal analysis of coherent offshore wind field structures measured by scanning Doppler-lidar

    Science.gov (United States)

    Valldecabres, L.; Friedrichs, W.; von Bremen, L.; Kühn, M.

    2016-09-01

    An analysis of the spatial and temporal power fluctuations of a simplified wind farm model is conducted on four offshore wind fields data sets, two from lidar measurements and two from LES under unstable and neutral atmospheric conditions. The integral length scales of the horizontal wind speed computed in the streamwise and the cross-stream direction revealed the elongation of the structures in the direction of the mean flow. To analyse the effect of the structures on the power output of a wind turbine, the aggregated equivalent power of two wind turbines with different turbine spacing in the streamwise and cross-stream direction is analysed at different time scales under 10 minutes. The fact of considering the summation of the power of two wind turbines smooths out the fluctuations of the power output of a single wind turbine. This effect, which is stronger with increasing spacing between turbines, can be seen in the aggregation of the power of two wind turbines in the streamwise direction. Due to the anti-correlation of the coherent structures in the cross-stream direction, this smoothing effect is stronger when the aggregated power is computed with two wind turbines aligned orthogonally to the mean flow direction.

  5. The value of Doppler LiDAR systems to monitor turbulence intensity during storm events in order to enhance aviation safety in Iceland

    Science.gov (United States)

    Yang, Shu; Nína Petersen, Guðrún; Finger, David C.

    2017-04-01

    Turbulence and wind shear are a major natural hazards for aviation safety in Iceland. The temporal and spatial scale of atmospheric turbulence is very dynamic, requiring an adequate method to detect and monitor turbulence with high resolution. The Doppler Light Detection and Ranging (LiDAR) system can provide continuous information about the wind field using the Doppler effect form emitted light signals. In this study, we use a Leosphere Windcube 200s LiDAR systems stationed near Reykjavik city Airport and at Keflavik International Airport, Iceland, to evaluate turbulence intensity by estimating eddy dissipation rate (EDR). For this purpose, we retrieved radial wind velocity observations from Velocity Azimuth Display (VAD) scans (360°scans at 15° and 75° elevation angle) to compute EDR. The method was used to monitor and characterize storm events in fall 2016 and the following winter. The preliminary result reveal that the LiDAR observations can detect and quantify atmospheric turbulence with high spatial and temporal resolution. This finding is an important step towards enhanced aviation safety in subpolar climate characterized by sever wind turbulence.

  6. Interaction of runaway electrons with lower hybrid waves via anomalous Doppler broadening

    Science.gov (United States)

    Martín-Solís, J. R.; Sánchez, R.; Esposito, B.

    2002-05-01

    Due to the relativistic decrease of the electron cyclotron frequency, a cyclotron resonance may appear between runaway electrons and lower hybrid waves. A single particle description of the runaway dynamics [J. R. Martín-Solís et al., Phys. Plasmas 5, 2370 (1998)] is extended to analyze the effect of the interaction of runaway electrons with lower hybrid waves via anomalous Doppler broadening. The conditions under which the resonant interaction can play a role in limiting the runaway energy are established and it is shown that, under typical lower hybrid current drive operation parameters, an efficient wave-particle coupling may occur. Observations of a fast pitch angle scattering event during the current decay phase of Ohmic discharges in the Toroidal Experiment for Technically Oriented Research (TEXTOR) [R. J. E. Jaspers, Ph.D. thesis, Technical University Eindhoven (1995)] are interpreted in terms of such interaction.

  7. Potential of the space-borne Doppler wind lidar measurements in a limited-area model for Europe

    Science.gov (United States)

    Šavli, Matic; Žagar, Nedjeljka

    2017-04-01

    Mesoscale models for numerical weather prediction (NWP) in Europe have reached the horizontal resolution close to 1 km. A large resolution increase in the last decade has not been accompanied by a sufficient increase in a number of observations to initialize the models. In particular, there is a large need for the direct wind observations as well as for humidity data in order to improve mesoscale analyses. The ADM-Aeolus mission of the European Space Agency, scheduled for launch in 2017, will contribute the global wind profiles from the Doppler wind lidar measurements of the horizontal line-of-sight (HLOS) winds. A number of studies addressed the potential impact of the ADM-Aeolus wind profiles in the global ECMWF model and showed significant benefits of the new data in the tropics where the analysis uncertainties are currently largest. Our study is the first effort to evaluate the potential of the ADM-Aeolus HLOS wind profiles in a limited-area NWP model for Europe. We present a special observing system simulation experiment (OSSE) framework involving the limited-area NWP Weather Research and Forecasting (WRF) model with the ensemble Kalman filter data assimilation system nested into the 50-member ensemble prediction system of ECMWF. The results are presented from a number of OSSE experiments that compare the information content of the HLOS winds with the two wind components and temperature observations with respect to dynamics and the flow-dependent background-error covariances. The results show that the ADM-Aeolus HLOS winds are on average more beneficial for the assimilation than any of the two components. We demonstrate how the application of the HLOS wind profiles in the ensemble Kalman filter data assimilation can improve the analysis of the baroclinic development in the northern Atlantic that leads to severe weather events over Europe.

  8. Design of a monolithic Michelson interferometer for fringe imaging in a near-field, UV, direct-detection Doppler wind lidar.

    Science.gov (United States)

    Herbst, Jonas; Vrancken, Patrick

    2016-09-01

    The low-biased, fast, airborne, short-range, and range-resolved determination of atmospheric wind speeds plays a key role in wake vortex and turbulence mitigation strategies and would improve flight safety, comfort, and economy. In this work, a concept for an airborne, UV, direct-detection Doppler wind lidar receiver is presented. A monolithic, tilted, field-widened, fringe-imaging Michelson interferometer (FWFIMI) combines the advantages of low angular sensitivity, high thermo-mechanical stability, independence of the specific atmospheric conditions, and potential for fast data evaluation. Design and integration of the FWFIMI into a lidar receiver concept are described. Simulations help to evaluate the receiver design and prospect sufficient performance under different atmospheric conditions.

  9. The Research Development of Lidar Micro-doppler in Target Recognition%激光微多普勒目标识别研究进展

    Institute of Scientific and Technical Information of China (English)

    魏文哲; 贾豫东; 张晓青

    2016-01-01

    The micro-doppler effect in lidar is a new technology research spot in recent years. The exquisite micro-doppler features in the micro electromagnetic scattering target are the unique features of the micro goal. It has unique advantages in target detection and recognition. This article firstly introduces the concept and goal of micro-doppler and the significance of micro-doppler characteristics identification. Then the research progress at home and abroad are reviewed from the theory of micro-doppler, the extraction method of micro target features and the recognition system of micro-doppler target. The vibration target detection system of Michelson interferometer technology and the working mechanism of the optical fiber coupling micro-doppler target recognition system are analyzed in detail. Finally, the micro-doppler target detection and recognition technology are expounded.%激光雷达中的微多普勒效应是近年来一个新的技术研究热点.微动目标电磁散射回波中包含的精细微多普勒特征是微动目标独一无二的特征,这在目标探测和识别方面具有独特的优势.本文首先介绍了微多普勒的概念及目标微多普勒特征识别的重要意义.然后从微多普勒理论、微动目标特征的提取方法和微多普勒目标识别系统方面综述了国内外研究发展进程,并详细分析了基于迈克尔逊干涉仪技术的振动目标探测系统及光纤耦合微多普勒目标识别系统的工作机理.最后对微多普勒目标探测与识别技术进行展望.

  10. An Observing System Simulation Experiment (OSSE to Assess the Impact of Doppler Wind Lidar (DWL Measurements on the Numerical Simulation of a Tropical Cyclone

    Directory of Open Access Journals (Sweden)

    Lei Zhang

    2010-01-01

    Full Text Available The importance of wind observations has been recognized for many years. However, wind observations—especially three-dimensional global wind measurements—are very limited. A satellite-based Doppler Wind Lidar (DWL is proposed to measure three-dimensional wind profiles using remote sensing techniques. Assimilating these observations into a mesoscale model is expected to improve the performance of the numerical weather prediction (NWP models. In order to examine the potential impact of the DWL three-dimensional wind profile observations on the numerical simulation and prediction of tropical cyclones, a set of observing simulation system experiments (OSSEs is performed using the advanced research version of the Weather Research and Forecasting (WRF model and its three-dimensional variational (3DVAR data assimilation system. Results indicate that assimilating the DWL wind observations into the mesoscale numerical model has significant potential for improving tropical cyclone track and intensity forecasts.

  11. Field test of an all-semiconductor laser-based coherent continuous-wave Doppler lidar for wind energy applications

    DEFF Research Database (Denmark)

    Sjöholm, Mikael; Dellwik, Ebba; Hu, Qi

    The wind energy industry is gaining interest in prevision of the rotor inflow for turbine control. The potential benefits are increased power production due to better alignment of the rotor to the mean wind direction as well as prolonged lifetime of the turbine due to load reductions. Several lidar......-produced all-semiconductor laser. The instrument is a coherent continuous-wave lidar with two fixed-focus telescopes for launching laser beams in two different directions. The alternation between the telescopes is achieved by a novel switching technique without any moving parts. Here, we report results from...

  12. A Simple Doppler Wind Lidar Sensor: Simulated Measurements and Impacts in a Global Assimilation and Forecast System

    Science.gov (United States)

    1991-10-01

    Xl. (a) Globa !, (b) Northern hemisphere, (c) Tropics, (d) Southern hemisphere. Shown are CONTROL (dot), LI)AR (solid), STATSAT (dash), and WINDSTI...assimilation period in which 4044 profiles were processed. In the table the tenns warm and cold cirrus refer to cirrus occurring at temperatures above and...backscatter. "Table 5. lidar Return Totals by Type dnd I.cvel for 6 flour Pcriod. Pressure Total Water Warm Cold Marine (mb) Returns Cloud Cirrus Cirrus

  13. MEMS characterization using new hybrid laser Doppler vibrometer/strobe video system

    Science.gov (United States)

    Lawrence, Eric M.; Rembe, Christian

    2004-01-01

    Laser Doppler Vibrometry (LDV) is a widely accepted tool for dynamic characterization of MEMS. Using automated scan capability, the Polytec system can measure structural resonance and display out-of-plane deflection shapes with amplitudes down to the picometer level and frequencies to 30 MHz. By adding stroboscopic video microscopy for in-plane motion analysis, our combined Micro Motion Analysis (MMA) system is capable of three-dimensional dynamic characterization. The MMA system opens up new possibilities to measure in-plane actuators previously difficult or impossible for LDV measurements. To exemplify the use of this technology, we present characterization measurements on MEMS devices fabricated by Sandia National Labs SUMMiT V process. Multi-axis measurements reveal the complex motions exhibited by an electrostatic comb drive driven at resonance. Also, ultra-high resolution velocity measurements are made on passive cantilever structures oscillating under thermal excitation. Picometer resolution makes possible detection of these purely mechanical resonances. Both comb drive and cantilever data are used to determine mechanical properties important to evaluate the reliability of fabrication processes. This study demonstrates the unique performance of our hybrid LDV / strobe video measurement system for quick, accurate, high-resolution dynamic response measurements.

  14. Evaluation of single and multiple Doppler lidar techniques to measure complex flow during the XPIA field campaign

    Energy Technology Data Exchange (ETDEWEB)

    Choukulkar, Aditya; Brewer, W. Alan; Sandberg, Scott P.; Weickmann, Ann; Bonin, Timothy A.; Hardesty, R. Michael; Lundquist, Julie K.; Delgado, Ruben; Iungo, G. Valerio; Ashton, Ryan; Debnath, Mithu; Bianco, Laura; Wilczak, James M.; Oncley, Steven; Wolfe, Daniel

    2017-01-01

    Accurate three-dimensional information of wind flow fields can be an important tool in not only visualizing complex flow but also understanding the underlying physical processes and improving flow modeling. However, a thorough analysis of the measurement uncertainties is required to properly interpret results. The XPIA (eXperimental Planetary boundary layer Instrumentation Assessment) field campaign conducted at the Boulder Atmospheric Observatory (BAO) in Erie, CO, from 2 March to 31 May 2015 brought together a large suite of in situ and remote sensing measurement platforms to evaluate complex flow measurement strategies.

    In this paper, measurement uncertainties for different single and multi-Doppler strategies using simple scan geometries (conical, vertical plane and staring) are investigated. The tradeoffs (such as time–space resolution vs. spatial coverage) among the different measurement techniques are evaluated using co-located measurements made near the BAO tower. Sensitivity of the single-/multi-Doppler measurement uncertainties to averaging period are investigated using the sonic anemometers installed on the BAO tower as the standard reference. Finally, the radiometer measurements are used to partition the measurement periods as a function of atmospheric stability to determine their effect on measurement uncertainty.

    It was found that with an increase in spatial coverage and measurement complexity, the uncertainty in the wind measurement also increased. For multi-Doppler techniques, the increase in uncertainty for temporally uncoordinated measurements is possibly due to requiring additional assumptions of stationarity along with horizontal homogeneity and less representative line-of-sight velocity statistics. It was also found that wind speed measurement uncertainty was lower during stable conditions compared to unstable conditions.

  15. Evaluation of single and multiple Doppler lidar techniques to measure complex flow during the XPIA field campaign

    Science.gov (United States)

    Choukulkar, Aditya; Brewer, W. Alan; Sandberg, Scott P.; Weickmann, Ann; Bonin, Timothy A.; Hardesty, R. Michael; Lundquist, Julie K.; Delgado, Ruben; Valerio Iungo, G.; Ashton, Ryan; Debnath, Mithu; Bianco, Laura; Wilczak, James M.; Oncley, Steven; Wolfe, Daniel

    2017-01-01

    Accurate three-dimensional information of wind flow fields can be an important tool in not only visualizing complex flow but also understanding the underlying physical processes and improving flow modeling. However, a thorough analysis of the measurement uncertainties is required to properly interpret results. The XPIA (eXperimental Planetary boundary layer Instrumentation Assessment) field campaign conducted at the Boulder Atmospheric Observatory (BAO) in Erie, CO, from 2 March to 31 May 2015 brought together a large suite of in situ and remote sensing measurement platforms to evaluate complex flow measurement strategies. In this paper, measurement uncertainties for different single and multi-Doppler strategies using simple scan geometries (conical, vertical plane and staring) are investigated. The tradeoffs (such as time-space resolution vs. spatial coverage) among the different measurement techniques are evaluated using co-located measurements made near the BAO tower. Sensitivity of the single-/multi-Doppler measurement uncertainties to averaging period are investigated using the sonic anemometers installed on the BAO tower as the standard reference. Finally, the radiometer measurements are used to partition the measurement periods as a function of atmospheric stability to determine their effect on measurement uncertainty. It was found that with an increase in spatial coverage and measurement complexity, the uncertainty in the wind measurement also increased. For multi-Doppler techniques, the increase in uncertainty for temporally uncoordinated measurements is possibly due to requiring additional assumptions of stationarity along with horizontal homogeneity and less representative line-of-sight velocity statistics. It was also found that wind speed measurement uncertainty was lower during stable conditions compared to unstable conditions.

  16. 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.

  17. Lidar to lidar calibration

    DEFF Research Database (Denmark)

    Fernandez Garcia, Sergio; Villanueva, Héctor

    This report presents the result of the lidar to lidar calibration performed for ground-based lidar. Calibration is here understood as the establishment of a relation between the reference lidar 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 the reference lidar measurements are given for information only....

  18. Lidar to lidar calibration

    DEFF Research Database (Denmark)

    Georgieva Yankova, Ginka; Courtney, Michael

    This report presents the result of the lidar to lidar calibration performed for ground-based lidar. Calibration is here understood as the establishment of a relation between the reference lidar 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 the reference lidar measurements are given for information only....

  19. Remote Sensing of Complex Flows by Doppler Wind Lidar: Summary of Issues and Preliminary Recommendations from IEA Wind Task 32 Phase 1

    Energy Technology Data Exchange (ETDEWEB)

    Clifton, Andrew

    2017-06-21

    IEA Wind Task 32 seeks to identify and mitigate the barriers to the adoption of lidar for wind energy applications. In Phase 1 of the task, a working group looked at the state of the art of wind lidar in complex flow conditions. This presentation is a short summary of that work, given at the start of Phase 2.

  20. Combined HSRL and Optical Autocovarience Wind Lidar (HOAWL) Demonstration Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Demonstrate 2β + 2α + 2δ High Spectral Resolution Lidar (HSRL) and Doppler wind lidar measurements simultaneously at 355nm and 532nm using a single...

  1. 3D Scene Reconstruction Using Omnidirectional Vision and LiDAR: A Hybrid Approach.

    Science.gov (United States)

    Vlaminck, Michiel; Luong, Hiep; Goeman, Werner; Philips, Wilfried

    2016-11-16

    In this paper, we propose a novel approach to obtain accurate 3D reconstructions of large-scale environments by means of a mobile acquisition platform. The system incorporates a Velodyne LiDAR scanner, as well as a Point Grey Ladybug panoramic camera system. It was designed with genericity in mind, and hence, it does not make any assumption about the scene or about the sensor set-up. The main novelty of this work is that the proposed LiDAR mapping approach deals explicitly with the inhomogeneous density of point clouds produced by LiDAR scanners. To this end, we keep track of a global 3D map of the environment, which is continuously improved and refined by means of a surface reconstruction technique. Moreover, we perform surface analysis on consecutive generated point clouds in order to assure a perfect alignment with the global 3D map. In order to cope with drift, the system incorporates loop closure by determining the pose error and propagating it back in the pose graph. Our algorithm was exhaustively tested on data captured at a conference building, a university campus and an industrial site of a chemical company. Experiments demonstrate that it is capable of generating highly accurate 3D maps in very challenging environments. We can state that the average distance of corresponding point pairs between the ground truth and estimated point cloud approximates one centimeter for an area covering approximately 4000 m 2 . To prove the genericity of the system, it was tested on the well-known Kitti vision benchmark. The results show that our approach competes with state of the art methods without making any additional assumptions.

  2. 3D Scene Reconstruction Using Omnidirectional Vision and LiDAR: A Hybrid Approach

    Directory of Open Access Journals (Sweden)

    Michiel Vlaminck

    2016-11-01

    Full Text Available In this paper, we propose a novel approach to obtain accurate 3D reconstructions of large-scale environments by means of a mobile acquisition platform. The system incorporates a Velodyne LiDAR scanner, as well as a Point Grey Ladybug panoramic camera system. It was designed with genericity in mind, and hence, it does not make any assumption about the scene or about the sensor set-up. The main novelty of this work is that the proposed LiDAR mapping approach deals explicitly with the inhomogeneous density of point clouds produced by LiDAR scanners. To this end, we keep track of a global 3D map of the environment, which is continuously improved and refined by means of a surface reconstruction technique. Moreover, we perform surface analysis on consecutive generated point clouds in order to assure a perfect alignment with the global 3D map. In order to cope with drift, the system incorporates loop closure by determining the pose error and propagating it back in the pose graph. Our algorithm was exhaustively tested on data captured at a conference building, a university campus and an industrial site of a chemical company. Experiments demonstrate that it is capable of generating highly accurate 3D maps in very challenging environments. We can state that the average distance of corresponding point pairs between the ground truth and estimated point cloud approximates one centimeter for an area covering approximately 4000 m 2 . To prove the genericity of the system, it was tested on the well-known Kitti vision benchmark. The results show that our approach competes with state of the art methods without making any additional assumptions.

  3. Laser sources for lidar applications

    Science.gov (United States)

    Kilmer, J.; Iadevaia, A.; Yin, Y.

    2012-06-01

    Advanced LIDAR applications such as next gen: Micro Pulse; Time of Flight (e.g., Satellite Laser Ranging); Coherent and Incoherent Doppler (e.g., Wind LIDAR); High Spectral Resolution; Differential Absorption (DIAL); photon counting LIDAR (e.g., 3D LIDAR); are placing more demanding requirements on conventional lasers (e.g., increased rep rates, etc.) and have inspired the development of new types of laser sources. Today, solid state lasers are used for wind sensing, 2D laser Radar, 3D scanning and flash LIDAR. In this paper, we report on the development of compact, highly efficient, high power all-solidstate diode pulsed pumped ns lasers, as well as, high average power/high pulse energy sub nanosecond (picosecond (lasers for these next gen LIDAR applications.

  4. Erosion - deposition evaluation through hybrid DTMs derived by LiDAR and colour bathymetry: the case study of the Brenta, Piave and Tagliamento rivers

    Directory of Open Access Journals (Sweden)

    J. Moretto

    2013-09-01

    Full Text Available Risk management and flood protection are frequently assessed through geo-morphometric evaluations resulting by floods events. If we aim at elevation models with high resolutions and covering large areas, airborne LiDAR surveys can represent a good compromise among costs, time and uncertainty. The major limitation of the nonbathymetric LiDAR surveys consists in the detection of wet areas. Indeed, accounting for more than 20 cm of water depth, LiDAR signal increases exponentially its error. In this paper we present a comparison of the results concerning the application of a colour bathymetry methodology for the production of hybrid DTMs (HDTM. These elevation models were derived by merging LiDAR data for the dry areas and colour bathymetry for the wet areas. The methodological approach consists in a statistical regression between water depth and RGB band intensity values from contemporary aerial images. This methodology includes the use of filters in order to reduce possible errors due to the application of the model, to estimate precise “in-channel” points. The study areas are three different human impacted gravel-bed rivers of the North-East of Italy. This methodology has been applied in three sub-reaches of Brenta River, two of Piave River and two of Tagliamento River before and after relevant flood events with recurrence interval 10 years. Potentials and limitations of the applied bathymetric method, the comparison of its use in different fluvial contexts and its possibility of employment for geo-morphometric evaluations, were then tested. DGPS control points (1841, 2638, 10473 respectively for Brenta, Piave and Tagliamento River were finally used to evaluate the accuracy of wet areas. Results showed that, in each model, wet areas vertical errors were comparable to those featured by LiDAR data for the dry areas.

  5. Direct-detection Doppler wind measurements with a Cabannes-Mie lidar: b. Impact of aerosol variation on iodine vapor filter methods.

    Science.gov (United States)

    She, Chiao-Yao; Yue, Jia; Yan, Zhao-Ai; Hair, Johnathan W; Guo, Jin-Jia; Wu, Song-Hua; Liu, Zhi-Shen

    2007-07-10

    Atmospheric line-of-sight (LOS) wind measurement by means of incoherent Cabannes- Mie lidar with three frequency analyzers, two double-edge Fabry-Perot interferometers, one at 1064 nm (IR-FPI) and another at 355 nm (UV-FPI), as well as an iodine vapor filter (IVF) at 532 nm, utilizing either a single absorption edge, single edge (se-IVF), or both absorption edges, double edge (de-IVF), was considered in a companion paper [Appl. Opt. 46, 4434 (2007)], assuming known atmospheric temperature and aerosol mixing ratio, Rb. The effects of temperature and aerosol variations on the uncertainty of LOS wind measurements are investigated and it is found that while the effect of temperature variation is small, the variation in R(b) can cause significant errors in wind measurements with IVF systems. Thus the means to incorporate a credible determination of R(b) into the wind measurement are presented as well as an assessment of the impact on wind measurement uncertainty. Unlike with IVF methods, researchers can take advantage of design flexibility with FPI methods to desensitize either molecular scattering for IR-FPI or aerosol scattering for UV-FPI. The additional wind measurement uncertainty caused by R(b) variation with FPI methods is thus negligible for these configurations. Assuming 100,000 photons from Cabannes scattering, and accounting for the Rb measurement incorporated into the IVF method in this paper, it is found that the lowest wind uncertainty at low wind speeds in aerosol-free air is still with UV-FPI, ~32% lower than with de-IVF. For 0.050.07, the IR-FPI outperforms all other methods. In addition to LOS wind uncertainty comparison under high wind speed conditions, the need of an appropriate and readily available narrowband filter for operating the wind lidar at visible wavelengths under sunlit condition is discussed; with such a filter the degradation of LOS wind measurement attributable to clear sky background is estimated to be 5% or less for practical lidar

  6. A coordinated study of 1-h gravity wave propagating from Logan to Boulder using two Na Doppler lidars and a temperature mapper

    Science.gov (United States)

    Lu, X.; Chen, C.; Zhao, J.; Huang, W.; Chu, X.; Cullens, C. Y.; Yuan, T.; Pautet, P. D.; Zhao, Y.; Taylor, M. J.

    2014-12-01

    Vertical winds in the mesosphere and lower thermosphere can be obtained with good accuracy and precision with the STAR sodium (Na) lidar system at Boulder (40.1°N, 105.2°W), CO, after its receiving efficiency has been substantially improved by an order of magnitude. A remarkable gravity wave signature with a period of ˜1h is the most prominent feature shown in the vertical wind on Nov 27, 2013 at Boulder. Similar wave signatures are also present in the temperature and Na density variations. From the USU lidar and the temperature mapper, the gravity wave oscillation with a period of ˜1h is also observed in the temperature and horizontal winds at Logan (41.7°N, 111.8°W), Utah. By combining the observations from these two stations, we determine the vertical wavelength is about 25 km and horizontal wavelength is about 327 km. This wave is propagating from Logan to Boulder with an elevation angle of 4.4° and an azimuth angle of 133°. The wave amplitudes in vertical wind, horizontal winds and temperature are provided and their ratios are in good agreement with the gravity wave polarization relation. This coordinated study has uniquely provided 3-D information and magnitude of the 1-h gravity wave, which has a great potential to be the seed of TIDs, affecting the ionospheric variabilities. Using the ray-tracing model, we find that the wave source is above 10 km. It is likely generated by the geostrophic adjustment of the jet stream, whose orientation is consistent with the horizontal propagation direction of the wave.

  7. 新型多普勒测风激光雷达Windcube的风参数观测与验证%Observation and Validation of Wind Parameters Measured by Doppler Wind Lidar Windcube

    Institute of Scientific and Technical Information of China (English)

    夏俊荣; 王普才; 闵敏

    2011-01-01

    2007年12月11~14日,中国科学院大气物理研究所与法国Leosphere公司在该研究所位于北京市北三环和北四环之间的325 m气象塔试验场内联合开展了一次测风激光雷达Windcube的外场演示试验.Windcube观测数据随后与325 m气象塔上的风杯风速仪测得的风速资料进行了对比,结果是:由两种手段获得的所有6层匹配高度(63 m、80 m、100m、120m、160m和200m)上的10 min风速平均值一致性很好,相关系数都达到或超过0.98.使用矢量法对6层高度上的风向资料进行平均,得到风向的10 min平均值,两者的相关系数均达到0.99.与国产测量低层大气风廓线的高精度多普勒激光雷达相比,Windcube的风速测量精度稍优,风向表现相当.验证结果表明,该型多普勒测风激光雷达是一款观测结果可靠、机动性能良好的低层大气风廓线测量仪器.%A field performance of Doppler wind lidar Windcube (released by Leosphere Company) was conducted by Institute of Atmospheric Physics, Chinese Academy of Sciences (IAP/CAS) and Leosphere Company (from France) at the 325-m meteorological tower site (a part of IAP, located between 3rd North Ring Road and 4th North Ring Road) from 11 December to 14 December 2007. The intercomparison of wind speed and wind direction obtained by Windcube and wind cup anemometers (fixed in the meteorological tower) shows that; 1) 10-min averaged wind speed is highly consistent between two types of wind data at six matched levels (63 m, 80 m, 100 m, 120 m, 160 m, and 200 m), the correlation coefficients all equal or exceed 0. 98. 2) 10-min averaged wind direction is calculated with the vector method, the correlation coefficients of averaged wind direction at the six levels are 0. 99. 3) In comparison with domestic Doppler wind lidar, Windcube performs slightly better in wind speed measuring, and equally well in wind direction measuring. The intercomparison indicates that Windcube is a reliable and

  8. Design of a Non-scanning Lidar for Wind Velocity and Direction Measurement

    Science.gov (United States)

    Liu, Bo; Peng, Zhangxian

    2016-06-01

    A Doppler lidar system for wind velocity and direction measurement is presented. The lidar use a wide field of view (FOV) objective lens as an optical antenna for both beam transmitting and signal receiving. By four fibers coupled on different position on the focal plane, the lidar can implement wind vector measurement without any scanning movement.

  9. Design of a Non-scanning Lidar for Wind Velocity and Direction Measurement

    Directory of Open Access Journals (Sweden)

    Liu Bo

    2016-01-01

    Full Text Available A Doppler lidar system for wind velocity and direction measurement is presented. The lidar use a wide field of view (FOV objective lens as an optical antenna for both beam transmitting and signal receiving. By four fibers coupled on different position on the focal plane, the lidar can implement wind vector measurement without any scanning movement.

  10. Lidar Uncertainty Measurement Experiment (LUMEX) - Understanding Sampling Errors

    Science.gov (United States)

    Choukulkar, A.; Brewer, W. A.; Banta, R. M.; Hardesty, M.; Pichugina, Y.; Senff, Christoph; Sandberg, S.; Weickmann, A.; Carroll, B.; Delgado, R.; Muschinski, A.

    2016-06-01

    Coherent Doppler LIDAR (Light Detection and Ranging) has been widely used to provide measurements of several boundary layer parameters such as profiles of wind speed, wind direction, vertical velocity statistics, mixing layer heights and turbulent kinetic energy (TKE). An important aspect of providing this wide range of meteorological data is to properly characterize the uncertainty associated with these measurements. With the above intent in mind, the Lidar Uncertainty Measurement Experiment (LUMEX) was conducted at Erie, Colorado during the period June 23rd to July 13th, 2014. The major goals of this experiment were the following: Characterize sampling error for vertical velocity statistics Analyze sensitivities of different Doppler lidar systems Compare various single and dual Doppler retrieval techniques Characterize error of spatial representativeness for separation distances up to 3 km Validate turbulence analysis techniques and retrievals from Doppler lidars This experiment brought together 5 Doppler lidars, both commercial and research grade, for a period of three weeks for a comprehensive intercomparison study. The Doppler lidars were deployed at the Boulder Atmospheric Observatory (BAO) site in Erie, site of a 300 m meteorological tower. This tower was instrumented with six sonic anemometers at levels from 50 m to 300 m with 50 m vertical spacing. A brief overview of the experiment outline and deployment will be presented. Results from the sampling error analysis and its implications on scanning strategy will be discussed.

  11. Pointing Verification Method for Spaceborne Lidars

    Directory of Open Access Journals (Sweden)

    Axel Amediek

    2017-01-01

    Full Text Available High precision acquisition of atmospheric parameters from the air or space by means of lidar requires accurate knowledge of laser pointing. Discrepancies between the assumed and actual pointing can introduce large errors due to the Doppler effect or a wrongly assumed air pressure at ground level. In this paper, a method for precisely quantifying these discrepancies for airborne and spaceborne lidar systems is presented. The method is based on the comparison of ground elevations derived from the lidar ranging data with high-resolution topography data obtained from a digital elevation model and allows for the derivation of the lateral and longitudinal deviation of the laser beam propagation direction. The applicability of the technique is demonstrated by using experimental data from an airborne lidar system, confirming that geo-referencing of the lidar ground spot trace with an uncertainty of less than 10 m with respect to the used digital elevation model (DEM can be obtained.

  12. Micropulse Lidar

    Data.gov (United States)

    Oak Ridge National Laboratory — The Micropulse Lidar (MPL) is a ground-based optical remote sensing system designed primarily to determine the altitude of clouds overhead. The physical principle is...

  13. 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...

  14. 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.

  15. Lidar to lidar calibration phase 2

    DEFF Research Database (Denmark)

    Yordanova, Ginka; Courtney, Michael

    This report presents the results from phase 2 of a lidar to lidar (L2L) calibration procedure. Phase two of the project included two measurement campaigns conducted at given sites. The purpose was to find out if the lidar-to-lidar calibration procedure can be conducted with similar results...

  16. Lidar to lidar calibration phase 1

    DEFF Research Database (Denmark)

    Yordanova, Ginka; Courtney, Michael

    This report presents a feasibility study of a lidar to lidar (L2L) calibration procedure. Phase one of the project was conducted at Høvsøre, Denmark. Two windcubes were placed next to the 116m met mast and different methods were applied to obtain the sensing height error of the lidars. The purpose...... is to find the most consistent method and use it in a potential lidar to lidar calibration procedure....

  17. Lidar Scanning of Momentum Flux in and above the Atmospheric Surface Layer

    DEFF Research Database (Denmark)

    Mann, Jakob; Pena Diaz, Alfredo; Bingöl, Ferhat

    2010-01-01

    Methods to measure the vertical flux of horizontal momentum using both continuous wave and pulsed Doppler lidar profilers are evaluated. The lidar measurements are compared to momentum flux observations performed with sonic anemometers over flat terrain at Høvsøre, Denmark, and profile-derived ve...... is the ratio of the turbulence scale to the size of the measuring volume. For the continuous wave lidar the reduction can largely be compensated by averaging Doppler spectra instead of radial velocities.......Methods to measure the vertical flux of horizontal momentum using both continuous wave and pulsed Doppler lidar profilers are evaluated. The lidar measurements are compared to momentum flux observations performed with sonic anemometers over flat terrain at Høvsøre, Denmark, and profile...

  18. Flexible High Energy Lidar Transmitter for Remote Gas and Wind Sensing Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Fibertek proposes a high energy and flexible operation 1570 nm pulsed lidar transmitter for airborne and space-based remote CO2 gas and doppler wind sensing. The...

  19. Lidar instruments for ESA Earth observation missions

    Science.gov (United States)

    Hélière, Arnaud; Armandillo, Errico; Durand, Yannig; Culoma, Alain; Meynart, Roland

    2004-06-01

    The idea of deploying a lidar system on an Earth-orbiting satellite stems from the need for continuously providing profiles of our atmospheric structure with high accuracy and resolution and global coverage. Interest in this information for climatology, meteorology and the atmospheric sciences in general is huge. Areas of application range from the determination of global warming and greenhouse effects, to monitoring the transport and accumulation of pollutants in the different atmospheric regions (such as the recent fires in Southeast Asia), to the assessment of the largely unknown microphysical properties and the structural dynamics of the atmosphere itself. Spaceborne lidar systems have been the subject of extensive investigations by the European Space Agency since mid 1970's, resulting in mission and instrument concepts, such as ATLID, the cloud backscatter lidar payload of the EarthCARE mission, ALADIN, the Doppler wind lidar of the Atmospheric Dynamics Mission (ADM) and more recently a water vapour Differential Absorption Lidar considered for the WALES mission. These studies have shown the basic scientific and technical feasibility of spaceborne lidars, but they have also demonstrated their complexity from the instrument viewpoint. As a result, the Agency undertook technology development in order to strengthen the instrument maturity. This is the case for ATLID, which benefited from a decade of technology development and supporting studies and is now studied in the frame of the EarthCARE mission. ALADIN, a Direct Detection Doppler Wind Lidar operating in the Ultra-Violet, will be the 1st European lidar to fly in 2007 as payload of the Earth Explorer Core Mission ADM. WALES currently studied at the level of a phase A, is based upon a lidar operating at 4 wavelengths in near infrared and aims to profile the water vapour in the lower part of the atmosphere with high accuracy and low bias. Lastly, the European Space Agency is extending the lidar instrument field

  20. Spatial averaging-effects on turbulence measured by a continuous-wave coherent lidar

    DEFF Research Database (Denmark)

    Sjöholm, Mikael; Mikkelsen, Torben; Mann, Jakob;

    2009-01-01

    The influence of spatial volume averaging of a focused continuous-wave coherent Doppler lidar on observed wind turbulence in the atmospheric surface layer is described and analysed. For the first time, comparisons of lidar-measured turbulent spectra with spectra simultaneously obtained from a mast...

  1. An Inter-Comparison Study of Multi- and DBS Lidar Measurements in Complex Terrain

    DEFF Research Database (Denmark)

    Pauscher, Lukas; Vasiljevic, Nikola; Callies, Doron

    2016-01-01

    WindScanners were focused on one point next to a reference mast in complex terrain. This multi-lidar (ML) technique is also compared to a profiling lidar using the Doppler beam swinging (DBS) method. First- and second-order statistics of the radial wind velocities from the individual instruments...

  2. Generic Methodology for Field Calibration of Nacelle-Based Wind Lidars

    OpenAIRE

    Antoine Borraccino; Michael Courtney; Rozenn Wagner

    2016-01-01

    Nacelle-based Doppler wind lidars have shown promising capabilities to assess power performance, detect yaw misalignment or perform feed-forward control. The power curve application requires uncertainty assessment. Traceable measurements and uncertainties of nacelle-based wind lidars can be obtained through a methodology applicable to any type of existing and upcoming nacelle lidar technology. The generic methodology consists in calibrating all the inputs of the wind field reconstruction algo...

  3. Lidar Characterization of Boundary Layer Transport and Mixing for Estimating Urban-Scale Greenhouse Gas Emissions

    Science.gov (United States)

    Hardesty, R. Michael; Brewer, W. Alan; Sandberg, Scott P.; Weickmann, Ann M.; Shepson, Paul B.; Cambaliza, Maria; Heimburger, Alexie; Davis, Kenneth J.; Lauvaux, Thomas; Miles, Natasha L.; Sarmiento, Daniel P.; Deng, A. J.; Gaudet, Brian; Karion, Anna; Sweeney, Colm; Whetstone, James

    2016-06-01

    A compact commercial Doppler lidar has been deployed in Indianapolis for two years to measure wind profiles and mixing layer properties as part of project to improve greenhouse measurements from large area sources. The lidar uses vertical velocity variance and aerosol structure to measure mixing layer depth. Comparisons with aircraft and the NOAA HRDL lidar generally indicate good performance, although sensitivity might be an issue under low aerosol conditions.

  4. Lidar Characterization of Boundary Layer Transport and Mixing for Estimating Urban-Scale Greenhouse Gas Emissions

    Directory of Open Access Journals (Sweden)

    Hardesty R. Michael

    2016-01-01

    Full Text Available A compact commercial Doppler lidar has been deployed in Indianapolis for two years to measure wind profiles and mixing layer properties as part of project to improve greenhouse measurements from large area sources. The lidar uses vertical velocity variance and aerosol structure to measure mixing layer depth. Comparisons with aircraft and the NOAA HRDL lidar generally indicate good performance, although sensitivity might be an issue under low aerosol conditions.

  5. All semiconductor laser Doppler anemometer at 1.55 μm

    DEFF Research Database (Denmark)

    Hansen, Rene Skov; Pedersen, Christian

    2008-01-01

    We report to our best knowledge the first all semiconductor Laser Doppler Anemometer (LIDAR) for wind speed determination. We will present the design and first experimental results on a focusing coherent cw laser Doppler anemometer for measuring atmospheric wind velocities in the 10 meters to 300...

  6. Special Relativity Corrections for Space-Based Lidars

    Science.gov (United States)

    RaoGudimetla, Venkata S.; Kavaya, Michael J.

    1999-01-01

    The theory of special relativity is used to analyze some of the physical phenomena associated with space-based coherent Doppler lidars aimed at Earth and the atmosphere. Two important cases of diffuse scattering and retroreflection by lidar targets are treated. For the case of diffuse scattering, we show that for a coaligned transmitter and receiver on the moving satellite, there is no angle between transmitted and returned radiation. However, the ray that enters the receiver does not correspond to a retroreflected ray by the target. For the retroreflection case there is misalignment between the transmitted ray and the received ray. In addition, the Doppler shift in the frequency and the amount of tip for the receiver aperture when needed are calculated, The error in estimating wind because of the Doppler shift in the frequency due to special relativity effects is examined. The results are then applied to a proposed space-based pulsed coherent Doppler lidar at NASA's Marshall Space Flight Center for wind and aerosol backscatter measurements. The lidar uses an orbiting spacecraft with a pulsed laser source and measures the Doppler shift between the transmitted and the received frequencies to determine the atmospheric wind velocities. We show that the special relativity effects are small for the proposed system.

  7. Turbulence characterization from a forward-looking nacelle lidar

    DEFF Research Database (Denmark)

    Peña, Alfredo; Mann, Jakob; Dimitrov, Nikolay Krasimirov

    2017-01-01

    We present two methods to characterize turbulence in the turbine inflow using radial velocity measurements from nacelle-mounted lidars. The first uses a model of the three-dimensional spectral velocity tensor combined with a model of the spatial radial velocity averaging of the lidars......, and the second uses the ensembleaveraged Doppler radial velocity spectrum. With the former, filtered turbulence estimates can be predicted, whereas the latter model-free method allows us to estimate unfiltered turbulence measures. Two types of forwardlooking nacelle lidars are investigated: a pulsed system...... that uses a five-beam configuration and a continuouswave system that scans conically. For both types of lidars, we show how the radial velocity spectra of the lidar beams are influenced by turbulence characteristics, and how to extract the velocity-tensor parameters that are useful to predict the loads...

  8. Evaluation of three lidar scanning strategies for turbulence measurements

    DEFF Research Database (Denmark)

    Newman, Jennifer F.; Klein, Petra M.; Wharton, Sonia

    2016-01-01

    , and w velocity variances and covariances. In order to assess the ability of these different scanning techniques to measure turbulence, a Halo scanning lidar, WindCube v2 pulsed lidar, and ZephIR continuous wave lidar were deployed at field sites in Oklahoma and Colorado with collocated sonic anemometers......Several errors occur when a traditional Doppler beam swinging (DBS) or velocity-azimuth display (VAD) strategy is used to measure turbulence with a lidar. To mitigate some of these errors, a scanning strategy was recently developed which employs six beam positions to independently estimate the u, v.......Results indicate that the six-beam strategy mitigates some of the errors caused by VAD and DBS scans, but the strategy is strongly affected by errors in the variance measured at the different beam positions. The ZephIR and WindCube lidars overestimated horizontal variance values by over 60% under unstable...

  9. 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.

  10. Ultrahigh field magnetic resonance and colour Doppler real-time fusion imaging of the orbit - a hybrid tool for assessment of choroidal melanoma

    Energy Technology Data Exchange (ETDEWEB)

    Walter, Uwe [University of Rostock, Department of Neurology, Rostock (Germany); Niendorf, Thoralf; Rieger, Jan [Berlin Ultrahigh Field Facility, Max-Delbrueck-Center for Molecular Medicine, Berlin (Germany); MRI.TOOLS GmbH, Berlin (Germany); Graessl, Andreas [Berlin Ultrahigh Field Facility, Max-Delbrueck-Center for Molecular Medicine, Berlin (Germany); Krueger, Paul-Christian; Langner, Soenke [University of Greifswald, Institute for Diagnostic Radiology and Neuroradiology, Greifswald (Germany); Guthoff, Rudolf F.; Stachs, Oliver [University of Rostock, Department of Ophthalmology, Rostock (Germany)

    2014-05-15

    A combination of magnetic resonance images with real-time high-resolution ultrasound known as fusion imaging may improve ophthalmologic examination. This study was undertaken to evaluate the feasibility of orbital high-field magnetic resonance and real-time colour Doppler ultrasound image fusion and navigation. This case study, performed between April and June 2013, included one healthy man (age, 47 years) and two patients (one woman, 57 years; one man, 67 years) with choroidal melanomas. All cases underwent 7.0-T magnetic resonance imaging using a custom-made ocular imaging surface coil. The Digital Imaging and Communications in Medicine volume data set was then loaded into the ultrasound system for manual registration of the live ultrasound image and fusion imaging examination. Data registration, matching and then volume navigation were feasible in all cases. Fusion imaging provided real-time imaging capabilities and high tissue contrast of choroidal tumour and optic nerve. It also allowed adding a real-time colour Doppler signal on magnetic resonance images for assessment of vasculature of tumour and retrobulbar structures. The combination of orbital high-field magnetic resonance and colour Doppler ultrasound image fusion and navigation is feasible. Multimodal fusion imaging promises to foster assessment and monitoring of choroidal melanoma and optic nerve disorders. (orig.)

  11. Testing and validation of multi-lidar scanning strategies for wind energy applications: Testing and validation of multi-lidar scanning strategies for wind energy applications

    Energy Technology Data Exchange (ETDEWEB)

    Newman, Jennifer F. [School of Meteorology, University of Oklahoma, Norman Oklahoma USA; Current affiliation: National Wind Technology Center, National Renewable Energy Laboratory, Golden Colorado USA; Bonin, Timothy A. [School of Meteorology, University of Oklahoma, Norman Oklahoma USA; Current affiliation: Cooperative Institute for Research in the Environmental Sciences, University of Colorado, and National Oceanic and Atmospheric Administration/Earth System Research Laboratory, Boulder Colorado USA; Klein, Petra M. [School of Meteorology, University of Oklahoma, Norman Oklahoma USA; Wharton, Sonia [Atmospheric, Earth and Energy Division, Lawrence Livermore National Laboratory, Livermore California USA; Newsom, Rob K. [Pacific Northwest National Laboratory, Richland Washington USA

    2016-03-16

    Several factors cause lidars to measure different values of turbulence than an anemometer on a tower, including volume averaging, instrument noise, and the use of a scanning circle to estimate the wind field. One way to avoid the use of a scanning circle is to deploy multiple scanning lidars and point them toward the same volume in space to collect velocity measurements and extract high-resolution turbulence information. This paper explores the use of two multi-lidar scanning strategies, the tri-Doppler technique and the virtual tower technique, for measuring 3-D turbulence. In Summer 2013, a vertically profiling Leosphere WindCube lidar and three Halo Photonics Streamline lidars were operated at the Southern Great Plains Atmospheric Radiation Measurement site to test these multi-lidar scanning strategies. During the first half of the field campaign, all three scanning lidars were pointed at approximately the same point in space and a tri-Doppler analysis was completed to calculate the three-dimensional wind vector every second. Next, all three scanning lidars were used to build a “virtual tower” above the WindCube lidar. Results indicate that the tri-Doppler technique measures higher values of horizontal turbulence than the WindCube lidar under stable atmospheric conditions, reduces variance contamination under unstable conditions, and can measure highresolution profiles of mean wind speed and direction. The virtual tower technique provides adequate turbulence information under stable conditions but cannot capture the full temporal variability of turbulence experienced under unstable conditions because of the time needed to readjust the scans.

  12. Lidar calibration experiments

    DEFF Research Database (Denmark)

    Ejsing Jørgensen, Hans; Mikkelsen, T.; Streicher, J.

    1997-01-01

    A series of atmospheric aerosol diffusion experiments combined with lidar detection was conducted to evaluate and calibrate an existing retrieval algorithm for aerosol backscatter lidar systems. The calibration experiments made use of two (almost) identical mini-lidar systems for aerosol cloud...... detection to test the reproducibility and uncertainty of lidars. Lidar data were obtained from both single-ended and double-ended Lidar configurations. A backstop was introduced in one of the experiments and a new method was developed where information obtained from the backstop can be used in the inversion...... algorithm. Independent in-situ aerosol plume concentrations were obtained from a simultaneous tracer gas experiment with SF6, and comparisons with the two lidars were made. The study shows that the reproducibility of the lidars is within 15%, including measurements from both sides of a plume...

  13. LIDAR Research & Development Lab

    Data.gov (United States)

    Federal Laboratory Consortium — The LIDAR Research and Development labs are used to investigate and improve LIDAR components such as laser sources, optical signal detectors and optical filters. The...

  14. Wind Measurement LIDAR Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Systems & Processes Engineering Corporation (SPEC) proposes a Wind Measurement LIDAR whose sensor assembly is composed of SPEC Gen IV LIDAR seeker, with 12.8...

  15. Lidar base specification

    Science.gov (United States)

    Heidemann, Hans Karl.

    2012-01-01

    In late 2009, a $14.3 million allocation from the “American Recovery and Reinvestment Act” for new light detection and ranging (lidar) elevation data prompted the U.S. Geological Survey (USGS) National Geospatial Program (NGP) to develop a common base specification for all lidar data acquired for The National Map. Released as a draft in 2010 and formally published in 2012, the USGS–NGP “Lidar Base Specification Version 1.0” (now Lidar Base Specification) was quickly embraced as the foundation for numerous state, county, and foreign country lidar specifications.

  16. Influence of speckle effect on doppler velocity measurement

    Science.gov (United States)

    Zheng, Zheng; Changming, Zhao; Haiyang, Zhang; Suhui, Yang; Dehua, Zhang; Xingyuan, Zheng; Hongzhi, Yang

    2016-06-01

    In a coherent Lidar system, velocity measurement of a target is achieved by measuring Doppler frequency shift between the echo and local oscillator (LO) signals. The measurement accuracy is proportional to the spectrum width of Doppler signal. Actually, the speckle effect caused by the scattering of laser from a target will broaden the Doppler signal's spectrum and bring uncertainty to the velocity measurement. In this paper, a theoretical model is proposed to predict the broadening of Doppler spectrum with respect to different target's surface and motion parameters. The velocity measurement uncertainty caused by the broadening of spectrum is analyzed. Based on the analysis, we design a coherent Lidar system to measure the velocity of the targets with different surface roughness and transverse velocities. The experimental results are in good agreement with theoretical analysis. It is found that the target's surface roughness and transverse velocity can significantly affect the spectrum width of Doppler signal. With the increase of surface roughness and transverse velocity, the measurement accuracy becomes worse. However, the influence of surface roughness becomes weaker when the spot size of laser beam on the target is smaller.

  17. Retrieving wind statistics from average spectrum of continuous-wave lidar

    Directory of Open Access Journals (Sweden)

    E. Branlard

    2013-07-01

    Full Text Available The aim of this study is to experimentally demonstrate that the time-average Doppler spectrum of a continuous-wave (cw lidar is proportional to the probability density function of the line-of-sight velocities. This would open the possibility of using cw lidars for the determination of the second-order atmospheric turbulence statistics. An atmospheric field campaign and a wind tunnel experiment are carried out to show that the use of an average Doppler spectrum instead of a time series of velocities determined from individual Doppler spectra significantly reduces the differences with the standard deviation measured using ordinary anemometers, such as ultra-sonic anemometers or hotwires. The proposed method essentially removes the spatial averaging effect intrinsic to the cw lidar systems.

  18. Advances in lidar applications

    Science.gov (United States)

    Lewandowski, Piotr Andrzej

    Quantitative laser remote sensing (lidar) measurements have always posed a challenge for the research community. The complexity of the data inversion and the instrumentation itself makes lidar results difficult to interpret. This dissertation presents a suite of 3 elastic lidar experiments. The goal of these studies was to quantitatively approach atmospheric physical phenomena such as rainfall (chapter 3), a distribution of concentration of particulates in Mexico City (chapter 4) and emission rates and emission factors from an agricultural facility in Iowa (chapter 5). The studies demonstrate that elastic lidar measurements are possible not only in a qualitative sense but also in a quantitative sense. The lidar study of rainfall was intended to provide rainfall data in small spatial and temporal scales (1.5m and 1s resolution). The two levels of lidar inversion algorithms allowed the calculation of rainfall rates in small scales. The problem of the distribution of particles over Mexico City required mobile lidar measurements. The elastic lidar data were successfully inverted to extinction coefficients which were then combined with aerosol size distribution. As a result, a spatial distribution of particulate concentration was created to illustrate the transport processes and intensity of Mexico City pollution. The measurements of particulate emission fluxes from a livestock facility involved a stationary scanning elastic lidar, in-situ aerosol size distribution measurements and wind measurements. The data from the 3 independent measurement platforms combined together resulted in emission rates and emission factors. The results from this experiment demonstrated that the new lidar approach is an adequate tool for measurement of aerosol emissions from livestock production facilities. The studies presented in the dissertation show quantitative lidar measurements in combination with other instruments measurements. This approach significantly extends the applications of

  19. 2015 Lowndes County (GA) Lidar

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — TASK NAME: NOAA OCM Lidar for Lowndes County, GA with the option to Collect Lidar in Cook and Tift Counties, GA Lidar Data Acquisition and Processing Production Task...

  20. 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...

  1. Retrieving wind statistics from average spectrum of continuous-wave lidar

    DEFF Research Database (Denmark)

    Branlard, Emmanuel; Pedersen, Anders Tegtmeier; Mann, Jakob

    2013-01-01

    -order atmospheric turbulence statistics. An atmospheric field campaign and a wind tunnel experiment are carried out to show that the use of an average Doppler spectrum instead of a time series of velocities determined from individual Doppler spectra significantly reduces the differences with the standard deviation...... measured using ordinary anemometers, such as ultra-sonic anemometers or hotwires. The proposed method essentially removes the spatial averaging effect intrinsic to the cw lidar systems....

  2. Applications of Telecommunication Transceiver Architectures in All-Fiber Coherent Detection Lidars

    DEFF Research Database (Denmark)

    Abari, Cyrus F.

    to exist between the two. In this thesis, I have presented some of the advances in fiber-optic transceivers, originally developed for high-speed data transmission, and shown how they can be integrated in micropulse and continuous-wave all-fiber coherent detection lidars. The presented technologies not only...... enable the possibility for performance improvements in existing lidars but also pave the way for the application of coherent detection lidars in areas where their presence was neither plausible nor easy to realize. This thesis, composed of an introduction and four scientific paper and one manuscript......, specifically presents the adoption of some of the contemporary fiber-optic communications transceiver architectures in coherent detection lidars. In paper I a new short-range all-fiber coherent Doppler lidar employing an image-reject homodyne receiver is described and demonstrated. In Paper II two different...

  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. Evaluation of three lidar scanning strategies for turbulence measurements

    Science.gov (United States)

    Newman, Jennifer F.; Klein, Petra M.; Wharton, Sonia; Sathe, Ameya; Bonin, Timothy A.; Chilson, Phillip B.; Muschinski, Andreas

    2016-05-01

    Several errors occur when a traditional Doppler beam swinging (DBS) or velocity-azimuth display (VAD) strategy is used to measure turbulence with a lidar. To mitigate some of these errors, a scanning strategy was recently developed which employs six beam positions to independently estimate the u, v, and w velocity variances and covariances. In order to assess the ability of these different scanning techniques to measure turbulence, a Halo scanning lidar, WindCube v2 pulsed lidar, and ZephIR continuous wave lidar were deployed at field sites in Oklahoma and Colorado with collocated sonic anemometers.Results indicate that the six-beam strategy mitigates some of the errors caused by VAD and DBS scans, but the strategy is strongly affected by errors in the variance measured at the different beam positions. The ZephIR and WindCube lidars overestimated horizontal variance values by over 60 % under unstable conditions as a result of variance contamination, where additional variance components contaminate the true value of the variance. A correction method was developed for the WindCube lidar that uses variance calculated from the vertical beam position to reduce variance contamination in the u and v variance components. The correction method reduced WindCube variance estimates by over 20 % at both the Oklahoma and Colorado sites under unstable conditions, when variance contamination is largest. This correction method can be easily applied to other lidars that contain a vertical beam position and is a promising method for accurately estimating turbulence with commercially available lidars.

  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. The Athena-OAWL Doppler Wind Lidar Mission

    Directory of Open Access Journals (Sweden)

    Tucker Sara C.

    2016-01-01

    Full Text Available With the objective of providing tropospheric wind profile data over the mid-latitude oceans and tropics for data-starved weather forecast models, the Earth Venture Instrument (EV-I Mission concept “Atmospheric Transport, Hurricanes, and Extratropical Numerical weAther prediction with the Optical Autocovariance Wind Lidar” (ATHENA-OAWL was proposed in November 2013. The mission concept is described here along with a brief history of the OAWL system development and current development of an ATHENA-OAWL airborne demonstrator under NASA’s Venture Technology development.

  8. Variations of the Wake Height over the Bolund Escarpment Measured by a Scanning Lidar

    DEFF Research Database (Denmark)

    Lange, Julia; Mann, Jakob; Angelou, Nikolas

    2016-01-01

    The wake zone behind the escarpment of the Bolund peninsula in the Roskilde Fjord, Denmark, has been investigated with the help of a continuous-wave Doppler lidar. The instrument measures the line-of-sight wind speed 390 times per second in highly resolved 7- m tall profiles by rapidly changing t...

  9. Exploring the Turbulent Urban Boundary by Use of Lidars and Microwave Radiometers

    Science.gov (United States)

    Arend, Mark; Valerio, Ivan; Neufeld, Stephen; Bishir, Raymond; Wu, Younghu; Moshary, Fred; Melecio-Vazquez, David; Gonzalez, Jorge

    2016-06-01

    A Doppler lidar has been developed using fiber optic based technologies and advanced signal processing techniques. Although this system has been operated in a scanning mode in the past, for this application, the system is operated in a vertically pointing mode and delivers a time series of vertical velocity profiles. By cooperating the Doppler lidar with other instruments, including a back scatter lidar, and a microwave radiometer, models of atmospheric stability can be tested, opening up an exciting path for researchers, applied scientists and engineers to discover unique phenomena related to fundamental atmospheric science processes. A consistent set of retrievals between each of these instruments emphasizes the utility for such a network of instruments to better characterize the turbulent atmospheric urban boundary layers which is expected to offer a useful capability for assessing and improving models that are in great need of such ground truth.

  10. Pulse subtraction Doppler

    Science.gov (United States)

    Mahue, Veronique; Mari, Jean Martial; Eckersley, Robert J.; Caro, Colin G.; Tang, Meng-Xing

    2010-01-01

    Recent advances have demonstrated the feasibility of molecular imaging using targeted microbubbles and ultrasound. One technical challenge is to selectively detect attached bubbles from those freely flowing bubbles and surrounding tissue. Pulse Inversion Doppler is an imaging technique enabling the selective detection of both static and moving ultrasound contrast agents: linear scatterers generate a single band Doppler spectrum, while non-linear scatterers generate a double band spectrum, one being uniquely correlated with the presence of contrast agents and non-linear tissue signals. We demonstrate that similar spectrums, and thus the same discrimination, can be obtained through a Doppler implementation of Pulse Subtraction. This is achieved by reconstructing a virtual echo using the echo generated from a short pulse transmission. Moreover by subtracting from this virtual echo the one generated from a longer pulse transmission, it is possible to fully suppress the echo from linear scatterers, while for non-linear scatterers, a signal will remain, allowing classical agent detection. Simulations of a single moving microbubble and a moving linear scatterer subject to these pulses show that when the virtual echo and the long pulse echo are used to perform pulsed Doppler, the power Doppler spectrum allows separation of linear and non-linear moving scattering. Similar results are obtained on experimental data acquired on a flow containing either microbubble contrast agents or linear blood mimicking fluid. This new Doppler method constitutes an alternative to Pulse Inversion Doppler and preliminary results suggest that similar dual band spectrums could be obtained by the combination of any non-linear detection technique with Doppler demodulation.

  11. Calibrating nacelle lidars

    DEFF Research Database (Denmark)

    Courtney, Michael

    Nacelle mounted, forward looking wind lidars are beginning to be used to provide reference wind speed measurements for the power performance testing of wind turbines. In such applications, a formal calibration procedure with a corresponding uncertainty assessment will be necessary. This report...... presents four concepts for performing such a nacelle lidar calibration. Of the four methods, two are found to be immediately relevant and are pursued in some detail. The first of these is a line of sight calibration method in which both lines of sight (for a two beam lidar) are individually calibrated...... a representative distribution of radial wind speeds. An alternative method is to place the nacelle lidar on the ground and incline the beams upwards to bisect a mast equipped with reference instrumentation at a known height and range. This method will be easier and faster to implement and execute but the beam...

  12. Lidar 2009 - All Returns

    Data.gov (United States)

    Kansas Data Access and Support Center — LIDAR-derived binary (.las) files containing classified points of all returns. We have 3 classifications Unclassified, Ground, Low points. The average Ground Sample...

  13. 2004 Connecticut Lidar

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — LIDAR data is remotely sensed high-resolution elevation data collected by an airborne collection platform. Using a combination of laser rangefinding, GPS positioning...

  14. 2003 Oahu Coastline Lidar

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — LIDAR data is remotely sensed high-resolution elevation data collected by an airborne collection platform. Using a combination of laser rangefinding, GPS positioning...

  15. Phoenix Lidar Operation Animation

    Science.gov (United States)

    2008-01-01

    [figure removed for brevity, see original site] Click on image for animation This is an animation of the Canadian-built meteorological station's lidar, which was successfully activated on Sol 2. The animation shows how the lidar is activated by first opening its dust cover, then emitting rapid pulses of light (resembling a brilliant green laser) into the Martian atmosphere. Some of the light then bounces off particles in the atmosphere, and is reflected back down to the lidar's telescope. This allows the lidar to detect dust, clouds and fog. The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  16. 2006 FEMA Hawaii Lidar

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The FEMA Task Order 26 LiDAR data set was collected by Airborne 1 Corporation of El Segundo, California in September - December of 2006 for URS Corp.

  17. LIDAR: Malheur NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This project was funded through the Region 1 Inventory and Monitoring Initiative RFP in 2011. LiDAR has been identified by the Malheur Lake Work Group as critical...

  18. 2004 Maine Lidar

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This metadata document describes the collection and processing of Light Detection and Ranging (LIDAR) data over an area along the coast of Maine. Data was collected...

  19. LIDAR: Malheur NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — LiDAR has been identified by the Malheur Lake Work Group as critical tool for planning, management, and restoration across the Harney Basin. In particular, this...

  20. Calibrating nacelle lidars

    OpenAIRE

    Courtney, Michael

    2013-01-01

    Nacelle mounted, forward looking wind lidars are beginning to be used to provide reference wind speed measurements for the power performance testing of wind turbines. In such applications, a formal calibration procedure with a corresponding uncertainty assessment will be necessary. This report presents four concepts for performing such a nacelle lidar calibration. Of the four methods, two are found to be immediately relevant and are pursued in some detail.The first of these is a line of sight...

  1. Steerable Doppler transducer probes

    Energy Technology Data Exchange (ETDEWEB)

    Fidel, H.F.; Greenwood, D.L.

    1986-07-22

    An ultrasonic diagnostic probe is described which is capable of performing ultrasonic imaging and Doppler measurement consisting of: a hollow case having an acoustic window which passes ultrasonic energy and including chamber means for containing fluid located within the hollow case and adjacent to a portion of the acoustic window; imaging transducer means, located in the hollow case and outside the fluid chamber means, and oriented to direct ultrasonic energy through the acoustic window toward an area which is to be imaged; Doppler transducer means, located in the hollow case within the fluid chamber means, and movably oriented to direct Doppler signals through the acoustic window toward the imaged area; means located within the fluid chamber means and externally controlled for controllably moving the Doppler transducer means to select one of a plurality of axes in the imaged area along which the Doppler signals are to be directed; and means, located external to the fluid chamber means and responsive to the means for moving, for providing an indication signal for identifying the selected axis.

  2. 2006 Volusia County, Florida Lidar

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset is the lidar data for Volusia County, Florida, approximately 1,432 square miles, acquired in early March of 2006. A total of 143 flight lines of Lidar...

  3. Sonoma County, CA, 2013 Lidar

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Sonoma County Vegetation Mapping and LiDAR Consortium retained WSI to provide lidar and Orthophoto data and derived products in Sonoma County, CA. A classified LAS...

  4. Chaotic LIDAR for Naval Applications

    Science.gov (United States)

    2014-09-30

    LIDAR for Naval Applications: FY12 Progress Report (7/1/2014- 9/30/2014) This document provides a progress report on the project "Chaotic LIDAR for...digital receiver to form a chaotic LIDAR (CLIDAR) ranging system. The design of the chaotic fiber ring laser and the fiber amplifiers are guided by...Wideband Amplifier Chain High Power Blue-Green Ranging Fig 1. The chaotic LIDAR (CLIDAR) transmitter approach. Several stages are used to

  5. Doppler cooling a microsphere

    CERN Document Server

    Barker, P F

    2010-01-01

    Doppler cooling the center-of-mass motion of an optically levitated microsphere via the velocity dependent scattering force from narrow whispering gallery mode (WGM) resonances is described. Light that is red detuned from the WGM resonance can be used to damp the center-of-mass motion in a process analogous to the Doppler cooling of atoms. Leakage of photons out of the microsphere when the incident field is near resonant with the narrow WGM resonance acts to damp the motion of the sphere. The scattering force is not limited by saturation, but can be controlled by the incident power. Cooling times on the order of seconds are calculated for a 20 micron diameter silica microsphere trapped within optical tweezers, with a Doppler temperature limit in the microKelvin regime.

  6. Automated integration of lidar into the LANDFIRE product suite

    Science.gov (United States)

    Peterson, Birgit; Nelson, Kurtis; Seielstad, Carl; Stoker, Jason; Jolly, W. Matt; Parsons, Russell

    2015-01-01

    Accurate information about three-dimensional canopy structure and wildland fuel across the landscape is necessary for fire behaviour modelling system predictions. Remotely sensed data are invaluable for assessing these canopy characteristics over large areas; lidar data, in particular, are uniquely suited for quantifying three-dimensional canopy structure. Although lidar data are increasingly available, they have rarely been applied to wildland fuels mapping efforts, mostly due to two issues. First, the Landscape Fire and Resource Planning Tools (LANDFIRE) program, which has become the default source of large-scale fire behaviour modelling inputs for the US, does not currently incorporate lidar data into the vegetation and fuel mapping process because spatially continuous lidar data are not available at the national scale. Second, while lidar data are available for many land management units across the US, these data are underutilized for fire behaviour applications. This is partly due to a lack of local personnel trained to process and analyse lidar data. This investigation addresses these issues by developing the Creating Hybrid Structure from LANDFIRE/lidar Combinations (CHISLIC) tool. CHISLIC allows individuals to automatically generate a suite of vegetation structure and wildland fuel parameters from lidar data and infuse them into existing LANDFIRE data sets. CHISLIC will become available for wider distribution to the public through a partnership with the U.S. Forest Service’s Wildland Fire Assessment System (WFAS) and may be incorporated into the Wildland Fire Decision Support System (WFDSS) with additional design and testing. WFAS and WFDSS are the primary systems used to support tactical and strategic wildland fire management decisions.

  7. 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

  8. 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.

  9. Additional development of remote sensing techniques for observing morphology, microphysics, and radiative properties of clouds and tests using a new, robust CO{sub 2} lidar. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Eberhard, W.L.; Brewer, W.A.; Intrieri, J.M.

    1998-09-28

    A three-year project with a goal of advancing CO{sub 2} lidar technology and measurement techniques for cloud studies was successfully completed. An eyesafe, infrared lidar with good sensitivity and improved Doppler accuracy was designed, constructed, and demonstrated. Dual-wavelength operation was achieved. A major leap forward in robustness was demonstrated. CO{sub 2} lidars were operated as part of two Intensive Operations Periods at the Southern Great Plains CART site. The first used an older lidar and was intended primarily for measurement technique development. The second used the new lidar and was primarily a demonstration and evaluation of its performance. Progress was demonstrated in the development, evaluation, and application of measurement techniques using CO{sub 2} lidar.

  10. Generic Methodology for Field Calibration of Nacelle-Based Wind Lidars

    Directory of Open Access Journals (Sweden)

    Antoine Borraccino

    2016-11-01

    Full Text Available Nacelle-based Doppler wind lidars have shown promising capabilities to assess power performance, detect yaw misalignment or perform feed-forward control. The power curve application requires uncertainty assessment. Traceable measurements and uncertainties of nacelle-based wind lidars can be obtained through a methodology applicable to any type of existing and upcoming nacelle lidar technology. The generic methodology consists in calibrating all the inputs of the wind field reconstruction algorithms of a lidar. These inputs are the line-of-sight velocity and the beam position, provided by the geometry of the scanning trajectory and the lidar inclination. The line-of-sight velocity is calibrated in atmospheric conditions by comparing it to a reference quantity based on classic instrumentation such as cup anemometers and wind vanes. The generic methodology was tested on two commercially developed lidars, one continuous wave and one pulsed systems, and provides consistent calibration results: linear regressions show a difference of ∼0.5% between the lidar-measured and reference line-of-sight velocities. A comprehensive uncertainty procedure propagates the reference uncertainty to the lidar measurements. At a coverage factor of two, the estimated line-of-sight velocity uncertainty ranges from 3.2% at 3 m · s − 1 to 1.9% at 16 m · s − 1 . Most of the line-of-sight velocity uncertainty originates from the reference: the cup anemometer uncertainty accounts for ∼90% of the total uncertainty. The propagation of uncertainties to lidar-reconstructed wind characteristics can use analytical methods in simple cases, which we demonstrate through the example of a two-beam system. The newly developed calibration methodology allows robust evaluation of a nacelle lidar’s performance and uncertainties to be established. Calibrated nacelle lidars may consequently be further used for various wind turbine applications in confidence.

  11. Advanced Digital Signal Processing for Hybrid Lidar

    Science.gov (United States)

    2013-09-30

    including better sensitivity due to large dynamic range digitizers and lossless digital demodulation and filtering, reconfigurability via software to...t 1 0.5 1.5 2 Az (factor of wavelength) 2.5 Figure 4. Pha ,sa response of single delay line cancaler Table 3. Optimal delays for selected

  12. All semiconductor laser Doppler anemometer at 1.55 microm.

    Science.gov (United States)

    Hansen, René Skov; Pedersen, Christian

    2008-10-27

    We report to our best knowledge the first all semiconductor Laser Doppler Anemometer (LIDAR) for wind speed determination. We will present the design and first experimental results on a focusing coherent cw laser Doppler anemometer for measuring atmospheric wind velocities in the 10 meters to 300 meters distance range. Especially, we will demonstrate that both the output power as well as the demanding coherence properties required from the laser source can be accomplished by an all semiconductor laser. Preliminary tests at a distance of 40 meters indicate a typical signal to noise ratio of 9 dB. This result is obtained at a clear day with an up-date rate of 12 Hz.

  13. Micro pulse lidar

    Science.gov (United States)

    Spinhirne, James D.

    1993-01-01

    An eye safe, compact, solid state lidar for profiling atmospheric cloud and aerosol scattering has been demonstrated. The transmitter of the micropulse lidar is a diode pumped micro-J pulse energy, high repetition rate Nd:YLF laser. Eye safety is obtained through beam expansion. The receiver employs a photon counting solid state Geiger mode avalanche photodiode detector. Data acquisition is by a single card multichannel scaler. Daytime background induced quantum noise is controlled by a narrow receiver field-of-view and a narrow bandwidth temperature controlled interference filter. Dynamic range of the signal is limited by optical geometric signal compression. Signal simulations and initial atmospheric measurements indicate that systems built on the micropulse lidar concept are capable of detecting and profiling all significant cloud and aerosol scattering through the troposphere and into the stratosphere. The intended applications are scientific studies and environmental monitoring which require full time, unattended measurements of the cloud and aerosol height structure.

  14. Scanning laser Doppler vibrometry

    DEFF Research Database (Denmark)

    Brøns, Marie; Thomsen, Jon Juel

    With a Scanning Laser Doppler Vibrometer (SLDV) a vibrating surface is automatically scanned over predefined grid points, and data processed for displaying vibration properties like mode shapes, natural frequencies, damping ratios, and operational deflection shapes. Our SLDV – a PSV-500H from...

  15. The Doppler Pendulum Experiment

    Science.gov (United States)

    Lee, C. K.; Wong, H. K.

    2011-01-01

    An experiment to verify the Doppler effect of sound waves is described. An ultrasonic source is mounted at the end of a simple pendulum. As the pendulum swings, the rapid change of frequency can be recorded by a stationary receiver using a simple frequency-to-voltage converter. The experimental results are in close agreement with the Doppler…

  16. Balloonborne Lidar Experiment.

    Science.gov (United States)

    1980-12-24

    system. 56 or 4~ I 4-, 570 It is required that the radiant output power be monitoreo at both wavelengths. Ihe monitor system is shown in the schematic of...cantilever bCdIII. The pointing mirrors will be co-aligneo, on the ground at ambient tern perature, at a position 45’ from the vertical nadir (lidar...ly thick and at the approximate temperature of the ambient at the given alti- tude, LI Q6 then their spectral radiance at 10 pn; would be as shown in

  17. Study on simulation and experiment of laser micro-Doppler effect for detecting complex vibration

    Science.gov (United States)

    Yuan, Shuai; Zhang, Juan; Liu, Mei-juan; Zhang, Jun

    2013-08-01

    The spectrum of radar signal will be modulated by moving target or vibration and turning part of the target, this is called micro-Doppler effect. It is a new way of using micro-Doppler effect to realize the feature extraction and target recognition. Because the complex vibration target has more complicated frequency component than the single frequency target, so it is very useful to do the research of simulation and experiment of laser micro-Doppler effect for detecting complex vibration. In this paper, the research on simulation and experiment of laser micro-Doppler effect for detecting complex vibration of moving target was developed based on the simulation research of micro-Doppler effect in lidar. Firstly, the geometry of complex vibrating target detection in radar was established. Secondly, the simulation and experiment signal sources were compared and also the returned signals in radar of the simulation and experiment were compared, the compared results showed that the two complex signal sources were very similar, and the frequency change trend of returned signals in radar was the same. Thirdly, joint time-frequency analysis method of the reassigned smoothed pseudo Wigner-Ville distribution (RSPWVD) was introduced to analyze the signals. The results showed that in RSPWVD, the waveform of the vibration target, the target vibration period, the Doppler frequency shift and the target's speed can be got. The simulation results and the experiment results got by the RSPWVD had the basically same frequency characteristics. So the RSPWVD can reflect very well the micro-Doppler characteristics of moving target's complex vibration. In conclusion it proved the validity of the simulated model, also it proved that using this time-frequency method to analyze the micro-Doppler signal of complex vibration was correct. And it laid the foundation of further using lidar to realize the classification and identification of target.

  18. Relativity effects for space-based coherent lidar experiments

    Science.gov (United States)

    Gudimetla, V. S. Rao

    1996-01-01

    An effort was initiated last year in the Astrionics Laboratory at Marshall Space Flight Center to examine and incorporate, if necessary, the effects of relativity in the design of space-based lidar systems. A space-based lidar system, named AEOLUS, is under development at Marshall Space Flight Center and it will be used to accurately measure atmospheric wind profiles. Effects of relativity were also observed in the performance of space-based systems, for example in case of global positioning systems, and corrections were incorporated into the design of instruments. During the last summer, the effects of special relativity on the design of space-based lidar systems were studied in detail, by analyzing the problem of laser scattering off a fixed target when the source and a co-located receiver are moving on a spacecraft. Since the proposed lidar system uses a coherent detection system, errors even in the order of a few microradians must be corrected to achieve a good signal-to-noise ratio. Previous analysis assumed that the ground is flat and the spacecraft is moving parallel to the ground, and developed analytical expressions for the location, direction and Doppler shift of the returning radiation. Because of the assumptions used in that analysis, only special relativity effects were involved. In this report, that analysis is extended to include general relativity and calculate its effects on the design.

  19. Innovative Solutions for Pulsed Wind Lidar Accuracy in Complex Terrain

    Science.gov (United States)

    Boquet, M.

    2010-12-01

    Accuracy of Lidar remote sensors for wind energy has been previously reported. Coherent Doppler lidars have shown very high correlation with calibrated cup anemometers in flat terrain, both onshore and offshore. However, in more complex terrain, not only more turbulent air flow but also loss of flow homogeneity occurs, and remote sensors measurement process needs to be closely examined. We compare and simulate cup’s point and lidar’s volume measurements to understand and explain for the two sensor’s response. We emphasize the main error term in the horizontal and vertical wind speed retrieval. Geometrical optimizations of pulsed Lidar measurement process are also investigated to get more reliable wind speed estimations, such as finding the right cone angle to reduce the error. We show our conclusions and results of the CFD simulation performed on a Spanish complex terrain case. We see that there is at least one possibility to strongly reduce the relative error between Lidar and anemometer measurements. Indeed, accessing to the vertical wind speed variations leads to a considerable improvement in the linear correlation and dispersion.

  20. Atmospheric Temperature Profile Measurements Using Mobile High Spectral Resolution Lidar

    Science.gov (United States)

    Razenkov, Ilya I.; Eloranta, Edwin W.

    2016-06-01

    The High Spectral Resolution Lidar (HSRL) designed at the University of Wisconsin-Madison discriminates between Mie and Rayleigh backscattering [1]. It exploits the Doppler effect caused by thermal motion of molecules, which broadens the spectrum of the transmitted laser light. That allows for absolute calibration of the lidar and measurements of the aerosol volume backscatter coefficient. Two iodine absorption filters with different absorption line widths (a regular iodine vapor filter and Argon buffered iodine filter) allow for atmospheric temperature profile measurements. The sensitivity of the measured signal-to-air temperature ratio is around 0.14%/K. The instrument uses a shared telescope transmitter-receiver design and operates in eyesafe mode (the product of laser average power and telescope aperture equals 0.1 Wm2 at 532 nm).

  1. Atmospheric Temperature Profile Measurements Using Mobile High Spectral Resolution Lidar

    Directory of Open Access Journals (Sweden)

    Razenkov Ilya I.

    2016-01-01

    Full Text Available The High Spectral Resolution Lidar (HSRL designed at the University of Wisconsin-Madison discriminates between Mie and Rayleigh backscattering [1]. It exploits the Doppler effect caused by thermal motion of molecules, which broadens the spectrum of the transmitted laser light. That allows for absolute calibration of the lidar and measurements of the aerosol volume backscatter coefficient. Two iodine absorption filters with different absorption line widths (a regular iodine vapor filter and Argon buffered iodine filter allow for atmospheric temperature profile measurements. The sensitivity of the measured signal-to-air temperature ratio is around 0.14%/K. The instrument uses a shared telescope transmitter-receiver design and operates in eyesafe mode (the product of laser average power and telescope aperture equals 0.1 Wm2 at 532 nm.

  2. Modern fibre-optic coherent lidars for remote sensing

    Science.gov (United States)

    Hill, Chris

    2015-10-01

    This paper surveys some growth areas in optical sensing that exploit near-IR coherent laser sources and fibreoptic hardware from the telecoms industry. Advances in component availability and performance are promising benefits in several military and commercial applications. Previous work has emphasised Doppler wind speed measurements and wind / turbulence profiling for air safety, with recent sharp increases in numbers of lidar units sold and installed, and with wider recognition that different lidar / radar wavebands can and should complement each other. These advances are also enabling fields such as microDoppler measurement of sub-wavelength vibrations and acoustic waves, including non-lineof- sight acoustic sensing in challenging environments. To shed light on these different applications we review some fundamentals of coherent detection, measurement probe volume, and parameter estimation - starting with familiar similarities and differences between "radar" and "laser radar". The consequences of changing the operating wavelength by three or four orders of magnitude - from millimetric or centimetric radar to a typical fibre-optic lidar working near 1.5 μm - need regular review, partly because of continuing advances in telecoms technology and computing. Modern fibre-optic lidars tend to be less complicated, more reliable, and cheaper than their predecessors; and they more closely obey the textbook principles of easily adjusted and aligned Gaussian beams. The behaviours of noises and signals, and the appropriate processing strategies, are as expected different for the different wavelengths and applications. For example, the effective probe volumes are easily varied (e.g. by translating a fibre facet) through six or eight orders of magnitude; as the average number of contributing scatterers varies, from >1, we should review any assumptions about "many" scatterers and Gaussian statistics. Finally, some much older but still relevant scientific work (by A G Bell, E H

  3. Lidar 2009 - IMG

    Data.gov (United States)

    Kansas Data Access and Support Center — ESRI Grids 1 meter resolution are created from the ground classified lidar points. The tiles are delivered in 5,000m by 5,000m tiles. The ESRI grids are exported to...

  4. 2004 Alaska Lidar Mapping

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The data sets are generated using the OPTECH ALTM 70 kHz LIDAR system mounted onboard AeroMap's twin-engine Cessna 320 aircraft. Classified data sets such as this...

  5. Nacelle lidar power curve

    DEFF Research Database (Denmark)

    Gómez Arranz, Paula; Wagner, Rozenn

    This report describes the power curve measurements performed with a nacelle LIDAR on a given wind turbine in a wind farm and during a chosen measurement period. The measurements and analysis are carried out in accordance to the guidelines in the procedure “DTU Wind Energy-E-0019” [1]. The reporting...

  6. Calibrating nacelle lidars

    Energy Technology Data Exchange (ETDEWEB)

    Courtney, M.

    2013-01-15

    Nacelle mounted, forward looking wind lidars are beginning to be used to provide reference wind speed measurements for the power performance testing of wind turbines. In such applications, a formal calibration procedure with a corresponding uncertainty assessment will be necessary. This report presents four concepts for performing such a nacelle lidar calibration. Of the four methods, two are found to be immediately relevant and are pursued in some detail. The first of these is a line of sight calibration method in which both lines of sight (for a two beam lidar) are individually calibrated by accurately aligning the beam to pass close to a reference wind speed sensor. A testing procedure is presented, reporting requirements outlined and the uncertainty of the method analysed. It is seen that the main limitation of the line of sight calibration method is the time required to obtain a representative distribution of radial wind speeds. An alternative method is to place the nacelle lidar on the ground and incline the beams upwards to bisect a mast equipped with reference instrumentation at a known height and range. This method will be easier and faster to implement and execute but the beam inclination introduces extra uncertainties. A procedure for conducting such a calibration is presented and initial indications of the uncertainties given. A discussion of the merits and weaknesses of the two methods is given together with some proposals for the next important steps to be taken in this work. (Author)

  7. The lidar dark band: An oddity of the radar bright band analogy

    Energy Technology Data Exchange (ETDEWEB)

    Sassen, K. [Univ. of Utah, Salt Lake City, UT (United States)

    1996-04-01

    Although much has sbeen learned from independent radar and lidar studies of atmospheric precipitations, occasionally supported by aircraft profiling, what has been lacking is combined optical, microwave, and insitu observations of the melting layer. Fortunately, the rainshowers on April 21, 1994, during the Remote Cloud Sensing intensive obervations Period (RCSIOP) at the Southern Great Plains Cloud and radiation Testbed (CART) site provided an opportunity for coordinated dual-wavelength University of Utah Polarization Diversity Lidar, University of Massachusetts Cloud Profiling Radar System Doppler Radar, and the University of North Dakota Citation aircraft measurements.

  8. Analytic model utilizing the complex ABCD method for range dependency of a monostatic coherent lidar

    DEFF Research Database (Denmark)

    Olesen, Anders Sig; Pedersen, Anders Tegtmeier; Hanson, Steen Grüner;

    2014-01-01

    In this work, we present an analytic model for analyzing the range and frequency dependency of a monostatic coherent lidar measuring velocities of a diffuse target. The model of the signal power spectrum includes both the contribution from the optical system as well as the contribution from...... the time dependencies of the optical field. A specific coherent Doppler wind lidar system measuring wind velocity in the atmosphere is considered, in which a Gaussian field is transmitted through a simple telescope consisting of a lens and an aperture. The effects of the aperture size, the beam waist...

  9. Simulation of the Performances of WIND, an Airborne CO2 Lidar

    Science.gov (United States)

    Oh, D.; Dabas, A.; Lieutaud, F.; Loth, C.; Flamant, P. H.

    1992-01-01

    An airborne Doppler coherent lidar is under development as a joint project between France and Germany. The instrument is designed around CO2 laser technology, heterodyne detection, and a conical scanning of the line-of-site. The 10 micron domain is suitable for long range measurements due to the maturity of the technology and because it corresponds to an atmospheric window. The objectives of WIND are twofold: (1) to conduct mesoscale scientific studies in particular over oceanic and inhomogeneous terrain areas; and (2) to support the Earth-orbiting wind lidar projects.

  10. Laser Doppler flowmetry imaging

    Science.gov (United States)

    Nilsson, Gert E.; Wardell, Karin

    1994-02-01

    A laser Doppler perfusion imager has been developed that makes possible mapping of tissue blood flow over surfaces with extensions up to about 12 cm X 12 cm. The He-Ne laser beam scans the tissue under study throughout 4096 measurement sites. A fraction of the backscattered and Doppler broadened light is detected by a photo diode positioned about 20 cm above the tissue surface. After processing, a signal that scales linearly with perfusion is stored in a computer and a color coded image of the spatial tissue perfusion is shown on a monitor. A full format scan is completed in about 4.5 minutes. Algorithms for calculating perfusion profiles and averages as well as substraction of one image from another, form an integral part of the system data analysis software. The perfusion images can also be exported to other software packages for further processing and analysis.

  11. 2006 MDEQ Camp Shelby, MS Lidar Survey

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This metadata record describes the acquisition and processing of bare earth lidar data, raw point cloud lidar data, lidar intensity data, and floodmap breaklines...

  12. Scanning laser Doppler vibrometry

    OpenAIRE

    2016-01-01

    With a Scanning Laser Doppler Vibrometer (SLDV) a vibrating surface is automatically scanned over predefined grid points, and data processed for displaying vibration properties like mode shapes, natural frequencies, damping ratios, and operational deflection shapes. Our SLDV – a PSV-500H from Polytec Inc. – was acquired and put to operation in October 2014, paid by a sub-donation of DKK 1,5 mill. of the total VILLUM CASMaT grant. Opening possibilities of measuring complicated vibration shapes...

  13. Holographic laser Doppler ophthalmoscopy

    CERN Document Server

    Simonutti, Manuel; Sahel, J A; Gross, Michel; Samson, Benjamin; Magnain, Caroline; Atlan, Michael; 10.1364/OL.35.001941

    2010-01-01

    We report laser Doppler ophthalmoscopic fundus imaging in the rat eye with near-IR heterodyne holography. Sequential sampling of the beat of the reflected radiation against a frequency-shifted optical local oscillator is made onto an array detector. Wide-field maps of fluctuation spectra in the 10 Hz to 25 kHz band exhibit angiographic contrasts in the retinal vascular tree without requirement of an exogenous marker.

  14. Laser double Doppler flowmeter

    Science.gov (United States)

    Poffo, L.; Goujon, J.-M.; Le Page, R.; Lemaitre, J.; Guendouz, M.; Lorrain, N.; Bosc, D.

    2014-05-01

    The Laser Doppler flowmetry (LDF) is a non-invasive method for estimating the tissular blood flow and speed at a microscopic scale (microcirculation). It is used for medical research as well as for the diagnosis of diseases related to circulatory system tissues and organs including the issues of microvascular flow (perfusion). It is based on the Doppler effect, created by the interaction between the laser light and tissues. LDF measures the mean blood flow in a volume formed by the single laser beam, that penetrate into the skin. The size of this measurement volume is crucial and depends on skin absorption, and is not directly reachable. Therefore, current developments of the LDF are focused on the use of always more complex and sophisticated signal processing methods. On the other hand, laser Double Doppler Flowmeter (FL2D) proposes to use two laser beams to generate the measurement volume. This volume would be perfectly stable and localized at the intersection of the two laser beams. With FL2D we will be able to determine the absolute blood flow of a specific artery. One aimed application would be to help clinical physicians in health care units.

  15. Advanced Photodetectors for Space Lidar

    Science.gov (United States)

    Sun, Xiaoli; Krainak, Michael A.; Abshire, James B.

    2014-01-01

    The detector in a space lidar plays a key role in the instrument characteristics and performance, especially in direct detection lidar. The sensitivity of the detector is usually the limiting factor when determining the laser power and the receiver aperture size, which in turn determines the instrument complexity and cost. The availability of a suitable detector is often a deciding factor in the choice of lidar wavelengths. A direct detection lidar can achieve the highest receiver performance, or the quantum limit, when its detector can detect signals at the single photon

  16. Improved CO [lidar detector

    Energy Technology Data Exchange (ETDEWEB)

    Jacobson, P.L.; Busch, G.E.; Thompson, D.C.; Remelius, D.K.; Wells, F.D.

    1999-07-18

    A high sensitivity, CO{sub 2} lidar detector, based on recent advances in ultra-low noise, readout integrated circuits (ROIC), is being developed. This detector will combine a high speed, low noise focal plane array (FPA) with a dispersive grating spectrometer. The spectrometer will filter the large background flux, thereby reducing the limiting background photon shot noise. In order to achieve the desired low noise levels, the HgCdTe FPA will be cooled to {approximately}50K. High speed, short pulse operation of the lidar system should enable the detector to operate with the order of a few noise electrons in the combined detector/ ROIC output. Current receiver design concepts will be presented, along with their expected noise performance.

  17. Flash Lidar Data Processing

    Science.gov (United States)

    Bergkoetter, M. D.; Ruppert, L.; Weimer, C. S.; Ramond, T.; Lefsky, M. A.; Burke, I. C.; Hu, Y.

    2009-12-01

    Late last year, a prototype Flash LIDAR instrument flew on a series of airborne tests to demonstrate its potential for improved vegetation measurements. The prototype is a precursor to the Electronically Steerable Flash LIDAR (ESFL) currently under development at Ball Aerospace and Technology Corp. with funding from the NASA Earth Science Technology Office. ESFL may soon significantly expand our ability to measure vegetation and forests and better understand the extent of their role in global climate change and the carbon cycle - all critical science questions relating to the upcoming NASA DESDynI and ESA BIOMASS missions. In order to more efficiently exploit data returned from the experimental Flash Lidar system and plan for data exploitation from future flights, Ball funded a graduate student project (through the Ball Summer Intern Program, summer 2009) to develop and implement algorithms for post-processing of the 3-Dimensional Flash Lidar data. This effort included developing autonomous algorithms to resample the data to a uniform rectangular grid, geolocation of the data, and visual display of large swaths of data. The resampling, geolocation, surface hit detection, and aggregation of frame data are implemented with new MATLAB code, and the efficient visual display is achieved with free commercial viewing software. These efforts directly support additional tests flights planned as early as October 2009, including possible flights over Niwot Ridge, CO, for which there is ICESat data, and a sea-level coastal area in California to test the effect of higher altitude (above ground level) on the divergence of the beams and the beam spot sizes.

  18. Airborne forward pointing UV Rayleigh lidar for remote clear air turbulence (CAT) detection: system design and performance

    CERN Document Server

    Vrancken, Patrick; Ehret, Gerhard; Barny, Hervé; Rondeau, Philippe; Veerman, Henk

    2016-01-01

    A high-performance airborne UV Rayleigh lidar system was developed within the European project DELICAT. With its forward-pointing architecture it aims at demonstrating a novel detection scheme for clear air turbulence (CAT) for an aeronautics safety application. Due to its occurrence in clear and clean air at high altitudes (aviation cruise flight level), this type of turbulence evades microwave radar techniques and in most cases coherent Doppler lidar techniques. The present lidar detection technique relies on air density fluctuations measurement and is thus independent of backscatter from hydrometeors and aerosol particles. The subtle air density fluctuations caused by the turbulent air flow demand exceptionally high stability of the setup and in particular of the detection system. This paper describes an airborne test system for the purpose of demonstrating this technology and turbulence detection method: a high-power UV Rayleigh lidar system is installed on a research aircraft in a forward-looking configu...

  19. 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

  20. Orientation correction of wind direction measurements by means of staring lidar

    Science.gov (United States)

    Schmidt, Michael; José Trujillo, Juan; Kühn, Martin

    2016-09-01

    In spite of the efforts made at the time of installation of wind vanes or ultrasonic anemometers (Sonic), there is always a remaining uncertainty of several degrees in the absolute north of such sensors. In this research a method is presented to reduce the azimuthal orientation error of wind direction sensors by means of Doppler Lidar measurements. The method is based on the comparison between the conventional sensor and a distant long range lidar pointing to it in staring mode. By comparing their line-of-sight wind speeds any misalignment between both systems can be estimated more accurately. This method was applied in an measurement campaign in the offshore wind farm alpha ventus next to the meteorological mast FINO 1. The maximum alignment error of a Sonic was reduced to below ±1°. This accurate alignment has asserted, that no bias exists between Lidar and Sonic wind speed measurements.

  1. LIDAR-Aided Inertial Navigation with Extended Kalman Filtering for Pinpoint Landing

    Science.gov (United States)

    Busnardo, David M.; Aitken, Matthew L.; Tolson, Robert H.; Pierrottet, Diego; Amzajerdian, Farzin

    2011-01-01

    In support of NASA s Autonomous Landing and Hazard Avoidance Technology (ALHAT) project, an extended Kalman filter routine has been developed for estimating the position, velocity, and attitude of a spacecraft during the landing phase of a planetary mission. The proposed filter combines measurements of acceleration and angular velocity from an inertial measurement unit (IMU) with range and Doppler velocity observations from an onboard light detection and ranging (LIDAR) system. These high-precision LIDAR measurements of distance to the ground and approach velocity will enable both robotic and manned vehicles to land safely and precisely at scientifically interesting sites. The filter has been extensively tested using a lunar landing simulation and shown to improve navigation over flat surfaces or rough terrain. Experimental results from a helicopter flight test performed at NASA Dryden in August 2008 demonstrate that LIDAR can be employed to significantly improve navigation based exclusively on IMU integration.

  2. Comparisons between PW Doppler system and enhanced FM Doppler system

    DEFF Research Database (Denmark)

    Wilhjelm, Jens E.; Pedersen, P. C.

    1995-01-01

    This paper presents a new implementation of an echo-ranging FM Doppler system with improved performance, relative to the FM Doppler system reported previously. The use of long sweeps provides a significant reduction in peak to average power ratio compared to pulsed wave (PW) emission. A PW Doppler...... system exploits the direct relationship between arrival time of the received signal and range from the transducer. In the FM Doppler systems, a similar relationship exists in the spectral domain of the demodulated received signals, so that range is represented by frequency. Thus, a shift in location...... of moving scatterers between consecutive emissions corresponds to a frequency shift in the spectral signature. The improvement relative to the earlier version of the FM Doppler system is attained by utilizing cross-correlation of real spectra rather than of magnitude spectra for assessing flow velocity...

  3. Research on Doppler frequency in incoherent FM/CW laser detection

    Science.gov (United States)

    Liu, Kai; Cui, Zhanzhong

    2010-10-01

    The principle of transmitted and received laser in incoherent FM/CW laser detection is different from the one in coherent FM/CW laser detection. The methods for distance solution in both detections are similar. Incoherent FM/CW laser detection uses subcarrier to modulate the intensity of laser, and the photodetector detects the intensity of received signal. The amplified photocurrent is mixed with local oscillator signal, and the intermediate frequency (IF) signal contains the information of distance from sensor to target. The Doppler frequency for this detection is related with the relative radial velocity between sensor and target. The optical frequency is directly modulated with electro-optic device in coherent FM/CW laser detection and the received laser signal is photomixed with transmitted laser signal. The Doppler frequency in the detection relates to the optical frequency. In distance-measuring lidar, the Doppler frequency affects the solution. The Doppler frequency in incoherent FM/CW laser detection is unrelated with optical frequency, and it is much less than the one in coherent FM/CW laser detection, correspondingly. The error in incoherent FM/CW laser detection is smaller. As a result, the incoherent FM/CW laser detection is more suitable for the use of distance-measuring lidar.

  4. ANL Doppler flowmeter

    Science.gov (United States)

    Karplus, H. B.; Raptis, A. C.; Lee, S.; Simpson, T.

    1985-10-01

    A flowmeter has been developed for measuring flow velocity in hot slurries. The flowmeter works on an ultrasonic Doppler principle in which ultrasound is injected into the flowing fluid through the solid pipe wall. Isolating waveguides separate the hot pipe from conventional ultrasonic transducers. Special clamp-on high-temperature transducers also can be adapted to work well in this application. Typical flows in pilot plants were found to be laminar, giving rise to broad-band Doppler spectra. A special circuit based on a servomechanism sensor was devised to determine the frequency average of such a broad spectrum. The device was tested at different pilot plants. Slurries with particulates greater than 70 microns (0.003 in.) yielded good signals, but slurries with extremely fine particulates were unpredictable. Small bubbles can replace the coarse particles to provide a good signal if there are not too many. Successful operation with very fine particulate slurries may have been enhanced by the presence of microbubbles.

  5. 2006 Fulton County Georgia Lidar

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Light Detection and Ranging (LiDAR) LAS dataset is a survey of Fulton County. The Fulton County LiDAR Survey project area consists of approximately 690.5 square...

  6. Can Wind Lidars Measure Turbulence?

    DEFF Research Database (Denmark)

    Sathe, Ameya; Mann, Jakob; Gottschall, Julia

    2011-01-01

    Modeling of the systematic errors in the second-order moments of wind speeds measured by continuous-wave (ZephIR) and pulsed (WindCube) lidars is presented. These lidars use the conical scanning technique to measure the velocity field. The model captures the effect of volume illumination and coni...

  7. Complex Terrain and Wind Lidars

    DEFF Research Database (Denmark)

    Bingöl, Ferhat

    This thesis includes the results of a PhD study about complex terrain and wind lidars. The study mostly focuses on hilly and forested areas. Lidars have been used in combination with cups, sonics and vanes, to reach the desired vertical measurement heights. Several experiments are performed...... in complex terrain sites and the measurements are compared with two different flow models; a linearised flow model LINCOM and specialised forest model SCADIS. In respect to the lidar performance in complex terrain, the results showed that horizontal wind speed errors measured by a conically scanning lidar....... The SCADIS model worked better than the LINCOM model at the forest edge but the model reported closer results to the measurements at upwind than the downwind and this should be noted as a limitation of the model. As the general conclusion of the study, it was stated that the lidars can be used in complex...

  8. Optimization of polarization lidar structure

    Science.gov (United States)

    Abramochkin, Alexander I.; Kaul, Bruno V.; Tikhomirov, Alexander A.

    1999-11-01

    The problems of the polarization lidar transceiver optimization are considered. The basic features and the optimization criteria of lidar polarization units are presented and the comparative analysis of polarization units is fulfilled. We have analyzed optical arrangements of the transmitter to form the desired polarization state of sounding radiation. We have also considered various types of lidar receiving systems: (1) one-channel, providing measurement of Stocks parameters at a successive change of position of polarization analyzers in the lidar receiver, and (2) multichannel, where each channel has a lens, an analyzer, and a photodetector. In the latter case measurements of Stocks parameters are carried out simultaneously. The optimization criteria of the polarization lidar considering the atmospheric state are determined with the purpose to decrease the number of polarization devices needed.

  9. Lidar arc scan uncertainty reduction through scanning geometry optimization

    Directory of Open Access Journals (Sweden)

    H. Wang

    2015-10-01

    Full Text Available Doppler lidars are frequently operated in a mode referred to as arc scans, wherein the lidar beam scans across a sector with a fixed elevation angle and the resulting measurements are used to derive an estimate of the n minute horizontal mean wind velocity (speed and direction. Previous studies have shown that the uncertainty in the measured wind speed originates from turbulent wind fluctuations and depends on the scan geometry (the arc span and the arc orientation. This paper is designed to provide guidance on optimal scan geometries for two key applications in the wind energy industry: wind turbine power performance analysis and annual energy production. We present a quantitative analysis of the retrieved wind speed uncertainty derived using a theoretical model with the assumption of isotropic and frozen turbulence, and observations from three sites that are onshore with flat terrain, onshore with complex terrain and offshore, respectively. The results from both the theoretical model and observations show that the uncertainty is scaled with the turbulence intensity such that the relative standard error on the 10 min mean wind speed is about 30 % of the turbulence intensity. The uncertainty in both retrieved wind speeds and derived wind energy production estimates can be reduced by aligning lidar beams with the dominant wind direction, increasing the arc span and lowering the number of beams per arc scan. Large arc spans should be used at sites with high turbulence intensity and/or large wind direction variation when arc scans are used for wind resource assessment.

  10. Laser Doppler Imaging of Microflow

    CERN Document Server

    Gross, Michel; Leng, Jacques

    2013-01-01

    We report a pilot study with a wide-field laser Doppler detection scheme used to perform laser Doppler anemometry and imaging of particle seeded microflow. The optical field carrying the local scatterers (particles) dynamic state, as a consequence of momentum transfer at each scattering event, is analyzed in the temporal frequencies domain. The setup is based on heterodyne digital holography, which is used to map the scattered field in the object plane at a tunable frequency with a multipixel detector. We show that wide-field heterodyne laser Doppler imaging can be used for quantitative microflow diagnosis; in the presented study, maps of the first-order moment of the Doppler frequency shift are used as a quantitative and directional estimator of the Doppler signature of particles velocity.

  11. LIDAR COMBINED SCANNING UNIT

    Directory of Open Access Journals (Sweden)

    V. V. Elizarov

    2016-11-01

    Full Text Available Subject of Research. The results of lidar combined scanning unit development for locating leaks of hydrocarbons are presented The unit enables to perform high-speed scanning of the investigated space in wide and narrow angle fields. Method. Scanning in a wide angular field is produced by one-line scanning path by means of the movable aluminum mirror with a frequency of 20Hz and amplitude of 20 degrees of swing. Narrowband scanning is performed along a spiral path by the deflector. The deflection of the beam is done by rotation of the optical wedges forming part of the deflector at an angle of ±50. The control function of the scanning node is performed by a specialized software product written in C# programming language. Main Results. This scanning unit allows scanning the investigated area at a distance of 50-100 m with spatial resolution at the level of 3 cm. The positioning accuracy of the laser beam in space is 15'. The developed scanning unit gives the possibility to browse the entire investigated area for the time not more than 1 ms at a rotation frequency of each wedge from 50 to 200 Hz. The problem of unambiguous definition of the beam geographical coordinates in space is solved at the software level according to the rotation angles of the mirrors and optical wedges. Lidar system coordinates are determined by means of GPS. Practical Relevance. Development results open the possibility for increasing the spatial resolution of scanning systems of a wide range of lidars and can provide high positioning accuracy of the laser beam in space.

  12. Hyperspectral-LIDAR system and data product integration for terrestrial applications

    Science.gov (United States)

    Corp, Lawrence A.; Cheng, Yen-Ben; Middleton, Elizabeth M.; Parker, Geoffrey G.; Huemmrich, K. Fred; Campbell, Petya K. E.

    2009-08-01

    This manuscript details the development and validation of a unique forward thinking instrument and methodology for monitoring terrestrial carbon dynamics through synthesis of existing hyperspectal sensing and Light Detection and Ranging (LIDAR) technologies. This technology demonstration is directly applicable to linking target mission concepts identified as scientific priorities in the National Research Council (NRC, 2007) Earth Science Decadal Survey; namely, DESDynI and HyspIRI. The primary components of the Hyperspec-LIDAR system are the ruggedized imaging spectrometer and a small footprint LIDAR system. The system is mounted on a heavy duty motorized pan-tilt unit programmed to support both push-broom style hyperspectral imaging and 3-D canopy LIDAR structural profiling. The integrated Hyperspec-LIDAR sensor system yields a hypserspectral data cube with up to 800 bands covering the spectral range of 400 to 1000 nm and a 3-D scanning LIDAR system accurately measuring the vertical distribution of intercepted surfaces within a range of 150 m with an accuracy of 15 mm. Preliminary field tests of the Hyperspec-LIDAR sensor system were conducted at a mature deciduous mixed forest tower site located at the Smithsonian Environmental Research Center in Edgewater, MD. The goal of this research is to produce integrated science and data products from ground observations that will support satellite-based hybrid spectral/structural profile linked through appropriate models to monitor Net Ecosystem Exchange and related parameters such as ecosystem Light Use Efficiency.

  13. Compressive full waveform lidar

    Science.gov (United States)

    Yang, Weiyi; Ke, Jun

    2017-05-01

    To avoid high bandwidth detector, fast speed A/D converter, and large size memory disk, a compressive full waveform LIDAR system, which uses a temporally modulated laser instead of a pulsed laser, is studied in this paper. Full waveform data from NEON (National Ecological Observatory Network) are used. Random binary patterns are used to modulate the source. To achieve 0.15 m ranging resolution, a 100 MSPS A/D converter is assumed to make measurements. SPIRAL algorithm with canonical basis is employed when Poisson noise is considered in the low illuminated condition.

  14. ITER LIDAR performance analysis.

    Science.gov (United States)

    Beurskens, M N A; Giudicotti, L; Kempenaars, M; Scannell, R; Walsh, M J

    2008-10-01

    The core LIDAR Thomson scattering for ITER is specified for core profile measurements with a spatial resolution of 7 cm (a/30) for the range of 500 eV3x10(19) m(-3) at an accuracy of system can meet its spatial and accuracy specifications for higher temperatures of T(e)>5 keV with a combination of a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser (lambda(0)=1064 nm, Delta lambdanear infrared detectors.

  15. Internet lidar system (ILIS): new generation of lidar system using Internet technology for realizing unattended lidar

    Science.gov (United States)

    Aihara, Hidenori; Asai, Kazuhiro; Aoki, Tetsuo; Mizutani, Kohei; Itabe, Toshikasu

    2001-02-01

    Most of lidar systems are being manually operated on site, therefore, a frequency of observations is limited due to a manpower etc if the lidar site is geographically far away from a laboratory. In such a case, an unattended automatic lidar system or a remote controllable one is expected as for increasing the frequencies. On the other hand, as well known, a computer is linked to the other through the Internet, and remotely operated each other. We have proposed the Internet LIdar System (named ILIS) as the unattended operational lidar. A concept of the ILIS is controllable through the Internet, anytime and anywhere. The ILIS proposed here has been successfully operating every night without any difficulty of the geographical distance of 1,000km.

  16. Generic methodology for calibrating profiling nacelle lidars

    OpenAIRE

    Borraccino, Antoine; Courtney, Michael; Wagner, Rozenn

    2015-01-01

    Improving power performance assessment by measuring at different heights has been demonstrated using ground-based profiling LIDARs. More recently, nacelle-mounted lidars studies have shown promising capabilities to assess power performance. Using nacelle lidars avoids the erection of expensive meteorology masts, especially offshore. A new generation of commercially developed profiling nacelle lidars has sophisticated measurement capabilities.As for any other measuring system, lidars measureme...

  17. Noticeable positive Doppler effect on optical bistability in an N-type active Raman gain atomic system

    Institute of Scientific and Technical Information of China (English)

    Chang Zeng-Guang; Niu Yue-Ping; Zhang Jing-Tao; Gong Shang-Qing

    2012-01-01

    We theoretically investigate the Doppler effect on optical bistability in an N type active Raman gain atomic system inside an optical ring cavity.It is shown that the Doppler effect can greatly enhance the dispersion and thus create the bistable behaviour or greatly increase the bistable region,which has been known as the positive Doppler effect on optical bistability.In addition,we find that a positive Doppler effect can change optical bistability from the hybrid dispersion-gain type to a dispersive type.

  18. Automatic Weather Station (AWS) Lidar

    Science.gov (United States)

    Rall, Jonathan A.R.; Abshire, James B.; Spinhirne, James D.; Smith, David E. (Technical Monitor)

    2000-01-01

    An autonomous, low-power atmospheric lidar instrument is being developed at NASA Goddard Space Flight Center. This compact, portable lidar will operate continuously in a temperature controlled enclosure, charge its own batteries through a combination of a small rugged wind generator and solar panels, and transmit its data from remote locations to ground stations via satellite. A network of these instruments will be established by co-locating them at remote Automatic Weather Station (AWS) sites in Antarctica under the auspices of the National Science Foundation (NSF). The NSF Office of Polar Programs provides support to place the weather stations in remote areas of Antarctica in support of meteorological research and operations. The AWS meteorological data will directly benefit the analysis of the lidar data while a network of ground based atmospheric lidar will provide knowledge regarding the temporal evolution and spatial extent of Type la polar stratospheric clouds (PSC). These clouds play a crucial role in the annual austral springtime destruction of stratospheric ozone over Antarctica, i.e. the ozone hole. In addition, the lidar will monitor and record the general atmospheric conditions (transmission and backscatter) of the overlying atmosphere which will benefit the Geoscience Laser Altimeter System (GLAS). Prototype lidar instruments have been deployed to the Amundsen-Scott South Pole Station (1995-96, 2000) and to an Automated Geophysical Observatory site (AGO 1) in January 1999. We report on data acquired with these instruments, instrument performance, and anticipated performance of the AWS Lidar.

  19. Study of wind retrieval from space-borne infrared coherent lidar in cloudy atmosphere.

    Science.gov (United States)

    Baron, Philippe; Ishii, Shoken; Mizutani, Kohei; Okamoto, Kozo; Ochiai, Satoshi

    2015-04-01

    Future spaceborne tropospheric wind missions using infrared coherent lidar are currently being studied in Japan and in the United States [1,2]. The line-of-sight wind velocity is retrieved from the Doppler shift frequency of the signal returned by aerosol particles. However a large percentage (70-80%) of the measured single-shot intensity profiles are expected to be contaminated by clouds [3]. A large number of cloud contaminated profiles (>40%) will be characterized by a cloud-top signal intensity stronger than the aerosol signal by a factor of one order of magnitude, and by a strong attenuation of the signal backscattered from below the clouds. Profiles including more than one cloud layer are also expected. This work is a simulation study dealing with the impacts of clouds on wind retrieval. We focus on the three following points: 1) definition of an algorithm for optimizing the wind retrieval from the cloud-top signal, 2) assessment of the clouds impact on the measurement performance and, 3) definition of a method for averaging the measurements before the retrieval. The retrieval simulations are conducted considering the instrumental characteristics selected for the Japanese study: wavelength at 2 µm, PRF of 30 Hz, pulse power of 0.125 mJ and platform altitude between 200-400 km. Liquid and ice clouds are considered. The analysis uses data from atmospheric models and statistics of cloud effects derived from CALIPSO measurements such as in [3]. A special focus is put on the average method of the measurements before retrieval. Good retrievals in the mid-upper troposphere implie the average of measured single-range power spectra over large horizontal (100 km) and vertical (1 km) ranges. Large differences of signal intensities due to the presence of clouds and the clouds non-uniform distribution have to be taken into account when averaging the data to optimize the measurement performances. References: [1] S. Ishii, T. Iwasaki, M. Sato, R. Oki, K. Okamoto, T

  20. Weibull Wind-Speed Distribution Parameters Derived from a Combination of Wind-Lidar and Tall-Mast Measurements Over Land, Coastal and Marine Sites

    DEFF Research Database (Denmark)

    Gryning, Sven-Erik; Floors, Rogier Ralph; Peña, Alfredo

    2016-01-01

    Wind-speed observations from tall towers are used in combination with observations up to 600 m in altitude from a Doppler wind lidar to study the long-term conditions over suburban (Hamburg), rural coastal (Høvsøre) and marine (FINO3) sites. The variability in the wind field among the sites is ex...

  1. Mapping and monitoring Mount Graham red squirrel habitat with Lidar and Landsat imagery

    Science.gov (United States)

    Hatten, James R.

    2014-01-01

    The Mount Graham red squirrel (Tamiasciurus hudsonicus grahamensis) is an endemic subspecies located in the Pinaleño Mountains of southeast Arizona. Living in a conifer forest on a sky-island surrounded by desert, the Mount Graham red squirrel is one of the rarest mammals in North America. Over the last two decades, drought, insect infestations, and fire destroyed much of its habitat. A federal recovery team is working on a plan to recover the squirrel and detailed information is necessary on its habitat requirements and population dynamics. Toward that goal I developed and compared three probabilistic models of Mount Graham red squirrel habitat with a geographic information system and logistic regression. Each model contained the same topographic variables (slope, aspect, elevation), but the Landsat model contained a greenness variable (Normalized Difference Vegetation Index) extracted from Landsat, the Lidar model contained three forest-inventory variables extracted from lidar, while the Hybrid model contained Landsat and lidar variables. The Hybrid model produced the best habitat classification accuracy, followed by the Landsat and Lidar models, respectively. Landsat-derived forest greenness was the best predictor of habitat, followed by topographic (elevation, slope, aspect) and lidar (tree height, canopy bulk density, and live basal area) variables, respectively. The Landsat model's probabilities were significantly correlated with all 12 lidar variables, indicating its utility for habitat mapping. While the Hybrid model produced the best classification results, only the Landsat model was suitable for creating a habitat time series or habitat–population function between 1986 and 2013. The techniques I highlight should prove valuable in the development of Landsat- or lidar-based habitat models range wide.

  2. Detailed signal model of coherent wind measurement lidar

    Science.gov (United States)

    Ma, Yuechao; Li, Sining; Lu, Wei

    2016-11-01

    Lidar is short for light detection and ranging, which is a tool to help measuring some useful information of atmosphere. In the recent years, more and more attention was paid to the research of wind measurement by lidar. Because the accurate wind information can be used not only in weather report, but also the safety guarantee of the airplanes. In this paper, a more detailed signal model of wind measurement lidar is proposed. It includes the laser transmitting part which describes the broadening of the spectral, the laser attenuation in the atmosphere, the backscattering signal and the detected signal. A Voigt profile is used to describe the broadening of the transmitting laser spectral, which is the most common situation that is the convolution of different broadening line shapes. The laser attenuation includes scattering and absorption. We use a Rayleigh scattering model and partially-Correlated quadratic-Velocity-Dependent Hard-Collision (pCqSDHC) model to describe the molecule scattering and absorption. When calculate the particles scattering and absorption, the Gaussian particles model is used to describe the shape of particles. Because of the Doppler Effect occurred between the laser and atmosphere, the wind velocity can be calculated by the backscattering signal. Then, a two parameter Weibull distribution is used to describe the wind filed, so that we can use it to do the future work. After all the description, the signal model of coherent wind measurement lidar is decided. And some of the simulation is given by MATLAB. This signal model can describe the system more accurate and more detailed, so that the following work will be easier and more efficient.

  3. High-resolution measurements of humidity and temperature with lidar

    Science.gov (United States)

    Behrendt, Andreas; Wulfmeyer, Volker; Spaeth, Florian; Hammann, Eva; Muppa, Shravan Kumar; Metzendorf, Simon; Riede, Andrea

    2015-04-01

    turbulent fluctuations of moisture and temperature in the convective boundary layer (CBL) from the surface to the entrainment zone, profiles of stability variables such as buoyancy as well as the CBL height, aerosol backscatter fields and cloud boundaries. The combination of these water vapor and temperature lidar instruments with Doppler lidar allows for deriving co-variances such as latent and sensible heat fluxes. The resulting new data sets are especially interesting for the validation and improvement of model parameterizations.

  4. Lidar Methods for Observing Mineral Dust

    Institute of Scientific and Technical Information of China (English)

    Nobuo SUGIMOTO; HUANG Zhongwei

    2014-01-01

    Lidar methods for observing mineral dust aerosols are reviewed. These methods include Mie scattering lidars, polarization lidars, Raman scattering lidars, high-spectral-resolution lidars, and fluorescence lidars. Some of the lidar systems developed by the authors and the results of the observations and applications are introduced. The largest advantage of the lidar methods is that they can observe vertical distribution of aerosols continuously with high temporal and spatial resolutions. Networks of ground-based lidars provide useful data for understanding the distribution and movement of mineral dust and other aerosols. The lidar network data are actually used for validation and assimilation of dust transport models, which can evaluate emission, transport, and deposition of mineral dust. The lidar methods are also useful for measuring the optical characteristics of aerosols that are essential to assess the radiative effects of aerosols. Evolution of the lidar data analysis methods for aerosol characterization is also reviewed. Observations from space and ground-based networks are two important approaches with the lidar methods in the studies of the effects of mineral dust and other aerosols on climate and the environment. Directions of the researches with lidar methods in the near future are discussed.

  5. 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.

  6. 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

  7. 2013 USGS Lidar: Norfolk (VA)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Laser Mapping Specialist, Inc (LMSI) and The Atlantic Group (Atlantic) provided high accuracy, calibrated multiple return LiDAR for roughly 1,130 square miles around...

  8. 2008 City of Baltimore Lidar

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In the spring of 2008, the City of Baltimore expressed an interest to upgrade the City GIS Database with mapping quality airborne LiDAR data. The City of Baltimore...

  9. 2005 Baltimore County Maryland Lidar

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In the spring of 2005, Sanborn as part of the Dewberry team was contracted to execute a LiDAR (Light Detection and Ranging) survey campaign to collect the...

  10. NASA_Airborne_Lidar_Flights

    Data.gov (United States)

    National Aeronautics and Space Administration — Data from the 1982 NASA Langley Airborne Lidar flights following the eruption of El Chichon beginning in July 1982 and continuing to January 1984. Data in ASCII...

  11. 2006 FEMA Lidar: Hawaiian Islands

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The FEMA Task Order 26 LiDAR data set was collected by Airborne 1 Corporation of El Segundo, California in September - December of 2006 for URS Corp.

  12. 2014 Mobile County, AL Lidar

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Atlantic was contracted to acquire high resolution topographic LiDAR (Light Detection and Ranging) data located in Mobile County, Alabama. The intent was to collect...

  13. 2009 SCDNR Charleston County Lidar

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Photoscience completed the original collection and classification of the multiple return LiDAR of Charleston County, South Carolina in the winter of 2006-2007. In...

  14. 2009 SCDNR Horry County Lidar

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Sanborn Map Company completed the original classification of the multiple return LiDAR of Horry County, South Carolina in 2009. In 2013, Dewberry was tasked with...

  15. 2009 SCDRN Lidar: Florence County

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The South Carolina Department of Natural Resources (SCDNR) contracted with Sanborn to provide LiDAR mapping services for Florence County, SC. Utilizing multi-return...

  16. 2014 NJMC Lidar: Hackensack Meadowlands

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In February 2014, Quantum Spatial, Inc. (QSI) was contracted by the New Jersey Meadowlands Commission (NJMC) to collect Light Detection and Ranging (LiDAR) data in...

  17. 2004 USACE Puerto Rico Lidar

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This record describes Light Detection and Ranging (Lidar) data acquired for the island of Puerto Rico. The data were acquired for USACE, St. Louis District by 3001,...

  18. 2009 Chatham County Georgia Lidar

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — LiDAR generated point cloud acquired in spring 2009 for Chatham County, Georgia for the Metropolitan Planning Commission. The data are classified as follows: Class 1...

  19. 2009 SCDNR Berkeley County Lidar

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Sanborn Map Company completed the original classification of the multiple return LiDAR of Berkeley County, South Carolina in 2009. In 2013, Dewberry was tasked with...

  20. 2009 Chatham County Georgia Lidar

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — LiDAR generated point cloud acquired in spring 2009 for Chatham County, Georgia for the Metropolitan Planning Commission. The data are classified as follows: Class...

  1. 2004 Harrison County, MS Lidar

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This metadata record describes the topographic mapping of Harrison County, Mississippi during March of 2004. Products generated include lidar point clouds in .LAS...

  2. Alabama 2003 Lidar Coverage, USACE

    Data.gov (United States)

    Army Corps of Engineers, Department of the Army, Department of Defense — The Joint Airborne Lidar Bathymetry Technical Center of Expertise (JALBTCX) has performed a coastal survey along the Gulf of Mexico in the summer of 2003. The data...

  3. Methane LIDAR Laser Technology Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Fibertek proposes to develop laser technology intended to meet NASA's need for innovative lidar technologies for atmospheric measurements of methane. NASA and the...

  4. Novel instantaneous laser Doppler velocimeter.

    Science.gov (United States)

    Avidor, J M

    1974-02-01

    A laser Doppler velocimeter capable of directly measuring instantaneous velocities is described. The new LDV uses a novel detection technique based on the utilization of a static slightly defocused spherical Fabry-Perot interferometer used in conjunction with a special mask for the detection of instantaneous Doppler frequency shifts. The essential characteristics of this LDV are discussed, and such a system recently developed is described. Results of turbulent flow measurements show good agreement with data obtained using hot wire anemometry.

  5. Recent results in imaging lidar

    Science.gov (United States)

    Ulich, Bobby L.; Lacovara, Philip; Moran, Steven E.; DeWeert, Michael J.

    1997-07-01

    Imaging lidar, in which light detection and ranging is implemented with sufficient spatial resolution to resolve the size and shape of an object, has demonstrated impressive performance for detecting and classifying underwater targets. During 1996 the U.S. Navy deployed its first imaging lidar system with Naval Air Reserve Squadron HSL-94. This paper reviews the Magic LanternR system and discusses new technology and trends for future systems.

  6. Urban Classification Techniques Using the Fusion of LiDAR and Spectral Data

    Science.gov (United States)

    2012-09-01

    probably be made to improve final results. 14. SUBJECT TERMS Fusion, Multi-Source, Hyperspectral , Multispectral, LiDAR, Urban Classification ...Landsat Thematic Mapper for 1986, 1991, 1998, and 2002. A hybrid supervised- unsupervised classification technique was developed that clustered the...The multispectral spectral resolution is not as high as that of a hyperspectral sensor. Using hyperspectral data, finer classifications could

  7. Balloonborne lidar payloads for remote sensing

    Science.gov (United States)

    Shepherd, O.; Aurilio, G.; Hurd, A. G.; Rappaport, S. A.; Reidy, W. P.; Rieder, R. J.; Bedo, D. E.; Swirbalus, R. A.

    1994-02-01

    A series of lidar experiments has been conducted using the Atmospheric Balloonborne Lidar Experiment payload (ABLE). These experiments included the measurement of atmospheric Rayleigh and Mie backscatter from near space (approximately 30 km) and Raman backscatter measurements of atmospheric constituents as a function of altitude. The ABLE payload consisted of a frequency-tripled Nd:YAG laser transmitter, a 50 cm receiver telescope, and filtered photodetectors in various focal plane configurations. The payload for lidar pointing, thermal control, data handling, and remote control of the lidar system. Comparison of ABLE performance with that of a space lidar shows significant performance advantages and cost effectiveness for balloonborne lidar systems.

  8. Retrieving the aerosol lidar ratio profile by combining ground- and space-based elastic lidars.

    Science.gov (United States)

    Feiyue, Mao; Wei, Gong; Yingying, Ma

    2012-02-15

    The aerosol lidar ratio is a key parameter for the retrieval of aerosol optical properties from elastic lidar, which changes largely for aerosols with different chemical and physical properties. We proposed a method for retrieving the aerosol lidar ratio profile by combining simultaneous ground- and space-based elastic lidars. The method was tested by a simulated case and a real case at 532 nm wavelength. The results demonstrated that our method is robust and can obtain accurate lidar ratio and extinction coefficient profiles. Our method can be useful for determining the local and global lidar ratio and validating space-based lidar datasets.

  9. 2007 USGS Lidar: Canyon Fire (CA)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This Southern California Light Detection and Ranging (LiDAR) data is to provide high accuracy LIDAR data. These datasets will be the initial acquisition to support...

  10. 2007 South Carolina DNR Lidar: Anderson County

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The LiDAR data acquisition was executed in 5 sessions, from March 7 to March 9, 2007. The airborne GPS (ABGPS) base stations supporting the LiDAR acquisition...

  11. 2008 St. Johns County, FL Countywide Lidar

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Airborne terrestrial LiDAR was collected for St. Johns County, FL. System Parameters/Flight Plan. The LiDAR system acquisition parameters were developed based on a...

  12. 2009 Bayfield County Lake Superior Lidar Survey

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The LIDAR survey presents digital elevation data sets of a bald earth surface model and 2ft interval contours covering Bayfield County, Wisconsin. The LIDAR data was...

  13. 2014 Horry County, South Carolina Lidar

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set is comprised of lidar point cloud data. This project required lidar data to be acquired over Horry County, South Carolina. The total area of the Horry...

  14. 2004 SWFWMD Citrus County Lidar Survey

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This metadata record describes the ortho & LIDAR mapping of Citrus County, FL. The mapping consists of LIDAR data collection, contour generation, and production...

  15. Iowa LiDAR Mapping Project

    Data.gov (United States)

    Federal Emergency Management Agency, Department of Homeland Security — This is collection level metadata for LAS and ASCII data files from the statewide Iowa Lidar Project. The Iowa Light Detection and Ranging (LiDAR) Project collects...

  16. 3D Flash LIDAR Space Laser Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Advanced Scientific Concepts, Inc. (ASC) is a small business that has developed 3D Flash LIDAR systems for space and terrestrial applications. 3D Flash LIDAR is...

  17. 2011 South Carolina DNR Lidar: York County

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Towill Inc. collected LiDAR for over 3,500 square miles in York, Pickens, Anderson, and Oconee Counties in South Carolina. This metadata covers the LiDAR produced...

  18. 2014 PSLC Lidar: City of Redmond

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In February 2014, Quantum Spatial (QSI) was contracted by the Puget Sound LiDAR Consortium (PSLC) to collect Light Detection and Ranging (LiDAR) data for the City of...

  19. 2002 Willapa Bay LiDAR Project

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA contracted with Spencer B. Gross, Inc. (SBG) to obtain airborne LiDAR of Willapa Bay, Washington during low tide conditions. The LiDAR data was processed to...

  20. Elevation - LIDAR Survey - Roseau County, Minnesota

    Data.gov (United States)

    Army Corps of Engineers, Department of the Army, Department of Defense — LIDAR Data for Roseau County Minnesota. This project consists of approximately 87 square miles of LIDAR mapping in Roseau County, Minnesota at two sites: area 1,...

  1. 2009 Bayfield County Lake Superior Lidar Survey

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The LIDAR survey presents digital elevation data sets of a bald earth surface model and 2ft interval contours covering Bayfield County, Wisconsin. The LIDAR data was...

  2. 2006 Volusia County Florida LiDAR

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset is the lidar data for Volusia County, Florida, approximately 1,432 square miles, acquired in early March of 2006. A total of 143 flight lines of Lidar...

  3. Backscatter LIDAR signal simulation applied to spacecraft LIDAR instrument design

    Science.gov (United States)

    Fochesatto, J.; Ristori, P.; Flamant, P.; Machado, M. E.; Singh, U.; Quel, E.

    2004-01-01

    In the framework of the scientific cooperation between the CEILAP laboratory (Argentina) and IPSL Institut Pierre Simon Laplace (France), devoted to the development of LIDAR techniques for Atmospheric sciences, a new area of scientific research, involving LIDARs, is starting in Argentine space technology. This new research area is under consideration at CEILAP in a joint effort with CONAE, the Argentine space agency, responsible for the development of future space missions. The LIDAR technique is necessary to improve our knowledge of meteorological, dynamic, and radiative processes in the South American region, for the whole troposphere and the lower stratosphere. To study this future mission, a simple model for the prediction of backscatter LIDAR signal from a spacecraft platform has been used to determine dimensions and detection characteristics of the space borne LIDAR instrument. The backscatter signal was retrieved from a modeled atmosphere considering its molecular density profile and taking into account different aerosols and clouds conditions. Signal-to-noise consideration, within the interval of possible dimension of the instrument parameters, allows us to constrain the telescope receiving area and to derive maximum range achievable, integration time and the final spatial and temporal resolutions of backscatter profiles.

  4. Asymmetric micro-Doppler frequency comb generation via magnetoelectric coupling

    Science.gov (United States)

    Filonov, Dmitry; Steinberg, Ben Z.; Ginzburg, Pavel

    2017-06-01

    Electromagnetic scattering from moving bodies, being an inherently time-dependent phenomenon, gives rise to a generation of new frequencies, which can be used to characterize the motion. Whereas an ordinary motion along a linear path produces a constant Doppler shift, an accelerated scatterer can generate a micro-Doppler frequency comb. The spectra produced by rotating objects were studied and observed in a bistatic lock-in detection scheme. The internal geometry of a scatterer was shown to determine the spectrum, and the degree of structural asymmetry was suggested to be identified via signatures in the micro-Doppler comb. In particular, hybrid magnetoelectric particles, showing an ultimate degree of asymmetry in forward and backward scattering directions, were investigated. It was shown that the comb in the backward direction has signatures at the fundamental rotation frequency and its odd harmonics, whereas the comb of the forward scattered field has a prevailing peak at the doubled frequency and its multiples. Additional features of the comb were shown to be affected by the dimensions of the particle and by the strength of the magnetoelectric coupling. Experimental verification was performed with a printed circuit board antenna based on a wire and a split ring, while the structure was illuminated at a 2 GHz carrier frequency. Detailed analysis of micro-Doppler combs enables remote detection of asymmetric features of distant objects and could find use in a span of applications, including stellar radiometry and radio identification.

  5. LIDAR for atmosphere research over Africa

    CSIR Research Space (South Africa)

    Sivakumar, V

    2008-11-01

    Full Text Available • Ozone measurements in the troposphere regions up to 18 km. LIDAR SURVEY A survey of ground-based lidars around the world was conducted via a web search. The survey is not by any means comprehensive and conclusive; and has been made with regard... and turbulence. Future plans include qualitative industrial pollutant measurements, 3D measurements using an XY scanner, a two channel lidar system, water-vapour measurements, the implementation of differential absorption lidar and ozone...

  6. Detection of Atmospheric Composition Based on Lidar

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Jinye; Tong Yala; Yang Xiaoling; Gong Jiaoli [School of science, Hubei University of Technology, Wuhan 430068 (China); Gong Wei, E-mail: yezi.zh@163.com [State Key Laboratory for Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, Wuhan 430079 (China)

    2011-02-01

    A summary overview about the types of lidar and their own applications on atmosphere detection is presented. Measurement of atmospheric aerosols by Mie lidar and Raman lidar is focused. The vertical profiles of aerosols in the atmosphere are retrieved. And at the same time, through analyzing aerosol vertical content distribution, the atmosphere boundary layer and the cloud are also observed. All the results show that the lidar has good performance on detecting the atmospheric composition.

  7. Computer simulation of the micropulse imaging lidar

    Science.gov (United States)

    Dai, Yongjiang; Zhao, Hongwei; Zhao, Yu; Wang, Xiaoou

    2000-10-01

    In this paper a design method of the Micro Pulse Lidar (MPL) is introduced, that is a computer simulation of the MPL. Some of the MPL parameters concerned air scattered and the effects on the performance of the lidar are discussed. The design software for the lidar with diode pumped solid laser is programmed by MATLAB. This software is consisted of six modules, that is transmitter, atmosphere, target, receiver, processor and display system. The method can be extended some kinds of lidar.

  8. Calibration of Nacelle-based Lidar instrument

    DEFF Research Database (Denmark)

    Yordanova, Ginka; Courtney, Michael

    This report presents the result of the lidar calibration performed for a two-beam nacelle 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....

  9. Calibration of Nacelle-based Lidar instrument

    DEFF Research Database (Denmark)

    Georgieva Yankova, Ginka; Courtney, Michael

    This report presents the result of the lidar calibration performed for a four-beam nacelle based lidar at DTU’s test site for large wind turbines at Høvsøre, Denmark.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....

  10. Turbine-Mounted Lidar:The pulsed lidar as a reliable alternative.

    OpenAIRE

    Braña, Isaac

    2011-01-01

    Expectations for turbine-mounted lidar are increasing. The installation of lidars in wind turbine nacelles for measuring incoming winds, preventing wind gusts and increasing energy productions is after recently studies, technically and economically feasible. Among available lidar types, the most studied were continuous wave lidars because they were the most reliable apparatus when this initiative began. However, after studying technical considerations and checking commercial lidars, it was fo...

  11. Lidar Measurements of Wind and Cloud Around Venus from an Orbiting or Floating/flying Platform

    Science.gov (United States)

    Singh, Upendra N.; Limaye, Sanjay; Emmitt, George D.; Refaat, Tamer F.; Kavaya, Michael J.; Yu, Jirong; Petros, Mulugeta

    2015-01-01

    Given the presence of clouds and haze in the upper portion of the Venus atmosphere, it is reasonable to consider a Doppler wind lidar (DWL) for making remote measurements of the 3-dimensional winds within the tops of clouds and the overlying haze layer. Assuming an orbit altitude of 250 kilometers and cloud tops at 60 kilometers (within the upper cloud layer), an initial performance assessment of an orbiting DWL was made using a numerical instrument and atmospheres model developed for both Earth and Mars. It is reasonable to expect vertical profiles of the 3-dimensional wind speed with 1 kilometer vertical resolution and horizontal spacing of 25 kilometers to several 100 kilometers depending upon the desired integration times. These profiles would begin somewhere just below the tops of the highest clouds and extend into the overlying haze layer to some to-be-determined height. Getting multiple layers of cloud returns is also possible with no negative impact on velocity measurement accuracy. The knowledge and expertise for developing coherent Doppler wind lidar technologies and techniques, for Earth related mission at NASA Langley Research Center is being leveraged to develop an appropriate system suitable for wind measurement around Venus. We are considering a fiber-laser-based lidar system of high efficiency and smaller size and advancing the technology level to meet the requirements for DWL system for Venus from an orbiting or floating/flying platform. This presentation will describe the concept, simulation and technology development plan for wind and cloud measurements on Venus.

  12. 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

    Determining the internal structure of the solar system's gas and ice giant planets is key to understanding their formation and evolution (Hubbard et al., 1999, 2002, Guillot 2005), and in turn the formation and evolution of the solar system. While internal structure can be constrained theoretically, measurements of internal density distributions are needed to uncover the details of the deep interior where significant ambiguities exist. To date the interiors of giant planets have been probed by measuring gravitational moments using spacecraft passing close to, or in orbit around the planet. Gravity measurements are effective in determining structure in the outer envelope of a planet, and also probing dynamics (e.g. the Cassini and Juno missions), but are less effective in probing deep structure or the presence of discrete boundaries. A promising technique for overcoming this limitation is planetary seismology (analogous to helioseismology in the solar case), postulated by Vorontsov, 1976. Using trapped pressure waves to probe giant planet interiors allows insight into the density and temperature distribution (via the sound speed) down to the planetary core, and is also sensitive to sharp boundaries, for example at the molecular to metallic hydrogen transition or at the core-envelope interface. Detecting such boundaries is not only important in understanding the overall structure of the planet, but also has implications for our understanding of the basic properties of matter at extreme pressures. Recent Doppler measurements of Jupiter by Gaulme et al (2011) claimed a promising detection of trapped oscillations, while Hedman and Nicholson (2013) have shown that trapped waves in Saturn cause detectable perturbations in Saturn's C ring. Both these papers have fueled interest in using seismology as a tool for studying the solar system's giant planets. To fully exploit planetary seismology as a tool for understanding giant planet structure, measurements need to be made

  13. General principles of carotid Doppler ultrasonography

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Whal [Dept. of Radiology, Seoul National University College of Medicine, Seoul (Korea, Republic of)

    2014-03-15

    Carotid Doppler ultrasonography is a popular tool for evaluating atherosclerosis of the carotid artery. Its two-dimensional gray scale can be used for measuring the intima-media thickness, which is very good biomarker for atherosclerosis and can aid in plaque characterization. The plaque morphology is related to the risk of stroke. The ulceration of plaque is also known as one of the strong predictors of future embolic event risk. Color Doppler ultrasonography and pulse Doppler ultrasonography have been used for detecting carotid artery stenosis. Doppler ultrasonography has unique physical properties. The operator should be familiar with the physics and other parameters of Doppler ultrasonography to perform optimal Doppler ultrasonography studies.

  14. Development of a Sodium LIDAR for Spaceborne Missions

    Science.gov (United States)

    Yu, Anthony W.; Krainak, Michael A.; Janches, Diego; Jones, Sarah L.; Blagojevic, Branimir; Chen, Jeffrey

    2015-01-01

    We are currently developing laser and electro-optic technologies to remotely measure Sodium (Na) by adapting existing lidar technology with space flight heritage. The developed instrumentation will serve as the core for the planning of a Heliophysics mission targeted to study the composition and dynamics of Earths mesosphere based on a spaceborne lidar that will measure the mesospheric Na layer. There is a pressing need in the Ionosphere Thermosphere - Mesosphere (ITM) community for high-resolution measurements that can characterize small-scale dynamics (i.e. Gravity Waves with wavelengths smaller than a few hundred km) and their effects in the Mesosphere-Lower-Termosphere (MLT) on a global basis. This is compelling because they are believed to be the dominant contributors to momentum transport and deposition in the MLT, which largely drive the global circulation and thermal structure and interactions with the tides and planetary waves in this region. We are developing a spaceborne remote sensing technique that will enable acquisition of global Na density, temperature and wind measurements in the MLT with the spatial and temporal resolution required to resolve issues associated with the structure, chemistry, dynamics, and energetics of this regionA nadir-pointing spaceborne Na Doppler resonance fluorescence LIDAR on board of the ISS will essentially make high-resolution, in time and space, Na density, temperature and vertical wind measurements, from 75-115 km (MLT region). Our instrument concept consisted of a high-energy laser transmitter at 589 nm and highly sensitive photon counting detector that allows for range-resolved atmospheric-sodium-temperature profiles. The atmospheric temperature is deduced from the linewidth of the resonant fluorescence from the atomic sodium vapor D2 line as measured by our tunable laser. We are currently developing a high power energy laser that allows for some day time sodium lidar observations with the help of a narrow bandpass

  15. Doppler peaks from active perturbations

    CERN Document Server

    Magueijo, J; Coulson, D; Ferreira, P; Magueijo, Joao; Albrecht, Andreas; Coulson, David; Ferreira, Pedro

    1995-01-01

    We examine how the qualitative structure of the Doppler peaks in the angular power spectrum of the cosmic microwave anisotropy depends on the fundamental nature of the perturbations which produced them. The formalism of Hu and Sugiyama is extended to treat models with cosmic defects. We discuss how perturbations can be ``active'' or ``passive'' and ``incoherent'' or ``coherent'', and show how causality and scale invariance play rather different roles in these various cases. We find that the existence of secondary Doppler peaks and the rough placing of the primary peak unambiguously reflect these basic properties.

  16. Inverse Doppler Effects in Flute

    CERN Document Server

    Zhao, Xiao P; Liu, Song; Shen, Fang L; Li, Lin L; Luo, Chun R

    2015-01-01

    Here we report the observation of the inverse Doppler effects in a flute. It is experimentally verified that, when there is a relative movement between the source and the observer, the inverse Doppler effect could be detected for all seven pitches of a musical scale produced by a flute. Higher tone is associated with a greater shift in frequency. The effect of the inverse frequency shift may provide new insights into why the flute, with its euphonious tone, has been popular for thousands of years in Asia and Europe.

  17. 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...

  18. 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...

  19. 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...

  20. 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...

  1. Doppler tomography in fusion plasmas and astrophysics

    CERN Document Server

    Salewski, Mirko; Heidbrink, Bill; Jacobsen, Asger Schou; Korsholm, Soren Bang; Leipold, Frank; Madsen, Jens; Moseev, Dmitry; Nielsen, Stefan Kragh; Rasmussen, Jesper; Stagner, Luke; Steeghs, Danny; Stejner, Morten; Tardini, Giovani; Weiland, Markus

    2015-01-01

    Doppler tomography is a well-known method in astrophysics to image the accretion flow, often in the shape of thin discs, in compact binary stars. As accretion discs rotate, all emitted line radiation is Doppler-shifted. In fast-ion D-alpha (FIDA) spectroscopy measurements in magnetically confined plasma, the D-alpha-photons are likewise Doppler-shifted ultimately due to gyration of the fast ions. In either case, spectra of Doppler-shifted line emission are sensitive to the velocity distribution of the emitters. Astrophysical Doppler tomography has lead to images of accretion discs of binaries revealing bright spots, spiral structures, and flow patterns. Fusion plasma Doppler tomography has lead to an image of the fast-ion velocity distribution function in the tokamak ASDEX Upgrade. This image matched numerical simulations very well. Here we discuss achievements of the Doppler tomography approach, its promise and limits, analogies and differences in astrophysical and fusion plasma Doppler tomography, and what ...

  2. Doppler Ultrasound: What Is It Used for?

    Science.gov (United States)

    ... in your neck (carotid artery stenosis) A Doppler ultrasound can estimate how fast blood flows by measuring the rate of change in its pitch (frequency). During a Doppler ultrasound, a technician trained in ultrasound imaging (sonographer) presses ...

  3. Design of an Autonomous Polarized Raman Lidar for Arctic Observations

    Science.gov (United States)

    Stillwell, R. A.; Neely, R. R., III; O'Neill, M.; Thayer, J. P.; Hayman, M. M.

    2014-12-01

    A dearth of high-spatial and temporal resolution measurements of atmospheric state variables in the Arctic directly inhibits scientific understanding of radiative and precipitation impacts on the changing surface environment. More reliable and frequent measurements are needed to better understand Arctic weather processes and constrain model predictions. To partially address the lack of Artic observations, a new autonomous Raman lidar system, which will measure through the troposphere water vapor mixing ratio, temperature, extinction, and cloud phase profiles, is under development for deployment to Summit Camp, Greenland (72° 36'N, 38° 25'W, 3250m). This high-altitude Arctic field site has co-located ancillary equipment such as a Doppler millimeter cloud radar, microwave radiometers, depolarization lidars, ceiliometer, an infrared interferometer and twice-daily radiosondes which are part of the Integrated Characterization of Energy, Clouds, Atmospheric State and Precipitation at Summit (ICECAPS) project and the Arctic Observing Network (AON). The current suite of instruments allows for a near comprehensive picture of the atmospheric state above Summit but increased spatial and temporal resolution of water vapor and temperature are needed to reveal detailed microphysical information. In this presentation, a system description will be provided with an emphasis on the features necessary for autonomous, full diurnal operation, and how the new system will help fill the observation gap within the already existing sensor suite.

  4. Lidar configurations for wind turbine control

    Science.gov (United States)

    Mirzaei, Mahmood; Mann, Jakob

    2016-09-01

    Lidar sensors have proved to be very beneficial in the wind energy industry. They can be used for yaw correction, feed-forward pitch control and load verification. However, the current lidars are expensive. One way to reduce the price is to use lidars with few measurement points. Finding the best configuration of an inexpensive lidar in terms of number of measurement points, the measurement distance and the opening angle is the subject of this study. In order to solve the problem, a lidar model is developed and used to measure wind speed in a turbulence box. The effective wind speed measured by the lidar is compared against the effective wind speed on a wind turbine rotor both theoretically and through simulations. The study provides some results to choose the best configuration of the lidar with few measurement points.

  5. Shear and Turbulence Effects on Lidar Measurements

    DEFF Research Database (Denmark)

    Courtney, Michael; Sathe, Ameya; Gayle Nygaard, Nicolai

    Wind lidars are now used extensively for wind resource measurements. It is known that lidar wind speed measure-ments are affected by both turbulence and wind shear. This report explains the mechanisms behind these sensitivities. For turbulence, it is found that errors in the scalar mean speed...... are usually only small. However, particularly in re-spect of a lidar calibration procedure, turbulence induced errors in the cup anemometer speed are seen to be signifi-cantly larger. Wind shear is shown to induce measurement errors both due to possible imperfections in the lidar sensing height and due...... to the averaging of a non-linear speed profile. Both effects in combination have to be included when modelling the lidar error. Attempts to evaluate the lidar error from ex-perimental data have not been successful probably due to a lack of detailed knowledge of both the wind shear and the actual lidar sensing...

  6. Lidar observations of wind over Xin Jiang, China: general characteristics and variation

    Science.gov (United States)

    Han, Yan; Sun, Dong-song; Weng, Ning-quan; Wang, Jian-guo; Dou, Xian-kang; Zhang, Yan-hong; Guan, Jun; Miao, Qingjian; Chen, Xin

    2016-08-01

    The mobile Rayleigh Doppler lidar based on a Fabry-Perot etalon is developed for wind measurement. The structure and technical parameters of this lidar system are described in brief. The 1740 wind profiles from 8 to 40 km altitudes by the lidar in Xinjiang, China, were obtained in 2010 and 2011, and were used to analyze the characteristics and variations of wind. The results shown that the wind velocity is within a three-layer structure: westerly jet layer (9-14 km), quasi-zero velocity layer (18-22 km) and gale layer (22-40 km). In August and September, the wind direction is within a three-layer structure: zonal westerly wind layer (5-18 km) where wind direction is west, zonal wind reverse layer (18-22 km) where wind direction is unstable and easterly wind layer (22-40 km) where wind direction is east. In October, wind direction is west (8-40 km). Wind observations by lidar are a realistic offset to the rawins.

  7. Dynamic displacement estimation by fusing LDV and LiDAR measurements via smoothing based Kalman filtering

    Science.gov (United States)

    Kim, Kiyoung; Sohn, Hoon

    2017-01-01

    This paper presents a smoothing based Kalman filter to estimate dynamic displacement in real-time by fusing the velocity measured from a laser Doppler vibrometer (LDV) and the displacement from a light detection and ranging (LiDAR). LiDAR can measure displacement based on the time-of-flight information or the phase-shift of the laser beam reflected off form a target surface, but it typically has a high noise level and a low sampling rate. On the other hand, LDV primarily measures out-of-plane velocity of a moving target, and displacement is estimated by numerical integration of the measured velocity. Here, the displacement estimated by LDV suffers from integration error although LDV can achieve a lower noise level and a much higher sampling rate than LiDAR. The proposed data fusion technique estimates high-precision and high-sampling rate displacement by taking advantage of both LiDAR and LDV measurements and overcomes their limitations by adopting a real-time smoothing based Kalman filter. To verify the performance of the proposed dynamic displacement estimation technique, a series of lab-scale tests are conducted under various loading conditions.

  8. Advanced 2-micron solid-state laser for wind and CO II lidar applications

    Science.gov (United States)

    Yu, Jirong; Trieu, Bo C.; Petros, Mulugeta; Bai, Yingxin; Petzar, Paul J.; Koch, Grady J.; Singh, Upendra N.; Kavaya, Michael J.

    2006-12-01

    Significant advancements in the 2-micron laser development have been made recently. Solid-state 2-micron laser is a key subsystem for a coherent Doppler lidar that measures the horizontal and vertical wind velocities with high precision and resolution. The same laser, after a few modifications, can also be used in a Diffrencial Absorption Lidar (DIAL) system for measuring atmospheric CO II concentration profiles. The world record 2-micron laser energy is demonstrated with an oscillator and two amplifiers system. It generates more than one joule per pulse energy with excellent beam quality. Based on the successful demonstration of a fully conductive cooled oscillator by using heat pipe technology, an improved fully conductively cooled 2-micron amplifier was designed, manufactured and integrated. It virtually eliminates the running coolant to increase the overall system efficiency and reliability. In addition to technology development and demonstration, a compact and engineering hardened 2-micron laser is under development. It is capable of producing 250 mJ at 10 Hz by an oscillator and one amplifier. This compact laser is expected to be integrated to a lidar system and take field measurements. The recent achievements push forward the readiness of such a laser system for space lidar applications. This paper will review the developments of the state-of-the-art solid-state 2-micron laser.

  9. Advanced 2-micron Solid-state Laser for Wind and CO2 Lidar Applications

    Science.gov (United States)

    Yu, Jirong; Trieu, Bo C.; Petros, Mulugeta; Bai, Yingxin; Petzar, Paul J.; Koch, Grady J.; Singh, Upendra N.; Kavaya, Michael J.

    2006-01-01

    Significant advancements in the 2-micron laser development have been made recently. Solid-state 2-micron laser is a key subsystem for a coherent Doppler lidar that measures the horizontal and vertical wind velocities with high precision and resolution. The same laser, after a few modifications, can also be used in a Differential Absorption Lidar (DIAL) system for measuring atmospheric CO2 concentration profiles. The world record 2-micron laser energy is demonstrated with an oscillator and two amplifiers system. It generates more than one joule per pulse energy with excellent beam quality. Based on the successful demonstration of a fully conductive cooled oscillator by using heat pipe technology, an improved fully conductively cooled 2-micron amplifier was designed, manufactured and integrated. It virtually eliminates the running coolant to increase the overall system efficiency and reliability. In addition to technology development and demonstration, a compact and engineering hardened 2-micron laser is under development. It is capable of producing 250 mJ at 10 Hz by an oscillator and one amplifier. This compact laser is expected to be integrated to a lidar system and take field measurements. The recent achievements push forward the readiness of such a laser system for space lidar applications. This paper will review the developments of the state-of-the-art solid-state 2-micron laser.

  10. 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.

  11. Velocity-aligned Doppler spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Z.; Koplitz, B.; Wittig, C.

    1989-03-01

    The technique of velocity-aligned Doppler spectrosocopy (VADS) is presented and discussed. For photolysis/probe experiments with pulsed initiation, VADS can yield Doppler profiles for nascent photofragments that allow detailed center-of-mass (c.m.) kinetic energy distributions to be extracted. When compared with traditional forms of Doppler spectroscopy, the improvement in kinetic energy resolution is dramatic. Changes in the measured profiles are a consequence of spatial discrimination (i.e., focused and overlapping photolysis and probe beams) and delayed observation. These factors result in the selective detection of species whose velocities are aligned with the wave vector of the probe radiation k/sub pr/, thus revealing the speed distribution along k/sub pr/ rather than the distribution of nascent velocity components projected upon this direction. Mathematical details of the procedure used to model VADS are given, and experimental illustrations for HI, H/sub 2/S, and NH/sub 3/ photodissociation are presented. In these examples, pulsed photodissociation produces H atoms that are detected by sequential two-photon, two-frequency ionization via Lyman-..cap alpha.. with a pulsed laser (121.6+364.7 nm), and measuring the Lyman-..cap alpha.. Doppler profile as a function of probe delay reveals both internal and c.m. kinetic energy distributions for the photofragments. Strengths and weaknesses of VADS as a tool for investigating photofragmentation phenomena are also discussed.

  12. Speckles in laser doppler perfusion imaging

    NARCIS (Netherlands)

    Rajan, Vinayakrishnan

    2007-01-01

    Laser Doppler Flowmetry (LDF) is a noninvasive diagnostic method to measure blood flow in tissue [1]. The technique is based on measuring the Doppler shift induced by moving red blood cells to the illuminating coherent light. A laser Doppler instrument often gives output signals related to the flux,

  13. 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

  14. 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

  15. 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)

  16. Three dimensional winds: A maximum cross-correlation application to elastic lidar data

    Energy Technology Data Exchange (ETDEWEB)

    Buttler, William Tillman [Univ. of Texas, Austin, TX (United States)

    1996-05-01

    Maximum cross-correlation techniques have been used with satellite data to estimate winds and sea surface velocities for several years. Los Alamos National Laboratory (LANL) is currently using a variation of the basic maximum cross-correlation technique, coupled with a deterministic application of a vector median filter, to measure transverse winds as a function of range and altitude from incoherent elastic backscatter lidar (light detection and ranging) data taken throughout large volumes within the atmospheric boundary layer. Hourly representations of three-dimensional wind fields, derived from elastic lidar data taken during an air-quality study performed in a region of complex terrain near Sunland Park, New Mexico, are presented and compared with results from an Environmental Protection Agency (EPA) approved laser doppler velocimeter. The wind fields showed persistent large scale eddies as well as general terrain-following winds in the Rio Grande valley.

  17. 2013-2014 Lidar Campaign: Measurements of Inflow at a Northern Oklahoma Wind Farm

    Energy Technology Data Exchange (ETDEWEB)

    Wharton, Sonia [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Newman, Jennifer [Univ. of Oklahoma, Norman, OK (United States); Irons, Zack [Enel Green Power North America, Inc., Andover, MA (United States); Miller, Wayne O. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2014-10-25

    In November 2013, LLNL deployed two vertically-profiling, Doppler Laser Detection and Ranging (lidar) instruments at Enel Green Power North America’s 235 MW wind farm in Northern Oklahoma to collect wind measurements. The lidars were used to measure wake-free observations of the free-stream wind flow (i.e., inflow) for purposes of quantifying rotor-disk wind characteristics under varying atmospheric conditions. The measurements included horizontal wind speed, vertical wind speed, wind direction, and turbulence intensity, taken at a ~1 Hz sampling rate and averaged over 10-minute intervals. From these measurements we also calculated wind shear across the turbine rotor disk and turbulence kinetic energy (TKE).

  18. Lidar measurements of plume statistics

    DEFF Research Database (Denmark)

    Ejsing Jørgensen, Hans; Mikkelsen, T.

    1993-01-01

    the source, instantaneous crosswind plume profiles were detected repetitively at high spatial (1.5 m) and temporal (3 sec) intervals by use of a mini LIDAR system. The experiments were accompanied by measurement of the surface-layer mean wind and turbulence quantities by sonic anemometers. On the basis...

  19. Mobile Lidar Operations at GSFC

    Science.gov (United States)

    McGee, Thomas J.

    2003-01-01

    Since the last meeting, the GSFC Stratospheric Ozone Lidar has participated in two campaigns at MLO - an ozone and temperature comparison and a water vapor comparison. The trailer has been returned to GSFC to begin transfer into a sea container, before deployment to Reunion Island in Spring, 2004.

  20. Complex terrain and wind lidars

    Energy Technology Data Exchange (ETDEWEB)

    Bingoel, F.

    2009-08-15

    This thesis includes the results of a PhD study about complex terrain and wind lidars. The study mostly focuses on hilly and forested areas. Lidars have been used in combination with cups, sonics and vanes, to reach the desired vertical measurement heights. Several experiments are performed in complex terrain sites and the measurements are compared with two different flow models; a linearised flow model LINCOM and specialised forest model SCADIS. In respect to the lidar performance in complex terrain, the results showed that horizontal wind speed errors measured by a conically scanning lidar can be of the order of 3-4% in moderately-complex terrain and up to 10% in complex terrain. The findings were based on experiments involving collocated lidars and meteorological masts, together with flow calculations over the same terrains. The lidar performance was also simulated with the commercial software WAsP Engineering 2.0 and was well predicted except for some sectors where the terrain is particularly steep. Subsequently, two experiments were performed in forested areas; where the measurements are recorded at a location deep-in forest and at the forest edge. Both sites were modelled with flow models and the comparison of the measurement data with the flow model outputs showed that the mean wind speed calculated by LINCOM model was only reliable between 1 and 2 tree height (h) above canopy. The SCADIS model reported better correlation with the measurements in forest up to approx6h. At the forest edge, LINCOM model was used by allocating a slope half-in half out of the forest based on the suggestions of previous studies. The optimum slope angle was reported as 17 deg.. Thus, a suggestion was made to use WAsP Engineering 2.0 for forest edge modelling with known limitations and the applied method. The SCADIS model worked better than the LINCOM model at the forest edge but the model reported closer results to the measurements at upwind than the downwind and this should be

  1. Airborne forward-pointing UV Rayleigh lidar for remote clear air turbulence detection: system design and performance.

    Science.gov (United States)

    Vrancken, Patrick; Wirth, Martin; Ehret, Gerhard; Barny, Hervé; Rondeau, Philippe; Veerman, Henk

    2016-11-10

    A high-performance airborne UV Rayleigh lidar system was developed within the European project DELICAT. With its forward-pointing architecture, it aims at demonstrating a novel detection scheme for clear air turbulence (CAT) for an aeronautics safety application. Due to its occurrence in clear and clean air at high altitudes (aviation cruise flight level), this type of turbulence evades microwave radar techniques and in most cases coherent Doppler lidar techniques. The present lidar detection technique relies on air density fluctuation measurement and is thus independent of backscatter from hydrometeors and aerosol particles. The subtle air density fluctuations caused by the turbulent air flow demand exceptionally high stability of the setup and in particular of the detection system. This paper describes an airborne test system for the purpose of demonstrating this technology and turbulence detection method: a high-power UV Rayleigh lidar system is installed on a research aircraft in a forward-looking configuration for use in cruise flight altitudes. Flight test measurements demonstrate this unique lidar system being able to resolve air density fluctuations occurring in light-to-moderate CAT at 5 km or moderate CAT at 10 km distance. A scaling of the determined stability and noise characteristics shows that such performance is adequate for an application in commercial air transport.

  2. Improving lidar turbulence estimates for wind energy

    Science.gov (United States)

    Newman, J. F.; Clifton, A.; Churchfield, M. J.; Klein, P.

    2016-09-01

    Remote sensing devices (e.g., lidars) are quickly becoming a cost-effective and reliable alternative to meteorological towers for wind energy applications. Although lidars can measure mean wind speeds accurately, these devices measure different values of turbulence intensity (TI) than an instrument on a tower. In response to these issues, a lidar TI error reduction model was recently developed for commercially available lidars. The TI error model first applies physics-based corrections to the lidar measurements, then uses machine-learning techniques to further reduce errors in lidar TI estimates. The model was tested at two sites in the Southern Plains where vertically profiling lidars were collocated with meteorological towers. Results indicate that the model works well under stable conditions but cannot fully mitigate the effects of variance contamination under unstable conditions. To understand how variance contamination affects lidar TI estimates, a new set of equations was derived in previous work to characterize the actual variance measured by a lidar. Terms in these equations were quantified using a lidar simulator and modeled wind field, and the new equations were then implemented into the TI error model.

  3. Analysis of a potassium lidar system for upper-atmospheric wind-temperature measurements.

    Science.gov (United States)

    Papen, G C; Gardner, C S; Pfenninger, W M

    1995-10-20

    We report a detailed analysis of wind-temperature (W/T) lidar systems based on mesospheric potassium as the tracer. Currently, most narrow-band (W/T) systems use sodium (Na) as the tracer because of its relatively large natural abundance, large cross section, and the ability to use Doppler-free Na spectroscopy to generate accurate absolute frequency markers. We show that a potassium-based system with existing near-infrared solid-state laser technology operating at the potassium D lines has the potential to make W/T measurements that are more accurate than current Na narrow-band systems and can be far simpler technically.

  4. Doppler indicates of uterine artery Doppler velocimetry by placental location

    Energy Technology Data Exchange (ETDEWEB)

    Han, Sung Shik; Park, Yong Won; Cho, Jae Sung; Kwon, Hye Kyeung; Kim, Jae Wook [Yonsei University College of Medicine, Seoul (Korea, Republic of)

    2001-09-15

    Our purpose was to investigate the relation between the vascular resistance of uterine artery and placental location and to establish the reference value of Doppler index in uterine artery by placental location. Placental location and flow velocity waveforms of both uterine arteries in 7,016 pregnant women after 18 weeks gestation were examined using color Doppler ultrasonography. Placental location was classified as central and lateral placental and the uterine artery with lateral placental were divided into ipsilateral uterine artery (same side of the placental) and contralateral uterine artery (opposite side of the placenta). The uterine artery with central placental was classified as the central uterine artery. Systolic-Diastolic ratio (S/D ratio) of uterine arteries by gestational weeks were calculated and compared with the placental location and perinatal outcomes. In the lateral placental group, the S/D ratio of the contralateral uterine artery was higher than the ipsilateral one (mean=2.08+0.34 vs 1.89+0.34, p=0.0001). S/D ratio of the uterine artery decreased during second trimester and the ratio after 27 weeks was a tendency to have a constant values(ipsilateral: 1.85+ 0.34, central : 1.96+ 0.40, contralateral: 2.01+0.54). S/D ratio of the uterine artery was affected by placental location. So when we evaluate Doppler spectrum of uterine artery, placental location should be considered and we established the reference value of Doppler index of uterine artery by placental location.

  5. Azimuthal Doppler Effect in Optical Vortex Spectroscopy

    Science.gov (United States)

    Aramaki, Mitsutoshi; Yoshimura, Shinji; Toda, Yasunori; Morisaki, Tomohiro; Terasaka, Kenichiro; Tanaka, Masayoshi

    2015-11-01

    Optical vortices (OV) are a set of solutions of the paraxial Helmholtz equation in the cylindrical coordinates, and its wave front has a spiral shape. Since the Doppler shift is caused by the phase change by the movement in a wave field, the observer in the OV, which has the three-dimensional structured wave front, feels a three-dimensional Doppler effect. Since the multi-dimensional Doppler components are mixed into a single Doppler spectrum, development of a decomposition method is required. We performed a modified saturated absorption spectroscopy to separate the components. The OV and plane wave are used as a probe beam and pump beam, respectively. Although the plane-wave pump laser cancels the z-direction Doppler shift, the azimuthal Doppler shift remains in the saturated dip. The spatial variation of the dip width gives the information of the azimuthal Doppler shift. The some results of optical vortex spectroscopy will be presented.

  6. Closure between ice-nucleating particle and ice crystal number concentrations in ice clouds embedded in Saharan dust: Lidar observation during the BACCHUS Cyprus 2015 campaign

    Science.gov (United States)

    Mamouri, Rodanthi-Elisavet; Ansmann, Albert; Bühl, Johannes; Engelmann, Ronny; Baars, Holger; Nisantzi, Argyro; Hadjimitsis, Diofantos; Atkinson, James; Kanji, Zamin; Vrekoussis, Michalis; Sciare, Jean; Mihalopoulos, Nikos

    2016-04-01

    For the first time, we compare ice-nucleating particle number concentration (INPC) derived from polarization lidar (Mamouri and Ansmann, 2015) with ice crystal number concentrations (ICNC) in ice cloud layers embedded in the observed Saharan dust layers (at heights above 6 km and corresponding temperatures from -20 to -40°C). ICNC is estimated from the respective cirrus extinction profiles obtained with the same polarization lidar in combination with Doppler lidar measurements of the ice crystal sedimentation speed from which the mean size of the crystals can be estimated. Good agreement between INPC and ICNC was obtained for two case studies of the BACCHUS Cyprus 2015 field campaign with focus on INPC profiling. The campaign was organized by the Cyprus Institute, Nicosia, where a lidar was deployed. Additionaly, observations of AERONET and EALINET Lidar stations during the BACCHUS Cyprus 2015 field campaign, performed by Cyprus University of Technology in Limassol. Both, INPC and ICNC were found in the range from 10-50 1/L. Lidar-derived INPC values were also compared with in-situ INPC measurements (Horizontal Ice Nucleation Chamber, HINC, ETH Zurich, deployed at Agia Marina, at 500 m a.s.l., 30 km west of the lidar site). Reasonable and partly good agreement (during dust events) was found between the two retrievals. The findings of these closure studies corroborate the applicability of available INPC parameterization schemes (DeMott et al., 2010, 2015) implemented in the lidar retrieval scheme, and more generally INPC profiling by using active remote sensing (at ground and in space with CALIPSO and EarthCARE lidars).

  7. 2004 Southwest Florida Water Management District Lidar: Pasco District

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This metadata record describes the ortho & lidar mapping of Pasco County, FL. The mapping consists of lidar data collected using a Leica ALS-40 Lidar Sensor,...

  8. 2006 MDEQ-FEMA Hinds County Lidar Survey

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This metadata record describes the acquisition and processing of bare earth lidar data, raw point cloud lidar data, lidar intensity data, and floodmap breaklines...

  9. 2004 Southwest Florida Water Management District Lidar: Sarasota District

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This metadata record describes the ortho & lidar mapping of Sarasota County, FL. The mapping consists of lidar data collected using a Leica ALS-40 Lidar Sensor,...

  10. 2006 MDEQ-FEMA Hinds County Lidar Survey

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This metadata record describes the acquisition and processing of bare earth lidar data, raw point cloud lidar data, lidar intensity data, and floodmap breaklines...

  11. 2006 Puget Sound LiDAR Consortium (PSLC) Topographic LiDAR: Lewis County, WA

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Watershed Sciences, Inc. collected Light Detection and Ranging (LiDAR) data of Western Lewis County for the Puget Sound LiDAR Consortium. This data set covers...

  12. 2012 MEGIS Topographic Lidar: Statewide Lidar Project Area 1 (Aroostook), Maine

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — LiDAR data is a remotely sensed high resolution elevation data collected by an airborne platform. The LiDAR sensor uses a combination of laser range finding, GPS...

  13. 2009 Puget Sound LiDAR Consortium (PSLC) Topographic LiDAR: Lewis County, Washington

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Watershed Sciences, Inc. (WSI) collected Light Detection and Ranging (LiDAR) data for the Lewis County survey area for the Puget Sound LiDAR Consortium. This data...

  14. 2011 Puget Sound LiDAR Consortium (PSLC) Topographic LiDAR: Quinault River Basin

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Watershed Sciences, Inc. (WSI) collected Light Detection and Ranging (LiDAR) data on the Quinault River Basin survey area for the Puget Sound LiDAR Consortium and...

  15. 2015 Puget Sound LiDAR Consortium (PSLC) LiDAR: WA DNR Lands (P2)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In June 2014, WSI, a Quantum Spatial Inc. (QSI) company, was contracted by the Puget Sound LiDAR Consortium (PSLC) to collect Light Detection and Ranging (LiDAR)...

  16. 2015 Puget Sound LiDAR Consortium (PSLC) LiDAR: WA DNR Lands (P1)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In June 2014, WSI, a Quantum Spatial Inc. (QSI) company, was contracted by the Puget Sound LiDAR Consortium (PSLC) to collect Light Detection and Ranging (LiDAR)...

  17. 2013 Puget Sound LiDAR Consortium (PSLC) Topographic LiDAR: Tulalip Partnership

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In October 2012, WSI (Watershed Sciences, Inc.) was contracted by the Puget Sound LiDAR Consortium (PSLC)to collect Light Detection and Ranging (LiDAR) data on a...

  18. 2013 Puget Sound LiDAR Consortium (PSLC) Topographic LiDAR: Nooksack

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In July 2012, WSI (Watershed Sciences, Inc.) was contracted by the Puget Sound LiDAR Consortium (PSLC) to collect Light Detection and Ranging (LiDAR) data on a...

  19. 2013 Puget Sound LiDAR Consortium (PSLC) Topographic LiDAR: Saddle Mountain

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In October 2013, WSI, a Quantum Spatial Company (QSI), was contracted by the Puget Sound LiDAR Consortium (PSLC) to collect Light Detection and Ranging (LiDAR) data...

  20. 2012 MEGIS Topographic Lidar: Statewide Lidar Project Areas 2 and 3 (Mid-Coastal Cleanup), Maine

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — LiDAR data is a remotely sensed high resolution elevation data collected by an airborne platform. The LiDAR sensor uses a combination of laser range finding, GPS...

  1. 2014 Puget Sound LiDAR Consortium (PSLC) Topographic LiDAR: Willapa Valley (Delivery 1)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In January, 2014 WSI, a Quantum Spatial (QSI) company, was contracted by the Puget Sound LiDAR Consortium (PSLC) to collect Light Detection and Ranging (LiDAR) data...

  2. Velocity-aligned Doppler spectroscopy

    Science.gov (United States)

    Xu, Z.; Koplitz, B.; Wittig, C.

    1989-03-01

    The use of velocity-aligned Doppler spectroscopy (VADS) to measure center-of-mass kinetic-energy distributions of nascent photofragments produced in pulsed-initiation photolysis/probe experiments is described and demonstrated. In VADS, pulsed photolysis and probe laser beams counterpropagate through the ionization region of a time-of-flight mass spectrometer. The theoretical principles of VADS and the mathematical interpretation of VADS data are explained and illustrated with diagrams; the experimental setup is described; and results for the photodissociation of HI, H2S, and NH3 are presented in graphs and characterized in detail. VADS is shown to give much higher kinetic-energy resolution than conventional Doppler spectroscopy.

  3. MST radar and polarization lidar observations of tropical cirrus

    Directory of Open Access Journals (Sweden)

    Y. Bhavani Kumar

    Full Text Available Significant gaps in our understanding of global cirrus effects on the climate system involve the role of frequently occurring tropical cirrus. Much of the cirrus in the atmosphere is largely due to frequent cumulus and convective activity in the tropics. In the Indian sub-tropical region, the deep convective activity is very prominent from April to December, which is a favorable period for the formation of deep cumulus clouds. The fibrous anvils of these clouds, laden with ice crystals, are one of the source mechanisms for much of the cirrus in the atmosphere. In the present study, several passages of tropical cirrus were investigated by simultaneously operating MST radar and a co-located polarization lidar at the National MST Radar Facility (NMRF, Gadanki (13.45° N, 79.18° E, India to understand its structure, the background wind field and the microphysics at the cloud boundaries. The lidar system used is capable of measuring the degree of depolarization in the laser backscatter. It has identified several different cirrus structures with a peak linear depolarization ratio (LDR in the range of 0.1 to 0.32. Simultaneous observations of tropical cirrus by the VHF Doppler radar indicated a clear enhancement of reflectivity detected in the vicinity of the cloud boundaries, as revealed by the lidar and are strongly dependent on observed cloud LDR. An inter-comparison of radar reflectivity observed for vertical and oblique beams reveals that the radar-enhanced reflectivity at the cloud boundaries is also accompanied by significant aspect sensitivity. These observations indicate the presence of anisotropic turbulence at the cloud boundaries. Radar velocity measurements show that boundaries of cirrus are associated with enhanced horizontal winds, significant vertical shear in the horizontal winds and reduced vertical velocity. Therefore, these measurements indicate that a circulation at the cloud boundaries suggest an entrainment taking place close to

  4. LIDAR Products, LiDAR, Published in 2006, 1:1200 (1in=100ft) scale, Dodge County, Wisconsin.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This LIDAR Products dataset, published at 1:1200 (1in=100ft) scale, was produced all or in part from LIDAR information as of 2006. It is described as 'LiDAR'. Data...

  5. Generic methodology for calibrating profiling nacelle lidars

    DEFF Research Database (Denmark)

    Borraccino, Antoine; Courtney, Michael; Wagner, Rozenn

    is calibrated rather than a reconstructed parameter. This contribution presents a generic methodology to calibrate profiling nacelle-mounted lidars. The application of profiling lidars to wind turbine power performance and corresponding need for calibration procedures is introduced in relation to metrological...... standards. Further, two different calibration procedure concepts are described along with their strengths and weaknesses. The main steps of the generic methodology are then explained and illustrated by calibration results from two types of profiling lidars. Finally, measurement uncertainty assessment...

  6. Ozone Lidar Observations for Air Quality Studies

    Science.gov (United States)

    Wang, Lihua; Newchurch, Mike; Kuang, Shi; Burris, John F.; Huang, Guanyu; Pour-Biazar, Arastoo; Koshak, William; Follette-Cook, Melanie B.; Pickering, Kenneth E.; McGee, Thomas J.; Sullivan, John T.; Langford, Andrew O.; Senff, Christoph J.; Alvarez, Raul; Eloranta, Edwin

    2015-01-01

    Tropospheric ozone lidars are well suited to measuring the high spatio-temporal variability of this important trace gas. Furthermore, lidar measurements in conjunction with balloon soundings, aircraft, and satellite observations provide substantial information about a variety of atmospheric chemical and physical processes. Examples of processes elucidated by ozone-lidar measurements are presented, and modeling studies using WRF-Chem, RAQMS, and DALES/LES models illustrate our current understanding and shortcomings of these processes.

  7. Lidar data used in the COFIN project

    DEFF Research Database (Denmark)

    Ejsing Jørgensen, Hans; Nielsen, Morten

    1999-01-01

    This report presents the Lidar data used in the COFIN project. The Lidar data have been obtained from several ground level dispersion experiments over flat and complex terrain. The method for treating the data and the conditons under which the data wereobtained are described in detail. Finally we...... describe the Tools to extract and visualize the Lidar data. Data, report, and visualisation tools are available on the Risø FTP server....

  8. Scalable lidar technique for fire detection

    Science.gov (United States)

    Utkin, Andrei B.; Piedade, Fernando; Beixiga, Vasco; Mota, Pedro; Lousã, Pedro

    2014-08-01

    Lidar (light detection and ranging) presents better sensitivity than fire surveillance based on imaging. However, the price of conventional lidar equipment is often too high as compared to passive fire detection instruments. We describe possibilities to downscale the technology. First, a conventional lidar, capable of smoke-plume detection up to ~10 km, may be replaced by an industrially manufactured solid-state laser rangefinder. This reduces the detection range to about 5 km, but decreases the purchase price by one order of magnitude. Further downscaling is possible by constructing the lidar smoke sensor on the basis of a low-cost laser diode.

  9. Lidar configurations for wind turbine control

    DEFF Research Database (Denmark)

    Mirzaei, Mahmood; Mann, Jakob

    2016-01-01

    configuration of an inexpensive lidar in terms of number of measurement points, the measurement distance and the opening angle is the subject of this study. In order to solve the problem, a lidar model is developed and used to measure wind speed in a turbulence box. The effective wind speed measured...... by the lidar is compared against the effective wind speed on a wind turbine rotor both theoretically and through simulations. The study provides some results to choose the best configuration of the lidar with few measurement points....

  10. Automating the Purple Crow Lidar

    Directory of Open Access Journals (Sweden)

    Hicks Shannon

    2016-01-01

    Full Text Available The Purple Crow LiDAR (PCL was built to measure short and long term coupling between the lower, middle, and upper atmosphere. The initial component of my MSc. project is to automate two key elements of the PCL: the rotating liquid mercury mirror and the Zaber alignment mirror. In addition to the automation of the Zaber alignment mirror, it is also necessary to describe the mirror’s movement and positioning errors. Its properties will then be added into the alignment software. Once the alignment software has been completed, we will compare the new alignment method with the previous manual procedure. This is the first among several projects that will culminate in a fully-automated lidar. Eventually, we will be able to work remotely, thereby increasing the amount of data we collect. This paper will describe the motivation for automation, the methods we propose, preliminary results for the Zaber alignment error analysis, and future work.

  11. Automating the Purple Crow Lidar

    Science.gov (United States)

    Hicks, Shannon; Sica, R. J.; Argall, P. S.

    2016-06-01

    The Purple Crow LiDAR (PCL) was built to measure short and long term coupling between the lower, middle, and upper atmosphere. The initial component of my MSc. project is to automate two key elements of the PCL: the rotating liquid mercury mirror and the Zaber alignment mirror. In addition to the automation of the Zaber alignment mirror, it is also necessary to describe the mirror's movement and positioning errors. Its properties will then be added into the alignment software. Once the alignment software has been completed, we will compare the new alignment method with the previous manual procedure. This is the first among several projects that will culminate in a fully-automated lidar. Eventually, we will be able to work remotely, thereby increasing the amount of data we collect. This paper will describe the motivation for automation, the methods we propose, preliminary results for the Zaber alignment error analysis, and future work.

  12. LIDAR and atmosphere remote sensing

    CSIR Research Space (South Africa)

    Venkataraman, S

    2008-05-01

    Full Text Available and to consist of theory and practical exercises • Theory: Remote sensing process, Photogrammetry, introduction to multispectral, remote sensing systems, Thermal infra-red remote sensing, Active and passive remote sensing, LIDAR, Application of remotely... Aerosol measurements and cloud characteristics head2right Water vapour measurements in the lower troposphere region up to 8 km head2right Ozone measurements in the troposphere regions up to 18 km Slide 22 © CSIR 2008 www...

  13. Lidar Observations of Wave Shape

    Science.gov (United States)

    Brodie, K. L.; Raubenheimer, B.; Spore, N.; Gorrell, L.; Slocum, R. K.; Elgar, S.

    2016-02-01

    As waves propagate across the inner-surf zone, through a shorebreak, to the swash, their shapes can evolve rapidly, particularly if there are large changes in water depth over a wavelength. As wave shapes evolve, the time history of near-bed wave-orbital velocities also changes. Asymmetrical near-bed velocities result in preferential directions for sediment transport, and spatial variations in asymmetries can lead to morphological evolution. Thus, understanding and predicting wave shapes in the inner-surf and swash zones is important to improving sediment transport predictions. Here, rapid changes in wave shape, quantified by 3rd moments (skewness and asymmetry) of the sea-surface elevation time series, were observed on a sandy Atlantic Ocean beach near Duck, NC using terrestrial lidar scanners that measure the elevation of the water surface along a narrow cross-shore transect with high spatial [O(1 cm)] and temporal [O(0.5 s)] resolution. The terrestrial lidar scanners were mounted on a tower on the beach dune (about 8 m above the water surface) and on an 8-m tall amphibious tripod [the Coastal Research Amphibious Buggy (CRAB)]. Observations with the dune lidar are used to investigate how bulk wave shape parameters such as wave skewness and asymmetry, and the ratio of wave height to water depth (gamma) vary with beach slope, tide level, and offshore wave conditions. Observations with the lidar mounted on the CRAB are used to investigate the evolution of individual waves propagating across the surf zone and shorebreak to the swash. For example, preliminary observations from the CRAB include a wave that appeared to shoal and then "pitch" backwards immediately prior to breaking and running up the beach. Funded by the USACE Coastal Field Data Collection Program, ASD(R&E), and ONR.

  14. Lidar Detection of Explosives Traces

    Directory of Open Access Journals (Sweden)

    Bobrovnikov Sergei M.

    2016-01-01

    Full Text Available The possibility of remote detection of traces of explosives using laser fragmentation/laser-induced fluorescence (LF/LIF is studied. Experimental data on the remote visualization of traces of trinitrotoluene (TNT, hexogen (RDX, trotyl-hexogen (Comp B, octogen (HMX, and tetryl with a scanning lidar detector of traces of nitrogen-containing explosives at a distance of 5 m are presented.

  15. LIDAR data compression using wavelets

    Science.gov (United States)

    Pradhan, B.; Mansor, Shattri; Ramli, Abdul Rahman; Mohamed Sharif, Abdul Rashid B.; Sandeep, K.

    2005-10-01

    The lifting scheme has been found to be a flexible method for constructing scalar wavelets with desirable properties. In this paper, it is extended to the LIDAR data compression. A newly developed data compression approach to approximate the LIDAR surface with a series of non-overlapping triangles has been presented. Generally a Triangulated Irregular Networks (TIN) are the most common form of digital surface model that consists of elevation values with x, y coordinates that make up triangles. But over the years the TIN data representation has become a case in point for many researchers due its large data size. Compression of TIN is needed for efficient management of large data and good surface visualization. This approach covers following steps: First, by using a Delaunay triangulation, an efficient algorithm is developed to generate TIN, which forms the terrain from an arbitrary set of data. A new interpolation wavelet filter for TIN has been applied in two steps, namely splitting and elevation. In the splitting step, a triangle has been divided into several sub-triangles and the elevation step has been used to 'modify' the point values (point coordinates for geometry) after the splitting. Then, this data set is compressed at the desired locations by using second generation wavelets. The quality of geographical surface representation after using proposed technique is compared with the original LIDAR data. The results show that this method can be used for significant reduction of data set.

  16. DOPPLER ANALYSIS IN PREGNANCY INDUCED HYPERTENSION

    Directory of Open Access Journals (Sweden)

    Tushar

    2014-12-01

    Full Text Available A study of 50 cases was conducted to evaluate the role of Colour Doppler imaging in pregnancy induced hypertension with women over 28 weeks of gestation, the initial scan was performed immediately after the diagnosis of PIH to avoid any influence of treatment on Doppler evaluation. This study was aimed to analyze the blood flow in umbilical artery, maternal uterine artery & fetal middle cerebral artery using Doppler ultrasound.

  17. Improving Lidar Turbulence Estimates for Wind Energy

    Energy Technology Data Exchange (ETDEWEB)

    Newman, Jennifer F.; Clifton, Andrew; Churchfield, Matthew J.; Klein, Petra

    2016-10-06

    Remote sensing devices (e.g., lidars) are quickly becoming a cost-effective and reliable alternative to meteorological towers for wind energy applications. Although lidars can measure mean wind speeds accurately, these devices measure different values of turbulence intensity (TI) than an instrument on a tower. In response to these issues, a lidar TI error reduction model was recently developed for commercially available lidars. The TI error model first applies physics-based corrections to the lidar measurements, then uses machine-learning techniques to further reduce errors in lidar TI estimates. The model was tested at two sites in the Southern Plains where vertically profiling lidars were collocated with meteorological towers. This presentation primarily focuses on the physics-based corrections, which include corrections for instrument noise, volume averaging, and variance contamination. As different factors affect TI under different stability conditions, the combination of physical corrections applied in L-TERRA changes depending on the atmospheric stability during each 10-minute time period. This stability-dependent version of L-TERRA performed well at both sites, reducing TI error and bringing lidar TI estimates closer to estimates from instruments on towers. However, there is still scatter evident in the lidar TI estimates, indicating that there are physics that are not being captured in the current version of L-TERRA. Two options are discussed for modeling the remainder of the TI error physics in L-TERRA: machine learning and lidar simulations. Lidar simulations appear to be a better approach, as they can help improve understanding of atmospheric effects on TI error and do not require a large training data set.

  18. Emboli detection using the Doppler ultrasound technique

    Institute of Scientific and Technical Information of China (English)

    WANG Yuanyuan; CHEN Xi; ZHANG Yu; WANG Weiqi

    2003-01-01

    Embolic detection is very important to the early diagnosis of vessel disease. The Doppler ultrasound technique is one of the common methods to detect the emboli non-invasively. When the emboli pass through the sample volume of the Doppler ultrasound instrument, there exist high intensity transient Doppler signals. Thus the emboli can be detected directly from the variation of Doppler signal amplitude. Since there may be some disturbance in the system, this general detection method has great limitation. To improve the accuracy of emboli auto-detection, several novel methods are studied to obtain the sensitive characteristic of the emboli signals using the new signal processing theories.

  19. Advances in High Energy Solid-State Pulsed 2-Micron Lidar Development for Ground and Airborne Wind, Water Vapor and CO2 Measurements

    Science.gov (United States)

    Singh, Upendra N.; Yu, Jirong; Petros, Mulugeta; Refaat, Tamer; Kavaya, Michael J.; Remus, Ruben

    2015-01-01

    NASA Langley Research Center has a long history of developing 2-micron lasers. From fundamental spectroscopy research, theoretical prediction of new materials, laser demonstration and engineering of lidar systems, it has been a very successful program spanning around two decades. Successful development of 2-micron lasers has led to development of a state-of-the-art compact lidar transceiver for a pulsed coherent Doppler lidar system for wind measurement with an unprecedented laser pulse energy of 250 millijoules in a rugged package. This high pulse energy is produced by a Ho:Tm:LuLiF laser with an optical amplifier. While the lidar is meant for use as an airborne instrument, ground-based tests were carried out to characterize performance of the lidar. Atmospheric measurements will be presented, showing the lidar's capability for wind measurement in the atmospheric boundary layer and free troposphere. Lidar wind measurements are compared to a balloon sonde, showing good agreement between the two sensors. Similar architecture has been used to develop a high energy, Ho:Tm:YLF double-pulsed 2-micron Integrated Differential Absorption Lidar (IPDA) instrument based on direct detection technique that provides atmospheric column CO2 measurements. This instrument has been successfully used to measure atmospheric CO2 column density initially from a ground mobile lidar trailer, and then it was integrated on B-200 plane and 20 hours of flight measurement were made from an altitude ranging 1500 meters to 8000 meters. These measurements were compared to in-situ measurements and National Oceanic and Atmospheric Administration (NOAA) airborne flask measurement to derive the dry mixing ratio of the column CO2 by reflecting the signal by various reflecting surfaces such as land, vegetation, ocean surface, snow and sand. The lidar measurements when compared showed a very agreement with in-situ and airborne flask measurement. NASA Langley Research Center is currently developing a

  20. Impacts of Geomagnetic storms on the mid-latitude mesosphere and lower thermosphere observed by a Na lidar and TIMED/GUVI

    Science.gov (United States)

    Yuan, T.; Zhang, Y.

    2015-12-01

    In this paper, we report our findings on the correlation between the neutral temperature (around the mesopause) and thermospheric column density O/N2 ratio, along with their response to geomagnetic storms above mid-latitude of North America. A temperature/wind Doppler Na lidar, operating at Fort Collins, CO (41°N, 105°W) and later at Logan, UT (42°N and 112°W), observed significant temperature increases (temperature anomaly) above 95 km (as much as 55 K at 105 km altitude) during four geomagnetic storms (April 2002, Nov. 2004, May 2005 and Oct. 2012). Coincident TIMED/GUVI observations indicate significant depletion in the thermospheric O/N2 ratio at the lidar locations. These observations suggest that the local mesopause warming seen by the lidar is due to transport of the high-latitude Joule and particle heated neutrals at the E and F layers to the mid-latitude region.

  1. Solid-State 2-Micron Laser Transmitter Advancement for Wind and Carbon Dioxide Measurements From Ground, Airborne, and Space-Based Lidar Systems

    Science.gov (United States)

    Singh, Upendra N.; Kavaya, Michael J.; Koch, Grady; Yu, Jirong; Ismail, Syed

    2008-01-01

    NASA Langley Research Center has been developing 2-micron lidar technologies over a decade for wind measurements, utilizing coherent Doppler wind lidar technique and carbon dioxide measurements, utilizing Differential Absorption Lidar (DIAL) technique. Significant advancements have been made towards developing state-of-the-art technologies towards laser transmitters, detectors, and receiver systems. These efforts have led to the development of solid-state lasers with high pulse energy, tunablility, wavelength-stability, and double-pulsed operation. This paper will present a review of these technological developments along with examples of high resolution wind and high precision CO2 DIAL measurements in the atmosphere. Plans for the development of compact high power lasers for applications in airborne and future space platforms for wind and regional to global scale measurement of atmospheric CO2 will also be discussed.

  2. First results of combined Fe-lidar/Radar measurements at Davis, 69° S.

    Science.gov (United States)

    Höffner, J.; Morris, R. J.; Kaifler, B.; Viehl, T.; Lübken, F.-J.

    2012-04-01

    The mobile scanning Fe-lidar of the IAP-Kühlungsborn was moved to Davis, Antarctica, 69° S, 78° E during November 2010. This location was chosen because PMSE/NLC observations by MST-radar/RMR-lidar have been performed since 2003/2001 by the Australian Antarctic Division. Davis is the only station in Antarctica where comparable long-term observations to Alomar, 69° N are available. A comparison of both locations allows a detailed comparison of differences or similarities between the northern (NH) / southern hemisphere (SH) at mesopause altitudes. The Fe-lidar is a two wavelength system which measures Doppler temperature/vertical wind and iron densities by resonance scattering at 386 nm. The fundamental wavelength at 772 nm is used for aerosol measurements from the stratosphere to the mesosphere including NLC in summer or PSC in winter. Measurements are almost background free which allows year round operation independent of sunlight. At Davis the lidar was in operation 24% of the first year (2150 hours) which has not been achieved elsewhere with a mesospheric lidar. This unusual and already largest lidar data base of Antarctica shows the thermal structure of the mesopause region and the iron layer in great detail. Strong tides throughout the year have been observed and a link of the early part of the PMSE season to the stratospheric vortex has been found. More than 700 hours of temperature observation during the PMSE-season are compared with common volume PMSE/NLC observations. For the first time temperature and vertical wind measurements through PMSE and NLC have been achieved by a lidar showing that the SH in particular in December/January differs significantly from the NH in June/July. The temperature measurements near 86 km altitude show that the summer mesopause is surprisingly similar to the NH at PMSE altitudes but differs significantly at higher altitudes. Unlike the NH the southern mesopause altitude changes throughout the season by several kilometres

  3. Standards – An Important Step for the (Public) Use of Lidars

    OpenAIRE

    Althausen Dietrich; Emeis Stefan; Flentje Harald; Guttenberger Josef; Jäckel Simon; Lehmann Volker; Mattis Ina; Münkel Christoph; Peters Gerhard; Ritter Christoph; Wiegner Matthias; Wille Holger

    2016-01-01

    Lidar standards are needed to ensure quality and lidar product control at the interface between lidar manufacturers and lidar users. Meanwhile three lidar standards have been published by German and international standardization organizations. This paper describes the cooperation between the lidar technique inventors, lidar instrument constructors, and lidar product users to establish useful standards. Presently a backscatter lidar standard is elaborated in Germany. Key points of this standar...

  4. 2006 South Carolina DNR Lidar: Aiken County

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The LiDAR data acquisition was executed in five sessions, on March 15, 16 & 17, 2006, using a Leica ALS50 LiDAR System. Specific details about the ALS50 system...

  5. Saginaw Bay, MI LiDAR

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — TASK NAME:(NRCS) Saginaw Bay, MI LiDAR LiDAR Data Acquisition and Processing Production Task USGS Contract No. G10PC00057 Task Order No. G11PD01254 Woolpert Order...

  6. Inclined test of nacelle wind lidar

    DEFF Research Database (Denmark)

    Courtney, Michael

    A nacelle wind lidar, placed at ground level, is tested by inclining the laser beams to bisect a measurement mast at a known distance and height. The horizontal wind speed reported by the lidar is compared to a reference cup anemometer mounted on the mast at the comparison height....

  7. Lidar measured vertical atmospheric scattering profiles

    NARCIS (Netherlands)

    Kunz, G.J.

    1985-01-01

    The vertical structure of the atmosphere, which is of invaluable interest to meteorologists, geo-physicists and environmental researchers, can be measured with LIDAR. A method has been proposed and applied to invert lidar signals from vertical soundings to height resolved scattering coefficients. In

  8. CALIPSO lidar ratio retrieval over the ocean.

    Science.gov (United States)

    Josset, Damien; Rogers, Raymond; Pelon, Jacques; Hu, Yongxiang; Liu, Zhaoyan; Omar, Ali; Zhai, Peng-Wang

    2011-09-12

    We are demonstrating on a few cases the capability of CALIPSO to retrieve the 532 nm lidar ratio over the ocean when CloudSat surface scattering cross section is used as a constraint. We are presenting the algorithm used and comparisons with the column lidar ratio retrieved by the NASA airborne high spectral resolution lidar. For the three cases presented here, the agreement is fairly good. The average CALIPSO 532 nm column lidar ratio bias is 13.7% relative to HSRL, and the relative standard deviation is 13.6%. Considering the natural variability of aerosol microphysical properties, this level of accuracy is significant since the lidar ratio is a good indicator of aerosol types. We are discussing dependencies of the accuracy of retrieved aerosol lidar ratio on atmospheric aerosol homogeneity, lidar signal to noise ratio, and errors in the optical depth retrievals. We are obtaining the best result (bias 7% and standard deviation around 6%) for a nighttime case with a relatively constant lidar ratio (in the vertical) indicative of homogeneous aerosol type.

  9. Conically scanning lidar error in complex terrain

    DEFF Research Database (Denmark)

    Bingöl, Ferhat; Mann, Jakob; Foussekis, Dimitri

    2009-01-01

    Conically scanning lidars assume the flow to be homogeneous in order to deduce the horizontal wind speed. However, in mountainous or complex terrain this assumption is not valid implying a risk that the lidar will derive an erroneous wind speed. The magnitude of this error ismeasured by collocating...

  10. Development of lidar techniques for environmental studies

    Energy Technology Data Exchange (ETDEWEB)

    Andersson, Mats

    1996-09-01

    The lidar group in Lund has performed many DIAL measurements with a mobile lidar system that was first described in 1987. The lidar system is based on a Nd:YAG-pumped dye laser. During the last few years the lidar group has focused on fluorescence imaging and mercury measurements in the troposphere. In 1994 we performed two campaigns: one fluorescence imaging measurement campaign outside Avignon, France and one unique lidar campaign at a mercury mine in Almaden, Spain. Both campaigns are described in this thesis. This thesis also describes how the mobile lidar system was updated with the graphical programming language LabVIEW to obtain a user friendly lidar system. The software controls the lidar system and analyses measured data. The measurement results are shown as maps of species concentration. All electronics and the major parts of the program are described. A new graphical technique to estimate wind speed from plumes is also discussed. First measurements have been performed with the new system. 31 refs, 19 figs, 1 tab

  11. Lidar measured vertical atmospheric scattering profiles

    NARCIS (Netherlands)

    Kunz, G.J.

    1985-01-01

    The vertical structure of the atmosphere, which is of invaluable interest to meteorologists, geo-physicists and environmental researchers, can be measured with LIDAR. A method has been proposed and applied to invert lidar signals from vertical soundings to height resolved scattering coefficients. In

  12. Backscatter nephelometer to calibrate scanning lidar

    Science.gov (United States)

    Cyle E. Wold; Vladmir A. Kovalev; Wei Min Hao

    2008-01-01

    The general concept of an open-path backscatter nephelometer, its design, principles of calibration and the operational use are discussed. The research-grade instrument, which operates at the wavelength 355 nm, will be co-located with a scanning-lidar at measurement sites near wildfires, and used for the lidar calibration. Such a near-end calibration has significant...

  13. 2013 NRCS-USGS Lidar: Lauderdale (MS)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — TASK NAME:NRCS LAUDERDALE MS 0.7M NPS LIDAR. LiDAR Data Acquisition and Processing Production Task. USGS Contract No. G10PC00057. Task Order No. G12PD000125 Woolpert...

  14. 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...

  15. 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...

  16. Application of coherent 10 micron imaging lidar

    Energy Technology Data Exchange (ETDEWEB)

    Simpson, M.L.; Hutchinson, D.P.; Richards, R.K.; Bennett, C.A.

    1997-04-01

    With the continuing progress in mid-IR array detector technology and high bandwidth fan-outs, i.f. electronics, high speed digitizers, and processing capability, true coherent imaging lidar is becoming a reality. In this paper experimental results are described using a 10 micron coherent imaging lidar.

  17. 2012 USGS Lidar: Elwha River (WA)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — TASK NAME: Elwha River, WA LiDAR LiDAR Data Acquisition and Processing Production Task USGS Contract No. G10PC00057 Task Order No. G11PD01088 Woolpert Order No....

  18. 0.355 μm direct detection wind lidar under testing during a field campaign in consideration of ESA's ADM-Aeolus Mission

    Directory of Open Access Journals (Sweden)

    S. Lolli

    2013-05-01

    Full Text Available The atmospheric wind field information is a key issue to Numerical Weather Prediction (NWP and climate studies. A space based Wind Doppler lidar mission so-called ADM-Aeolus is currently developed by the European Space Agency for a launch in 2015. Such a Doppler lidar will provide accurate direct measurements of horizontal wind velocity in the depth of atmosphere. The wind data will be evenly distributed at a global scale. The goal is to enhance the present meteorological observation system over sparse wind data regions, and more important to provide direct wind information in the tropics where no geostrophic wind can be derived from passive radiometer satellite. ADM-Aeolus is basically a 0.355 μm high spectral resolution backscatter lidar. This concept was under test during a field campaign conducted at the Haute Provence Observatory in France 1999. It was the opportunity to address the self-consistency of wind measurements made by different active remote sensors i.e. lidars and a 72-MHz radar, and balloon radio soundings.

  19. 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.

  20. 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.

  1. Generating passive NIR images from active LIDAR

    Science.gov (United States)

    Hagstrom, Shea; Broadwater, Joshua

    2016-05-01

    Many modern LIDAR platforms contain an integrated RGB camera for capturing contextual imagery. However, these RGB cameras do not collect a near-infrared (NIR) color channel, omitting information useful for many analytical purposes. This raises the question of whether LIDAR data, collected in the NIR, can be used as a substitute for an actual NIR image in this situation. Generating a LIDAR-based NIR image is potentially useful in situations where another source of NIR, such as satellite imagery, is not available. LIDAR is an active sensing system that operates very differently from a passive system, and thus requires additional processing and calibration to approximate the output of a passive instrument. We examine methods of approximating passive NIR images from LIDAR for real-world datasets, and assess differences with true NIR images.

  2. Calibration Methods for a Space Borne Backscatter Lidar

    NARCIS (Netherlands)

    Kunz, G.J.

    1996-01-01

    Lidar returns from cloud decks and from the Earth's surface are useful for calibrating single scatter lidar signals from space. To this end analytical methods (forward and backward) are presented for inverting lidar waveforms in terms of the path integrated lidar retum and the transmission losses ov

  3. Vapor Measurements from the GSFC Stratospheric Ozone Lidar

    Science.gov (United States)

    McGee, T.

    2003-01-01

    Water vapor measurements from the GSFC Stratospheric Ozone Lidar were made for the first time during a campaign at NOAA's Mauna Loa Observatory. Comparisons were made among the GSFC lidar, the NOAA Lidar and water vapor sondes which were flown from the observatory at times coincident with the lidar measurements.

  4. Calibration Methods for a Space Borne Backscatter Lidar

    NARCIS (Netherlands)

    Kunz, G.J.

    1996-01-01

    Lidar returns from cloud decks and from the Earth's surface are useful for calibrating single scatter lidar signals from space. To this end analytical methods (forward and backward) are presented for inverting lidar waveforms in terms of the path integrated lidar retum and the transmission losses

  5. Performance test of the synergetic use of simulated lidar and microwave radiometer observations for mixing-layer height detection

    Science.gov (United States)

    Saeed, Umar; Rocadenbosch, Francesc; Crewell, Susanne

    2015-10-01

    There are several instruments and methods to retrieve the atmospheric Mixing Layer Height (MLH). However, none of these instruments or methods can measure the development of the MLH under all atmospheric conditions. For example, aerosol signatures measured by backscatter lidars can be used to determine the MLH but this approach is reasonable only when the atmosphere is well-mixed. Microwave Radiometer (MWR) derived profiles have low vertical resolution and cannot resolve fine structures in the boundary layer, especially, at higher altitudes. Here we propose a method which combines data from a ground-based lidar and a MWR, in simulated as well as real measurements scenarios, to overcome these limitations. The method works by fitting an erf-like transition model function to the section of range-corrected lidar backscatter signal. The section of the lidar backscatter signal for fitting the model function is obtained by incorporating the MWR estimates of MLH along with their uncertainties. The fitting is achieved by using an extended Kalman filter (EKF). The proposed approach, by exploiting the synergy between the two instruments, enables to detect MLH with original vertical and temporal resolutions. Test cases combining simulated data for a co-located lidar-ceilometer and a MWR are presented. The simulated data is obtained from the Dutch Atmospheric Large Eddy Simulation (DALES) model for boundary layer studies. Doppler wind lidar along with radiosondes (whenever available) data is used to assess the quality of the synergetic MLH estimates. Data from the HD(CP)2 Observational Prototype Experiment (HOPE) campaign at Jülich, Germany is used to test the proposed method.

  6. Full-Scale Field Test of a Blade-Integrated Dual-Telescope Wind Lidar

    DEFF Research Database (Denmark)

    Pedersen, Anders Tegtmeier; Sjöholm, Mikael; Angelou, Nikolas

    Introduction In recent years the use of wind lidars mounted directly on wind turbines has received increasing attention, and such systems are becoming commercially available. One aim of turbine-mounted wind lidars is to use them for prevision in connection with advanced feed-forward control systems...... for alleviating loads and also for active individual pitch control. Approach Two small telescope units with 1” optics were mounted on either side of one blade of a Vestas NM80 turbine, 15 m from the spinner and connected through fibre optical cables to a modified ZephIR 300 continuous-wave Doppler lidar from...... Natural Power, UK. The ZephIR was installed in the tip of the spinner of the turbine. The two telescopes’ line-of-sights were converging with 10 angle, resulting in an intersection at 5 m in front of the blade along the cord extension line. By using an optical switch, the line-of-sight wind speeds could...

  7. Measurement and Study of Lidar Ratio by Using a Raman Lidar in Central China.

    Science.gov (United States)

    Wang, Wei; Gong, Wei; Mao, Feiyue; Pan, Zengxin; Liu, Boming

    2016-05-18

    We comprehensively evaluated particle lidar ratios (i.e., particle extinction to backscatter ratio) at 532 nm over Wuhan in Central China by using a Raman lidar from July 2013 to May 2015. We utilized the Raman lidar data to obtain homogeneous aerosol lidar ratios near the surface through the Raman method during no-rain nights. The lidar ratios were approximately 57 ± 7 sr, 50 ± 5 sr, and 22 ± 4 sr under the three cases with obviously different pollution levels. The haze layer below 1.8 km has a large particle extinction coefficient (from 5.4e-4 m(-1) to 1.6e-4 m(-1)) and particle backscatter coefficient (between 1.1e-05 m(-1)sr(-1) and 1.7e-06 m(-1)sr(-1)) in the heavily polluted case. Furthermore, the particle lidar ratios varied according to season, especially between winter (57 ± 13 sr) and summer (33 ± 10 sr). The seasonal variation in lidar ratios at Wuhan suggests that the East Asian monsoon significantly affects the primary aerosol types and aerosol optical properties in this region. The relationships between particle lidar ratios and wind indicate that large lidar ratio values correspond well with weak winds and strong northerly winds, whereas significantly low lidar ratio values are associated with prevailing southwesterly and southerly wind.

  8. Performance simulation of a spaceborne infrared coherent lidar for measuring tropospheric wind profiles.

    Science.gov (United States)

    Baron, Philippe; Ishii, Shoken; Kyoka, Gamo; Mizutani, Kohei; Chikako, Takahashi; Itabe, Toshikazu; Iwasaki, Toshiki; Kubota, Takuji; Okamoto, Kozo; Oki, Riko; Satoh, Masaki; Satoh, Yohei

    2014-05-01

    An effort has begun in Japan to develop a spaceborne instrument for measuring tropospheric winds. This project is a collaboration between the Japan Aerospace Exploration Agency (JAXA), the Meteorological Research Institute (MRI, Japan) and the National Institute of Information and Communications Technology (NICT, Japan) [1,2]. The aim is to measure the horizontal wind field in the troposphere on a global scale with a precision better than 3 ms-1, and a vertical and horizontal (along the satellite ground track) resolution better than 1 km and 100 km, respectively. In order to support the definition and the development of the instrument, an end-to-end simulator has been implemented including modules for i) simulating the time-dependent laser shot return power, ii) for averaging the spectral power of several returns and iii) for estimating the line-of-sight wind from the Doppler shift of the averaged spectra. The simulations take into account the satellite position and motion along the orbit track, the observational and instrumental characteristics, a 3-D representation of the relevant atmospheric parameters (i.e. wind field, cloud coverage and aerosols distribution) and the Earth surface characteristics. The simulator and the method for estimating the line-of-sight wind will be presented. We will show the results obtained for a payload composed of two 2-μm coherent LIDARs looking in orthogonal directions, and for a satellite moving on a low orbit. The precision, accuracy and the vertical and horizontal resolution of the wind estimates will be discussed. References: [1] S. Ishii, T. Iwasaki, M. Sato, R. Oki, K. Okamoto, T. Ishibashi, P. Baron, and T. Nishizawa, Future Doppler lidar wind measurement from space in Japan, Proc. of SPIE Vol. 8529, 2012 [2] S. Ishii, H. Iwai, K. Mizutani, P. Baron, T. Itabe, H. Fukuoka, T. Ishikawa, A. Sato and A. Asai, 2-μm coherent LIDAR for CO2 and wind measurements, Proc. of SPIE Vol. 8872, 2013

  9. Doppler tomography in fusion plasmas and astrophysics

    DEFF Research Database (Denmark)

    Salewski, Mirko; Geiger, B.; Heidbrink, W. W.

    2015-01-01

    Doppler tomography is a well-known method in astrophysics to image the accretion flow, often in the shape of thin discs, in compact binary stars. As accretion discs rotate, all emitted line radiation is Doppler-shifted. In fast-ion Dα (FIDA) spectroscopy measurements in magnetically confined plas...

  10. 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.

  11. Doppler tomography in fusion plasmas and astrophysics

    NARCIS (Netherlands)

    Salewski, M.; Geiger, B.; Heidbrink, W. W.; Jacobsen, A. S.; Korsholm, S. B.; Leipold, F.; Madsen, J.; Moseev, D.; Nielsen, S.K.; Rasmussen, J.; Stagner, L.; Steeghs, D.; Stejner, M.; Tardini, G.; Weiland, M.; ASDEX Upgrade team,

    2015-01-01

    Doppler tomography is a well-known method in astrophysics to image the accretion flow, often in the shape of thin discs, in compact binary stars. As accretion discs rotate, all emitted line radiation is Doppler-shifted. In fast-ion D-alpha (FIDA) spectroscopy measurements in magnetically confined pl

  12. Inverse Doppler Effects in Broadband Acoustic Metamaterials.

    Science.gov (United States)

    Zhai, S L; Zhao, X P; Liu, S; Shen, F L; Li, L L; Luo, C R

    2016-08-31

    The Doppler effect refers to the change in frequency of a wave source as a consequence of the relative motion between the source and an observer. Veselago theoretically predicted that materials with negative refractions can induce inverse Doppler effects. With the development of metamaterials, inverse Doppler effects have been extensively investigated. However, the ideal material parameters prescribed by these metamaterial design approaches are complex and also challenging to obtain experimentally. Here, we demonstrated a method of designing and experimentally characterising arbitrary broadband acoustic metamaterials. These omni-directional, double-negative, acoustic metamaterials are constructed with 'flute-like' acoustic meta-cluster sets with seven double meta-molecules; these metamaterials also overcome the limitations of broadband negative bulk modulus and mass density to provide a region of negative refraction and inverse Doppler effects. It was also shown that inverse Doppler effects can be detected in a flute, which has been popular for thousands of years in Asia and Europe.

  13. Inverse Doppler Effects in Broadband Acoustic Metamaterials

    Science.gov (United States)

    Zhai, S. L.; Zhao, X. P.; Liu, S.; Shen, F. L.; Li, L. L.; Luo, C. R.

    2016-08-01

    The Doppler effect refers to the change in frequency of a wave source as a consequence of the relative motion between the source and an observer. Veselago theoretically predicted that materials with negative refractions can induce inverse Doppler effects. With the development of metamaterials, inverse Doppler effects have been extensively investigated. However, the ideal material parameters prescribed by these metamaterial design approaches are complex and also challenging to obtain experimentally. Here, we demonstrated a method of designing and experimentally characterising arbitrary broadband acoustic metamaterials. These omni-directional, double-negative, acoustic metamaterials are constructed with ‘flute-like’ acoustic meta-cluster sets with seven double meta-molecules; these metamaterials also overcome the limitations of broadband negative bulk modulus and mass density to provide a region of negative refraction and inverse Doppler effects. It was also shown that inverse Doppler effects can be detected in a flute, which has been popular for thousands of years in Asia and Europe.

  14. Observation of the Zero Doppler Effect

    Science.gov (United States)

    Ran, Jia; Zhang, Yewen; Chen, Xiaodong; Fang, Kai; Zhao, Junfei; Chen, Hong

    2016-04-01

    The normal Doppler effect has well-established applications in many areas of science and technology. Recently, a few experimental demonstrations of the inverse Doppler effect have begun to appear in negative-index metamaterials. Here we report an experimental observation of the zero Doppler effect, that is, no frequency shift irrespective of the relative motion between the wave signal source and the detector in a zero-index metamaterial. This unique phenomenon, accompanied by the normal and inverse Doppler effects, is generated by reflecting a wave from a moving discontinuity in a composite right/left-handed transmission line loaded with varactors when operating in the near zero-index passband, or the right/left-handed passband. This work has revealed a complete picture of the Doppler effect in metamaterials and may lead to potential applications in electromagnetic wave related metrology.

  15. 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...

  16. Differential absorption lidar measurements of atmospheric water vapor using a pseudonoise code modulated AlGaAs laser. Thesis

    Science.gov (United States)

    Rall, Jonathan A. R.

    1994-01-01

    Lidar measurements using pseudonoise code modulated AlGaAs lasers are reported. Horizontal path lidar measurements were made at night to terrestrial targets at ranges of 5 and 13 km with 35 mW of average power and integration times of one second. Cloud and aerosol lidar measurements were made to thin cirrus clouds at 13 km altitude with Rayleigh (molecular) backscatter evident up to 9 km. Average transmitter power was 35 mW and measurement integration time was 20 minutes. An AlGaAs laser was used to characterize spectral properties of water vapor absorption lines at 811.617, 816.024, and 815.769 nm in a multipass absorption cell using derivative spectroscopy techniques. Frequency locking of an AlGaAs laser to a water vapor absorption line was achieved with a laser center frequency stability measured to better than one-fifth of the water vapor Doppler linewidth over several minutes. Differential absorption lidar measurements of atmospheric water vapor were made in both integrated path and range-resolved modes using an externally modulated AlGaAs laser. Mean water vapor number density was estimated from both integrated path and range-resolved DIAL measurements and agreed with measured humidity values to within 6.5 percent and 20 percent, respectively. Error sources were identified and their effects on estimates of water vapor number density calculated.

  17. Color doppler sonography in thickened gallbladder wall

    Energy Technology Data Exchange (ETDEWEB)

    Han, Sang Suk; Choi, Seok Jin; Seo, Chang Hae; Eun, Choong Ki [Inje Univ. College of Medicine, Kimhae (Korea, Republic of)

    1996-11-01

    The thickening of the gallbladder wall is a valuable finding for the diagnosis of cholecystitis, but may be seen in non-cholecystic disease as well as in acute or chronic cholecystitis. The purpose of this study is to determine the value of color Doppler sonography in differentiating the causes of thickened gallbladder wall. Ninety eight patients with thickened gallbladder wall(more than 3mm) which was not due to gallbladder cancer were prospectively evaluated with color Doppler sonography. Sixty-six cases, confirmed by pathologic reports and clinical records, were analyzed for correlation between thickened gallbladder wall and color flow signal according to the underlying causes. Of the 66 patients, 28 cases were cholecystitis and 38 cases had non-cholecystic causes such as liver cirrhosis, ascites, hepatitis, pancreatitis, renal failure, and hypoalbuminemia. Of the 28 patients with cholecystitis(12 acute, 16 chronic), 23(82%) had color Doppler flow signals in the thickened gallbladder wall. Of the 38 patients with non-cholecystic causes, eight(21%) had color Doppler flow signals. There was a statistically significant difference of color Doppler flow signals between the cholecystitis and non-cholecystic groups(p=0.0001). No significant difference of color Doppler flow signals was found between cases of acute and chronic cholecystitis. Of the 23 patients with color Doppler flow signals in 28 cases of cholecystitis, 18(78.3%) showed a linear pattern and five(21.7%) showed a spotty pattern. Of the eight patients with color Doppler flow signals in the 38 non-cholecystic cases, four(50%) showed a linear pattern and four(50%) showed a spotty pattern. In cholecystitis, a linear color Doppler flow signal pattern is a much more frequent finding than a spotty pattern. Color Doppler sonography is a useful and adequate method for determining whether a thickened gallbladder wall is the result of cholecystitis or has non-cholecystic causes.

  18. Vertical Profiles of the 3-D Wind Velocity Retrieved from Multiple Wind Lidars Performing Triple Range-Height-Indicator Scans

    Energy Technology Data Exchange (ETDEWEB)

    Debnath, Mithu; Iungo, G. Valerio; Ashton, Ryan; Brewer, W. Alan; Choukulkar, Aditya; Delgado, Ruben; Lundquist, Julie K.; Shaw, William J.; Wilczak, James M.; Wolfe, Daniel

    2017-02-06

    Vertical profiles of 3-D wind velocity are retrieved from triple range-height-indicator (RHI) scans performed with multiple simultaneous scanning Doppler wind lidars. This test is part of the eXperimental Planetary boundary layer Instrumentation Assessment (XPIA) campaign carried out at the Boulder Atmospheric Observatory. The three wind velocity components are retrieved and then compared with the data acquired through various profiling wind lidars and high-frequency wind data obtained from sonic anemometers installed on a 300 m meteorological tower. The results show that the magnitude of the horizontal wind velocity and the wind direction obtained from the triple RHI scans are generally retrieved with good accuracy. However, poor accuracy is obtained for the evaluation of the vertical velocity, which is mainly due to its typically smaller magnitude and to the error propagation connected with the data retrieval procedure and accuracy in the experimental setup.

  19. Large Aperture Scanning Lidar Based on Holographic Optical Elements

    Science.gov (United States)

    Schwemmer, Geary K.; Miller, David O.; Wilkerson, Thomas D.; Andrus, Ionio; Guerra, David V.; Einaudi, Franco (Technical Monitor)

    2001-01-01

    Lidar remote sensing instruments can make a significant contribution to satisfying many of the required measurements of atmospheric and surface parameters for future spaceborne platforms, including topographic altimeters, atmospheric profiles of, wind, humidity, temperature, trace molecules, aerosols, and clouds. It is highly desirable to have wide measurement swaths for rapid coverage rather than just the narrow ribbon of data that is obtained with a nadir only observation. For most applications global coverage is required, and for wind measurements scanning or pointing is required in order to retrieve the full 3-D wind vector from multiple line-of-sight Doppler measurements. Conventional lidar receivers make up a substantial portion of the instrument's size and weight. Wide angle scanning typically requires a large scanning mirror in front of the receiver telescope, or pointing the entire telescope and aft optics assembly, Either of these methods entails the use of large bearings, motors, gearing and their associated electronics. Spaceborne instruments also need reaction wheels to counter the torque applied to the spacecraft by these motions. NASA has developed simplified conical scanning telescopes using Holographic Optical Elements (HOEs) to reduce the size, mass, angular momentum, and cost of scanning lidar systems. NASA has developed two operating lidar systems based on 40 cm diameter HOEs. The first such system, named Prototype Holographic Atmospheric Scanner for Environmental Remote Sensing (PHASERS) was a joint development between NASA Goddard Space Flight Center (GSFC) and the University of Maryland College Park. PHASERS is based on a reflection HOE for use at the doubled Nd:YAG laser wavelength of 532 nm and has recently undergone a number of design changes in a collaborative effort between GSFC and Saint Anselm College in New Hampshire. The next step was to develop IR transmission HOEs for use with the Nd:YAG fundamental in the Holographic Airborne

  20. Flash lidar performance testing: configuration and results

    Science.gov (United States)

    Poberezhskiy, Ilya; Johnson, Andrew; Chang, Daniel; Ek, Eric; Natzic, David; Spiers, Gary; Penniman, Steve; Short, Brad

    2012-06-01

    Future planetary and lunar landers can benefit from a hazard detection (HD) system that employs a lidar to create a highresolution 3D terrain map in the vicinity of the landing site and an onboard computer to process the lidar data and identify the safest landing site within the surveyed area. A divert maneuver would then be executed to land in this safe site. An HD system enables landing in regions with a relatively high hazard abundance that would otherwise be considered unacceptably risky, but are of high interest to the scientific community. A key component of a HD system is a lidar with the ability to generate a 3D terrain image with the required range precision in the prescribed time and fits within the project resource constraints. In this paper, we present the results obtained during performance testing of a prototype "GoldenEye" 3D flash lidar developed by ASC, Inc. The testing was performed at JPL with the lidar and the targets separated by 200 m. The analysis of the lidar performance obtained for different target types and albedos, pulse energies, and fields of view is presented and compared to key HD lidar requirements identified for the Mars 2018 lander.

  1. RF-modulated pulsed fiber optic lidar transmitter for improved underwater imaging and communications

    Science.gov (United States)

    Kimpel, F.; Chen, Y.; Fouron, J.-L.; Akbulut, M.; Engin, D.; Gupta, S.

    2011-03-01

    We present results on the design, development and initial testing of a fiber-optic based RF-modulated lidar transmitter operating at 532nm, for underwater imaging application in littoral waters. The design implementation is based on using state-of-the-art high-speed FPGAs, thereby producing optical waveforms with arbitrary digital-RF-modulated pulse patterns with carrier frequencies >= 3GHz, with a repetition rate of 0.5-1MHz, and with average powers >=5W (at 532nm). Use of RF-modulated bursts above 500MHz, instead of single optical pulse lidar detection, reduces the effect of volumetric backscatter for underwater imaging application, leading to an improved signal-to-noise-ratio (SNR) and contrast, for a given range. Initial underwater target detection tests conducted at Patuxent River Naval Air Station, MD, in a large water-tank facility, validates the advantages of this hybrid-lidar-radar (HLR) approach for improved underwater imaging, over a wide range of turbidity levels and both white and black targets. The compact, robust and power-efficient fiber laser architecture lends very well to lidar sensor integration on unmanned-underwater-vehicle (UUV) platforms. HLR transmitters can also provide similar advantages in active-sensing situations dominated by continuous backscatter, e.g. underwater communications, imaging through smoke and fire environment, rotor-craft landing in degraded visual environment, and pointing-tracking of active-EO sensors through fog.

  2. Eye-safe diode laser Doppler lidar with a MEMS beam-scanner

    DEFF Research Database (Denmark)

    Hu, Qi; Pedersen, Christian; Rodrigo, Peter John

    2016-01-01

    at the probing distance (R = 60 m) of each lineof-sight – relevant for meeting eye-safety requirements. The switching time of the MEMS-SM is measured to be in the order of a few milliseconds. Time-shared (0.25 s per line-of-sight) radial wind speed measurements at 50 Hz data rate are experimentally demonstrated...

  3. Pulsed Compression for Aerosol Ranging with Coherent Pulse-Doppler Lidar Systems

    Science.gov (United States)

    1990-12-01

    generation technique requires an impulse function or short time duration pulse as the input to a dispersive phase filter . The frequency transfer...function H(f) of the dispersive phase filter can be expressed in general as H(f) = IH(f)Iexp lU(f)] (122) where the magnitude of the transfer function IH(f...response of the dispersive phase filter to a short time duration signal with large bandwidth B is a long time duration signal with the bandwidth B of

  4. Detection of High Altitude Aircraft Wake Vortices Using Infrared Doppler Lidar: An Assessment

    Science.gov (United States)

    1990-12-01

    velocity distribution ( Tipler , 1987:69). The velocity distribution in ont. direction, say the x-direction, is a i Gaussian distribution with standard...Coherent Laser Radar, Report #CTI-TR-8903. Contract OF33615-88-C-1756. Boulder, CO: Coherent Technologies, Inc., Octo- ber 1989. Tipler , Paul A

  5. Field performance of an all-semiconductor laser coherent Doppler lidar

    DEFF Research Database (Denmark)

    Rodrigo, Peter John; Pedersen, Christian

    2012-01-01

    of providing high data availability, ranging from 85% to 100% even under varying outdoor (temperature and humidity) conditions during the test period. We also show the use of our SL-CDL for monitoring the dependence of aerosol backscatter on relative humidity. This work points to the feasibility of a more...

  6. Performance evaluation of an all-fiber image-reject homodyne coherent Doppler wind lidar

    DEFF Research Database (Denmark)

    Foroughi Abari, Farzad; Pedersen, A. T.; Dellwik, Ebba

    2015-01-01

    a sonic anemometer, as the reference instrument. The measurements clearly show that the image-reject architecture results in more accurate measurements of radial wind velocities close to zero. Close-to-zero velocities are usually associated with the vertical component of the wind and are important...

  7. Estimating the Wind Resource in Uttarakhand: Comparison of Dynamic Downscaling with Doppler Lidar Wind Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Lundquist, J. K.; Pukayastha, A.; St. Martin, C.; Newsom, R.

    2014-03-01

    Previous estimates of the wind resources in Uttarakhand, India, suggest minimal wind resources in this region. To explore whether or not the complex terrain in fact provides localized regions of wind resource, the authors of this study employed a dynamic down scaling method with the Weather Research and Forecasting model, providing detailed estimates of winds at approximately 1 km resolution in the finest nested simulation.

  8. Building Extraction from LIDAR Based Semantic Analysis

    Institute of Scientific and Technical Information of China (English)

    YU Jie; YANG Haiquan; TAN Ming; ZHANG Guoning

    2006-01-01

    Extraction of buildings from LIDAR data has been an active research field in recent years. A scheme for building detection and reconstruction from LIDAR data is presented with an object-oriented method which is based on the buildings' semantic rules. Two key steps are discussed: how to group the discrete LIDAR points into single objects and how to establish the buildings' semantic rules. In the end, the buildings are reconstructed in 3D form and three common parametric building models (flat, gabled, hipped) are implemented.

  9. What Good is Raman Water Vapor Lidar?

    Science.gov (United States)

    Whitman, David

    2011-01-01

    Raman lidar has been used to quantify water vapor in the atmosphere for various scientific studies including mesoscale meteorology and satellite validation. Now the international networks of NDACC and GRUAN have interest in using Raman water vapor lidar for detecting trends in atmospheric water vapor concentrations. What are the data needs for addressing these very different measurement challenges. We will review briefly the scientific needs for water vapor accuracy for each of these three applications and attempt to translate that into performance specifications for Raman lidar in an effort to address the question in the title of "What good is Raman water vapor Iidar."

  10. The long term stability of lidar calibrations

    DEFF Research Database (Denmark)

    Courtney, Michael; Gayle Nygaard, Nicolai

    Wind lidars are now used extensively for wind resource measurements. One of the requirements for the data to be accepted in support of project financing (so-called ‘banka-bility’) is to demonstrate the long-term stability of lidar cali-brations. Calibration results for six Leosphere WindCube li-dars......-ters pertaining in the different calibration periods. This is supported by sliding-window analyses of one lidar at one location where the same order of variation is observed as between pre-service and post-service calibrations....

  11. 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....

  12. Lidar Turbulence Measurements for Wind Energy

    DEFF Research Database (Denmark)

    Mann, Jakob; Sathe, Ameya; Gottschall, Julia

    2012-01-01

    Modeling of the systematic errors in the second-order moments of wind speeds measured by continuous-wave (ZephIR) and pulsed (WindCube) lidars is presented. These lidars use the velocity azimuth display technique to measure the velocity vector. The model is developed for the line-of-sight averaging......, whereas they are up to 70% for the horizontal velocity variances. The systematic errors also vary with atmospheric stability, being lowest for the very unstable conditions. It is concluded that with the current measurement configuration, these lidars cannot be used to measure turbulence precisely....

  13. Optical Doppler tomography and spectral Doppler imaging of localized ischemic stroke in a mouse model

    Science.gov (United States)

    Yu, Lingfeng; Nguyen, Elaine; Liu, Gangjun; Rao, Bin; Choi, Bernard; Chen, Zhongping

    2010-02-01

    We present a combined optical Doppler tomography/spectral Doppler imaging modality to quantitatively evaluate the dynamic blood circulation and the artery blockage before and after a localized ischemic stroke in a mouse model. Optical Doppler Tomography (ODT) combines the Doppler principle with optical coherence tomography for noninvasive localization and measurement of particle flow velocity in highly scattering media with micrometer scale spatial resolution. Spectral Doppler imaging (SDI) provides complementary temporal flow information to the spatially distributed flow information of Doppler imaging. Fast, repeated, ODT scans across an entire vessel were performed to record flow dynamic information with high temporal resolution of cardiac cycles. Spectral Doppler analysis of continuous Doppler images demonstrates how the velocity components and longitudinally projected flow-volume-rate change over time for scatters within the imaging volume using spectral Doppler waveforms. Furthermore, vascular conditions can be quantified with various Doppler-angle-independent flow indices. Non-invasive in-vivo mice experiments were performed to evaluate microvascular blood circulation of a localized ischemic stroke mouse model.

  14. 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.

  15. Rotational Doppler effect in nonlinear optics

    Science.gov (United States)

    Li, Guixin; Zentgraf, Thomas; Zhang, Shuang

    2016-08-01

    The translational Doppler effect of electromagnetic and sound waves has been successfully applied in measurements of the speed and direction of vehicles, astronomical objects and blood flow in human bodies, and for the Global Positioning System. The Doppler effect plays a key role for some important quantum phenomena such as the broadened emission spectra of atoms and has benefited cooling and trapping of atoms with laser light. Despite numerous successful applications of the translational Doppler effect, it fails to measure the rotation frequency of a spinning object when the probing wave propagates along its rotation axis. This constraint was circumvented by deploying the angular momentum of electromagnetic waves--the so-called rotational Doppler effect. Here, we report on the demonstration of rotational Doppler shift in nonlinear optics. The Doppler frequency shift is determined for the second harmonic generation of a circularly polarized beam passing through a spinning nonlinear optical crystal with three-fold rotational symmetry. We find that the second harmonic generation signal with circular polarization opposite to that of the fundamental beam experiences a Doppler shift of three times the rotation frequency of the optical crystal. This demonstration is of fundamental significance in nonlinear optics, as it provides us with insight into the interaction of light with moving media in the nonlinear optical regime.

  16. Staggered Multiple-PRF Ultrafast Color Doppler.

    Science.gov (United States)

    Posada, Daniel; Poree, Jonathan; Pellissier, Arnaud; Chayer, Boris; Tournoux, Francois; Cloutier, Guy; Garcia, Damien

    2016-06-01

    Color Doppler imaging is an established pulsed ultrasound technique to visualize blood flow non-invasively. High-frame-rate (ultrafast) color Doppler, by emissions of plane or circular wavefronts, allows severalfold increase in frame rates. Conventional and ultrafast color Doppler are both limited by the range-velocity dilemma, which may result in velocity folding (aliasing) for large depths and/or large velocities. We investigated multiple pulse-repetition-frequency (PRF) emissions arranged in a series of staggered intervals to remove aliasing in ultrafast color Doppler. Staggered PRF is an emission process where time delays between successive pulse transmissions change in an alternating way. We tested staggered dual- and triple-PRF ultrafast color Doppler, 1) in vitro in a spinning disc and a free jet flow, and 2) in vivo in a human left ventricle. The in vitro results showed that the Nyquist velocity could be extended to up to 6 times the conventional limit. We found coefficients of determination r(2) ≥ 0.98 between the de-aliased and ground-truth velocities. Consistent de-aliased Doppler images were also obtained in the human left heart. Our results demonstrate that staggered multiple-PRF ultrafast color Doppler is efficient for high-velocity high-frame-rate blood flow imaging. This is particularly relevant for new developments in ultrasound imaging relying on accurate velocity measurements.

  17. First results from an iron lidar and a VHF radar at Davis, Antarctica

    Science.gov (United States)

    Luebken, F.; Morris, R. J.; Hoeffner, J.; Kaifler, B.; Viehl, T.

    2012-12-01

    We present temperature measurements at Davis, Antarctica (69°S, 78°E), and compare with simultaneous and co-located radar measurements of polar mesosphere summer echoes (PMSE). The mobile scanning iron lidar of the IAP in Kuehlungsborn was installed at Davis in December 2010. It measures iron densities, vertical winds, and temperatures in the iron layer, i. e. from approximately 80 to 100 km. It is based on probing the Doppler broadened resonance line of iron atoms at 386 nm and can operate under daylight conditions. Typical values for temperature uncertainty, altitude and time resolution are 3-5 K, 1 km, and 1 hour, respectively. The lidar also measures neutral air densities and temperatures in the stratosphere and lower mesosphere. At Davis the lidar has up to now achieved approximately 2700 hours of data which is presumably the largest nearly continuous data set in Antarctica. The mesopause altitude changes throughout the summer season by several kilometers, significantly different from the northern hemisphere summer. Depending on altitude, temperatures can be warmer or colder compared to the NH summer. Temperatures at Davis near 86 km are rather similar to the NH, but they are much colder at higher altitudes. The thermal structure around the mesopause at Davis is closely related to the general circulation in the stratosphere, namely to the transition from winter to summer conditions. Different from expectations we sometimes find the mesopause significantly higher and colder(!) compared to the NH. Furthermore, we find large thermal tides in the summer months with amplitudes of up to 6-7~K, which is much larger than expected from models. The Australien Antarctic Division operates a 55 MHz VHF radar at Davis since February 2003. We report first simultaneous measurements of PMSE and temperatures by the Fe lidar. PMSE are strong radar echoes related to ice particles and therefore require atmospheric temperatures being lower than the frost point temperature

  18. Frequency Stepped Pulse Train Modulated Wind Sensing Lidar

    DEFF Research Database (Denmark)

    Olesen, Anders Sig; Pedersen, Anders Tegtmeier; Rottwitt, Karsten

    2011-01-01

    In this paper a wind sensing lidar utilizing a Frequency Stepped Pulse Train (FSPT) is demonstrated. One of the advantages in the FSTP lidar is that it enables direct measurement of wind speed as a function of distance from the lidar. Theoretically the FSPT lidar continuously produces measurements...... as is the case with a CW lidar, but at the same time with a spatial resolution, and without the range ambiguity originating from e.g. clouds. The FSPT lidar utilizes a frequency sweeping source for generation of the FSPT. The source generates a pulse train where each pulse has an optical carrier frequency...... of frequency shifts corresponding to a specific distance. The spatial resolution depends on the repetition rate of the pulses in the pulse train. Directional wind measurements are shown and compared to a CW lidar measurement. The carrier to noise ratio of the FSPT lidar compared to a CW lidar is discussed...

  19. Special relativity effects for space-based coherent lidar experiments

    Science.gov (United States)

    Raogudimetla, V. S.

    1994-01-01

    case of the space-based coherent lidar, assuming flat ground. Here an interest in developing analytical expression for the location of the receiving point for the return with respect to the satellite, receiving angle and Doppler shift in frequency and amount of tip, all as measured in the satellite moving coordinate system and the diffuse scattering angle at the ground which does not require any compensation. All the three cases of retro-reflection, specular reflection and diffuse scattering by the ground should be treated though retro-reflection and diffuse scattering are more important.

  20. Doppler backscatter properties of a blood-mimicking fluid for Doppler performance assessment.

    Science.gov (United States)

    Ramnarine, K V; Hoskins, P R; Routh, H F; Davidson, F

    1999-01-01

    The Doppler backscatter properties of a blood-mimickig fluid (BMF) were studied to evaluate its suitability for use in a Doppler flow test object. Measurements were performed using a flow rig with C-flex tubing and BMF flow produced by a roller pump or a gear pump. A SciMed Doppler system was used to measure the backscattered Doppler power with a root-mean-square power meter connected to the audio output. Studies investigated the dependence of the backscattered Doppler power of the BMF with: circulation time; batch and operator preparations; storage; sieve size; flow speed; and pump type. A comparison was made with human red blood cells resuspended in saline. The backscatter properties are stable and within International Electrotechnical Commission requirements. The BMF is suitable for use in a test object for Doppler performance assessment.