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Sample records for absorption lidar dial

  1. Estimation of boundary layer humidity fluxes and statistics from airborne differential absorption lidar (DIAL)

    Kiemle, Christoph; Ehret, Gerhard; Giez, Andreas; Davis, Kenneth J.; Lenschow, Donald H.; Oncley, Steven P.

    1997-12-01

    The water vapor differential absorption lidar (DIAL) of the German Aerospace Research Establishment (DLR) was flown aboard the National Center for Atmospheric Research (NCAR) Electra research aircraft during the Boreal Ecosystem-Atmosphere Study (BOREAS). The downward looking lidar system measured two-dimensional fields of aerosol backscatter and water vapor mixing ratio in the convective boundary layer (CBL) and across the CBL top (zt). We show a case study of DIAL observations of vertical profiles of mean water vapor, water vapor variance, skewness, and integral scale in the CBL. In the entrainment zone (EZ) and down to about 0.3 zi the DIAL observations agree with in situ observations and mixed-layer similarity theory. Below, the water vapor optical depth becomes large and the DIAL signal-to-noise ratio degrades. Knowing the water vapor surface flux and the convective velocity scale w* from in situ aircraft measurements, we derive entrainment fluxes by applying the mixed-layer gradient (MLG) and mixed-layer variance (MLV) methods to DIAL mixing ratio gradient and variance profiles. Entrainment flux estimates are sensitive to our estimate of zt. They are shown to be rather insensitive to the input surface flux and to the DIAL data spatial resolution within the investigated range. The estimates break down above about 0.9 zt as the flux-gradient and flux-variance relationships were developed to describe the large-scale mixing in the mid-CBL. The agreement with in situ entrainment flux estimations is within 30% for the MLV method. On a flight leg with significant mesoscale variability the entrainment flux turns out to be 70% higher than the in situ value. This is in good agreement with the fact that large-eddy simulations (LES) of mean water vapor profiles and variances, upon which the MLG and MLV methods are based, do not include mesoscale variability. The additional water vapor variance from mesoscales may then lead to the overestimate of the flux. Deviations from

  2. Diode-laser-based water vapor differential absorption lidar (DIAL) profiler evaluation

    Spuler, S.; Weckwerth, T.; Repasky, K. S.; Nehrir, A. R.; Carbone, R.

    2012-12-01

    We are in the process of evaluating the performance of an eye-safe, low-cost, diode-laser-based, water vapor differential absorption lidar (DIAL) profiler. This class of instrument may be capable of providing continuous water vapor and aerosol backscatter profiles at high vertical resolution in the atmospheric boundary layer (ABL) for periods of months to years. The technology potentially fills a national long term observing facility gap and could greatly benefit micro- and meso-meteorology, water cycle, carbon cycle and, more generally, biosphere-hydrosphere-atmosphere interaction research at both weather and climate variability time scales. For the evaluation, the Montana State University 3rd generation water vapor DIAL was modified to enable unattended operation for a period of several weeks. The performance of this V3.5 version DIAL was tested at MSU and NCAR in June and July of 2012. Further tests are currently in progress with Howard University at Beltsville, Maryland; and with the National Weather Service and Oklahoma University at Dallas/Fort Worth, Texas. The presentation will include a comparison of DIAL profiles against meteorological "truth" at the aforementioned locations including: radiosondes, Raman lidars, microwave and IR radiometers, AERONET and SUOMINET systems. Instrument reliability, uncertainty, systematic biases, detection height statistics, and environmental complications will be evaluated. Performance will be judged in the context of diverse scientific applications that range from operational weather prediction and seasonal climate variability, to more demanding climate system process studies at the land-canopy-ABL interface. Estimating the extent to which such research and operational applications can be satisfied with a low cost autonomous network of similar instruments is our principal objective.

  3. Development of a Differential Absorption Lidar (DIAL) for Carbon Sequestration Site Monitoring

    Johnson, W.; Bares, A.; Nehrir, A. R.; Repasky, K. S.; Carlsten, J.

    2010-12-01

    Rising levels of carbon dioxide (CO2) in the Earth’s atmosphere have been identified as a major contributor to climate change. Geologic carbon sequestration has the potential for mitigating CO2 emission into the atmosphere by capturing CO2 at power generation facilities and storing the CO2 in geologic formations. Several technological challenges need to be overcome for successful geologic sequestration of CO2 including surface monitoring tools and techniques for monitoring CO2 sequestration sites to ensure site integrity and public safety. Researchers at Montana State University are developing an eye-safe scanning differential absorption lidar (DIAL) capable of spatially mapping above-ground CO2 number densities for carbon sequestration site monitoring. The eye-safe scanning CO2 DIAL utilizes a temperature tunable fiber pigtailed distributed feedback (DFB) laser operating wavelength of 1.573 μm to access CO2 absorption features. The output of the DFB laser is split using an inline fiber splitter with part of the light sent to an optical wavemeter to monitor the operating wavelength of the laser transmitter. The remaining light is modulated using an inline acousto-optic modulator producing a pulse train with a 20 kHz pulse repetition frequency and a 2 μs duration. This pulse train is amplified in a commercial fiber amplifier producing up to 80 μJ per pulse energy. The output from the fiber amplifier is sent horizontally through the atmosphere and the scattered light is collected using a 28 cm diameter commercial Schmidt-Cassegrain telescope. The light collected by the telescope is collimated and focused into a multimode optical fiber. A fiber coupled photomultiplier (PMT) tube is then used to monitor the light collected by the DIAL receiver. Data is collected in the following manner. The DFB laser is tuned to the online wavelength of the CO2 absorption feature and data is collected for a user defined time. A feedback loop utilizing the optical wavemeter is used

  4. Ultra Narrowband Optical Filters for Water Vapor Differential Absorption Lidar (DIAL) Atmospheric Measurements

    Stenholm, Ingrid; DeYoung, Russell J.

    2001-01-01

    Differential absorption lidar (DIAL) systems are being deployed to make vertical profile measurements of atmospheric water vapor from ground and airborne platforms. One goal of this work is to improve the technology of such DIAL systems that they could be deployed on space-based platforms. Since background radiation reduces system performance, it is important to reduce it. One way to reduce it is to narrow the bandwidth of the optical receiver system. However, since the DIAL technique uses two or more wavelengths, in this case separated by 0.1 nm, a fixed-wavelength narrowband filter that would encompass both wavelengths would be broader than required for each line, approximately 0.02 nm. The approach employed in this project is to use a pair of tunable narrowband reflective fiber Bragg gratings. The Bragg gratings are germanium-doped silica core fiber that is exposed to ultraviolet radiation to produce index-of-refraction changes along the length of the fiber. The gratings can be tuned by stretching. The backscattered laser radiation is transmitted through an optical circulator to the gratings, reflected back to the optical circulator by one of the gratings, and then sent to a photodiode. The filter reflectivities were >90 percent, and the overall system efficiency was 30 percent.

  5. Field-deployable diode-laser-based differential absorption lidar (DIAL) for profiling water vapor

    Spuler, S. M.; Repasky, K. S.; Morley, B.; Moen, D.; Hayman, M.; Nehrir, A. R.

    2015-03-01

    A field-deployable water vapor profiling instrument that builds on the foundation of the preceding generations of diode-laser-based differential absorption lidar (DIAL) laboratory prototypes was constructed and tested. Significant advances are discussed, including a unique shared telescope design that allows expansion of the outgoing beam for eye-safe operation with optomechanical and thermal stability; multistage optical filtering enabling measurement during daytime bright-cloud conditions; rapid spectral switching between the online and offline wavelengths enabling measurements during changing atmospheric conditions; and enhanced performance at lower ranges by the introduction of a new filter design and the addition of a wide field-of-view channel. Performance modeling, testing, and intercomparisons are performed and discussed. In general, the instrument has a 150 m range resolution with a 10 min temporal resolution; 1 min temporal resolution in the lowest 2 km of the atmosphere is demonstrated. The instrument is shown capable of autonomous long-term field operation - 50 days with a > 95% uptime - under a broad set of atmospheric conditions and potentially forms the basis for a ground-based network of eye-safe autonomous instruments needed for the atmospheric sciences research and forecasting communities.

  6. Field deployable diode-laser-based differential absorption lidar (DIAL) for profiling water vapor

    Spuler, S. M.; Repasky, K. S.; Morley, B.; Moen, D.; Hayman, M.; Nehrir, A. R.

    2014-11-01

    A field deployable water vapor profiling instrument that builds on the foundation of the preceding generations of diode-laser-based differential absorption lidar (DIAL) laboratory prototypes has been constructed and tested. Significant advances are discussed, including: a unique shared telescope design that allows expansion of the outgoing beam for eye-safe operation with opto-mechanical and thermal stability, multi-stage optical filtering enabling measurement during daytime bright-cloud conditions, rapid spectral switching between the online and offline wavelengths enabling measurements during changing atmospheric conditions, and enhanced performance at lower ranges by the introduction of a new filter design and the addition of a wide field-of-view channel. Performance modeling, testing and intercomparisons have been performed and are discussed. In general, the instrument has 150 m range resolution with 10 min temporal resolution - 1 min temporal resolution in the lowest 2 km of the atmosphere is demonstrated. The instrument was shown capable of autonomous long term field operation - 50 days with a >95% uptime - under a broad set of atmospheric conditions and potentially forms the basis for a ground-based network of eye-safe autonomous instruments needed for the atmospheric sciences research and forecasting communities.

  7. Theory and operation of the real-time data acquisition system for the NASA-LaRC differential absorption lidar (DIAL)

    Butler, Carolyn; Spencer, Randall

    1988-01-01

    The improvement of computer hardware and software of the NASA Multipurpose Differential Absorption Lidar (DIAL) system is documented. The NASA DIAL system has undergone development and experimental deployment at NASA/Langley Res. Center for the remote measurement of atmospheric trace gas concentrations from ground and aircraft platforms. A viable DIAL system was developed capable of remotely measuring O3 and H2O concentrations from an aircraft platform. The DIAL Data Acquisition System (DAS) has undergone a number of improvements also. Due to the participation of the DIAL in the Global Tropospheric Experiment, modifications and improvements of the system were tested and used both in the lab and in air. Therefore, this is an operational manual for the DIAL DAS.

  8. Compact Ti:Sapphire laser with its Third Harmonic Generation (THG) for an airborne ozone Differential Absorption Lidar (DIAL) transmitter

    Chen, Songsheng; Storm, Mark E.; Marsh, Waverly D.; Petway, Larry B.; Edwards, William C.; Barnes, James C.

    2001-02-01

    A compact and high-pulse-energy Ti:Sapphire laser with its Third Harmonic Generation (THG) has been developed for an airborne ozone differential absorption lidar (DIAL) to study the distributions and concentrations of the ozone throughout the troposphere. The Ti:Sapphire laser, pumped by a frequency-doubled Nd:YAG laser and seeded by a single mode diode laser, is operated either at 867 nm or at 900 nm with a pulse repetition frequency of 20 Hz. High energy laser pulses (more than 110 mJ/pulse) at 867 nm or 900 nm with a desired beam quality have been achieved and utilized to generate its third harmonics at 289nm or 300nm, which are on-line and off-line wavelengths of an airborne ozone DIAL. After experimentally compared with Beta-Barium Borate (b-BaB2O4 or BBO) nonlinear crystals, two Lithium Triborate (LBO) crystals (5'5'20 mm3) are selected for the Third Harmonic Generation (THG). In this paper, we report the Ti:Sapphire laser at 900nm and its third harmonics at 300nm. The desired high ultraviolet (UV) output pulse energy is more than 30mJ at 300nm and the energy conversion efficiency from 900nm to 300nm is 30%.

  9. Compact Ozone Differential Absorption Lidar (DIAL) Transmitter Using Solid-State Dye Polymers

    Jones, Alton L., Jr.; DeYoung, Russell J.; Elsayid-Ele, Hani

    2001-01-01

    A new potential DIAL laser transmitter is described that uses solid-state dye laser materials to make a simpler, more compact, lower mass laser system. Two solid-state dye laser materials were tested to evaluate their performance in a laser oscillator cavity end pumped by a pulsed Nd:YAG laser at 532 nm. The polymer host polymethyl-methacrylate was injected with a pyrromethene laser dye, PM 580, or PM 597. A narrowband laser oscillator cavity was constructed to produce visible wavelengths of 578 and 600 nm which were frequency doubled into the UV region (299 or 300 nm) by using a BBO crystal, resulting in a maximum energy of 11 mJ at a wavelength of 578 nm when pumped by the Nd:YAG laser at an energy of 100 mJ (532 nm). A maximum output energy of 378 microJ was achieved in the UV region at a wavelength of 289 nm but lasted only 2000 laser shots at a repetition rate of 10 Hz. The results are promising and show that a solid-state dye laser based ozone DIAL system is possible with improvements in the design of the laser transmitter.

  10. Progress towards an Autonomous Field Deployable Diode-Laser-Based Differential Absorption Lidar (DIAL for Profiling Water Vapor in the Lower Troposphere

    Kevin S. Repasky

    2013-11-01

    Full Text Available A laser transmitter has been developed and incorporated into a micro-pulse differential absorption lidar (DIAL for water vapor profiling in the lower troposphere as an important step towards long-term autonomous field operation. The laser transmitter utilizes two distributed Bragg reflector (DBR diode lasers to injection seed a pulsed tapered semiconductor optical amplifier (TSOA, and is capable of producing up to 10 mJ of pulse energy with a 1 ms pulse duration and a 10 kHz pulse repetition frequency. The on-line wavelength of the laser transmitter can operate anywhere along the water vapor absorption feature centered at 828.187 nm (in vacuum depending on the prevailing atmospheric conditions, while the off-line wavelength operates at 828.287 nm. This laser transmitter has been incorporated into a DIAL instrument utilizing a 35.6 cm Schmidt-Cassegrain telescope and fiber coupled avalanche photodiode (APD operating in the photon counting mode. The performance of the DIAL instrument was demonstrated over a ten-day observation period. During this observation period, data from radiosondes were used to retrieve water vapor number density profiles for comparisons with the number density profiles retrieved from the DIAL data.

  11. Progress Toward an Autonomous Field Deployable Diode Laser Based Differential Absorption Lidar (DIAL) for Profiling Water Vapor in the Lower Troposphere

    Repasky, K. S.; Spuler, S.; Nehrir, A. R.; Moen, D.

    2013-12-01

    Water vapor is the most dominant greenhouse gas in the atmosphere and plays an important role in many key atmospheric processes associated with both weather and climate. Water vapor is highly variable in space and time due to large scale transport and biosphere-atmosphere interactions. Having long-term, high-resolution, vertical profiles of water vapor will help to better understand the water vapor structure and variability and its associated impact on weather and climate. A diode laser based differential absorption lidar (DIAL) for full-time water vapor and aerosol profiling in the lower troposphere has been demonstrated at Montana State University. This prototype instrument has the potential to form the basis of a ground based network of eye-safe autonomous instruments that can provide important information on the spatial and temporal variability of water vapor in the lower troposphere. To achieve this potential, major improvements to the prototype instrument need to be implemented and demonstrated including developing a laser transmitter capable of long term operation and modifying the optical receiver to make measurement below 0.5 km. During the past year, work on incorporating a new laser transmitter based on two distributed Bragg reflector (DBR) diode lasers, one operating at the on-line/side-line wavelength and the second operating at the off-line wavelength to injection seed a tapered semiconductor optical amplifier (TSOA) in a master oscillator power amplifier (MOPA) configuration has been completed. Recent work on the optical receiver is driven by the fact that the majority of the atmospheric water vapor resides below 2 km. The current single channel DIAL receiver has a narrow field of view and does not come in to full overlap until approximately 2 km. A two channel DIAL receiver has been designed that will allow the DIAL to achieve full overlap at ranges of less the 0.5 km providing significant improvement to the instrument performance. A discussion of

  12. A Compact Ti:Sapphire Laser With its Third Harmonic Generation (THG) for an Airborne Ozone Differential Absorption Lidar (DIAL) Transmitter

    Chen, Songsheng; Storm, Mark E.; Marsh, Waverly D.; Petway, Larry B.; Edwards, William C.; Barnes, James C.

    2000-01-01

    A compact and high-pulse-energy Ti:Sapphire laser with its Third Harmonic Generation (THG) has been developed for an airborne ozone differential absorption lidar (DIAL) to study the distributions and concentrations of the ozone throughout the troposphere. The Ti:Sapphire laser, pumped by a frequency-doubled Nd:YAG laser and seeded by a single mode diode laser, is operated either at 867 nm or at 900 nm with a pulse repetition frequency of 20 Hz. High energy laser pulses (more than 110 mJ/pulse) at 867 nm or 900 nm with a desired beam quality have been achieved and utilized to generate its third harmonic at 289nm or 300nm, which are on-line and off-line wavelengths of an airborne ozone DIAL. After being experimentally compared with Beta-Barium Borate (beta - BaB2O4 or BBO) nonlinear crystals, two Lithium Triborate (LBO) crystals (5 x 5 x 20 cu mm) are selected for the Third Harmonic Generation (THG). In this paper, we report the Ti:Sapphire laser at 900 nm and its third harmonic at 300 nm. The desired high ultraviolet (UV) output pulse energy is more than 30 mJ at 300 nm and the energy conversion efficiency from 900 nm to 300 nm is 30%.

  13. Development and Deployment of a Compact Eye-Safe Scanning Differential absorption Lidar (DIAL) for Spatial Mapping of Carbon Dioxide for Monitoring/Verification/Accounting at Geologic Sequestration Sites

    Repasky, Kevin

    2014-03-31

    A scanning differential absorption lidar (DIAL) instrument for monitoring carbon dioxide has been developed. The laser transmitter uses two tunable discrete mode laser diodes (DMLD) operating in the continuous wave (cw) mode with one locked to the online absorption wavelength and the other operating at the offline wavelength. Two in-line fiber optic switches are used to switch between online and offline operation. After the fiber optic switch, an acousto- optic modulator (AOM) is used to generate a pulse train used to injection seed an erbium doped fiber amplifier (EDFA) to produce eye-safe laser pulses with maximum pulse energies of 66 {micro}J, a pulse repetition frequency of 15 kHz, and an operating wavelength of 1.571 {micro}m. The DIAL receiver uses a 28 cm diameter Schmidt-Cassegrain telescope to collect that backscattered light, which is then monitored using a photo-multiplier tube (PMT) module operating in the photon counting mode. The DIAL instrument has been operated from a laboratory environment on the campus of Montana State University, at the Zero Emission Research Technology (ZERT) field site located in the agricultural research area on the western end of the Montana State University campus, and at the Big Sky Carbon Sequestration Partnership site located in north-central Montana. DIAL data has been collected and profiles have been validated using a co-located Licor LI-820 Gas Analyzer point sensor.

  14. First attempt to monitor atmospheric glyoxal using differential absorption lidar

    Mei, Liang; Lundin, Patrik; Somesfalean, Gabriel; Hu, Jiandong; Zhao, Guangyu; Svanberg, Sune; Bood, Joakim; Vrekoussis, Mihalis; Papayannis, Alexandros

    2012-11-01

    Glyoxal (CHOCHO), as an indicator of photochemical "hot spots", was for the first time the subject of a differential absorption lidar (DIAL) campaign. The strongest absorption line of glyoxal in the blue wavelength region - 455.1 nm - was chosen as the experimental absorption wavelength. In order to handle the effects of absorption cross-section variation of the interfering gas - nitrogen dioxide (NO2) - three-wavelength DIAL measurements simultaneously detecting glyoxal and NO2, were performed. The differential absorption curves, recorded in July 2012, indicate an extremely low glyoxal concentration in Lund, Sweden, although it is expected to be peaking at this time of the year.

  15. Compact mid-infrared DIAL lidar for ground-based and airborne pipeline monitoring

    Degtiarev, Egor V.; Geiger, Allen R.; Richmond, Richard D.

    2003-04-01

    We report the progress in the development of a compact mid-infrared differential absorption lidar (DIAL) for ground-based and airborne monitoring of leaks in natural gas pipeline systems. This sensor, named Lidar II, weighs approximately 30 kg (70 lbs) and occupies a volume of 0.08 m3 (3.5 ft3). Lidar II can be used on the ground in a topographic mode or in a look-down mode from a helicopter platform. The 10-Hz pulse repetition rate and burst-mode averaging currently limit the airborne inspection speed to 30 km/h. The Lidar II laser transmitter employs an intracavity optical parametric oscillator. Wavelength tuning is accomplished through two mechanisms: a servo-controlled crystal rotation for slow and broad-band tuning and a fast piezo-activated wavelength shifter for on-line/off-line switching in less than 10 ms. The sensor operates in the 3.2-3.5-μm band with the primary focus on hydrocarbons and volatile organics. In the pipeline inspection work, the two main targets are methane and ethane, the latter chemical being important in preventing false positives. Initial results of Lidar II testing on actual pipeline leaks are reported. To supplement the mapping capabilities of Lidar II with range-resolved information, a short-range (less than 300 m) aerosol backscatter lidar is currently under development.

  16. Water vapor differential absorption lidar development and evaluation

    Browell, E. V.; Wilkerson, T. D.; Mcllrath, T. J.

    1979-01-01

    A ground-based differential absorption lidar (DIAL) system is described which has been developed for vertical range-resolved measurements of water vapor. The laser transmitter consists of a ruby-pumped dye laser, which is operated on a water vapor absorption line at 724.372 nm. Part of the ruby laser output is transmitted simultaneously with the dye laser output to determine atmospheric scattering and attenuation characteristics. The dye and ruby laser backscattered light is collected by a 0.5-m diam telescope, optically separated in the receiver package, and independently detected using photomultiplier tubes. Measurements of vertical water vapor concentration profiles using the DIAL system at night are discussed, and comparisons are made between the water vapor DIAL measurements and data obtained from locally launched rawinsondes. Agreement between these measurements was found to be within the uncertainty of the rawinsonde data to an altitude of 3 km. Theoretical simulations of this measurement were found to give reasonably accurate predictions of the random error of the DIAL measurements. Confidence in these calculations will permit the design of aircraft and Shuttle DIAL systems and experiments using simulation results as the basis for defining lidar system performance requirements

  17. Remote Detection of Iodine By using Differential Absorption Lidar

    Differential absorption lidar (DIAL) is frequently used for atmospheric gas monitoring to detect impurities such as nitrogen dioxide, sulfur dioxide, iodine, and ozone. In this paper, DIAL technique of using remote sensing experiment is performed in the previous step. Radioactive iodine emitted by nuclear plants, however, is not frequently measured using DIAL because of the difficulty in preparing samples and its dangerous characteristics. In this paper, we configurated the DIAL system in our laboratory. A head detect the iodine gas of air and detect the iodine gas of cell in the distance of 90m. To lock the frequency of Nd:YAG laser, the iodine cell was used for discriminator. We acquired the signals from iodine cell by various frequency locking ratio that were from 0.1 to 0.9 by steps of 0.1. In the paper, we confirmed that the signals from the iodine target cell was proportional to the frequency locking ratio of the laser. For the iodine measurement, the transmission ratio using the injection-seeded laser is locked to 0.9 (off line) and 0.1 (on line) on the edges of the iodine absorption line to stabilize the frequency. The DIAL measurements were performed using a target iodine cell in the laboratory. We confirmed that the on- to off-line ratio decreased after the laser passed through the iodine cell

  18. Two micron Heterodyne Doppler DIAL Lidar remote sensing of atmospheric CO2

    This work deals with the development of a differential absorption lidar (DIAL) instrument and its use for absolute CO2 measurements with a 1-2% precision. The first chapter describes the scientific framework of the thesis: atmospheric branch of the carbon cycle, climatic change and Kyoto protocol, present day monitoring network and main space missions. The modeling, experimental and theoretical aspects of the study are presented in the more general framework of the recovery of surface fluxes and atmospheric CO2 measurements. Chapter 2 treats of the evolution of atmospheric CO2 at the meso-scale. The time, horizontal and vertical representativeness of a CO2 measurement is evaluated. The processes at the origin of the variability of a mixing ratio in the different parts of the atmosphere is presented in order to develop an efficient measurement method. Chapter 3 discusses the DIAL measurement and its optimization for a maximum preciseness of the concentration measurement. A particular attention is given to the spectroscopy and to the optimization of parameters like the optical thickness of the air column, the energy of laser pulses in the atmosphere, and the analysis of statistical and systematic errors. Chapter 4 describes the experimental setup 'LIDIA', the existing Lidar used, its transformations and added parts. A particular attention is given to the signal processing. Then follows the presentation and discussion of the measurements performed night and day during the end of 2004 and during 2005: integrated measurements at the ground level and validation using in-situ measurements, vertical measurements inside the atmospheric boundary layer (ABL), use of cloudy targets, measurements inside the free troposphere and resolved measurements inside the ABL. The contribution of simultaneous wind and vertical velocity measurements with concentration measurements is used to explain the natural and anthropic processes at the origin of the variations with time of the CO2

  19. Optimization of the GSFC TROPOZ DIAL retrieval using synthetic lidar returns and ozonesondes - Part 1: Algorithm validation

    Sullivan, J. T.; McGee, T. J.; Leblanc, T.; Sumnicht, G. K.; Twigg, L. W.

    2015-04-01

    The main purpose of the NASA Goddard Space Flight Center TROPospheric OZone DIfferential Absorption Lidar (GSFC TROPOZ DIAL) is to measure the vertical distribution of tropospheric ozone for science investigations. Because of the important health and climate impacts of tropospheric ozone, it is imperative to quantify background photochemical and aloft ozone concentrations, especially during air quality episodes. To better characterize tropospheric ozone, the Tropospheric Ozone Lidar Network (TOLNet) has recently been developed, which currently consists of five different ozone DIAL instruments, including the TROPOZ. This paper addresses the necessary procedures to validate the TROPOZ retrieval algorithm and develops a primary standard for retrieval consistency and optimization within TOLNet. This paper is focused on ensuring the TROPOZ and future TOLNet algorithms are properly quantifying ozone concentrations and the following paper will focus on defining a systematic uncertainty analysis standard for all TOLNet instruments. Although this paper is used to optimize the TROPOZ retrieval, the methodology presented may be extended and applied to most other DIAL instruments, even if the atmospheric product of interest is not tropospheric ozone (e.g. temperature or water vapor). The analysis begins by computing synthetic lidar returns from actual TROPOZ lidar return signals in combination with a known ozone profile. From these synthetic signals, it is possible to explicitly determine retrieval algorithm biases from the known profile, thereby identifying any areas that may need refinement for a new operational version of the TROPOZ retrieval algorithm. A new vertical resolution scheme is presented, which was upgraded from a constant vertical resolution to a variable vertical resolution, in order to yield a statistical uncertainty of instrument and provides a standard for current and future TOLNet algorithms.

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

    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

  1. Feasibility Study of Multi-Wavelength Differential Absorption LIDAR for CO2 Monitoring

    Chengzhi Xiang

    2016-06-01

    Full Text Available To obtain a better understanding of carbon cycle and accurate climate prediction models, highly accurate and temporal resolution observation of atmospheric CO2 is necessary. Differential absorption LIDAR (DIAL remote sensing is a promising technology to detect atmospheric CO2. However, the traditional DIAL system is the dual-wavelength DIAL (DW-DIAL, which has strict requirements for wavelength accuracy and stability. Moreover, for on-line and off-line wavelengths, the system’s optical efficiency and the change of atmospheric parameters are assumed to be the same in the DW-DIAL system. This assumption inevitably produces measurement errors, especially under rapid aerosol changes. In this study, a multi-wavelength DIAL (MW-DIAL is proposed to map atmospheric CO2 concentration. The MW-DIAL conducts inversion with one on-line and multiple off-line wavelengths. Multiple concentrations of CO2 are then obtained through difference processing between the single on-line and each of the off-line wavelengths. In addition, the least square method is adopted to optimize inversion results. Consequently, the inversion concentration of CO2 in the MW-DIAL system is found to be the weighted average of the multiple concentrations. Simulation analysis and laboratory experiments were conducted to evaluate the inversion precision of MW-DIAL. For comparison, traditional DW-DIAL simulations were also conducted. Simulation analysis demonstrated that, given the drifting wavelengths of the laser, the detection accuracy of CO2 when using MW-DIAL is higher than that when using DW-DIAL, especially when the drift is large. A laboratory experiment was also performed to verify the simulation analysis.

  2. Design and development of a compact lidar/DIAL system for aerial surveillance of urban areas

    Gaudio, P.; Gelfusa, M.; Malizia, A.; Richetta, M.; Antonucci, A.; Ventura, P.; Murari, A.; Vega, J.

    2013-10-01

    Recently surveying large areas in an automatic way, for early detection of harmful chemical agents, has become a strategic objective of defence and public health organisations. The Lidar-Dial techniques are widely recognized as a cost-effective alternative to monitor large portions of the atmosphere but, up to now, they have been mainly deployed as ground based stations. The design reported in this paper concerns the development of a Lidar-Dial system compact enough to be carried by a small airplane and capable of detecting sudden releases in air of harmful and/or polluting substances. The proposed approach consists of continuous monitoring of the area under surveillance with a Lidar type measurement. Once a significant increase in the density of backscattering substances is revealed, it is intended to switch to the Dial technique to identify the released chemicals and to determine its concentration. In this paper, the design of the proposed system is described and the simulations carried out to determine its performances are reported. For the Lidar measurements, commercially available Nd- YAG laser sources have already been tested and their performances, in combination with avalanche photodiodes, have been experimentally verified to meet the required specifications. With regard to the DIAL measurements, new compact CO2 laser sources are being investigated. The most promising candidate presents an energy per pulse of about 50 mJ typical, sufficient for a range of at least 500m. The laser also provides the so called "agile tuning" option that allows to quickly tune the wavelength. To guarantee continuous, automatic surveying of large areas, innovative solutions are required for the data acquisition, self monitoring of the system and data analysis. The results of the design, the simulations and some preliminary tests illustrate the potential of the chosen, integrated approach.

  3. Towards quantitative atmospheric water vapor profiling with differential absorption lidar.

    Dinovitser, Alex; Gunn, Lachlan J; Abbott, Derek

    2015-08-24

    Differential Absorption Lidar (DIAL) is a powerful laser-based technique for trace gas profiling of the atmosphere. However, this technique is still under active development requiring precise and accurate wavelength stabilization, as well as accurate spectroscopic parameters of the specific resonance line and the effective absorption cross-section of the system. In this paper we describe a novel master laser system that extends our previous work for robust stabilization to virtually any number of multiple side-line laser wavelengths for the future probing to greater altitudes. In this paper, we also highlight the significance of laser spectral purity on DIAL accuracy, and illustrate a simple re-arrangement of a system for measuring effective absorption cross-section. We present a calibration technique where the laser light is guided to an absorption cell with 33 m path length, and a quantitative number density measurement is then used to obtain the effective absorption cross-section. The same absorption cell is then used for on-line laser stabilization, while microwave beat-frequencies are used to stabilize any number of off-line lasers. We present preliminary results using ∼300 nJ, 1 μs pulses at 3 kHz, with the seed laser operating as a nanojoule transmitter at 822.922 nm, and a receiver consisting of a photomultiplier tube (PMT) coupled to a 356 mm mirror. PMID:26368258

  4. Preliminary results of a lidar-dial integrated system for the automatic detection of atmospheric pollutants

    Gaudio, P.; Gelfusa, M.; Richetta, M.

    2012-11-01

    In the last decades, atmospheric pollution in urban and industrial areas has become a major concern of both developed and developing countries. In this context, surveying relative large areas in an automatic way is an increasing common objective of public health organisations. The Lidar-Dial techniques are widely recognized as a cost-effective approach to monitor large portions of the atmosphere and, for example, they have been successful applied to the early detection of forest fire. The studies and preliminary results reported in this paper concern the development of an integrated Lidar-Dial system able to detect sudden releases in air of harmful and polluting substances. The propose approach consists of continuous monitoring of the area under surveillance with a Lidar type measurement (by means of a low cost system). Once a significant increase in the density of a pollutant is revealed, the Dial technique is used to identify the released chemicals. In this paper, the specifications of the proposed station are discussed. The most stringent requirement is the need for a very compact system with a range of at least 600-700 m. Of course, the optical wavelengths must be in an absolute eye-safe range for humans. A conceptual design of the entire system is described and the most important characteristic of the main elements are provided. In particular the capability of the envisaged laser sources, Nd:YAG and CO2 lasers, to provide the necessary quality of the measurements is carefully assessed. Since the detection of dangerous substances must be performed in an automatic way, the monitoring station will be equipped with an adequate set of control and communication devices for independent autonomous operation. The results of the first preliminary tests illustrate the potential of the chosen approach.

  5. Novel algorithm for simultaneously detecting multiple vapor materials with multiple-wavelength differential absorption lidar

    Shirong Yin; Weiran Wang

    2006-01-01

    Differential absorption lidar (DIAL) has been successfully used to detect vapor material, however limited to detect single vapor using two closely spaced wavelengths. The progress in multiple-wavelength lasers motivates the need for detection and estimation algorithms that have the capability for simultaneous detection of multiple materials. In this paper, a simple and accurate algorithm is presented for simultaneously detecting and estimating multiple vapor materials with multiple-wavelength DIAL, which based on the maximum likelihood estimation (MLE) methodology. The performance of the algorithm is evaluated by simulation experiments, the results show that this algorithm can separately identify and quantify vapor material in mixtures and perform quite well.

  6. Detection and monitoring of pollutant sources with Lidar/Dial techniques

    Gaudio, P.; Gelfusa, M.; Malizia, A.; Parracino, S.; Richetta, M.; De Leo, L.; Perrimezzi, C.; Bellecci, C.

    2015-11-01

    It's well known that air pollution due to anthropogenic sources can have adverse effects on humans and the ecosystem. Therefore, in the last years, surveying large regions of the atmosphere in an automatic way has become a strategic objective of various public health organizations for early detection of pollutant sources in urban and industrial areas. The Lidar and Dial techniques have become well established laser based methods for the remote sensing of the atmosphere. They are often implemented to probe almost any level of the atmosphere and to acquire information to validate theoretical models about different topics of atmospheric physics. They can also be used for environment surveying by monitoring particles, aerosols and molecules. The aim of the present work is to demonstrate the potential of these methods to detect pollutants emitted from local sources (such as particulate and/or chemical compounds) and to evaluate their concentration. This is exemplified with the help of experimental data acquired in an industrial area in the south of Italy by mean of experimental campaign by use of pollutants simulated source. For this purpose, two mobile systems Lidar and Dial have been developed by the authors. In this paper there will be presented the operating principles of the system and the results of the experimental campaign.

  7. Atmospheric effects on CO{sub 2} differential absorption lidar sensitivity

    Petrin, R.R.; Nelson, D.H.; Schmitt, M.J. [and others

    1996-03-01

    The ambient atmosphere between the laser transmitter and the target can affect CO{sub 2} differential absorption lidar (DIAL) measurement sensitivity through a number of different processes. In this work, we will address two of the sources of atmospheric interference with CO{sub 2} DIAL measurements: effects due to beam propagation through atmospheric turbulence and extinction due to absorption by atmospheric gases. Measurements of atmospheric extinction under different atmospheric conditions are presented and compared to a standard atmospheric transmission model (FASCODE). We have also investigated the effects of atmospheric turbulence on system performance. Measurements of the effective beam size after propagation are compared to model predictions using simultaneous measurements of atmospheric turbulence as input to the model. These results are also discussed in the context of the overall effect of beam propagation through atmospheric turbulence on the sensitivity of DIAL measurements.

  8. The accuracy and sensitivity of infrared differential absorption lidar measurements of hydrocarbon emissions from process units

    Walmsley, Harold L.; O'Connor, Simon J.

    1998-07-01

    Shell Research Ltd has been using an infrared DIAL (differential absorption lidar) facility for two and a half years to measure hydrocarbon emissions to the atmosphere from petroleum industry process units. This paper describes the procedures used for measurement, emission rate calculation and data display, and then discusses the factors that affect the accuracy and detection limits of column content and emission rate measurements under practical operating conditions.

  9. Measurement of atmospheric emissions from process units using differential absorption lidar

    Walmsley, Harold L.; O Connor, Simon J.

    1997-05-01

    Shell Research Ltd has been using an IR differential absorption LIDAR (DIAL) facility for about two years to measure the emission rates (fluxes) of VOCs from petroleum industry process units. This paper describes the measurement, flux calculation and data display procedures used. Careful system setup and tuning plus the use of appropriate calculation procedures are needed to obtain accurate measurements. The factors that affect flux measurement accuracy and detection limits under practical conditions are discussed.

  10. 3-D water vapor field in the atmospheric boundary layer observed with scanning differential absorption lidar

    Späth, Florian; Behrendt, Andreas; Muppa, Shravan Kumar; Metzendorf, Simon; Riede, Andrea; Wulfmeyer, Volker

    2016-01-01

    High-resolution three-dimensional (3-D) water vapor data of the atmospheric boundary layer (ABL) are required to improve our understanding of land–atmosphere exchange processes. For this purpose, the scanning differential absorption lidar (DIAL) of the University of Hohenheim (UHOH) was developed as well as new analysis tools and visualization methods. The instrument determines 3-D fields of the atmospheric water vapor number density with a temporal resolution of a few secon...

  11. 3D Water Vapor Field in the Atmospheric Boundary Layer Observed with Scanning Differential Absorption Lidar

    Späth, F.; A. Behrendt; Muppa, S. K.; S. Metzendorf; A. Riede; V. Wulfmeyer

    2016-01-01

    The scanning differential absorption lidar (DIAL) of the University of Hohenheim (UHOH) determines fields of the atmospheric water vapor number density with a temporal resolution of a few seconds and spatial resolution of up to a few tens of meters. We present three case studies which show that this high resolution combined with 2- and 3-dimensional scans allows for new insights in the 3-dimensional structure of the water vapor field in the atmospheric boundary layer (ABL). In spring 2013, th...

  12. Infrared differential absorption lidar for stand-off detection of chemical agents

    A K Razdan; S Veerabuthiran; M K Jindal; R K Sharma

    2014-02-01

    A compact trolley-mounted pulsed transverse electric atmospheric pressure (TEA) carbon dioxide laser-based differential absorption lidar (DIAL) system capable of stand-off detection of chemical clouds in aerosol and vapour form upto about 200 m range in the atmosphere has been developed and assembled at Laser Science and Technology Centre (LASTEC), Delhi. The system was tested successfully with diethyl ether (DEE) (a toxic industrial chemical (TIC)) and differential absorption signals at on (strong absorption, 9R16) and off (weak absorption, 10R26) wavelengths were recorded for stand-off distances upto ∼100 m (open air ground path). This paper discusses the technical details of trolley-mounted CO2 DIAL system and the data generated during the test and evaluation of this sensor using DEE aerosols.

  13. Advances in Diode-Laser-Based Water Vapor Differential Absorption Lidar

    Spuler, Scott; Repasky, Kevin; Morley, Bruce; Moen, Drew; Weckwerth, Tammy; Hayman, Matt; Nehrir, Amin

    2016-06-01

    An advanced diode-laser-based water vapor differential absorption lidar (WV-DIAL) has been developed. The next generation design was built on the success of previous diode-laser-based prototypes and enables accurate measurement of water vapor closer to the ground surface, in rapidly changing atmospheric conditions, and in daytime cloudy conditions up to cloud base. The lidar provides up to 1 min resolution, 150 m range resolved measurements of water vapor in a broad range of atmospheric conditions. A description of the instrument and results from its initial field test in 2014 are discussed.

  14. Ozone Differential Absorption Lidar Algorithm Intercomparison

    Godin, Sophie; Carswell, Allen I.; Donovan, David P.; Claude, Hans; Steinbrecht, Wolfgang; McDermid, I. Stuart; McGee, Thomas J.; Gross, Michael R.; Nakane, Hideaki; Swart, Daan P. J.; Bergwerff, Hans B.; Uchino, Osamu; von der Gathen, Peter; Neuber, Roland

    1999-10-01

    An intercomparison of ozone differential absorption lidar algorithms was performed in 1996 within the framework of the Network for the Detection of Stratospheric Changes (NDSC) lidar working group. The objective of this research was mainly to test the differentiating techniques used by the various lidar teams involved in the NDSC for the calculation of the ozone number density from the lidar signals. The exercise consisted of processing synthetic lidar signals computed from simple Rayleigh scattering and three initial ozone profiles. Two of these profiles contained perturbations in the low and the high stratosphere to test the vertical resolution of the various algorithms. For the unperturbed profiles the results of the simulations show the correct behavior of the lidar processing methods in the low and the middle stratosphere with biases of less than 1% with respect to the initial profile to as high as 30 km in most cases. In the upper stratosphere, significant biases reaching 10% at 45 km for most of the algorithms are obtained. This bias is due to the decrease in the signal-to-noise ratio with altitude, which makes it necessary to increase the number of points of the derivative low-pass filter used for data processing. As a consequence the response of the various retrieval algorithms to perturbations in the ozone profile is much better in the lower stratosphere than in the higher range. These results show the necessity of limiting the vertical smoothing in the ozone lidar retrieval algorithm and questions the ability of current lidar systems to detect long-term ozone trends above 40 km. Otherwise the simulations show in general a correct estimation of the ozone profile random error and, as shown by the tests involving the perturbed ozone profiles, some inconsistency in the estimation of the vertical resolution among the lidar teams involved in this experiment.

  15. Development of a differential absorption lidar for identification of carbon sequestration site leakage

    Johnson, William Eric

    This thesis describes the development and deployment of a near-infrared scanning micropulse differential absorption lidar (DIAL) system for monitoring carbon dioxide sequestration site integrity. The DIAL utilizes a custom-built lidar (light detection and ranging) transmitter system based on two commercial tunable diode lasers operating at 1.571 microm, an acousto-optic modulator, fiber optic switches, and an Erbium-doped fiber amplifier to generate 65 microJ 200 ns pulses at a 15 kHz repetition rate. Backscattered laser transmitter light is collected with an 11 inch Schmidt-Cassegrain telescope where it is optically filtered to reduce background noise. A fiber-coupled photomultiplier tube operating in the photon counting mode is then used to monitor the collected return signal. Averaging over periods typically of one hour permit range-resolved measurements of carbon dioxide from 1 to 2.5 km with a typical error of 40 ppm. For monitoring a field site, the system scans over a field area by pointing the transmitter and receiver with a computer controlled motorized commercial telescope base. The system has made autonomous field measurements in an agricultural field adjacent to Montana State University and at the Kevin Dome carbon sequestration site in rural northern Montana. Comparisons have been made with an in situ sensor showing agreement between the two measurements to within the 40 error of the DIAL. In addition to the work on the 1.57 micron DIAL, this thesis also presents work done at NASA Langley Research Center on the development and deployment of a 2 micron integrated path differential absorption (IPDA) lidar. The 2 micron system utilizes a low repetition rate 140 mJ double pulsed Ho:Tm:YLF laser developed at NASA Langley.

  16. On-Line Wavelength Calibration of Pulsed Laser for CO2 Differential Absorption LIDAR

    Xiang, Chengzhi; Ma, Xin; Han, Ge; Liang, Ailin; Gong, Wei

    2016-06-01

    Differential absorption lidar (DIAL) remote sensing is a promising technology for atmospheric CO2 detection. However, stringent wavelength accuracy and stability are required in DIAL system. Accurate on-line wavelength calibration is a crucial procedure for retrieving atmospheric CO2 concentration using the DIAL, particularly when pulsed lasers are adopted in the system. Large fluctuations in the intensities of a pulsed laser pose a great challenge for accurate on-line wavelength calibration. In this paper, a wavelength calibration strategy based on multi-wavelength scanning (MWS) was proposed for accurate on-line wavelength calibration of a pulsed laser for CO2 detection. The MWS conducted segmented sampling across the CO2 absorption line with appropriate number of points and range of widths by using a tunable laser. Complete absorption line of CO2 can be obtained through a curve fitting. Then, the on-line wavelength can be easily found at the peak of the absorption line. Furthermore, another algorithm called the energy matching was introduced in the MWS to eliminate the backlash error of tunable lasers during the process of on-line wavelength calibration. Finally, a series of tests was conducted to elevate the calibration precision of MWS. Analysis of tests demonstrated that the MWS proposed in this paper could calibrate the on-line wavelength of pulsed laser accurately and steadily.

  17. Compact, Rugged and Low-Cost Atmospheric Ozone DIAL Transmitter Project

    National Aeronautics and Space Administration — Bridger Photonics Inc. (Bridger) proposes to develop the most compact, efficient and low-cost ultra-violet ozone differential absorption lidar (DIAL) transmitter...

  18. Spaceborne profiling of atmospheric temperature and particle extinction with pure rotational Raman lidar and of relative humidity in combination with differential absorption lidar: performance simulations

    The performance of a spaceborne temperature lidar based on the pure rotational Raman (RR) technique in the UV has been simulated. Results show that such a system deployed onboard a low-Earth-orbit satellite would provide global-scale clear-sky temperature measurements in the troposphere and lower stratosphere with precisions that satisfy World Meteorological Organization (WMO) threshold observational requirements for numerical weather prediction and climate research applications. Furthermore, nighttime temperature measurements would still be within the WMO threshold observational requirements in the presence of several cloud structures. The performance of aerosol extinction measurements from space, which can be carried out simultaneously with temperature measurements by RR lidar, is also assessed. Furthermore, we discuss simulations of relative humidity measurements from space obtained from RR temperature measurements and water-vapor data measured with the differential absorption lidar (DIAL) technique

  19. Optimization of A 2-Micron Laser Frequency Stabilization System for a Double-Pulse CO2 Differential Absorption Lidar

    Chen, Songsheng; Yu, Jirong; Bai, Yingsin; Koch, Grady; Petros, Mulugeta; Trieu, Bo; Petzar, Paul; Singh, Upendra N.; Kavaya, Michael J.; Beyon, Jeffrey

    2010-01-01

    A carbon dioxide (CO2) Differential Absorption Lidar (DIAL) for accurate CO2 concentration measurement requires a frequency locking system to achieve high frequency locking precision and stability. We describe the frequency locking system utilizing Frequency Modulation (FM), Phase Sensitive Detection (PSD), and Proportional Integration Derivative (PID) feedback servo loop, and report the optimization of the sensitivity of the system for the feed back loop based on the characteristics of a variable path-length CO2 gas cell. The CO2 gas cell is characterized with HITRAN database (2004). The method can be applied for any other frequency locking systems referring to gas absorption line.

  20. Evaluation of tropospheric water vapor profiling using eye-safe, infrared differential absorption lidar

    Rye, B.J. [Colorado Univ., Boulder, CO (United States). Cooperative Inst. for Research in Environmental Sciences]|[National Oceanic and Atmospheric Administration, Boulder, CO (United States). Environmental Technology Lab.; Machol, J.L.; Grund, C.J.; Hardesty, R.M. [National Oceanic and Atmospheric Administration, Boulder, CO (United States). Environmental Technology Lab.

    1996-05-14

    Continuous, high quality profiles of water vapor, free of systematic bias, and of moderate temporal and spatial resolution are fundamental to the success of the ARM CART program. In addition, these should be acquired over long periods at low operational and maintenance cost. The development and verification of realistic climate model parameterizations for clouds and net radiation balance, and the correction of other CART site sensor observations for interferences due to the presence of water vapor are critically dependent on water vapor profile measurements. To date, application of profiles have been limited by vertical resolution and uniqueness and high operating cost, or diminished daytime performance, lack of eye-safety, and high maintenance cost. Recent developments in infrared laser and detector technology make possible compact IR differential absorption lidar (DIAL) systems at eye-safe wavelengths. In the studies reported here, we develop DIAL system performance models and examine the potential of solving some of the shortcomings of previous methods using parameters representative of current technologies. These simulations are also applied to determine the strengths and weaknesses unique to the DIAL method for this application.

  1. Correction of Doppler-broadened Rayleigh backscattering effects in H2O dial measurements

    Ansmann, A.; Bosenberg, J.

    1986-01-01

    A general method of solutions for treating effects of Doppler-broadened Rayleigh backscattering in H2O Differential Absorption Lidar (DIAL) measurements are described and discussed. Errors in vertical DIAL measuremtns caused by this laser line broadening effect can be very large and, therfore, this effect has to be accounted for accurately. To analyze and correct effects of Doppler-broadened Rayleigh backscattering in DIAL experiments, a generalized DIAL approximation was derived starting from a lidar equation, which includes Doppler broadening. To evaluate the accuracy of H2O DIAL measurements, computer simulations were performed. It was concluded that correction of Doppler broadened Rayleigh backscattering is possible with good accuracy in most cases of tropospheric H2O DIAL measurements, but great care has to be taken when layers with steep gradients of Mie backscattering like clouds or inversion layers are present.

  2. Feasibility of tropospheric water vapor profiling using infrared heterodyne differential absorption lidar

    Grund, Christian J.; Hardesty, R. Michael; Rye, Barry J.

    1995-04-01

    Continuous, high quality profiles of water vapor, free of systematic bias, and of moderate temporal and spatial resolution, acquired over long periods at low operational and maintenance cost, are fundamental to the success of the ARM CART program. The development and verification of realistic climate model parameterizations for clouds and net radiation balance, and the correction of other CART site sensor observations for interferences due to the presence of water vapor are critically dependent on water vapor profile measurements. Application of profiles acquired with current techniques, have, to date, been limited by vertical resolution and uniqueness of solution (e.g. high resolution infrared (IR) Fourier transform radiometry), poor spatial and temporal coverage and high operating cost (e.g. radiosondes), or diminished daytime performance, lack of eye-safety, and high maintenance cost (e.g. Raman lidar). Recent developments in infrared laser and detector technology make possible compact IR differential absorption lidar (DIAL) systems at eye-safe wavelengths. In the study reported here, we develop DIAL system performance models and examine the potential to solve some of the shortcomings of previous methods using parameterizations representative of current technologies. These models are also applied to diagnose and evaluate other strengths and weaknesses unique to the DIAL method for this application. This work is to continue in the direction of evaluating yet smaller and lower-cost laser diode-based systems for routine monitoring of the lower altitudes using photon counting detection methods. We regard the present report as interim in nature and will update and extend it as a final report at the end of the term of the contract.

  3. Pre-shuttle lidar system research

    Lang, R. H.; Zaghloul, M. E.

    1986-01-01

    Included are the results of the initial phase of a simulation study in connection with photomultiplier tubes (PMT) and associated networks and an analytical study of atmospheric physics (including multiscattering) leading to modeling studies in connection with differential absorption lidar (DIAL) observations. This effort was in support of the ER-2 aircraft DIAL projects.

  4. Characterization of Cirrus Cloud Properties by Airborne Differential Absorption and High Spectral Resolution Lidar Measurements

    Ehret, G.; Gross, S.; Schäfler, A.; Wirth, M.; Fix, A.; Kiemle, C.

    2014-12-01

    Despite the large impact of cirrus clouds on the Earth's climate system, their effects are still only poorly understood. Our knowledge of the climate effect of cirrus clouds is mainly based on theoretical simulations using idealized cloud structure and microphysics, as well as radiative transfer approximations. To improve the representation of cirrus clouds in idealized simulations and circulation models, we need a better understanding of the micro- and macrophysical properties of cirrus clouds. Airborne lidar measurements provide two-dimensional information of the atmospheric structure, and are thus a suitable tool to study the fine-structure of cirrus clouds, as well as their macrophysical properties. Aerosol and water vapor was measured with the airborne high spectral resolution lidar (HSRL) and differential absorption lidar (DIAL) system WALES of the German Aerospace Center (DLR), Oberpfaffenhofen. The system was operated onboard the German high altitude and long range research aircraft HALO during the Next-generation remote sensing for validation studies campaign (NARVAL) in December 2013 over the tropical North-Atlantic and in January 2014 out of Iceland, and during the ML-Cirrus campaign in March/April 2014 over Central and Southern Europe. During NARVAL 18 flights with more than 110 flight hours were performed providing a large number of cirrus cloud overpasses with combined lidar and radar instrumentation. In the framework of the ML-Cirrus campaign 17 flights with more than 80 flight hours were performed to characterize cirrus cloud properties in different environmental conditions using a combination of remote sensing (e.g. lidar) and in-situ observations. In our presentation we will give a general overview of the campaigns and of the WALES measurements. We will show first results from the aerosol and water vapor lidar measurements with focus on the structure of cirrus clouds, the humidity distribution within and outside the cloud and on the impact of the

  5. Development and Testing of a Scanning Differential Absorption Lidar For Carbon Sequestration Site Monitoring

    Soukup, B.; Johnson, W.; Repasky, K. S.; Carlsten, J. L.

    2013-12-01

    A scanning differential absorption lidar (DIAL) instrument for carbon sequestration site monitoring is under development and testing at Montana State University. The laser transmitter uses two tunable discrete mode laser diodes (DMLD) operating in the continuous wave (cw) mode with one locked to the on-line absorption wavelength at 1571.4067 nm and the second operating at the off-line wavelength at 1571.2585 nm. Two in-line fiber optic switches are used to switch between on-line and off-line operation. After the fiber optic switches, an acousto-optic modulator (AOM) is used to generate a pulse train used to injection seed an erbium doped fiber amplifier (EDFA) to produce eye-safe laser pulses with maximum pulse energies of 66 J and a pulse repetition frequency of 15 kHz. The DIAL receiver uses a 28 cm diameter Schmidt-Cassegrain telescope to collect that backscattered light, which is then monitored using a fiber coupled photo-multiplier tube (PMT) module operating in the photon counting mode. The PMT has a 3% quantum efficiency, a dark count rate of 90 kHz, and a maximum count rate of 1 MHz. Recently, a fiber coupled avalanche photodiode (APD) operating in the geiger mode has been incorporated into the DIAL receiver. The APD has a quantum efficiency of 10%, a dark count rate of 10 kHz, and a maximum count rate of 1 MHz and provides a much larger dynamic range than the PMT. Both the PMT and APD provide TTL logic pulses that are monitored using a multichannel scaler card used to count the return photons as a function of time of flight and are thus interchangeable. The DIAL instrument was developed at the 1.571 m wavelength to take advantage of commercial-off-the-shelf components. The instrument is operated using a custom Labview program that switches to the DMLD operating at the on-line wavelength, locks this laser to a user defined wavelength setting, and collects return signals for a user defined time. The control program switches to the DMLD operating at the off

  6. Optical parametric oscillators in lidar sounding of trace atmospheric gases in the mid infrared region

    Romanovskii, O. A.; Sadovnikov, S. A.; Kharchenko, O. V.; Shumskii, V. K.; Yakovlev, S. V.

    2015-12-01

    Applicability of a KTA crystal-based laser system with optical parametric generation to lidar sounding of the atmosphere in the spectral range 3-4 μm is studied in this work. A technique developed for lidar sounding of trace atmospheric gases is based on differential absorption (DIAL) technique and differential optical absorption spectroscopy (DOAS). The DIAL-DOAS technique is tested to estimate its efficiency for lidar sounding of atmospheric trace gases.

  7. Nd:Glass-Raman laser for water vapor dial

    Kagann, R. H.; Petheram, J. C.; Rosenberg, A.

    1986-01-01

    A tunable solid-state Raman shifted laser which was used in a water vapor Differential Absorption Lidar (DIAL) system at 9400 A is described. The DIAL transmitter is based on a tunable glass laser operating at 1.06 microns, a hydrogen Raman cell to shift the radiation to 1.88 microns, and a frequency doubling crystal. The results of measurements which characterize the output of the laser with respect to optimization of optical configuration and of Raman parameters were reported. The DIAL system was also described and preliminary atmospheric returns shown.

  8. High-resolution atmospheric water vapor measurements with a scanning differential absorption lidar

    Späth, F.; Behrendt, A.; Muppa, S. K.; Metzendorf, S.; Riede, A.; Wulfmeyer, V.

    2014-11-01

    The scanning differential absorption lidar (DIAL) of the University of Hohenheim (UHOH) is presented. The UHOH DIAL is equipped with an injection-seeded frequency-stabilized high-power Ti:sapphire laser operated at 818 nm with a repetition rate of 250 Hz. A scanning transceiver unit with a 80 cm primary mirror receives the atmospheric backscatter signals. The system is capable of water vapor measurements with temporal resolutions of a few seconds and a range resolution between 30 and 300 m at daytime. It allows to investigate surface-vegetation-atmosphere exchange processes with high resolution. In this paper, we present the design of the instrument and illustrate its performance with recent water vapor measurements taken in Stuttgart-Hohenheim and in the frame of the HD(CP)2 Observational Prototype Experiment (HOPE). HOPE was located near research center Jülich, in western Germany, in spring 2013 as part of the project "High Definition of Clouds and Precipitation for advancing Climate Prediction" (HD(CP)2). Scanning measurements reveal the 3-dimensional structures of the water vapor field. The influence of uncertainties within the calculation of the absorption cross-section at wavelengths around 818 nm for the WV retrieval is discussed. Radiosonde intercomparisons show a very small bias between the instruments of only (-0.04 ± 0.11) g m-3 or (-1.0 ± 2.3) % in the height range of 0.5 to 3 km.

  9. Differential absorption lidar measurements of atmospheric water vapor using a pseudonoise code modulated AlGaAs laser. Thesis

    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.

  10. CALIOPE airborne CO{sub 2} DIAL (CACDI) system design

    Mietz, D.; Archuleta, B.; Archuleta, J. [and others

    1997-09-01

    Los Alamos National Laboratory is currently developing an airborne CO{sub 2} Differential Absorption Lidar (DIAL) system based on second generation technology demonstrated last summer at NTS. The CALIOPE Airborne CO{sub 2} DIAL (CACDI) system requirements have been compiled based on the mission objectives and SONDIAL model trade studies. Subsystem designs have been developed based on flow down from these system requirements, as well as experience gained from second generation ground tests and N-ABLE (Non-proliferation AirBorne Lidar Experiments) airborne experiments. This paper presents the CACDI mission objectives, system requirements, the current subsystem design, and provides an overview of the airborne experimental plan.

  11. 3-D water vapor field in the atmospheric boundary layer observed with scanning differential absorption lidar

    Späth, Florian; Behrendt, Andreas; Muppa, Shravan Kumar; Metzendorf, Simon; Riede, Andrea; Wulfmeyer, Volker

    2016-04-01

    High-resolution three-dimensional (3-D) water vapor data of the atmospheric boundary layer (ABL) are required to improve our understanding of land-atmosphere exchange processes. For this purpose, the scanning differential absorption lidar (DIAL) of the University of Hohenheim (UHOH) was developed as well as new analysis tools and visualization methods. The instrument determines 3-D fields of the atmospheric water vapor number density with a temporal resolution of a few seconds and a spatial resolution of up to a few tens of meters. We present three case studies from two field campaigns. In spring 2013, the UHOH DIAL was operated within the scope of the HD(CP)2 Observational Prototype Experiment (HOPE) in western Germany. HD(CP)2 stands for High Definition of Clouds and Precipitation for advancing Climate Prediction and is a German research initiative. Range-height indicator (RHI) scans of the UHOH DIAL show the water vapor heterogeneity within a range of a few kilometers up to an altitude of 2 km and its impact on the formation of clouds at the top of the ABL. The uncertainty of the measured data was assessed for the first time by extending a technique to scanning data, which was formerly applied to vertical time series. Typically, the accuracy of the DIAL measurements is between 0.5 and 0.8 g m-3 (or < 6 %) within the ABL even during daytime. This allows for performing a RHI scan from the surface to an elevation angle of 90° within 10 min. In summer 2014, the UHOH DIAL participated in the Surface Atmosphere Boundary Layer Exchange (SABLE) campaign in southwestern Germany. Conical volume scans were made which reveal multiple water vapor layers in three dimensions. Differences in their heights in different directions can be attributed to different surface elevation. With low-elevation scans in the surface layer, the humidity profiles and gradients can be related to different land cover such as maize, grassland, and forest as well as different surface layer

  12. 2-Micron Triple-Pulse Integrated Path Differential Absorption Lidar Development for Simultaneous Airborne Column Measurements of Carbon Dioxide and Water Vapor in the Atmosphere

    Singh, Upendra N.; Petros, Mulugeta; Refaat, Tamer F.; Yu, Jirong

    2016-01-01

    For more than 15 years, NASA Langley Research Center (LaRC) has contributed in developing several 2-micron carbon dioxide active remote sensors using the DIAL technique. Currently, an airborne 2-micron triple-pulse integrated path differential absorption (IPDA) lidar is under development at NASA LaRC. This paper focuses on the advancement of the 2-micron triple-pulse IPDA lidar development. Updates on the state-of-the-art triple-pulse laser transmitter will be presented including the status of wavelength control, packaging and lidar integration. In addition, receiver development updates will also be presented, including telescope integration, detection systems and data acquisition electronics. Future plan for IPDA lidar system for ground integration, testing and flight validation will be presented.

  13. Characterization of a 16-Bit Digitizer for Lidar Data Acquisition

    Williamson, Cynthia K.; DeYoung, Russell J.

    2000-01-01

    A 6-MHz 16-bit waveform digitizer was evaluated for use in atmospheric differential absorption lidar (DIAL) measurements of ozone. The digitizer noise characteristics were evaluated, and actual ozone DIAL atmospheric returns were digitized. This digitizer could replace computer-automated measurement and control (CAMAC)-based commercial digitizers and improve voltage accuracy.

  14. A New Differential Absorption Lidar to Measure Sub-Hourly Fluctuation of Tropospheric Ozone Profiles in the Baltimore - Washington D.C. Region

    Sullivan, J. T.; McGee, T. J.; Sumnicht, G. K.; Twigg, L. W.; Hoff, R. M.

    2014-01-01

    Tropospheric ozone profiles have been retrieved from the new ground based National Aeronautics and Space Administration (NASA) Goddard Space Flight Center TROPospheric OZone DIfferential Absorption Lidar (GSFC TROPOZ DIAL) in Greenbelt, MD (38.99 N, 76.84 W, 57 meters ASL) from 400 m to 12 km AGL. Current atmospheric satellite instruments cannot peer through the optically thick stratospheric ozone layer to remotely sense boundary layer tropospheric ozone. In order to monitor this lower ozone more effectively, the Tropospheric Ozone Lidar Network (TOLNet) has been developed, which currently consists of five stations across the US. The GSFC TROPOZ DIAL is based on the Differential Absorption Lidar (DIAL) technique, which currently detects two wavelengths, 289 and 299 nm. Ozone is absorbed more strongly at 289 nm than at 299 nm. The DIAL technique exploits this difference between the returned backscatter signals to obtain the ozone number density as a function of altitude. The transmitted wavelengths are generated by focusing the output of a quadrupled Nd:YAG laser beam (266 nm) into a pair of Raman cells, filled with high pressure hydrogen and deuterium. Stimulated Raman Scattering (SRS) within the focus generates a significant fraction of the pump energy at the first Stokes shift. With the knowledge of the ozone absorption coefficient at these two wavelengths, the range resolved number density can be derived. An interesting atmospheric case study involving the Stratospheric-Tropospheric Exchange (STE) of ozone is shown to emphasize the regional importance of this instrument as well as assessing the validation and calibration of data. The retrieval yields an uncertainty of 16-19 percent from 0-1.5 km, 10-18 percent from 1.5-3 km, and 11-25 percent from 3 km to 12 km. There are currently surface ozone measurements hourly and ozonesonde launches occasionally, but this system will be the first to make routine tropospheric ozone profile measurements in the Baltimore

  15. Development of a 2-micron Pulsed Differential Absorption Lidar for Atmospheric CO2 Concentration Measurement by Direct Detection Technique

    Yu, J.; Singh, U. N.; Petros, M.; Bai, Y.

    2011-12-01

    Researchers at NASA Langley Research Center are developing a 2-micron Pulsed Differential Absorption Lidar instrument for ground and airborne measurements via direct detection method. This instrument will provide an alternate approach to measure atmospheric CO2 concentrations with significant advantages. A high energy pulsed approach provides high-precision measurement capbility by having high signal-to-noise level and unambiguously eliminates the contamination from aerosols and clouds that can bias the IPDA measurement. A key component of the CO2 DIAL system, transceiver, is an existing, airborne ready, robust hardware which can provide 250mJ at 10Hz with double pulse format specifically designed for DIAL instrument. The exact wavelengths of the transceiver are controlled by well defined CW seed laser source to provide the required injection source for generating on-and-off line wavelength pulses sequentially. The compact, rugged, highly reliable transceiver is based on the unique Ho:Tm:YLF high-energy 2-micron pulsed laser technology. All the optical mounts are custom designed and have space heritage. They are designed to be adjustable and lockable and hardened to withstand vibrations that can occur in airborne operation. For the direct detection lidar application, a large primary mirror size is preferred. A 14 inch diameter telescope will be developed for this program. The CO2 DIAL/IPDA system requires many electronic functions to operate. These include diode, RF, seed laser, and PZT drivers; injection seeding detection and control; detector power supplies; and analog inputs to sample various sensors. Under NASA Laser Risk Reduction Program (LRRP), a control unit Compact Laser Electronics (CLE), is developed for the controlling the coherent wind lidar transceiver. Significant modifications and additions are needed to update it for CO2 lidar controls. The data acquisition system was built for ground CO2 measurement demonstration. The software will be updated for

  16. A High Spectral Resolution Lidar Based on Absorption Filter

    Piironen, Paivi

    1996-01-01

    A High Spectral Resolution Lidar (HSRL) that uses an iodine absorption filter and a tunable, narrow bandwidth Nd:YAG laser is demonstrated. The iodine absorption filter provides better performance than the Fabry-Perot etalon that it replaces. This study presents an instrument design that can be used a the basis for a design of a simple and robust lidar for the measurement of the optical properties of the atmosphere. The HSRL provides calibrated measurements of the optical properties of the atmospheric aerosols. These observations include measurements of aerosol backscatter cross sections, optical depth, backscatter phase function depolarization, and multiple scattering. The errors in the HSRL data are discussed and the effects of different errors on the measured optical parameters are shown.

  17. Pulsed Airborne Lidar Measurements of C02 Column Absorption

    Abshire, James B.; Riris, Haris; Allan, Graham R.; Weaver, Clark J.; Mao, Jianping; Sun, Xiaoli; Hasselbrack, William E.; Rodriquez, Michael; Browell, Edward V.

    2011-01-01

    We report on airborne lidar measurements of atmospheric CO2 column density for an approach being developed as a candidate for NASA's ASCENDS mission. It uses a pulsed dual-wavelength lidar measurement based on the integrated path differential absorption (IPDA) technique. We demonstrated the approach using the CO2 measurement from aircraft in July and August 2009 over four locations. The results show clear CO2 line shape and absorption signals, which follow the expected changes with aircraft altitude from 3 to 13 km. The 2009 measurements have been analyzed in detail and the results show approx.1 ppm random errors for 8-10 km altitudes and approx.30 sec averaging times. Airborne measurements were also made in 2010 with stronger signals and initial analysis shows approx. 0.3 ppm random errors for 80 sec averaging times for measurements at altitudes> 6 km.

  18. Feasibility of tropospheric water vapor profiling using infrared heterodyne differential absorption lidar

    Grund, C.J.; Hardesty, R.M. [National Oceanic and Atmospheric Administration Environmental Technology Laboratoy, Boulder, CO (United States); Rye, B.J. [Univ. of Colorado, Boulder, CO (United States)

    1996-04-01

    The development and verification of realistic climate model parameterizations for clouds and net radiation balance and the correction of other site sensor observations for interferences due to the presence of water vapor are critically dependent on water vapor profile measurements. In this study, we develop system performance models and examine the potential of infrared differential absoroption lidar (DIAL) to determine the concentration of water vapor.

  19. IR differential-absorption lidars for ecological monitoring of the environment

    Vasil'ev, B. I.; Mannoun, O. M.

    2006-01-01

    A review of studies on lidar sensing of the environment by the method of IR differential absorption is presented. The differential-absorption method is described and its various applications are considered. A comparison of this method with other methods of lidar sensing showed that a differential-ab

  20. Gating characteristics of photomultiplier tubes for Lidar applications

    Barrick, J. D. W.

    1986-01-01

    A detector test facility was developed and applied in the evaluation and characterization of lidar detectors in support of the multipurpose airborne differential absorption lidar (DIAL) system based at the Langley Research Center (LaRC). A performance data base of various detector configurations available to the DIAL system was obtained for optimum lidar detector selection. Photomultiplier tubes (PMT's) with multialkaline and bialkaline photocathodes were evaluated in voltage-divider networks (bases) by using either the focusing electrode or dynodes as a gating mechanism. Characteristics used for detector evaluation included gain stability, signal rise time, and the ability to block unwanted high light levels.

  1. The study on the lidar's detection limit for Iodine Gas

    Kim, Dong-lyul; Baik, Seung-Hoon; Park, Seung-Kyu; Park, Nak-Gyu; Ahn, Yong-Jin [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-05-15

    A powerful and reliable tool for range-resolved remote sensing of gas concentrations that has proven its capabilities in a variety of studies is the differential absorption lidar (DIAL). Differential absorption lidar (DIAL) is frequently used for atmospheric gas monitoring to detect impurities such as nitrogen dioxide, sulfur dioxide, iodine, and ozone. DIAL can measure air pollutant concentrations with a high spatial resolution by adopting two laser systems with different degrees of absorption between the two different wavelengths. The absorption of the reference wavelength is very weak, while the absorption of the other wavelength is very strong. In this paper, we measured the limit of detection capability of our designed DIAL system. The DIAL measurements were performed using a target iodine cell in the laboratory. We confirmed that the concentration of iodine gas ratio increased after the laser passed through the iodine cell. The system of DIAL(Differential Absorption Lidar) was effective to detect the iodine gas. We obtained the signals from the iodine target cell and the lidar signal from the iodine target cell was proportional to frequency locking ratios.

  2. An airborne high spectral resolution lidar based on an iodine absorption filter

    Esselborn, Michael; Wirth, Martin; Fix, Andreas; Ehret, Gerhard

    2007-01-01

    Aerosols directly influence the fluxes of solar and terrestrial radiation within the atmosphere by absorption and scattering of light. The quantification of this effect accounts for accurate determination of the aerosol’s optical properties. With conventional backscatter lidars climatically relevant aerosol properties like aerosol extinction can only be derived by inverting the lidar signal under the assumption of a a priori known lidar ratio, which generally is a highly var...

  3. A lidar system for remote sensing of aerosols and water vapor from NSTS and Space Station Freedom

    Delorme, Joseph F.

    1989-01-01

    The Tropical Atmospheric Lidar Observing System (TALOS) is proposed to be developed as a Differential Absorption Lidar (DIAL) system for flight aboard the earth orbiting Space Station Freedom. TALOS will be capable of making high resolution vertical profile measurements of tropospheric water and tropospheric and stratospheric aerosols, clouds and temperature.

  4. Airborne differential absorption lidar for water vapour measurements in the upper troposphere and lower stratosphere in the spectral region around 940 nm

    Poberaj, G.

    2000-07-01

    Two all-solid-state laser systems were developed and studied in detail to optimise their performance for an airborne water vapour differential absorption lidar (DIAL). Their special features are high average output powers and excellent spectral properties in the 940-nm spectral region relevant for monitoring very low water vapour contents in the upper troposphere and lower stratosphere. One system is an injection-seeded pulsed Ti:sapphire ring laser with a spectral bandwidth of 105 MHz and an average power of 1.1 W. The other system is an injection-seeded optical parametric oscillator (OPO) in a ring configuration. Using KTP as nonlinear crystal, a signal output with a spectral bandwidth of 140 MHz and an average power of 1.2 W was achieved. Both systems, the Ti:sapphire ring laser and the KTP OPO, possess spectral purity values higher than 99%. The pump source for these systems is a frequency doubled diode-pumped Nd:YAG laser operating at a repetition rate of 100 Hz. The KTP OPO system has been used as a transmitter in a new airborne water vapour DIAL instrument. For the first time, measurements of two-dimensional water vapour distributions with a high vertical (500 m) and horizontal (20 km) resolution across several potential vorticity streamers were performed. Very low water vapour mixing ratios (10-50 ppmv) and strong gradients were observed in the tropopause region. The sensitivity of the DIAL instrument in the centre of a stratospheric intrusion ranges from 3% in the near field to 12% in the far field (4 km). The first comparison experiments with in situ measuring instruments show a good agreement. Considerable differences are found between DIAL measurements and data obtained from the ECMWF operational analyses and a mesoscale numerical model. (orig.)

  5. AM-CW Integrated Path Differential Absorption Lidar Project

    National Aeronautics and Space Administration — This proposal addresses NASA's science objectives with innovative lidar architecture for atmospheric CO2 measurements. Specifically, the proposed work can support...

  6. Lidar Remote Sensing for Industry and Environment Monitoring

    Singh, Upendra N. (Editor); Itabe, Toshikazu (Editor); Sugimoto, Nobuo (Editor)

    2000-01-01

    Contents include the following: 1. Keynote paper: Overview of lidar technology for industrial and environmental monitoring in Japan. 2. lidar technology I: NASA's future active remote sensing mission for earth science. Geometrical detector consideration s in laser sensing application (invited paper). 3. Lidar technology II: High-power femtosecond light strings as novel atmospheric probes (invited paper). Design of a compact high-sensitivity aerosol profiling lidar. 4. Lasers for lidars: High-energy 2 microns laser for multiple lidar applications. New submount requirement of conductively cooled laser diodes for lidar applications. 5. Tropospheric aerosols and clouds I: Lidar monitoring of clouds and aerosols at the facility for atmospheric remote sensing (invited paper). Measurement of asian dust by using multiwavelength lidar. Global monitoring of clouds and aerosols using a network of micropulse lidar systems. 6. Troposphere aerosols and clouds II: Scanning lidar measurements of marine aerosol fields at a coastal site in Hawaii. 7. Tropospheric aerosols and clouds III: Formation of ice cloud from asian dust particles in the upper troposphere. Atmospheric boundary layer observation by ground-based lidar at KMITL, Thailand (13 deg N, 100 deg. E). 8. Boundary layer, urban pollution: Studies of the spatial correlation between urban aerosols and local traffic congestion using a slant angle scanning on the research vessel Mirai. 9. Middle atmosphere: Lidar-observed arctic PSC's over Svalbard (invited paper). Sodium temperature lidar measurements of the mesopause region over Syowa Station. 10. Differential absorption lidar (dIAL) and DOAS: Airborne UV DIAL measurements of ozone and aerosols (invited paper). Measurement of water vapor, surface ozone, and ethylene using differential absorption lidar. 12. Space lidar I: Lightweight lidar telescopes for space applications (invited paper). Coherent lidar development for Doppler wind measurement from the International Space

  7. A user friendly Lidar system based on LabVIEW

    Andersson, Mats; Weibring, P.

    1996-09-01

    Mobile differential absorption lidar (DIAL) systems have been used for the last two decades. The lidar group in Lund has performed many DIAL measurements with a mobile lidar system which was first described in 1987. This report describes how that system was updated with the graphical programming language LabVIEW in order to get a user friendly system. The software controls the lidar system and analyses measurement data. The measurement results are shown as maps of species concentration. New electronics to support the new lidar program have also been installed. The report describes how all supporting electronics and the program work. A user manual for the new program is also given. 19 refs, 79 figs, 23 charts

  8. Application of Optical Parametric Generator for Lidar Sensing of Minor Gas Components of the Atmosphere in 3-4 μm Spectral Range

    Romanovskii, O. A.; Sadovnikov, S. A.; Kharchenko, O. V.; Shumskii, V. K.; Yakovlev, S. V.

    2016-07-01

    Possibility of application of a laser system with parametric light generation based on a nonlinear KTA crystal for lidar sensing of the atmosphere in the 3-4 μm spectral range is investigated. A technique for lidar measurements of gas components in the atmosphere with the use of differential absorption lidar (DIAL) and differential optical absorption spectroscopy (DOAS) method is developed. The DIAL-DOAS technique is tested for estimating the possibility of laser sensing of minor gas components in the atmosphere.

  9. High-power Ti:sapphire laser at 820 nm for scanning ground-based water-vapor differential absorption lidar.

    Wagner, Gerd; Behrendt, Andreas; Wulfmeyer, Volker; Späth, Florian; Schiller, Max

    2013-04-10

    The Ti:sapphire (TISA) laser transmitter of the mobile, three-dimensional-scanning water-vapor differential absorption lidar (DIAL) of the University of Hohenheim is described in detail. The dynamically-stable, unidirectional ring resonator contains a single Brewster-cut TISA crystal, which is pumped from both sides with 250 Hz using a diode-pumped frequency-doubled Nd:YAG laser. The resonator is injection seeded and actively frequency-stabilized using a phase-sensitive technique. The TISA laser is operating near 820 nm, which is optimum for ground-based water-vapor DIAL measurements. An average output power of up to 6.75 W with a beam quality factor of M2<2 is reached. The pointing stability is <13 μrad (rms), the depolarization <1%. The overall optical-optical conversion efficiency is up to 19%. The pulse length is 40 ns with a pulse linewidth of <157 MHz. The short- and long-term frequency stabilities are 10 MHz (rms). A spectral purity of 99.9% was determined by pointing to a stratus cloud in low-elevation scanning mode with a cloud bottom height of ≈2.4 km. PMID:23670775

  10. Lidar Measurements of Ozone in the Upper Troposphere - Lower Stratosphere at Siberian Lidar Station in Tomsk

    Romanovskii, O. A.; Dolgii, S. I.; Burlakov, V. D.; Nevzorov, A. A.; Nevzorov, A. V.

    2016-06-01

    The paper presents the results of DIAL measurements of the vertical ozone distribution at the Siberian lidar station. Sensing is performed according to the method of differential absorption and scattering at wavelength pair of 299/341 nm, which are, respectively, the first and second Stokes components of SRS conversion of 4th harmonic of Nd:YAG laser (266 nm) in hydrogen. Lidar with receiving mirror 0.5 m in diameter is used to implement sensing of vertical ozone distribution in altitude range of 6-16 km. The temperature correction of zone absorption coefficients is introduced in the software to reduce the retrieval errors.

  11. Lidar technologies for airborne and space-based applications

    This study identifies technologies required to extend the capabilities of airborne light detection and ranging (lidar) systems and establish the feasibility of autonomous space-based lidars. Work focused on technologies that enable the development of a lightweight, low power, rugged and autonomous Differential Absorption Lidar (DIAL) instruments. Applications for airborne or space-based DIAL include the measurement of water vapor profiles in support of climate research and processing-plant emissions signatures for environmental and nonproliferation monitoring. A computer-based lidar performance model was developed to allow trade studies to be performed on various technologies and system configurations. It combines input from the physics (absorption line strengths and locations) of the problem, the system requirements (weight, power, volume, accuracy), and the critical technologies available (detectors, lasers, filters) to produce the best conceptual design. Conceptual designs for an airborne and space-based water vapor DIAL, and a detailed design of a ground-based water vapor DIAL demonstration system were completed. Future work planned includes the final testing, integration, and operation of the demonstration system to prove the capability of the critical enabling technologies identified

  12. Peculiarities of standardization efforts for lidar measurements

    Weitkamp, Klaus C. H.; Nikowa, Ljuba A.

    1997-12-01

    Lidar, and in particular, differential absorption and scattering lidar or DIAL have today reached a high degree of maturity. It now appears appropriate that efforts be taken in the direction of standardization of the technique and assurance and control of the quality of its results. To this end the German Commission on Air Pollution of VDI and DIN established a working group whose task was to prepare a set of recommendations for the use and operation of lidar systems. This group now completed, as a first result, a guideline for the use of differential absorption and scattering lidar for gas concentration measurements. Peculiarities associated with such a task are presented, and the contents of the draft of the resulting guideline VDI 4210 Part 1 are discussed.

  13. Evaluation of ECMWF water vapour fields by airborne differential absorption lidar measurements: a case study between Brazil and Europe

    H. Flentje

    2007-10-01

    Full Text Available Three extended airborne Differential Absorption Lidar (DIAL sections of tropospheric water vapour across the tropical and sub-tropical Atlantic in March 2004 are compared to short-term forecasts of the European Centre for Medium Range Weather Forecasts (ECMWF. The humidity fields between 28° S and 36° N exhibit large inter air-mass gradients and reflect typical transport patterns of low- and mid-latitudes like convection (e.g. Hadley circulation, subsidence and baroclinic development with stratospheric intrusion. These processes re-distribute water vapour vertically such that locations with extraordinary dry/moist air-masses are observed in the lower/upper troposphere, respectively. The mixing ratios range over 3 orders of magnitude. Back-trajectories are used to trace and characterize the observed air-masses.

    Overall, the observed water vapour distributions are largely reproduced by the short-term forecasts at 0.25° resolution (T799/L91, the correlation ranges from 0.69 to 0.92. Locally, large differences occur due to comparably small spatial shifts in presence of strong gradients. Systematic deviations are found associated with specific atmospheric domains. The planetary boundary layer in the forecast is too moist and to shallow. Convective transport of humidity to the middle and upper troposphere tends to be overestimated. Potential impacts arising from data assimilation and model physics are considered. The matching of air-mass boundaries (transport is discussed with repect to scales and the representativity of the 2-D sections for the 3-D humidity field. The normalized bias of the model with respect to the observations is 6%, 11% and 0% (moist model biases for the three along-flight sections, whereby however the lowest levels are excluded.

  14. Differential Absorption Lidar to Measure Subhourly Variation of Tropospheric Ozone Profiles

    Kuang, Shi; Burris, John F.; Newchurch, Michael J.; Johnson, Steve; Long, Stephania

    2011-01-01

    A tropospheric ozone Differential Absorption Lidar system, developed jointly by The University of Alabama in Huntsville and the National Aeronautics and Space Administration, is making regular observations of ozone vertical distributions between 1 and 8 km with two receivers under both daytime and nighttime conditions using lasers at 285 and 291 nm. This paper describes the lidar system and analysis technique with some measurement examples. An iterative aerosol correction procedure reduces the retrieval error arising from differential aerosol backscatter in the lower troposphere. Lidar observations with coincident ozonesonde flights demonstrate that the retrieval accuracy ranges from better than 10% below 4 km to better than 20% below 8 km with 750-m vertical resolution and 10-min 17 temporal integration.

  15. Airborne lidar measurements of surface ozone depletion over Arctic sea ice

    Seabrook, J. A.; Whiteway, J. A.; Gray, L. H.; Staebler, R.; A. Herber

    2013-01-01

    A differential absorption lidar (DIAL) for measurement of atmospheric ozone concentration was operated aboard the Polar 5 research aircraft in order to study the depletion of ozone over Arctic sea ice. The lidar measurements during a flight over the sea ice north of Barrow, Alaska, on 3 April 2011 found a surface boundary layer depletion of ozone over a range of 300 km. The photochemical destruction of surface level ozone was strongest at the most northern point of the flight, and steadily de...

  16. DIAL monitoring of atmospheric climate-determining gases employing high-power pulsed laser diodes

    Penchev, Stoyan P.; Naboko, Sergei V.; Naboko, Vassily N.; Pencheva, Vasilka H.; Donchev, T.; Pavlov, Lyubomir Y.; Simeonov, P.

    2003-11-01

    High-power pulsed laser diodes are employed for determining atmospheric humidity and methane. The proposed DIAL method optimizes the spectral properties of laser radiation within the molecular absorption bands of 0.86 - 0.9 μm of these major greenhouse gases. The explicit absorption spectrum is explored by computational convolution method based on reference data on spectral linestrengths modulated by the characteristic broad laser line of the selected laser diodes. The lidar scheme is ultimately compact, of low-energy consumption and suggests a large potential for ecological monitoring.

  17. Measurement of Lower-Atmospheric CO2 Concentration Distribution Using a Compact 1.6 μm DIAL

    Shibata, Yasukuni; Nagasawa, Chikao; Abo, Makoto

    2016-06-01

    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. The differential absorption lidar (DIAL) is expected to measure atmospheric CO2 profiles in the atmospheric boundary layer and lower troposphere from a ground platform. We have succeeded to develop a compact 1.6 μm DIAL system for measuring CO2 concentration profiles in the lower atmosphere. This 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 and the receiving optics that included the near-infrared photomultiplier tube operating at the analog mode and a 25 cm telescope. CO2 concentration profiles were obtained up to 2.5 km altitude.

  18. Investigations on Frequency and Energy References for a Space-borne Integrated Path Differential Absorption Lidar

    Fix, Andreas; Matthey, Renaud; Amediek, Axel; Ehret, Gerhard; Gruet, Florian; Kiemle, Christoph; Klein, Volker; Mileti, Gaetano; Pereira do Carmo, Joao; Quatrevalet, Mathieu

    2014-01-01

    The Integrated Path Differential Absorption Lidar (IPDA) technique using hard target reflection the near IR has the potential to deliver CO2 column measurements from space with unprecedented accuracy which is a prerequisite to understand the sources and sinks of this dominant anthropogenic greenhouse gas. The observational needs, however, demand for very stringent system requirements, of which two were thoroughly investigated. The first is the online frequency accuracy. With a sub-100-kHz ...

  19. Future Performance of Ground-Based and Airborne Water-Vapor Differential Absorption Lidar. II. Simulations of the Precision of a Near-Infrared, High-Power System

    Wulfmeyer, Volker; Walther, Craig

    2001-10-01

    Taking into account Poisson, background, amplifier, and speckle noise, we can simulate the precision of water-vapor measurements by using a 10-W average-power differential absorption lidar (DIAL) system. This system is currently under development at Hohenheim University, Germany, and at the American National Center for Atmospheric Research. For operation in the 940-nm region, a large set of measurement situations is described, including configurations that are considered for the first time to the authors knowledge. They include ultrahigh-resolution measurements in the surface layer (resolutions, 1.5 m and 0.1 s) and vertically pointing measurements (resolutions, 30 m and 1 s) from the ground to 2 km in the atmospheric boundary layer. Even during daytime, the DIAL system will have a measurement range from the ground to the upper troposphere (300 m, 10 min) that can be extended from a mountain site to the lower stratosphere. From the ground, for the first time of which the authors are aware, three-dimensional fields of water vapor in the boundary layer can be investigated within a range of the order of 15 km and with an averaging time of 10 min. From an aircraft, measurements of the atmospheric boundary layer (60 m, 1 s) can be performed from a height of 4 km to the ground. At higher altitudes, up to 18 km, water-vapor profiles can still be obtained from aircraft height level to the ground. When it is being flown either in the free troposphere or in the stratosphere, the system will measure horizontal water-vapor profiles up to 12 km. We are not aware of another remote-sensing technique that provides, simultaneously, such high resolution and accuracy.

  20. Airborne Measurements of CO2 Column Absorption and Range Using a Pulsed Direct-Detection Integrated Path Differential Absorption Lidar

    Abshire, James B.; Riris, Haris; Weaver, Clark J.; Mao, Jianping; Allan, Graham R.; Hasselbrack, William E.; Browell, Edward V.

    2013-01-01

    We report on airborne CO2 column absorption measurements made in 2009 with a pulsed direct-detection lidar operating at 1572.33 nm and utilizing the integrated path differential absorption technique. We demonstrated these at different altitudes from an aircraft in July and August in flights over four locations in the central and eastern United States. The results show clear CO2 line shape and absorption signals, which follow the expected changes with aircraft altitude from 3 to 13 km. The lidar measurement statistics were also calculated for each flight as a function of altitude. The optical depth varied nearly linearly with altitude, consistent with calculations based on atmospheric models. The scatter in the optical depth measurements varied with aircraft altitude as expected, and the median measurement precisions for the column varied from 0.9 to 1.2 ppm. The altitude range with the lowest scatter was 810 km, and the majority of measurements for the column within it had precisions between 0.2 and 0.9 ppm.

  1. Assimilation of ground-based and airborne lidar data into the MM5 4D-Var system

    Grzeschik, Matthias

    2010-01-01

    This work investigates the impact of assimilating water vapor Light Detection and Ranging (lidar) data into mesoscale Numerical Weather Prediction (NWP) models. Two cases from the field campaigns International H20 Project 2002 (IHOP_2002) and International Lindenberg Campaign for Assessment of Humidity- and Cloud-Profiling Systems and its Impact on High-Resolution Modelling 2005 (LAUNCH-2005) are presented. In the first case, airborne water vapor Differential Absorption Lidar (DIAL) data ar...

  2. Development and Integration of a Pulsed 2-micron Direct Detection Integrated Path Differential Absorption (IPDA) Lidar for CO2 Column Measurement from Airborne platform Project

    National Aeronautics and Space Administration — Develop, integrate and demonstrate a 2-micron pulsed Integrated Path Differential Absorption Lidar (IPDA) instrument CO2 Column Measurement from Airborne platform...

  3. High Spectral Resolution Lidar Measurements Using an I2 Absorption Filter

    Eloranta, E. W.; Piironen, P.

    1996-01-01

    The University of Wisconsin high spectral resolution lidar (HSRL) measures optical properties of the atmosphere by separating the Doppler-broadened molecular backscatter return from the unbroadened aerosol return. The HSRL was modified to use an I2 absorption cell The modified HSRL transmitter uses a continuously pumped, Q-switched, injection seeded, frequency doubled Nd:YAG laser operating at a 4 kHz pulse repetition rate. This laser is tunable over a 124 GHz frequency range by temperature tuning the seed laser under computer control.

  4. Recent lidar technology developments and their influence on measurements of tropospheric water vapor

    Ismail, Syed; Browell, Edward V.

    1994-01-01

    In this paper the influences of recent technology developments in the areas of lasers, detectors, andoptical filters of a differential absorption lidar (DIAL) system on the measurenent of tropospheric water vapor (H2O) profiles are discussed. The lidar parameters selected are based upon a diode-seeded Ti:sapphire laser that is locked to an H2O line in the 820- or 930-nm band of H2O. To assess the influence of the mode of deployment on the measurement of tropospheric H2O, DIAL performance is evaluated for operation from a medium-altitude (12 km) aircraft, the ground, and space-based systems. It is found that incorporation of these developments could greatly enhance DIAL measurement capability.

  5. Atomic mercury flux monitoring using an optical parametric oscillator based lidar system

    Sjöholm, Mikael; Weibring, Petter; Edner, Hans; Svanberg, Sune

    2004-01-01

    A newly developed optical parametric oscillator (OPO) based differential absorption lidar (DIAL) system has been applied to the monitoring of atomic mercury emissions at several chlor-alkali plants in Europe. The versatility of the system is illustrated by measured time series of mercury flux and movies of vertical and horizontal concentration distributions, which yield important input parameters for the environmental community. Long term measurements of the resonance absorption of mercury at...

  6. Wavelength Locking to CO2 Absorption Line-Center for 2-Micron Pulsed IPDA Lidar Application

    Refaat, Tamer F.; Petros, Mulugeta; Antill, Charles W.; Singh, Upendra N.; Yu, Jirong

    2016-01-01

    An airborne 2-micron triple-pulse integrated path differential absorption (IPDA) lidar is currently under development at NASA Langley Research Center (LaRC). This IPDA lidar system targets both atmospheric carbon dioxide (CO2) and water vapor (H2O) column measurements. Independent wavelength control of each of the transmitted laser pulses is a key feature for the success of this instrument. The wavelength control unit provides switching, tuning and locking for each pulse in reference to a 2-micron CW (Continuous Wave) laser source locked to CO2 line-center. Targeting the CO2 R30 line center, at 2050.967 nanometers, a wavelength locking unit has been integrated using semiconductor laser diode. The CO2 center-line locking unit includes a laser diode current driver, temperature controller, center-line locking controller and CO2 absorption cell. This paper presents the CO2 center-line locking unit architecture, characterization procedure and results. Assessment of wavelength jitter on the IPDA measurement error will also be addressed by comparison to the system design.

  7. Spectroscopic measurements of a CO2 absorption line in an open vertical path using an airborne lidar

    Ramanathan, Anand; Allan, Graham R; Riris, Haris; Weaver, Clark J; Hasselbrack, William E; Browell, Edward V; Abshire, James B

    2013-01-01

    We use an airborne pulsed integrated path differential absorption lidar to make spectroscopic measurements of the pressure-induced line broadening and line center shift of atmospheric CO2 at the 1572.335 nm absorption line. We measure the absorption lineshape in the vertical column between the aircraft and ground. A comparison of our measured absorption lineshape to calculations based on HITRAN shows excellent agreement with the peak optical depth accurate to within 0.3%. Additionally, we measure changes in the line center position to within 5.2 MHz of calculations, and the absorption linewidth to within 0.6% of calculations.

  8. A case study of CO2, CO and particles content evolution in the suburban atmospheric boundary layer using a 2-μm Doppler DIAL, a 1-μm backscatter lidar and an array of in-situ sensors

    A network of remote and in-situ sensors was deployed in a Paris suburb in order to evaluate the mesoscale evolution of the daily cycle of CO2 and related tracers in the atmospheric boundary layer (ABL) and its relation to ABL dynamics and nearby natural and anthropogenic sources and sinks. A 2-μ m heterodyne Doppler differential absorption lidar, which combines measurements of (1) structure of the atmosphere (2) radial velocity, and (3) CO2 differential absorption was a particularly unique element of the observational array. We analyse the differences in the diurnal cycle of CO, CO2, lidar reflectivity (a proxy for aerosol content) and H2O using the lidar, airborne measurements in the free troposphere and ground-based measurements made at two sites located few kilometres apart. We demonstrate that vertical mixing dominates the early morning drawdown of CO and aerosol content trapped in the former nocturnal layer but not the H2O and CO2 mixing ratio variations. Surface fluxes, vertical mixing and advection all contribute to the ABL CO2 mixing ratio decrease during the morning transition, with the relative importance depending on the rate and timing of ABL rise. We also show evidence that when the ABL is stable, small-scale (0.1-km vertical and 1-km horizontal) gradients of CO2 and CO are large. The results illustrate the complexity of inferring surface fluxes of CO2 from atmospheric budgets in the stable boundary layer. (authors)

  9. Pulsed Lidar Measurements of Atmospheric CO2 Column Absorption in the ASCENDS 2011 Airborne Campaign

    Abshire, James B.; Riris, Haris; Allan, Graham R.; Ramanathan, Anand; Hasselbrack, William E.; Mao, Jianping; Weaver, Clark; Browell, Edward V.

    2012-01-01

    We have previously demonstrated an efficient pulsed, wavelength-resolved IPDA lidar technique for measuring the tropospheric CO2 concentrations as a candidate for NASA's ASCENDS mission. Our team participated in the 2010 ASCENDS airborne campaigns we flew airborne version of the CO2 and O2 lidar on the NASA DC-8. The CO2 lidar measures the atmospheric backscatter profiles and shape of the 1572.33 nm absorption line using 250 mW average laser power, 30 wavelength samples per scan and 300 scans per second. Most flights had 5-6 altitude steps to greater than 12 km, and clear CO2 line shapes were observed at all altitudes. Our post-flight analysis estimated the Iidar range and pulse energies at each wavelength every second. We then solved for the best-fit CO2 absorption line shape, and calculated the Differential Optical Depth (DOD) at the line peak. We compared these to CO2 DODs calculated from spectroscopy based on HITRAN 2008 and the conditions from airborne in-situ readings. Analysis of the 2010 measurements over the Pacific Ocean and Lamont OK shows the expected -linear change of the peak DOD with altitude. For measurements at altitudes greater than 6 km the random errors were approximately 0.3 ppm for 80 sec averaging times. After the 2010 flights we improved the airborne lidar's scan uniformity, calibration and receiver sensitivity. Our team participated in the seven ASCENDS science flights during late July and August 2011. These flights were made over a wide variety of surface and cloud conditions near the US, including over the central valley of California, over several mountain ranges, over both broken and solid stratus cloud deck over the Pacific Ocean, snow patches on mountain tops, over thin and broken clouds above the US Southwest and Iowa, and over forests near the WLEF tower in Wisconsin. Analyses show the retrievals of lidar range and CO2 column absorption, as wen as estimates of CO2 mixing ratio worked well when measuring over topography with rapidly

  10. Design of a near-IR coherent lidar for high spatial and velocity resolution wind measurement

    Grund, Christian J.; Post, Madison J.

    1992-01-01

    A coherent Doppler lidar based on a CW diode-pumped, injection seeded, Th:YAG laser operating at approx. 2.02 microns is currently under development. This system is optimized for measurements of boundary layer winds with high spatial, temporal, and velocity resolution. Initially, the system will run alongside a new high repetition rate (5-10 kHz) CO2 mini-Master Oscillator Power Amplifier (mini-MOPA) Doppler lidar, which will provide simultaneous range-resolved Differential Absorption Lidar (DIAL) water vapor measurements. Water vapor DIAL operation of the 2 micron system is being considered as a future option. The anticipated specifications and the preliminary design are discussed.

  11. Spaceborne lidar system for measurements of atmospheric water vapor and aerosols

    Browell, E. V.; Ismail, S.; Mccormick, M. P.; Swissler, T. J.

    1985-01-01

    The inclusion of a differential absorption lidar (DIAL) system as part of the NASA Earth Observing System (EOS) is proposed. Functioning at 720 nm, the DIAL could provide atmospheric water vapor profiles in the troposphere and stratosphere, and provide data for characterizing the physical properties of clouds. The use of frequency doubling of the laser could also open a window on the 355 nm region, and thereby molecular density and temperature profiles. The date would be of use in studies of the global hydrological cycle, the global radiation balance, climate, meteorology, and atmospheric structure and transport phenomena.

  12. Performance evaluation of a 1.6-µm methane DIAL system from ground, aircraft and UAV platforms.

    Refaat, Tamer F; Ismail, Syed; Nehrir, Amin R; Hair, John W; Crawford, James H; Leifer, Ira; Shuman, Timothy

    2013-12-16

    Methane is an efficient absorber of infrared radiation and a potent greenhouse gas with a warming potential 72 times greater than carbon dioxide on a per molecule basis. Development of methane active remote sensing capability using the differential absorption lidar (DIAL) technique enables scientific assessments of the gas emission and impacts on the climate. A performance evaluation of a pulsed DIAL system for monitoring atmospheric methane is presented. This system leverages a robust injection-seeded pulsed Nd:YAG pumped Optical Parametric Oscillator (OPO) laser technology operating in the 1.645 µm spectral band. The system also leverages an efficient low noise, commercially available, InGaAs avalanche photo-detector (APD). Lidar signals and error budget are analyzed for system operation on ground in the range-resolved DIAL mode and from airborne platforms in the integrated path DIAL (IPDA) mode. Results indicate system capability of measuring methane concentration profiles with system has a unique capability of combining signals from the atmospheric scattering from layers above the surface with ground return signals, which provides methane column measurement between the atmospheric scattering layer and the ground directly. In such case 0.5% and 1.2% total errors are achieved with 10 sec average from airborne platforms at 8 km and 15.24 km altitudes, respectively. Due to the pulsed nature of the transmitter, the system is relatively insensitive to aerosol and cloud interferences. Such DIAL system would be ideal for investigating high latitude methane releases over polar ice sheets, permafrost regions, wetlands, and over ocean during day and night. This system would have commercial potential for fossil fuel leaks detection and industrial monitoring applications. PMID:24514619

  13. Autonomous Ozone and Aerosol LIDAR Profiling of the Troposphere: A Synergistic Approach

    Strawbridge, K. B.

    2015-12-01

    LIDAR technology is an excellent tool to probe the complex vertical structure of the atmosphere at high spatial and temporal resolution. This provides the critical vertical context for the interpretation of ground-based chemistry measurements, airborne measurements and model/satellite verification and validation. In recent years, Environment Canada has designed several autonomous aerosol LIDAR systems for deployment across several regions of Canada. The current system builds on the successes of these autonomous LIDARS but using a synergistic approach by combining tropospheric ozone DIAL (Differential Absorption LIDAR) technology with simultaneous 3+2+1 aerosol LIDAR measurements. It operates 24 hours a day, seven days a week except during precipitation events. The system is operated remotely and the data are updated every hour to a website to allow near real-time capability. A few case studies are shown emphasizing the synergistic approach of coupling ozone and aerosol profiles to better understand air quality impacts on local and regional scales.

  14. UV Lidar Receiver Analysis for Tropospheric Sensing of Ozone

    Pliutau, Denis; DeYoung, Russell J.

    2013-01-01

    A simulation of a ground based Ultra-Violet Differential Absorption Lidar (UV-DIAL) receiver system was performed under realistic daytime conditions to understand how range and lidar performance can be improved for a given UV pulse laser energy. Calculations were also performed for an aerosol channel transmitting at 3 W. The lidar receiver simulation studies were optimized for the purpose of tropospheric ozone measurements. The transmitted lidar UV measurements were from 285 to 295 nm and the aerosol channel was 527-nm. The calculations are based on atmospheric transmission given by the HITRAN database and the Modern Era Retrospective Analysis for Research and Applications (MERRA) meteorological data. The aerosol attenuation is estimated using both the BACKSCAT 4.0 code as well as data collected during the CALIPSO mission. The lidar performance is estimated for both diffuseirradiance free cases corresponding to nighttime operation as well as the daytime diffuse scattered radiation component based on previously reported experimental data. This analysis presets calculations of the UV-DIAL receiver ozone and aerosol measurement range as a function of sky irradiance, filter bandwidth and laser transmitted UV and 527-nm energy

  15. Airborne dial remote sensing of the Arctic ozone layer

    A combined ozone and aerosol LIDAR was developed at the Institute of Physics of the Atmosphere at the DLR in Oberpfaffenhofen. It is an airborne version, that, based on the DIAL-principle, permits the recording of two-dimensional ozone profiles. This presentation will focus on the ozone-part; the aerosol subsection will be treated later

  16. Utilization of pulsed diode lasers to lidar remote sensing

    Penchev, S.; Pencheva, Vasilka H.; Naboko, Vassily N.; Naboko, Sergei V.; Simeonov, P.

    2001-04-01

    Investigation of new aspects of application of pulsed quantum well (In)GaAs/AlGaAs diode lasers to atmospheric spectroscopy and lidar remote sensing is reported. The presented method utilizing these powerful multichipstack diode lasers of broad radiation line is approved theoretically and experimentally for monitoring of atmospheric humidity. Molecular absorption of gas species in the investigated spectral band 0.85 - 0.9 micrometer implemented by laser technology initiates further development of prospective DIAL analysis. A mobile lidar system is realized, employing optimal photodetection based on computer-operated boxcar and adaptive digital filter processing of the lidar signal in the analytical system. Aerosol profile exhibiting cloud strata in open atmosphere by testing of the sensor is demonstrative of the efficiency and high sensitivity of long-range sounding.

  17. Solid-State 2-Micron Laser Transmitter Advancement for Wind and Carbon Dioxide Measurements From Ground, Airborne, and Space-Based Lidar Systems

    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.

  18. Analysis of Pulsed Airborne Lidar Measurements of Atmospheric CO2 Column Absorption from 3-13 km Altitudes

    Abshire, James B.; Weaver, Clark J.; Riris, Haris; Mao, Jianping; Sun, Xiaoli; Allan, Graham R.; Hasselbrack, William; Browell, Edward V.

    2011-01-01

    We have developed a pulsed lidar technique for measuring the tropospheric CO2 concentrations as a candidate for NASA's ASCENDS space mission [1]. It uses two pulsed laser transmitters allowing simultaneous measurement of a CO2 absorption line in the 1575 nm band, O2 extinction in the Oxygen A-band, surface height and backscatter profile. The lasers are precisely stepped in wavelength across the CO2 line and an O2 line region during the measurement. The direct detection receiver measures the energies of the laser echoes from the surface along with the range profile of scattering in the path. The column densities for the CO2 and O2 gases are estimated from the ratio of the on- and off-line signals via the integrated path differential absorption (IPDA) technique. The time of flight of the laser pulses is used to estimate the height of the scattering surface and to reject laser photons scattered in the atmosphere. We developed an airborne lidar to demonstrate an early version of the CO2 measurement from the NASA Glenn Lear-25 aircraft. The airborne lidar stepped the pulsed laser's wavelength across the selected CO2 line with 20 wavelength steps per scan. The line scan rate is 450 Hz, the laser pulse widths are 1 usec, and laser pulse energy is 24 uJ. The time resolved laser backscatter is collected by a 20 cm telescope, detected by a NIR photomultiplier and is recorded on every other reading by a photon counting system [2]. During August 2009 we made a series of 2.5 hour long flights and measured the atmospheric CO2 absorption and line shapes using the 1572.33 nm CO2 line. Measurements were made at stepped altitudes from 3-13 km over locations in the US, including the SGP ARM site in Oklahoma, central Illinois, north-eastern North Carolina, and over the Chesapeake Bay and the eastern shore of Virginia. Although the received signal energies were weaker than expected for ASCENDS, clear CO2 line shapes were observed at all altitudes, and some measurements were made

  19. Characteristics of the OPG System USIG Quasiphase-Matched Nonlinear Crystals for 1.6 μm CO2 Dial

    Shibata, Yasukuni; Nagasawa, Chikao; Abo, Makoto

    2016-06-01

    We have developed a direct detection 1.6 μm differential absorption lidar (DIAL) technique to perform range-resolved measurements of vertical CO2 concentration profiles in the atmosphere. Our 1.6 μm DIAL system consists of the optical parametric generator (OPG) and amplifier (OPA) transmitter that excited by the LD pumped Nd:YAG laser with high repetition rate (500 Hz). The OPG system consists of a quasi-phase-matched (QPM) crystal and does not need a cavity. The output power of the OPA system is 6 mJ, the full width at half maximum (FWHM) of the spectrum is about 280 MHz and spectrum purity is 91.0 +- 0.2 ~ 0.5%. CO2 concentration error from fluctuation of the spectrum purity is 0.3% at 6 km altitude and 0.4 % at 10 km altitude.

  20. Atmospheric aerosol and gas sensing using Scheimpflug lidar

    Mei, Liang; Brydegaard, Mikkel

    2015-04-01

    This work presents a new lidar technique for atmospheric remote sensing based on Scheimpflug principle, which describes the relationship between nonparallel image- and object-planes[1]. When a laser beam is transmitted into the atmosphere, the implication is that the backscattering echo of the entire illuminated probe volume can be in focus simultaneously without diminishing the aperture. The range-resolved backscattering echo can be retrieved by using a tilted line scan or two-dimensional CCD/CMOS camera. Rather than employing nanosecond-pulsed lasers, cascade detectors, and MHz signal sampling, all of high cost and complexity, we have developed a robust and inexpensive atmospheric lidar system based on compact laser diodes and array detectors. We present initial applications of the Scheimpflug lidar for atmospheric aerosol monitoring in bright sunlight, with a 3 W, 808 nm CW laser diode. Kilohertz sampling rates are also achieved with applications for wind speed and entomology [2]. Further, a proof-of-principle demonstration of differential absorption lidar (DIAL) based on the Scheimpflug lidar technique is presented [3]. By utilizing a 30 mW narrow band CW laser diode emitting at around 760 nm, the detailed shape of an oxygen absorption line can be resolved remotely with an integration time of 6 s and measurement cycle of 1 minute during night time. The promising results demonstrated in this work show potential for the Scheimpflug lidar technique for remote atmospheric aerosol and gas sensing, and renews hope for robust and realistic instrumentation for atmospheric lidar sensing. [1] F. Blais, "Review of 20 years of range sensor development," Journal of Electronic Imaging, vol. 13, pp. 231-243, Jan 2004. [2] M. Brydegaard, A. Gebru, and S. Svanberg, "Super resolution laser radar with blinking atmospheric particles - application to interacting flying insects " Progress In Electromagnetics Research, vol. 147, pp. 141-151, 2014. [3] L. Mei and M. Brydegaard

  1. Triple-Pulsed Two-Micron Integrated Path Differential Absorption Lidar: A New Active Remote Sensing Capability with Path to Space

    Singh, Upendra N.; Refaat, Tamer F.; Petros, Mulugeta; Yu, Jirong

    2016-06-01

    The two-micron wavelength is suitable for monitoring atmospheric water vapor and carbon dioxide, the two most dominant greenhouse gases. Recent advances in 2-μm laser technology paved the way for constructing state-of-the-art lidar transmitters for active remote sensing applications. In this paper, a new triple-pulsed 2-μm integrated path differential absorption lidar is presented. This lidar is capable of measuring either two species or single specie with two different weighting functions, simultaneously and independently. Development of this instrument is conducted at NASA Langley Research Center. Instrument scaling for projected future space missions will be discussed.

  2. Triple-Pulsed Two-Micron Integrated Path Differential Absorption Lidar: A New Active Remote Sensing Capability with Path to Space

    Singh Upendra N.; Refaat Tamer F.; Petros Mulugeta; Yu Jirong

    2016-01-01

    The two-micron wavelength is suitable for monitoring atmospheric water vapor and carbon dioxide, the two most dominant greenhouse gases. Recent advances in 2-μm laser technology paved the way for constructing state-of-the-art lidar transmitters for active remote sensing applications. In this paper, a new triple-pulsed 2-μm integrated path differential absorption lidar is presented. This lidar is capable of measuring either two species or single specie with two different weighting functions, s...

  3. Triple-Pulsed Two-Micron Integrated Path Differential Absorption Lidar: A New Active Remote Sensing Capability with Path to Space

    Singh Upendra N.

    2016-01-01

    Full Text Available The two-micron wavelength is suitable for monitoring atmospheric water vapor and carbon dioxide, the two most dominant greenhouse gases. Recent advances in 2-μm laser technology paved the way for constructing state-of-the-art lidar transmitters for active remote sensing applications. In this paper, a new triple-pulsed 2-μm integrated path differential absorption lidar is presented. This lidar is capable of measuring either two species or single specie with two different weighting functions, simultaneously and independently. Development of this instrument is conducted at NASA Langley Research Center. Instrument scaling for projected future space missions will be discussed.

  4. Tropospheric ozone lidar intercomparison experiment, TROLIX '91, field phase report

    The Tropospheric Ozone Lidar Intercomparison Experiment TROLIX '91 has been initiated as part of the TESLAS subproject of the cooperative programme EUROTRAC. It has been performed in June 1991 at the Rijksinstitut voor Volksgezondheid en Milieuhygiene (RIVM) in Bilthoven, The Netherlands. The experiment was based on the simultaneous operation of different types of differential absorption lidars (DIAL), a special version of a Differential Optical Absorption Spectroscopy Instrument (DOAS), helicopter borne in situ instruments, and many other supporting measurements. After a short introduction to the general methodology the instruments are described, the experimental operations are explained, and a selection of data are presented. Some examples are given for the results of the intercomparison, as far as they have been available at the present stage of evaluation. The main purpose of this report, however, is to provide an overview over the material collected during the experiment, on order to facilitate further detailed studies in cooperation between the different groups which have participated. (orig.)

  5. Lidar Observation of Tropopause Ozone Profiles in the Equatorial Region

    Shibata, Yasukuni; Nagasawa, Chikao; Abo, Makoto

    2016-06-01

    Tropospheric ozone in the tropics zone is significant in terms of the oxidizing efficiency and greenhouse effect. However, in the upper troposphere, the ozone budget in the tropics has not been fully understood yet because of the sparsity of the range-resolved observations of vertical ozone concentration profiles. A DIAL (differential absorption lidar) system for vertical ozone profiles have been installed in the equatorial tropopause region over Kototabang, Indonesia (100.3E, 0.2S). We have observed large ozone enhancement in the upper troposphere, altitude of 13 - 17 km, concurring with a zonal wind oscillation associated with the equatorial Kelvin wave around the tropopause at equatorial region.

  6. Complementarity of UV and IR differential absorption lidar for global measurements of atmospheric species

    Megie, G.; Menzies, R. T.

    1980-01-01

    An analysis of the potential capabilities of a spectrally diversified DIAL technique for monitoring atmospheric species is presented assuming operation from an earth-orbiting platform. Emphasis is given to the measurement accuracies and spatial and temporal resolutions required to meet present atmospheric science objectives. The discussion points out advantages of spectral diversity to perform comprehensive studies of the atmosphere; in general it is shown that IR systems have an advantage in lower atmospheric measurements, while UV systems are superior for middle and upper atmospheric measurements.

  7. Airborne remote sensing of tropospheric water vapor using a near infrared DIAL system

    Ehret, G.; Kiemle, C.; Renger, W.; Simmet, G.

    1992-01-01

    Summarized here are the results of airborne water vapor measurements in the lower middle and upper troposphere using the Differential Absorption Lidar (DIAL) technique in the near infrared. The measurements were performed in July 1990 in Southern Bavaria between Allersberg and Straubing from 20 to 23 UTC taking advantage of night time conditions. The tropospheric H2O profiles were range investigated both horizontally and vertically. With the DIAL system that was used, water vapor measurements in the upper troposphere have been carried out for the first time. To calibrate the H2O-retrievals, effective absorption cross sections of selected H2O lines in terms of altitude around 724 nm were calculated using line parameter data from the literature (B. E. Grossmann et al). The frequency of the on-line measurements was adjusted by the spectra of a Polyacenic Semiconductor (PAS) cell filled with H2O. We found that the calibration error ranged between 0.005 and 0.015 cm(exp -1). The systematic errors of the H2O as a function of altitude were estimated below 7 km and 12 percent accuracy in the upper troposphere. The vertical H2O profile agrees well with in situ measurements in the investigated range between the top of the planetary boundary layer (PBL) up to near the tropopause. Horizontal and vertical H2O profiles are calculated by means of averaging single lidar returns. Typical horizontal resolutions range from 4 km in the lower to 11 km in the upper troposphere with vertical resolutions varying from 0.3 km up to 1 km, respectively, in order to satisfy a 5 - 10 percent accuracy in the statistical error. The measurement sensibility of the water vapor mixing ration in the upper troposphere is 0.01 g/kg.

  8. Frequency-agile CO2 DIAL for environmental monitoring

    Carr, Lewis W.; Fletcher, Leland; Crittenden, Max; Carlisle, Clinton B.; Gotoff, Steve W.; Reyes, Felix; D'Amico, Francis

    1994-06-01

    SRI International has designed and developed a fully automated frequency-agile CO2 DIAL (differential absorption lidar) system. The system sensor head consists of a single, frequency- agile, CO2, TEA laser; a 10-inch receiver telescope, a liquid-nitrogen-cooled HgCdTe detector; and a transmit energy monitor. The sensor head and its auxiliary equipment (including the data acquisition and processing system, laser power supply, and water cooler) are mounted in a Grumman-Olson 11-ft step van. The self-contained, mobile system can be used to detect and quantify many volatile organic compounds (VOCs) at parts per million sensitivities over open-path ranges to 5 km. Characterization and demonstration of the system is ongoing. However, data collected on benzene, toluene, xylene, methanol, ethyl acetate, acetic anhydride, and other VOCs will be described herein. The system could be used by industry and government agencies in stand-off monitoring to map VOC emission sources and transport patterns into surrounding communities. A single mobile system could be used for several locations to verify compliance with environmental regulations such as the 1990 Clean Air Act Amendments.

  9. Lidar reflectance from snow at 2.05  μm wavelength as measured by the JPL Airborne Laser Absorption Spectrometer.

    Spiers, Gary D; Menzies, Robert T; Jacob, Joseph C

    2016-03-10

    We report airborne measurements of lidar directional reflectance (backscatter) from land surfaces at a wavelength in the 2.05 μm CO₂ absorption band, with emphasis on snow-covered surfaces in various natural environments. Lidar backscatter measurements using this instrument provide insight into the capabilities of lidar for both airborne and future global-scale CO₂ measurements from low Earth orbit pertinent to the NASA Active Sensing of CO₂ Emissions over Nights, Days, and Seasons mission. Lidar measurement capability is particularly useful when the use of solar scattering spectroscopy is not feasible for high-accuracy atmospheric CO₂ measurements. Consequently, performance in high-latitude and winter season environments is an emphasis. Snow-covered surfaces are known to be dark in the CO₂ band spectral regions. The quantitative backscatter data from these field measurements help to elucidate the range of backscatter values that can be expected in natural environments. PMID:26974792

  10. A Fast, Locally Adaptive, Interactive Retrieval Algorithm for the Analysis of DIAL Measurements

    Samarov, D. V.; Rogers, R.; Hair, J. W.; Douglass, K. O.; Plusquellic, D.

    2010-12-01

    Differential absorption light detection and ranging (DIAL) is a laser-based tool which is used for remote, range-resolved measurement of particular gases in the atmosphere, such as carbon-dioxide and methane. In many instances it is of interest to study how these gases are distributed over a region such as a landfill, factory, or farm. While a single DIAL measurement only tells us about the distribution of a gas along a single path, a sequence of consecutive measurements provides us with information on how that gas is distributed over a region, making DIAL a natural choice for such studies. DIAL measurements present a number of interesting challenges; first, in order to convert the raw data to concentration it is necessary to estimate the derivative along the path of the measurement. Second, as the distribution of gases across a region can be highly heterogeneous it is important that the spatial nature of the measurements be taken into account. Finally, since it is common for the set of collected measurements to be quite large it is important for the method to be computationally efficient. Existing work based on Local Polynomial Regression (LPR) has been developed which addresses the first two issues, but the issue of computational speed remains an open problem. In addition to the latter, another desirable property is to allow user input into the algorithm. In this talk we present a novel method based on LPR which utilizes a variant of the RODEO algorithm to provide a fast, locally adaptive and interactive approach to the analysis of DIAL measurements. This methodology is motivated by and applied to several simulated examples and a study out of NASA Langley Research Center (LaRC) looking at the estimation of aerosol extinction in the atmosphere. A comparison study of our method against several other algorithms is also presented. References Chaudhuri, P., Marron, J.S., Scale-space view of curve estimation, Annals of Statistics 28 (2000) 408-428. Duong, T., Cowling

  11. Modular lidar systems for high-resolution 4-dimensional measurements of water vapor, temperature, and aerosols

    Behrendt, Andreas; Wagner, Gerd; Petrova, Anna; Shiler, Max; Pal, Sandip; Schaberl, Thorsten; Wulfmeyer, Volker

    2005-01-01

    Three lidar systems are currently in development at University of Hohenheim. A water vapor lidar based on the differential absorption lidar (DIAL) technology working near 815 or 935 nm, a temperature and aerosol lidar employing the rotational Raman technique at 355 nm, and an aerosol lidar working with eye-safe laser radiation near 1.5 μm. The transmitters of these three systems are based on an injection-seeded, diode laser pumped Nd:YAG laser with an average power of 100 W at 1064 nm and a repetition rate of 250 Hz. This laser emits a nearly Gaussian-shaped beam which permits frequency-doubling and tripling with high efficiencies. The frequency-doubled 532-nm radiation is employed for pumping a Ti:Sapphire ring-resonator which will be used for DIAL water vapor measurements. In a second branch, a Cr4+:YAG crystal is pumped with the 1064-nm radiation to reach 1400 to 1500 nm for eye-safe monitoring of aerosol particles and clouds. The 532 and 1064 nm radiation are also used for backscatter lidar observations. Frequency tripling gives 355-nm radiation for measurements of temperature with the rotational Raman technique and particle extinction and particle backscattering coefficients in the UV. High transmitter power and effective use of the received signals will allow scanning operation of these three lidar systems. The lidar transmitters and detectors are designed as modules which can be combined for simultaneous measurements with one scanning telescope unit in a ground-based mobile container. Alternatively, they can be connected to different Nd:YAG pump lasers and to telescope units on separate platforms.

  12. Airborne Differential Absorption and High Spectral Resolution Lidar Measurements for Cirrus Cloud Studies

    Gross, Silke; Schaefler, Andreas; Wirth, Martin; Fix, Andreas

    2016-06-01

    Aerosol and water vapor measurements were performed with the lidar system WALES of the German Aerospace Center (DLR) onboard the German research aircraft G550-HALO during the HALO Techno-Mission in October and November 2010 and during the ML-Cirrus mission in March and April 2014 over Central Europe and the North Atlantic region. Curtains composed of lidar profiles beneath the aircraft show the water vapor mixing ratio and the backscatter ratio. Temperature data from ECMWF model analysis are used to calculate the relative humidity above ice (RHi) in the 2-D field along the flight track to study the RHi distribution inside and outside of cirrus clouds at different stages of cloud evolution.

  13. Development of the Global Ozone Lidar Demonstrator (GOLD) Instrument for Deployment on the NASA Global Hawk

    Hair, Jonathan W.; Browell, Edward V.; McGee, Thomas; Butler, Carolyn; Fenn, Marta; Os,ao (. Sued); Notari, Anthony; Collins, James; Cleckner, Craig; Hostetler, Chris

    2010-01-01

    A compact ozone (O3) and aerosol lidar system is being developed for conducting global atmospheric investigations from the NASA Global Hawk Uninhabited Aerial Vehicle (UAV) and for enabling the development and test of a space-based O3 and aerosol lidar. GOLD incorporates advanced technologies and designs to produce a compact, autonomously operating O3 and aerosol Differential Absorption Lidar (DIAL) system for a UAV platform. The GOLD system leverages advanced Nd:YAG and optical parametric oscillator laser technologies and receiver optics, detectors, and electronics. Significant progress has been made toward the development of the GOLD system, and this paper describes the objectives of this program, basic design of the GOLD system, and results from initial ground-based atmospheric tests.

  14. Linear operating region in the ozone dial photon counting system

    Andrawis, Madeleine

    1995-01-01

    Ozone is a relatively unstable molecule found in Earth's atmosphere. An ozone molecule is made up of three atoms of oxygen. Depending on where ozone resides, it can protect or harm life on Earth. High in the atmosphere, about 15 miles up, ozone acts as a shield to protect Earth's surface from the sun's harmful ultraviolet radiation. Without this shield, we would be more susceptible to skin cancer, cataracts, and impaired immune systems. Closer to Earth, in the air we breathe, ozone is a harmful pollutant that causes damage to lung tissue and plants. Since the early 1980's, airborne lidar systems have been used for making measurements of ozone. The differential absorption lidar (DIAL) technique is used in the remote measurement of O3. This system allows the O3 to be measured as function of the range in the atmosphere. Two frequency-doubled Nd:YAG lasers are used to pump tunable dye lasers. The lasers are operating at 289 nm for the DIAL on-line wavelength of O3, and the other one is operated at 300 nm for the off-line wavelength. The DIAL wavelengths are produced in sequential laser pulses with a time separation of 300 micro s. The backscattered laser energy is collected by telescopes and measured using photon counting systems. The photon counting system measures the light signal by making use of the photon nature of light. The output pulse from the Photo-Multiplier Tube (PE), caused by a photon striking the PMT photo-cathode, is amplified and passed to a pulse height discriminator. The peak value of the pulse is compared to a reference voltage (discrimination level). If the pulse amplitude exceeds the discrimination level, the discriminator generates a standard pulse which is counted by the digital counter. Non-linearity in the system is caused by the overlapping of pulses and the finite response time of the electronics. At low count rates one expects the system to register one event for each output pulse from the PMT corresponding to a photon incident upon the

  15. MERLIN (Methane Remote Sensing Lidar Mission): an Overview

    Pierangelo, C.; Millet, B.; Esteve, F.; Alpers, M.; Ehret, G.; Flamant, P.; Berthier, S.; Gibert, F.; Chomette, O.; Edouart, D.; Deniel, C.; Bousquet, P.; Chevallier, F.

    2016-06-01

    The Methane Remote Sensing Lidar Mission (MERLIN), currently in phase B, is a joint cooperation between France and Germany on the development, launch and operation of a methane (CH4) monitoring satellite. MERLIN is focused on global measurements of the spatial and temporal gradients of atmospheric CH4, the second most anthropogenic gas, with a precision and accuracy sufficient to constrain Methane fluxes significantly better than with the current observation network. For the first time, measurements of atmospheric composition will be performed from space thanks to an IPDA (Integrated Path Differential Absorption) LIDAR (Light Detecting And Ranging). This payload is under the responsibility of the German space agency (DLR), while the platform (MYRIADE Evolutions product line) is developed by the French space agency (CNES). The IPDA technique relies on DIAL (Differential Absorption LIDAR) measurements using a pulsed laser emitting at two wavelengths, one wavelength accurately locked on a spectral feature of the methane absorption line, and the other wavelength free from absorption to be used as reference. This technique enables measurements in all seasons, at all latitudes. It also guarantees almost no contamination by aerosols or water vapour cross-sensitivity, and thus has the advantage of an extremely low level of systematic error on the dry-air column mixing ratio of CH4.

  16. Lidar measurements of aerosol and ozone distributions during the 1992 Airborne Arctic Stratospheric Expedition

    The LaRC airborne lidar system was operated from the ARC DC-8 aircraft during the 1992 Airborne Arctic Stratospheric Expedition (ASEE-2) to investigate the distribution of stratospheric aerosols and O3 across the Arctic vortex from Jan. to Mar. 1992. Monthly flights were made across the Arctic vortex from Anchorage, Alaska, to Stavanger, Norway, and then back to Bangor, Maine, and additional round-trip flights north into the vortex were made each month from either Stavanger or Bangor depending on the location of the vortex that month. The airborne lidar system uses the differential absorption lidar (DIAL) technique at laser wavelengths of 301.5 and 310.8 nm to measure O3 profiles above the DC-8 over the 12-25 km altitude range. Lidar measurements of aerosol backscatter and depolarization profiles over the 12-30 km altitude range are made simultaneously with the O3 measurements using infrared (IR) and visible (VIS) laser wavelengths of 603 and 1064 nm, respectively. The measurements of Pinatubo aerosols, polar stratospheric clouds, and O3 made with the airborne DIAL system during the AASE-2 expedition and to chemical and dynamical process that contribute to O3 depletion in the wintertime Arctic stratosphere

  17. A Broad Bank Lidar for Precise Atmospheric CO2 Column Absorption Measurement from Space

    Georgieva, E. M.; Heaps, W. S.; Huang, W.

    2010-01-01

    Accurate global measurement of carbon dioxide column with the aim of discovering and quantifying unknown sources and sinks has been a high priority for the last decade. In order to uncover the "missing sink" that is responsible for the large discrepancies in the budget the critical precision for a measurement from space needs to be on the order of 1 ppm. To better understand the CO2 budget and to evaluate its impact on global warming the National Research Council (NRC) in its recent decadal survey report (NACP) to NASA recommended a laser based total CO2 mapping mission in the near future. That's the goal of Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) mission - to significantly enhance the understanding of the role of CO2 in the global carbon cycle. Our current goal is to develop an ultra precise, inexpensive new lidar system for column measurements of CO2 changes in the lower atmosphere that uses a Fabry-Perot interferometer based system as the detector portion of the instrument and replaces the narrow band laser commonly used in lidars with a high power broadband source. This approach reduces the number of individual lasers used in the system and considerably reduces the risk of failure. It also tremendously reduces the requirement for wavelength stability in the source putting this responsibility instead on the Fabry- Perot subsystem.

  18. 2-micron Pulsed Direct Detection IPDA Lidar for Atmospheric CO2 Measurements

    Yu, J.; Singh, U.; Petros, M.

    2012-12-01

    A 2-micron high energy, pulsed Integrated Path Differential Absorption (IPDA) lidar is being developed for atmospheric CO2 measurements. Development of this lidar heavily leverages the 2-micron laser technologies developed in LaRC over the last decade. The high pulse energy, direct detection lidar operating at CO2 2-micron absorption band provides an alternate approach to measure CO2 concentrations with significant advantages. It is expected to provide high-precision measurement capability by unambiguously eliminating contamination from aerosols and clouds that can bias the IPDA measurement. Our objective is to integrate an existing high energy double-pulsed 2-micron laser transmitter with a direct detection receiver and telescope to enable an airborne capability to perform a first proof of principle demonstration of airborne direct detection CO2 measurements. The 2-micron transmitter provides 100mJ at 10Hz with double pulse format specifically designed for DIAL/IPDA instrument. The compact, rugged, highly reliable transceiver is based on unique Ho:Tm:YLF high-energy 2-micron pulsed laser technology. All the optical mounts are custom designed and have space heritage. A 16-inch diameter telescope has been designed and being manufactured for the direct detection lidar. The detector is an InGaAs Positive-Intrinsic-Negative (PIN) photodiode manufactured by Hamamatsu Corporation. The performance of the detector is characterized at various operating temperatures and bias voltages for spectral response, NEP, response time, dynamic range, and linearity. A collinear lidar structure is designed to be integrated to NASA UC12 or B200 research aircrafts. This paper will describe the design of the airborne 2-micron pulsed IPDA lidar system; the lidar operation parameters; the wavelength pair selection; laser transmitter energy, pulse rate, beam divergence, double pulse generation and accurate frequency control; detector characterization; telescope design; lidar structure design

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

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

    2015-04-01

    3-dimensional thermodynamic fields of temperature and moisture including their turbulent fluctuations have been observed with the two scanning lidar systems of University of Hohenheim in three field campaigns in 2013 and 2014. In this contribution, we will introduce these two self-developed instruments and illustrate their performance with measurement examples. Finally, an outlook to envisioned future research activities with the new data sets of the instruments is given. Our temperature lidar is based on the rotational Raman technique. The scanning rotational Raman lidar (RRL) uses a seeded frequency-doubled Nd:YAG laser at a wavelength of 355 nm. A two-mirror scanner with a 40-cm telescope collects the atmospheric backscatter signals. Humidity measurements are made with a scanning water vapor differential absorption lidar (DIAL) which uses a titanium sapphire laser at 820 nm as transmitter. This laser is pumped with a frequency-doubled Nd:YAG laser and injection-seeded for switching between the online and offline wavelengths. The DIAL receiver consists of a scanning 80-cm telescope. The measured temperature and humidity profiles of both instruments have typical resolutions of only a few seconds and 100 m in the atmospheric boundary layer both in day- and night-time. Recent field experiments with the RRL and the DIAL of University of Hohenheim were (1) the HD(CP)2 Prototype Experiment (HOPE) in spring 2013 in western Germany - this activity is embedded in the project HD(CP)2 (High-definition clouds and precipitation for advancing climate prediction); (2) a measurement campaign in Hohenheim in autumn 2013; (3) the campaign SABLE (Surface Atmospheric Boundary Layer Exchange) in south-western Germany in summer 2014. The collected moisture and temperature data will serve as initial thermodynamic fields for forecast experiments related to the formation of clouds and precipitation. Due to their high resolution and high precision, the systems are capable of resolving

  20. Radium dial workers

    The population of radium dial workers who were exposed to radium 30 to 50 years ago are currently being followed by the Center for Human Radiobiology at the Argonne National Laboratory. It is not clear that radium has induced additional malignancies in this population, other than the well-known bone sarcomas and head carcinomas, but elevated incidence rates for multiple myeloma and cancers of the colon, rectum, stomach, and breast suggest that radium might be involved. Continued follow-up of this population may resolve these questions. Finally, the question of the effect of fetal irradiation on the offspring of these women remains to be resolved. No evidence exists to suggest that any effects have occurred, but there is no question that a chronic irradiation of the developing fetus did take place. No formal follow-up of these children has yet been initiated

  1. First airborne water vapor lidar measurements in the tropical upper troposphere and mid-latitudes lower stratosphere: accuracy evaluation and intercomparisons with other instruments

    C. Schiller

    2008-09-01

    Full Text Available In the tropics, deep convection is the major source of uncertainty in water vapor transport to the upper troposphere and into the stratosphere. Although accurate measurements in this region would be of first order importance to better understand the processes that govern stratospheric water vapor concentrations and trends in the context of a changing climate, they are sparse because of instrumental shortcomings and observational challenges. Therefore, the Falcon research aircraft of the Deutsches Zentrum für Luft- und Raumfahrt (DLR flew a zenith-viewing water vapor differential absorption lidar (DIAL during the Tropical Convection, Cirrus and Nitrogen Oxides Experiment (TROCCINOX in 2004 and 2005 in Brazil. The measurements were performed alternatively on three water vapor absorption lines of different strength around 940 nm. These are the first aircraft DIAL measurements in the tropical upper troposphere and in the mid-latitudes lower stratosphere. Sensitivity analyses reveal an accuracy of 5% between altitudes of 8 and 16 km. This is confirmed by intercomparisons with the Fast In-situ Stratospheric Hygrometer (FISH and the Fluorescent Advanced Stratospheric Hygrometer (FLASH onboard the Russian M-55 Geophysica research aircraft during five coordinated flights. The average relative differences between FISH and DIAL amount to −3%±8% and between FLASH and DIAL to −8%±14%, negative meaning DIAL is more humid. The average distance between the probed air masses was 129 km. The DIAL is found to have no altitude- or latitude-dependent bias. A comparison with the balloon ascent of a laser absorption spectrometer gives an average difference of 0%±19% at a distance of 75 km. Six tropical DIAL under-flights of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS on board ENVISAT reveal a mean difference of −8%±49% at an average distance of 315 km. While the comparison with MIPAS is somewhat less significant due to poorer

  2. Temporal correlation measurements of pulsed dual CO2 lidar returns. [for atmospheric pollution detection

    Menyuk, N.; Killinger, D. K.

    1981-01-01

    A pulsed dual-laser direct-detection differential-absorption lidar DIAL system, operating near 10.6 microns, is used to measure the temporal correlation and statistical properties of backscattered returns from specular and diffuse topographic targets. Results show that atmospheric-turbulence fluctuations can effectively be frozen for pulse separation times on the order of 1-3 msec or less. The diffuse target returns, however, yielded a much lower correlation than that obtained with the specular targets; this being due to uncorrelated system noise effects and different statistics for the two types of target returns.

  3. A comparison of mixing depths observed by ground-based wind profilers and an airborne lidar

    White, A.B.; Senff, C. [Univ. of Colorado/NOAA Environmental Technology Lab., Cooperative Inst. for Research in Environmental Sciences, Boulder, CO (United States); Banta, R.M. [NOAA Environmental Technology Lab., Boulder, CO (United States)

    1997-10-01

    The mixing depth is one of the most important parameters in air pollution studies because it determines the vertical extent of the `box` in which pollutants are mixed and dispersed. During the 1995 Southern Oxidants Study (SOS95), scientists from the National Oceanic and Atmospheric Administration Environmental Technology Laboratory (NOAA/ETL) deployed four 915-MHz boundary-layer radar/wind profilers (hereafter radars) in and around the Nashville, Tennessee metropolitan area. Scientists from NOAA/ETL also operated an ultraviolet differential absorption lidar (DIAL) onboard a CASA-212 aircraft. Profiles from radar and DIAL can be used to derive estimates of the mixing depth. The methods used for both instruments are similar in that they depend on information derived from the backscattered power. However, different scattering mechanisms for the radar and DIAL mean that different tracers of mixing depth are measured. In this paper we compare the mixing depth estimates obtained from the radar and DIAL and discuss the similarities and differences that occur. (au)

  4. Autonomous Ozone and Aerosol Lidar Platform: Preliminary Results

    Strawbridge, K. B.

    2014-12-01

    Environment Canada is developing an autonomous tropospheric ozone and aerosol lidar system for deployment in support of short-term field studies. Tropospheric ozone and aerosols (PM10 and PM2.5) are important atmospheric constituents in low altitude pollution affecting human health and vegetation. Ozone is photo-chemically active with nitrogen oxides and can have a distinct diurnal variability. Aerosols contribute to the radiative budget, are a tracer for pollution transport, undergo complex mixing, and contribute to visibility and cloud formation. This particular instrument will employ two separate lidar transmitter and receiver assemblies. The tropospheric ozone lidar, based on the differential absorption lidar (DIAL) technique, uses the fourth harmonics of a Nd:YAG laser directed into a CO2 Raman cell to produce 276 nm, 287nm and 299 nm (first to third Stokes lines) output wavelengths. The aerosol lidar is based on the 3+2 design using a tripled Nd:YAG to output 355 nm, 532 nm and 1064nm wavelengths. Both lidars will be housed in a modified cargo trailer allowing for easy deployment to remote areas. The unit can be operated and monitored 24 hours a day via an internet link and requires an external power source. Simultaneous ozone and aerosol lidar measurements will provide the vertical context necessary to understand the complex mixing and transformation of pollutants - particularly when deployed near other ground-based in-situ sensors. Preliminary results will be shown from a summer field study at the Centre For Atmospheric Research Experiments (CARE).

  5. Development of a Ground-based 2-Micron DIAL System to Profile Tropospheric CO2 and Aerosol Distributions for Atmospheric Studies

    Ismail, S.; Koch, G. J.; Abedin, N.; Refaat, T.; Rubio, M.; Davis, K.; Miller, C.; Singh, U.

    2006-12-01

    NASA Earth Science Technology Office (ESTO) has funded a 3 year Instrument Incubator Program to develop a ground-based 2-micron Differential Absorption Lidar (DIAL) CO2 profiling system. This is a collaborative program between NASA Langley, Pennsylvania State University (PSU), and the Jet Propulsion Laboratory (JPL). Development of this field deployable instrument is an initial step towards the eventual development of a space-based DIAL system and involves the design, development, evaluation, and fielding of a ground-based CO2 profiling system. This system will be capable of providing high resolution measurements of CO2 and aerosol profiles and will be used in a number of atmospheric studies involving the atmospheric boundary layer where the sources and sinks of CO2 are located; and in the studies of dynamical, transport, pollution, and biogenic activity in the atmosphere. After a successful development of this system, it can be used as a validation tool of the OCO (Orbiting Carbon Observatory). This instrument leverages 2-micron laser technology developed under a number of NASA programs to develop new solid-state YLF laser technology that provides high pulse energy, tunable, wavelength-stabilized, and double-pulsed lasers that are operable over pre-selected temperature insensitive strong CO2 absorption lines suitable for profiling of lower tropospheric CO2. It also incorporates high quantum efficiency, high gain, and relatively low noise AlGaAsSb/InGaAsSb phototransistors, and a new receiver/signal processor system to cover a large signal dynamic range with minimum signal distortions to achieve high precision DIAL measurements. High sensitivity in situ LI-COR 7000 sensors are being calibrated at PSU for the validation of DIAL measurements and high resolution spectroscopic measurements are being conducted at JPL to characterize the CO2 line parameters for DIAL application. This paper will review the need for and the advantage of a CO2 DIAL profiling system, provide

  6. Comparison of Long Term Tropospheric Ozone Trends Measured by Lidar and ECC Ozonesondes from 1991 to 2010 in Southern France

    Ancellet, G.; Gaudel, A.; Godin-Beekmann, S.

    2016-06-01

    ECC (Electrochemical Concentration Cell) ozonesondes and UV DIAL (Differential Absorption Lidar) measurements have been carried out simultaneously at OHP (Observatoire de Haute Provence, 44°N, 6.7°E, 690 m) since 1991. A unique long-term trend assessment by two different instruments operated routinely at the same location is possible. Air mass trajectories have been calculated for all the ozone observations available at OHP. The bias between the seasonal mean calculated with lidar and ECC ozone vertical profiles for 4 timeperiods of 5 years is 0.6 ppbv in the free troposphere (4-8 km). Larger differences (> 10 ppbv) are explained by the need for clear sky conditions during lidar observations. The measurements of both instruments have been combined to decrease the impact of short-term atmospheric variability on the trend estimate.

  7. Weather and climate needs for Lidar observations from space and concepts for their realization. [wind, temperature, moisture, and pressure data needs

    Atlas, D.; Korb, C. L.

    1980-01-01

    The spectrum of weather and climate needs for Lidar observations from space is discussed with emphasis on the requirements for wind, temperature, moisture, and pressure data. It is shown that winds are required to realistically depict all atmospheric scales in the tropics and the smaller scales at higher latitudes, where both temperature and wind profiles are necessary. The need for means to estimate air-sea exchanges of sensible and latent heat also is noted. A concept for achieving this through a combination of Lidar cloud top heights and IR cloud top temperatures of cloud streets formed during cold air outbreaks over the warmer ocean is outlined. Recent theoretical feasibility studies concerning the profiling of temperatures, pressure, and humidity by differential absorption Lidar (DIAL) from space and expected accuracies are reviewed. An alternative approach to Doppler Lidar wind measurements also is presented. The concept involves the measurement of the displacement of the aerosol backscatter pattern, at constant heights, between two successive scans of the same area, one ahead of the spacecraft and the other behind it a few minutes later. Finally, an integrated space Lidar system capable of measuring temperature, pressure, humidity, and winds which combines the DIAL methods with the aerosol pattern displacement concept is described.

  8. Analysis of a random modulation single photon counting differential absorption lidar system for space-borne atmospheric CO2 sensing.

    Ai, X; Pérez-Serrano, A; Quatrevalet, M; Nock, R W; Dahnoun, N; Ehret, G; Esquivias, I; Rarity, J G

    2016-09-01

    The ability to observe the Earth's carbon cycles from space provides scientists an important tool to analyze climate change. Current proposed systems are mainly based on pulsed integrated path differential absorption lidar, in which two high energy pulses at different wavelengths interrogate the atmosphere sequentially for its transmission properties and are back-scattered by the ground. In this work an alternative approach based on random modulation single photon counting is proposed and analyzed; this system can take advantage of a less power demanding semiconductor laser in intensity modulated continuous wave operation, benefiting from a better efficiency, reliability and radiation hardness. Our approach is validated via numerical simulations considering current technological readiness, demonstrating its potential to obtain a 1.5 ppm retrieval precision for 50 km averaging with 2.5 W average power in a space-borne scenario. A major limiting factor is the ambient shot noise, if ultra-narrow band filtering technology could be applied, 0.5 ppm retrieval precision would be attainable. PMID:27607715

  9. Development of a UAV-based Global Ozone Lidar Demonstrator (GOLD)

    Browell, E. V.; Deyoung, R. J.; Hair, J. W.; Ismail, S.; McGee, T.; Hardesty, R. M.; Brewer, W. A.; McDermid, I. S.

    2006-12-01

    Global ozone measurements are needed across the troposphere with high vertical resolution to enable comprehensive studies of continental and intercontinental atmospheric chemistry and dynamics, which are affected by diverse natural and human-induced processes. The development of a unattended aerial vehicle (UAV) based Global Ozone Lidar Demonstrator (GOLD) is an important step in enabling a space-based ozone and aerosol lidar and for conducting unique UAV-based large-scale atmospheric investigations. The GOLD system will incorporate the most advanced technology developed under the NASA Laser Risk Reduction Program (LRRP) and the Small Business Innovative Research (SBIR) program to produce a compact, autonomously operating ozone and aerosol Differential Absorption Lidar (DIAL) system for a UAV platform. This system will leverage advanced Nd:YAG and optical parametric oscillator (OPO) laser technologies being developed by ITT Industries under the LRRP and the autonomously operating ozone DIAL system being developed by Science and Engineering Services Inc. (SESI) under an SBIR Phase-3 contract. Laser components from ITT will be integrated into the SESI DIAL system, and the resulting GOLD system will be flight tested on a NASA UAV. The development of the GOLD system was initiated as part of the NASA Instrument Incubator Program in December 2005, and great progress has been made towards completing major GOLD subsystems. ITT has begun construction of the high-power Nd:YAG pump laser and the ultraviolet OPO for generating the ozone DIAL wavelengths of 290 and 300 nm and the aerosol visible wavelength at 532 nm. SESI is completing the Phase-3 SBIR contract for the delivery and demonstration of the ozone DIAL receiver and data system, and NOAA is completing detector evaluations for use in the GOLD system. Welch Mechanical is examining system designs for integrating GOLD into the external pod that will be hung under the new IKANA (Predator-B) UAV that NASA Dryden is

  10. Column CO2 Measurement From an Airborne Solid-State Double-Pulsed 2-Micron Integrated Path Differential Absorption Lidar

    Singh, U. N.; Yu, J.; Petros, M.; Refaat, T. F.; Remus, R.; Fay, J.; Reithmaier, K.

    2014-01-01

    NASA LaRC is developing and integrating a double-Pulsed 2-micron direct detection IPDA lidar for CO2 column measurement from an airborne platform. The presentation will describe the development of the 2-micrometers IPDA lidar system and present the airborne measurement of column CO2 and will compare to in-situ measurement for various ground target of different reflectivity.

  11. Airborne lidar mapping of vertical ozone distributions in support of the 1990 Clean Air Act Amendments

    The 1990 Clean Air Act Amendments mandated attainment of the ozone standard established by the U.S. Environmental Protection Agency. Improved photochemical models validated by experimental data are needed to develop strategies for reducing near surface ozone concentrations downwind of urban and industrial centers. For more than 10 years, lidar has been used on large aircraft to provide unique information on ozone distributions in the atmosphere. However, compact airborne lidar systems are needed for operation on small aircraft of the type typically used on regional air quality investigations to collect data with which to develop and validate air quality models. Data presented in this paper will consist of a comparison between airborne differential absorption lidar (DIAL) and airborne in-situ ozone measurements. Also discussed are future plans to improve the airborne ultraviolet-DIAL for ozone and other gas observations and addition of a Fourier Transform Infrared (FTIR) emission spectrometer to investigate the effects of other gas species on vertical ozone distribution

  12. Development and operation of a real-time data acquisition system for the NASA, Langley Research Center Differential Absorption Lidar

    Butler, C.; Kindle, E. C.

    1984-01-01

    The capabilities of the DIAL data acquisition system (DAS) for the remote measurement of atmospheric trace gas concentrations from ground and aircraft platforms were extended through the purchase and integration of other hardware and the implementation of improved software. An operational manual for the current system is presented. Hardware and peripheral device registers are outlined only as an aid in debugging any DAS problems which may arise.

  13. Double-pulse 2-μm integrated path differential absorption lidar airborne validation for atmospheric carbon dioxide measurement.

    Refaat, Tamer F; Singh, Upendra N; Yu, Jirong; Petros, Mulugeta; Remus, Ruben; Ismail, Syed

    2016-05-20

    Field experiments were conducted to test and evaluate the initial atmospheric carbon dioxide (CO2) measurement capability of airborne, high-energy, double-pulsed, 2-μm integrated path differential absorption (IPDA) lidar. This IPDA was designed, integrated, and operated at the NASA Langley Research Center on-board the NASA B-200 aircraft. The IPDA was tuned to the CO2 strong absorption line at 2050.9670 nm, which is the optimum for lower tropospheric weighted column measurements. Flights were conducted over land and ocean under different conditions. The first validation experiments of the IPDA for atmospheric CO2 remote sensing, focusing on low surface reflectivity oceanic surface returns during full day background conditions, are presented. In these experiments, the IPDA measurements were validated by comparison to airborne flask air-sampling measurements conducted by the NOAA Earth System Research Laboratory. IPDA performance modeling was conducted to evaluate measurement sensitivity and bias errors. The IPDA signals and their variation with altitude compare well with predicted model results. In addition, off-off-line testing was conducted, with fixed instrument settings, to evaluate the IPDA systematic and random errors. Analysis shows an altitude-independent differential optical depth offset of 0.0769. Optical depth measurement uncertainty of 0.0918 compares well with the predicted value of 0.0761. IPDA CO2 column measurement compares well with model-driven, near-simultaneous air-sampling measurements from the NOAA aircraft at different altitudes. With a 10-s shot average, CO2 differential optical depth measurement of 1.0054±0.0103 was retrieved from a 6-km altitude and a 4-GHz on-line operation. As compared to CO2 weighted-average column dry-air volume mixing ratio of 404.08 ppm, derived from air sampling, IPDA measurement resulted in a value of 405.22±4.15  ppm with 1.02% uncertainty and 0.28% additional bias. Sensitivity analysis of environmental

  14. Modelling the performance of a LIDAR system for the measurement of atmospheric carbon dioxide

    Lawrence, J. P.; Leigh, R. J.; Bösch, H.; Monks, P. S.; Remedios, J. J.

    2009-04-01

    With atmospheric carbon dioxide concentrations rising steadily, investigations into locations and magnitudes of the sources, sinks and net surface fluxes are of increasing importance. Active space-borne measurement systems such as LIDAR offer one potential technique to derive global, near-surface concentrations. However, significant instrumental challenges need to be overcome for such measurements to achieve a useful degree of accuracy and precision. This poster presents the work being carried out at the University of Leicester to accurately model a spaceborne LiDAR system. The model aims at providing an insight into the performance of a differential absorption LiDAR system (DIAL) based on current and future technology in a realistic environment. This is achieved by accurately modelling the surface footprint of a laser system based on expected orbital parameters, and using atmospheric profiles, topographic information and BRDF's to simulate the laser lights interaction with the environment. The model readily simulates LiDAR systems operating at 1.57 and 2.05µm wavelengths using Voigt convolved HITRAN line centres to obtain accurate vertical sensitivity to the atmosphere as a result of spectral line broadening. This method allows any spectral line to be selected and any offset from the line centre to be applied to optimize the systems performance. It also offers the potential for investigating multi-spectral LiDAR systems and the benefits that this method has versus the standard duel wavelength DIAL systems. In order to retrieve near-surface CO2 concentrations of a few ppm the resulting instrument requirements are unquestionably demanding, but provide a benchmark for new technology development initiatives such as A-SCOPE and ASCENDS.

  15. Ground-based, integrated path differential absorption LIDAR measurement of CO2, CH4, and H2O near 1.6  μm.

    Wagner, Gerd A; Plusquellic, David F

    2016-08-10

    A ground-based, integrated path, differential absorption light detection and ranging (IPDA LIDAR) system is described and characterized for a series of nighttime studies of CO2, CH4, and H2O. The transmitter is based on an actively stabilized, continuous-wave, single-frequency external-cavity diode laser (ECDL) operating from 1.60 to 1.65 μm. The fixed frequency output of the ECDL is microwave sideband tuned using an electro-optical phase modulator driven by an arbitrary waveform generator and filtered using a confocal cavity to generate a sequence of 123 frequencies separated by 300 MHz. The scan sequence of single sideband frequencies of 600 ns duration covers a 37 GHz region at a spectral scan rate of 10 kHz (100 μs per scan). Simultaneously, an eye-safe backscatter LIDAR system at 1.064 μm is used to monitor the atmospheric boundary layer. IPDA LIDAR measurements of the CO2 and CH4 dry air mixing ratios are presented in comparison with those from a commercial cavity ring-down (CRD) instrument. Differences between the IPDA LIDAR and CRD concentrations in several cases appear to be well correlated with the atmospheric aerosol structure from the backscatter LIDAR measurements. IPDA LIDAR dry air mixing ratios of CO2 and CH4 are determined with fit uncertainties of 2.8 μmol/mol (ppm) for CO2 and 22 nmol/mol (ppb) for CH4 over 30 s measurement periods. For longer averaging times (up to 1200 s), improvements in these detection limits by up to 3-fold are estimated from Allan variance analyses. Two sources of systematic error are identified and methods to remove them are discussed, including speckle interference from wavelength decorrelation and the seed power dependence of amplified spontaneous emission. Accuracies in the dry air retrievals of CO2 and CH4 in a 30 s measurement period are estimated at 4 μmol/mol (1% of ambient levels) and 50 nmol/mol (3%), respectively. PMID:27534472

  16. Lidar Measurements of Tropospheric Ozone in the Arctic

    Seabrook, Jeffrey; Whiteway, James

    2016-06-01

    This paper reports on differential absorption lidar (DIAL) measurements of tropospheric ozone in the Canadian Arctic during springtime. Measurements at Eureka Weather Station revealed that mountains have a significant effect on the vertical structure of ozone above Ellesmere Island. Ozone depletion events were observed when air that had spent significant time near to the frozen surface of the Arctic Ocean reached Eureka. This air arrived at Eureka by flowing over the surrounding mountains. Surface level ozone depletions were not observed during periods when the flow of air from over the sea ice was blocked by mountains. In the case of blocking there was an enhancement in the amount of ozone near the surface as air from the mid troposphere descended in the lee of the mountains. Three case studies will be shown in the presentation, while one is described in this paper.

  17. Lidar Measurements of Tropospheric Ozone in the Arctic

    Seabrook Jeffrey

    2016-01-01

    Full Text Available This paper reports on differential absorption lidar (DIAL measurements of tropospheric ozone in the Canadian Arctic during springtime. Measurements at Eureka Weather Station revealed that mountains have a significant effect on the vertical structure of ozone above Ellesmere Island. Ozone depletion events were observed when air that had spent significant time near to the frozen surface of the Arctic Ocean reached Eureka. This air arrived at Eureka by flowing over the surrounding mountains. Surface level ozone depletions were not observed during periods when the flow of air from over the sea ice was blocked by mountains. In the case of blocking there was an enhancement in the amount of ozone near the surface as air from the mid troposphere descended in the lee of the mountains. Three case studies will be shown in the presentation, while one is described in this paper.

  18. Analysis and design methodology for the development of optimized direct detection CO2 DIAL receivers

    Cooke, Bradly J.; Laubscher, Bryan E.; Cafferty, Maureen M.; Olivas, Nicholas L.; Schmitt, Mark J.; Fuller, Kenneth R.; Goeller, Roy M.; Mietz, Donald E.; Tiee, Joseph J.; Sander, Robert K.; Vampola, John L.; Price, Stephen L.; Kasai, Ichiro

    1997-10-01

    The analysis methodology and corresponding analytical tools for the design of optimized, low-noise, hard target return CO2 differential absorption lidar (DIAL) receiver systems implementing both single element detectors and multi-pixel imaging arrays for passive/active, remote-sensing applications are presented. System parameters and components composing the receiver include: aperture, focal length, field of view, cold shield requirements, image plane dimensions, pixel dimensions, pixel pitch and fill factor, detection quantum efficiency, optical filter requirements, amplifier and temporal sampling parameters. The performance analysis is accomplished by calculating the system's CO2 laser range response, total noise, optical geometric form factor and optical resolution. The noise components include speckle, photon noise due to signal, scene and atmospheric background, cold shield, and electronic noise. System resolution is simulated through cascaded optical transfer functions and incudes effects due to atmosphere, optics, image sampling, and system motion. Experimental results of a developmental single-element detector receiver designed to detect 100 ns wide laser pulses (10 - 100 kHz pulse repetition rates) backscattered from hard- targets at nominal ranges of 10 km are presented. The receiver sensitivity is near-background noise limited, given an 8.5 - 11.5 micrometer radiant optical bandwidth, with the total noise floor spectrally white for maximum pulse averaging efficiency.

  19. Characterizing the Vertical Processes of Ozone in Colorado's Front Range Using the GSFC Ozone DIAL

    Sullivan, John T.; McGee, Thomas J.; Hoff, Raymond M.; Sumnicht, Grant; Twigg, Laurence

    2016-06-01

    Although characterizing the interactions of ozone throughout the entire troposphere are important for health and climate processes, there is a lack of routine measurements of vertical profiles within the United States. In order to monitor this lower ozone more effectively, the National Aeronautics and Space Administration (NASA) Goddard Space Flight Center TROPospheric OZone DIfferential Absorption Lidar (GSFC TROPOZ DIAL) has been developed and validated within the Tropospheric Ozone Lidar Network (TOLNet). Two scientifically interesting ozone episodes are presented that were observed during the 2014 Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality (DISCOVER AQ) campaign at Ft. Collins, Colorado. The first case study, occurring between 22-23 July 2014, indicates enhanced concentrations of ozone at Ft. Collins during nighttime hours, which was due to the complex recirculation of ozone within the foothills of the Rocky Mountain region. Although quantifying the ozone increase aloft during recirculation episodes has been historically difficult, results indicate that an increase of 20 - 30 ppbv of ozone at the Ft. Collins site has been attributed to this recirculation. The second case, occurring between Aug 4-8th 2014, characterizes a dynamical exchange of ozone between the stratosphere and the troposphere. This case, along with seasonal model parameters from previous years, is used to estimate the stratospheric contribution to the Rocky Mountain region. Results suggest that a large amount of stratospheric air is residing in the troposphere in the summertime near Ft. Collins, CO. The results also indicate that warmer tropopauses are correlated with an increase in stratospheric air below the tropopause in the Rocky Mountain Region.

  20. Development of an Airborne Triple-Pulse 2-Micron Integrated Path Differential Absorption Lidar (IPDA) for Simultaneous Airborne Column Measurements of Carbon Dioxide and Water Vapor in the Atmosphere

    Singh, Upendra N.; Petros, Mulugeta; Refaat, Tamer F.; Yu, Jirong; Antill, Charles W.; Remus, Ruben

    2016-01-01

    This presentation will provide status and details of an airborne 2-micron triple-pulse integrated path differential absorption (IPDA) lidar being developed at NASA Langley Research Center with support from NASA ESTO Instrument Incubator Program. The development of this active optical remote sensing IPDA instrument is targeted for measuring both atmospheric carbon dioxide and water vapor in the atmosphere from an airborne platform. This presentation will focus on the advancement of the 2-micron triple-pulse IPDA lidar development. Updates on the state-of-the-art triple-pulse laser transmitter will be presented including the status of seed laser locking, wavelength control, receiver and detector upgrades, laser packaging and lidar integration. Future plan for IPDA lidar system for ground integration, testing and flight validation will also be presented.

  1. On the remote monitoring of gaseous uranium hexafluoride in the lower atmosphere using lidar

    Shayeganrad, Gholamreza

    2013-10-01

    Uranium hexafluoride (UF6), a major material for uranium enrichment, is highly toxic and can have adverse effects on the environment and human health if it escapes into the atmosphere. This paper proposes a contactless enhanced remote-sensing system for spatial and temporal detection of gaseous UF6 in the atmosphere and visualization of the leakage location. The system is composed of a combination of differential absorption lidar (DIAL) and Raman lidar for the simultaneous detection of gaseous UF6 and HF. The DIAL provides information on the UF6 concentration using a frequency-quadrupled Nd:YAG laser at 266 nm for the off-wavelength and a Nd:YAG-pumped Coumarin 450 dye laser using a Littrow grating mounting operating in the frequency-doubled mode at 245 nm for the on-wavelength. The Raman scattering of molecular HF at a wavelength of 297.3 nm (with a Raman frequency shift of 3959 cm-1) is a versatile technique used to identify the HF as a probe for real-time detection of the toxic UF6 leakage location. Combining the simultaneous measurements of UF6 and HF allows for a reduction of the uncertainty and an increase in the sensitivity of remote sensing of UF6.

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

    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.

  3. Explicaciones dialécticas

    Rotsztein, Ricardo Ariel; García, Alejandro Javier; Simari, Guillermo Ricardo

    2007-01-01

    Este artículo reporta el estudio realizado hasta el momento en la línea de investigación de explicaciones dialécticas [4] y propone direcciones para el trabajo a futuro. Dentro de varias áreas de la Inteligencia Artificial se ha puesto atención al rol de las explicaciones, en particular en sistemas expertos [7, 10, 6]. El objetivo de brindar explicaciones en sistemas expertos es brindar mayor confianza al usuario con respecto a las respuestas dadas por el sistema. No obstante, pocos han anali...

  4. Gas analysis within remote porous targets using LIDAR multi-scatter techniques

    Guan, Z. G.; Lewander, M.; Grönlund, R.; Lundberg, H.; Svanberg, S.

    2008-11-01

    Light detection and ranging (LIDAR) experiments are normally pursued for range resolved atmospheric gas measurements or for analysis of solid target surfaces using fluorescence of laser-induced breakdown spectroscopy. In contrast, we now demonstrate the monitoring of free gas enclosed in pores of materials, subject to impinging laser radiation, employing the photons emerging back to the surface laterally of the injection point after penetrating the medium in heavy multiple scattering processes. The directly reflected light is blocked by a beam stop. The technique presented is a remote version of the newly introduced gas in scattering media absorption spectroscopy (GASMAS) technique, which so far was pursued with the injection optics and the detector in close contact with the sample. Feasibility measurements of LIDAR-GASMAS on oxygen in polystyrene foam were performed at a distance of 6 m. Multiple-scattering induced delays of the order of 50 ns, which corresponds to 15 m optical path length, were observed. First extensions to a range of 60 m are discussed. Remote observation of gas composition anomalies in snow using differential absorption LIDAR (DIAL) may find application in avalanche victim localization or for leak detection in snow-covered natural gas pipelines. Further, the techniques may be even more useful for short-range, non-intrusive GASMAS measurements, e.g., on packed food products.

  5. Development and Field Testing of a Continuously Operating CO2 Lidar Profiling System

    Ismail, S.; Refaat, T.; Koch, G. J.; Davis, K.; Abedin, N. M.; Rubio, M. A.; Singh, U. N.

    2009-05-01

    A ground-based 2-micron DIAL system for profiling atmospheric CO2 was developed at NASA Langley Research Center (LaRC) under the NASA Instrument Incubator Program. This system leverages 2-micron laser technology developed under a number of NASA programs to develop new solid-state YLF laser technology that provides high pulse energy, tunable, wavelength-stabilized, and double-pulsed lasers that are operable over pre-selected temperature insensitive strong CO2 absorption lines suitable for profiling of lower tropospheric CO2. It also incorporates new high quantum efficiency, high gain, and relatively low noise phototransistors, and a new receiver/signal processor system to achieve high precision DIAL measurements. The DIAL system was integrated and tested at LaRC, and then incorporated in a field experiment for evaluation. The field experiment was conducted during June-July 2008, at West Branch, Iowa, which is located at the center of a domain rich in complementary CO2 measurements. The objective of the experiment was to evaluate the accuracy and precision of the system and its ability to distinguish contents between boundary layer and free troposphere. Therefore, the experiment was co-located with other CO2 measurement setups that aid the evaluation. These setups include NOAA WBI tower with in-situ CO2 sampling sensors at 31, 99 and 379 m altitudes; NOAA airborne CO2 profiling; and radiosondes for atmospheric temperature, pressure and relative humidity profiling at the site. The lidar operations included daytime CO2 measurements to sense the well-mixed atmospheric boundary layer and overlying troposphere; day-to-night and night-to-day transitions; and night observations to capture CO2 mixing ratio differences within the boundary layer. Measurements included atmospheric CO2 spatial and temporal profiles as well as column measurements using high altitude clouds. Examples of CO2 DIAL system capability and measurements from the field experiment will be presented.

  6. The Use of a Pseudo Noise Code for DIAL Lidar

    Burris, John F.

    2010-01-01

    Retrievals of CO2 profiles within the planetary boundary layer (PBL) are required to understand CO2 transport over regional scales and for validating the future space borne CO2 remote sensing instrument, such as the CO2 Laser Sounder, for the ASCENDS mission, We report the use of a return-to-zero (RZ) pseudo noise (PN) code modulation technique for making range resolved measurements of CO2 within the PBL using commercial, off-the-shelf, components. Conventional, range resolved, measurements require laser pulse widths that are s#rorter than the desired spatial resolution and have pulse spacing such that returns from only a single pulse are observed by the receiver at one time (for the PBL pulse separations must be greater than approximately 2000m). This imposes a serious limitation when using available fiber lasers because of the resulting low duty cycle (less than 0.001) and consequent low average laser output power. RZ PN code modulation enables a fiber laser to operate at much higher duty cycles (approaching 0.1) thereby more effectively utilizing the amplifier's output. This results in an increase in received counts by approximately two orders of magnitude. The approach involves employing two, back to back, CW fiber amplifiers seeded at the appropriate on and offline CO2 wavelengths (approximately 1572 nm) using distributed feedback diode lasers modulated by a PN code at rates significantly above 1 megahertz. An assessment of the technique, discussions of measurement precision and error sources as well as preliminary data will be presented.

  7. How hot is your dial

    Many items, particularly of military equipment, manufactured during the 1930s to the 1960s contained 226Ra in the form of radioluminescent paint. When instituting or reviewing health physics procedures in museums that hold items of this type it is necessary to estimate the activity of 226Ra, its contamination potential and the amount of 222Rn emanation. Accurate estimation of the 226Ra activity of these types of items can be difficult because the radium is not a point source and is generally surrounded by casing. In principle it should be possible to estimate the 226Ra activity on a typical dial or instrument by comparing available literature values with dose rate measurements at the surface and at a distance and with the estimated amount of radium paint contained on an object. However, appropriate literature values are limited. There is a lack of specific values for particular objects and considerable variation is reported between amounts of 226Ra per gram in paint both within and between countries of manufacture. The magnitude of error in estimating the amount of paint containing 226Ra is considerable due to variations in the geometry, thickness and shielding of the paint, the difference in 226Ra activity per weight of paint and correlation of literature values to particular instruments. In addition to this the density of radium paint is unknown and there is no quantitative way of estimating the amount of paint on a dial without removing it. Radon emanation is dependent on the activity of radium present and upon containment provided by the casing and sealants within the casing. It was proposed to measure the activity of 226Ra on a series of typical aviation instrument dials using high resolution gamma-ray spectrometry making empirical corrections for the lack of ideal geometry. The 226Ra activities and radon emanation of three altimeters from Germany and the US, two from Australia and 1 from Japan were compared. Measurements of radon concentration in air were

  8. Lidar Technology at the Goddard Laser and Electro-Optics Branch

    Heaps, William S.; Obenschain, Arthur F. (Technical Monitor)

    2000-01-01

    Discovery-class orbiters now in the NASA planetary program. The purpose of the lidar is to continuously profile the water vapor and dust in the Mars atmosphere from orbit in order to quantify its dynamics, their relationship in the diurnal cycles, and to infer water vapor exchange with the Mars surface. To remotely measure the water-vapor height profiles, we will use the differential absorption lidar (DIAL) technique. We are also developing a laser sensor for measuring the total column content of CO2 in the atmosphere of the earth. CO2 is the principal greenhouse gas and has increased by roughly 80 ppm in the last century and a half. We will report our efforts in the development of the laser transmitter and photon counting detector components for a Mars Orbiting DIAL system and for the CO2 sounder.

  9. Spatio-Temporal Variability of Water Vapor in the Free Troposphere Investigated by Dial and Ftir Vertical Soundings

    Vogelmann, H.; Sussmann, R.; Trickl, T.; Reichert, A.

    2016-06-01

    We report on the free tropospheric spatio-temporal variability of water vapor investigated by the analysis of a five-year period of water vapor vertical soundings above Mt. Zugspitze (2962 m a.s.l., Germany). Our results are obtained from a combination of measurements of vertically integrated water vapor (IWV), recorded with a solar Fourier Transform InfraRed (FTIR) spectrometer and of water vapor profiles recorded with the nearby differential absorption lidar (DIAL). The special geometrical arrangement of one zenith-viewing and one sun-pointing instrument and the temporal resolution of both optical instruments allow for an investigation of the spatio-temporal variability of IWV on a spatial scale of less than one kilometer and on a time scale of less than one hour. We investigated the short-term variability of both IWV and water vapor profiles from statistical analyses. The latter was also examined by case studies with a clear assignment to certain atmospheric processes as local convection or long-range transport. This study is described in great detail in our recent publication [1].

  10. Solid-state Raman frequency converters for CO2-DIAL systems at 1.6 μm

    Rhee, Hanjo; Lisinetskii, Victor; Kaminskii, Alexander A.; Eichler, Hans-Joachim

    2009-09-01

    Measurement of the three-dimensional distribution of atmospheric trace gases, especially CO2, is an important factor to improve the accuracy of climate models and to understand the global effects of the greenhouse effect. This can be achieved by differential absorption Lidar (DIAL). The absorption spectrum of CO2 features several suitable absorption lines for a ground-based or air-borne DIAL system working at wavelengths between 1.57 μm and 1.61 μm. An appropriate laser transmitter must emit laser pulses with pulse energies of more than 10 mJ and pulse duration in the nanosecond range. For high spectral purity the bandwidth is required to be less than 60 MHz. OPOs and Er-doped solid-state lasers emit around 1.6 μm, but we describe here alternatively Nd:YAG and Nd:glass laser systems with Raman converters. The use of stimulated Raman scattering in crystalline and ceramic materials is a possibility to shift the wavelength of existing lasers depending on the size of the Raman shift. After the investigation of a large number of Raman-active materials some of them could be identified as promising candidates for the conversion of typical Nd:YAG emission wavelengths, including LiNH2C6H4SO3•H2O, Ba(NO3)2, Li2SO4•H2O, Y(HCOO)3•2H2O, β-BBO and diamond. Our experiments with Ba(NO3)2 showed that the choice of the material should not be restricted to those with an adequate first order Stokes Raman line position, but also second or third order Raman shift should be considered. Development of Raman frequency converters for high pulse energies concentrates on linear and folded resonator designs and seeded Raman amplifiers using the Raman material as a direct amplifier. With Ba(NO3)2 pulse energy up to 116 mJ and 42 % quantum efficiency at the third Stokes wavelength with 1599 nm has been demonstrated. High power operation at 5 W with compensation of thermal lensing was achieved.

  11. Development of lidar techniques for environmental studies

    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

  12. A High Energy 2-microns Laser for Multiple Lidar Applications

    Yu, Jirong; Singh, Upendra N.; Barnes, James C.; Barnes, Norman P.; Petros, Mulugeta

    2000-01-01

    Solid-state 2-microns laser has been receiving considerable interest because of its eye-safe property and efficient diode pump operation, It has potential for multiple lidar applications to detect water vapor. carbon dioxide and winds. In this paper, we describe a 2-microns double pulsed Ho:Tm:YLF laser and end-pumped amplifier system. A comprehensive theoretical model has been developed to aid the design and optimization of the laser performance. In a single Q-switched pulse operation the residual energy stored in the Tm atoms will be wasted. However, in a double pulses operation mode, the residual energy stored in the Tm atoms will repopulate the Ho atoms that were depleted by the extraction of the first Q-switched pulse. Thus. the Tin sensitized Ho:YLF laser provides a unique advantage in applications that require double pulse operation, such as Differential Absorption Lidar (DIAL). A total output energy of 146 mJ per pulse pair under Q-switch operation is achieved with as high as 4.8% optical to optical efficiency. Compared to a single pulse laser, 70% higher laser efficiency is realized. To obtain high energy while maintaining the high beam quality, a master-oscillator-power-amplifier 2-microns system is designed. We developed an end-pumped Ho:Tm:YLF disk amplifier. This amplifier uses two diode arrays as pump source. A non-imaging lens duct is used to couple the radiation from the laser diode arrays to the laser disk. Preliminary result shows that the efficiency of this laser can be as high as 3%, a factor of three increases over side-pump configuration. This high energy, highly efficient and high beam quality laser is a promising candidate for use in an efficient, multiple lidar applications.

  13. New ground-based lidar enables volcanic CO2 flux measurements

    Aiuppa, Alessandro; Fiorani, Luca; Santoro, Simone; Parracino, Stefano; Nuvoli, Marcello; Chiodini, Giovanni; Minopoli, Carmine; Tamburello, Giancarlo

    2015-01-01

    There have been substantial advances in the ability to monitor the activity of hazardous volcanoes in recent decades. However, obtaining early warning of eruptions remains challenging, because the patterns and consequences of volcanic unrests are both complex and nonlinear. Measuring volcanic gases has long been a key aspect of volcano monitoring since these mobile fluids should reach the surface long before the magma. There has been considerable progress in methods for remote and in-situ gas sensing, but measuring the flux of volcanic CO2—the most reliable gas precursor to an eruption—has remained a challenge. Here we report on the first direct quantitative measurements of the volcanic CO2 flux using a newly designed differential absorption lidar (DIAL), which were performed at the restless Campi Flegrei volcano. We show that DIAL makes it possible to remotely obtain volcanic CO2 flux time series with a high temporal resolution (tens of minutes) and accuracy (volcanic CO2 represents a major step forward in volcano monitoring, and will contribute improved volcanic CO2 flux inventories. Our results also demonstrate the unusually strong degassing behavior of Campi Flegrei fumaroles in the current ongoing state of unrest. PMID:26324399

  14. Florence Kelley and the radium dial painters

    All health physicists are familiar with the radium dial painter episode of the early 1900s and how one of today's primary radiation limits was set after studying both the health effects of these workers. The social history of this event is not as well known to health physicists. This paper tells of the efforts by Florence Kelley of the National Consumers League and others on behalf of the dial painters and of the events that led to Kelley's interest in the problem. Known as the 'Impatient Crusader', Florence Kelley worked to have legislation passed that would eliminate the radiation hazards of dial painting and to obtain compensation for those who were injured. (author)

  15. Tunable diode laser measurement of pressure-induced shift coefficients of CO2 around 2.05 μm for Lidar application

    Atmospheric carbon dioxide (CO2) is one of the main contributors to the greenhouse effect. A global monitoring of CO2 from space is foreseen as a key issue to quantify its sources and sinks at a regional scale and to better predict future levels of CO2 and their effect on climate change. Differential Absorption Lidar (DiAL) is a promising and novel spectroscopic technique for remote sensing CO2 spatial and temporal concentration distribution with a high level of accuracy. However, a precise knowledge of spectroscopic parameters of CO2 molecular transitions and their dependence with temperature and pressure is required for reducing the uncertainty on DiAl measurements. Hence, to support remote sensing of carbon dioxide in the troposphere, we report on the accurate determination of air pressure-induced shift coefficients for eight absorption lines belonging to the R branch of (2001)III 00)I band of CO2 at 2.05 μm. Purposely, a high-resolution tunable diode laser absorption spectrometer (TDLAS) coupled to a cryogenically cooled optical cell was implemented. From these measurements, we have further determined the temperature-dependencies of the air pressure-induced shift coefficients.

  16. Simultaneous NO and NO(2) DIAL measurement using BBO crystals.

    Kölsch, H J; Rairoux, P; Wolf, J P; Wöste, L

    1989-06-01

    We report a new differential absorption lidar technique for measuring simultaneously the concentrations of NO and NO(2) in the atmosphere. The technique is based on the correlation of the 450-nm absorption band of NO(2) and 227-nm absorption band of NO by frequency doubling. This performance has been allowed by the advent of a new and highly efficient frequency doubling crystal: the beta-BaB(2)O(4). A test experiment on a NO/NO(2) emitter has been performed, demonstrating the efficiency of the technique. The detection limit is estimated to be ~1 ppm .m for NO(2) and 100 ppb.m for NO. The range of measurement is limited to 1 km, due to the strong UV Rayleigh scattering and O(2) absorption. PMID:20555467

  17. Long term Monitoring of tropospheric ozone with excimer laser based DIAL system

    The description of automatic DIAL system for the long-term monitoring of ozone density in 0.5 km - 12 km altitude range is presented. The lidar is based on XeCl and KrF excimer lasers. The radiation of KrF laser is converted in hydrogen and deuterium Raman cells to obtain 277 nm and 292 nm wavelengths. The radiation backscattered from atmosphere is collected by a 60-cm-aperture Cassegraine telescope. Optical signals are detected by the PMTs operated in analog moge and digitized by 12 bit 30 MHz ADCs. The low altitude range (0.5 km-2 km) is covered by an additional 30-cm-aperture Newtonian telescope. Ozone density is calculated from the standard DIAL expressions with correction for differential backscattering and extinction. The system is operated in automatic mode and the duration of sounding session is determined only by weather conditions. The results of long-term sessions are presented as 3-D or color maps. The additional information about ozone fluxes is obtained from the correlation analysis of lidar data

  18. A study on the atmospheric concentrations of primary and secondary air pollutants in the Athens basin performed by DOAS and DIAL measuring techniques.

    Kalabokas, P D; Papayannis, A D; Tsaknakis, G; Ziomas, I

    2012-01-01

    In this work an analysis of continuous Differential Optical Absorption Spectroscopy (DOAS) measurements of primary and secondary air pollutants (SO(2), NO(2) and O(3)) in the Athens basin is performed combined with Differential Absorption Lidar (DIAL) vertical ozone measurements obtained inside the Planetary Boundary Layer (PBL) and the lower free troposphere. The measurements took place during the period May 2005-February 2007, at the National Technical University of Athens Campus (200 m above sea level (asl.), 37.96 °N, 23.78 °E). The SO(2) and NO(2) DOAS measurements showed maximum 1-hour mean values (around 20 μg/m(3) and 74 μg/m(3), respectively) in winter and did not exceed the current European Union (EU) air quality standards (European Council Directive 2008/50/EC), in contrast to ozone, which shows its maximum (around 128 μg/m(3)) in summer and frequently exceeds the EU standard for human health protection (120 μg/m(3)). If the measurements are classified according to the two most frequent flow-patterns of the air masses in the Athens basin (northern-southern circulation), it is observed that in general the atmospheric concentrations of all measured pollutants including ozone are higher when the southern circulation occurs, in comparison to the corresponding values under the northern circulation. The vertical ozone profiles obtained by DIAL were also higher under the southern circulation. During the summer months a mean difference (between the southern-northern circulations) of the order of 15-20 μg/m(3), maximized at the 0.9-1.1 km and 1.7-1.8 km height, was observed within the PBL. It was also observed that the summer surface ozone levels remained relatively high (around 80-110 μg/m(3)) even during strong northerly winds, verifying the high levels of rural surface ozone in the surrounding area reported by previous studies. PMID:22153607

  19. Field Testing of a Two-Micron DIAL System for Profiling Atmospheric Carbon Dioxide

    Refaat, Tamer F.; Ismail, Syed; Koch, Grady J.; Diaz, Liza; Davis, Ken; Rubio, Manuel

    2010-01-01

    A 2-m DIAL system has been developed at NASA Langley Research Center through the NASA Instrument Incubator Program. The system utilizes a tunable 2-m pulsed laser and an IR phototransistor for the transmitter and the receiver, respectively. The system targets the CO2 absorption line R22 in the 2.05-m band. Field experiments were conducted at West Branch, Iowa, for evaluating the system for CO2 measurement by comparison with in-situ sensors. The CO2 in-situ sensors were located on the NOAA's WBI tower at 31, 99 and 379 m altitudes, besides the NOAA s aircraft was sampling at higher altitudes. Preliminary results demonstrated the capabilities of the DIAL system in profiling atmospheric CO2 using the 2-m wavelength. Results of these experiments will be presented and discussed.

  20. Dialéctica y escucha

    Cepeda, Margarita

    2010-01-01

    La práctica de la escucha como actitud vital abierta y flexible afín a la hermenéutica de Gadamer es un acompasarse con el movimiento dialéctico no sólo del lenguaje, sino de la vida misma; de ahí que rebase al escuchar que tiene lugar en el lenguaje concebido como logos, como razón discursiva. El ejemplo de la meditación yoga ilustra esta tesis.

  1. Dial a Ride from k-forest

    Gupta, Anupam; Nagarajan, Viswanath; Ravi, R

    2007-01-01

    The k-forest problem is a common generalization of both the k-MST and the dense-$k$-subgraph problems. Formally, given a metric space on $n$ vertices $V$, with $m$ demand pairs $\\subseteq V \\times V$ and a ``target'' $k\\le m$, the goal is to find a minimum cost subgraph that connects at least $k$ demand pairs. In this paper, we give an $O(\\min\\{\\sqrt{n},\\sqrt{k}\\})$-approximation algorithm for $k$-forest, improving on the previous best ratio of $O(n^{2/3}\\log n)$ by Segev & Segev. We then apply our algorithm for k-forest to obtain approximation algorithms for several Dial-a-Ride problems. The basic Dial-a-Ride problem is the following: given an $n$ point metric space with $m$ objects each with its own source and destination, and a vehicle capable of carrying at most $k$ objects at any time, find the minimum length tour that uses this vehicle to move each object from its source to destination. We prove that an $\\alpha$-approximation algorithm for the $k$-forest problem implies an $O(\\alpha\\cdot\\log^2n)$-ap...

  2. High resolution and high precision absorption spectroscopy using high finesse cavities: application to the study of molecules with atmospheric interest; Cavites de haute finesse pour la spectroscopie d'absorption haute sensibilite et haute precision: application a l'etude de molecules d'interet atmospherique

    Motto-Ros, V.

    2005-12-15

    High finesse cavities are used to measure very weak absorption features. Two different methodologies are investigated and applied to the study of molecules with atmospheric interest. First, Continuous Wave - Cavity Ring Down Spectroscopy (CW-CRDS) is used to study the atmospheric spectra of water vapour in the near infrared range. These measurements are performed for temperature and pressure of atmospheric relevance for DIAL applications (Differential Absorption Lidar). This study, financed by the European Space Agency (ESA), goes with the WALES mission (Water Vapour Lidar Experiment in Space). The experimental setup was conceived in order to control pressure, temperature and relative humidity conditions. A particular attention is done to characterize and describe the spectrometer. Then, measurements of red Oxygen B band are performed to demonstrate the huge performance of Optical Feedback Cavity Enhanced Absorption Spectroscopy (OF-CEAS). The desired optical feedback is obtained by light injection into the high finesse cavity through a glass plate placed inside the cavity and closed to the Brewster angle. We show a measurement dynamical range of 5 orders of magnitude (10{sup -5} to 10{sup -10} /cm) and a sensitivity of 10{sup -10} /cm/{radical} Hz. Also, sampling absorption spectra by the super linear cavity frequency comb allows very precise frequency measurements. This is demonstrated by the determination of Oxygen pressure shifts with an absolute accuracy of around 5 x 10{sup -5} cm{sup -1}/atm. To our knowledge, we provide the highest accuracy ever reported for this parameter. (author)

  3. Lidar to lidar calibration phase 2

    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 at...

  4. Lidar to lidar calibration phase 1

    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....

  5. 2.5 MHz Line-Width High-energy, 2 Micrometer Coherent Wind Lidar Transmitter

    Petros, Mulugeta; Yu, Jirong; Trieu, Bo; Bai, Yingxin; Petzar, Paul; Singh, Upendra N.; Reithmaier, Karl

    2007-01-01

    2 micron solid-state lasers are the primary choice for coherent Doppler wind detection. As wind lidars, they are used for wake vortex and clear air turbulence detection providing air transport safety. In addition, 2 micron lasers are one of the candidates for CO2 detection lidars. The rich CO2 absorption line around 2 micron, combined with the long upper state life of time, has made Ho based 2 micron lasers a viable candidate for CO2 sensing DIAL instrument. The design and fabrication of a compact coherent laser radar transmitter for Troposphere wind sensing is under way. This system is hardened for ground as well as airborne applications. As a transmitter for a coherent wind lidar, this laser has stringent spectral line width and beam quality requirements. Although the absolute wavelength does not have to be fixed for wind detection, to maximize return signal, the output wavelength should avoid atmospheric CO2 and H2O absorption lines. The base line laser material is Ho:Tm:LuLF which is an isomorph of Ho:Tm:YLF. LuLF produces 20% more output power than Ho:Tm:YLF. In these materials the Tm absorption cross-section, the Ho emission cross-section, the Tm to Ho energy transfer parameters and the Ho (sup 5) I (sub 7) radiative life time are all identical. However, the improved performance of the LuLF is attributed to the lower thermal population in the (sup 5) I (sub 8) manifold. It also provides higher normal mode to Q-switch conversion than YLF at high pump energy indicating a lower up-conversion. The laser architecture is composed of a seed laser, a ring oscillator, and a double pass amplifier. The seed laser is a single longitudinal mode with a line width of 13 KHz. The 100mJ class oscillator is stretched to 3 meters to accommodate the line-width requirement without compromising the range resolution of the instrument. The amplifier is double passed to produce greater than 300mJ energy.

  6. Lidar system for remote environmental studies

    Gondal, M.A.; Mastromarino, J. [Laser Research Section, Centre for Applied Physical Sciences, The Research Institute, King Fahd University of Petroleum and Minerals, 31261 Dhahran (Saudi Arabia)

    2000-10-02

    Light detection and ranging (lidar) system has been developed for remote monitoring of the environment. The system has been tested for measuring the size of clouds and by measurement of differential absorption due to pollutant gases like NO{sub 2} and SO{sub 2} in a cell. The lidar measurements revealed strong scattered signals from clouds situated around 11 km above the earth surface. The lidar data indicates that cloud thickness varied from 0.8 to 3.6 km at various times.

  7. Data acquisition system for atmospheric Lidar

    For the purpose of improving the detection range of lidar which is used in atmospheric environmental monitoring, a solution that single photon counter and photomultiplier work together was proposed. The photomultiplier was applied to detect strong signal echoing from a short distance, while single photon counter was used to record remote and weak echo signal. The data acquired in this way were accumulated to increase SRN. According to the requirement of DIAL, A high-speed and high-precision dual-channel data acquisition system was designed and implemented for lidar. The system which was based on FPGA sampled signals with a 14 bits ADC and acquired data in real time through hardware logic as well as transported data to computer via USB2.0 bus. The result of experiments demonstrates that the detection range of atmospheric lidar is improved by this system. The result also shows that the system acquires data promptly, and provides high temporal and spatial resolution, which means that it can satisfy the requirements of atmospheric Liar. (authors)

  8. Lidar postcards

    Schreppel, Heather A.; Cimitile, Matthew J.

    2011-01-01

    The U.S. Geological Survey (USGS) Coastal and Marine Geology Program develops and uses specialized technology to build high-resolution topographic and habitat maps. High-resolution maps of topography, bathymetry, and habitat describe important features affected by coastal-management decisions. The mapped information serves as a baseline for evaluating resources and tracking the effectiveness of resource- and conservation-management decisions. These data products are critical to researchers, decision makers, resource managers, planners, and the public. To learn more about Lidar (light detection and ranging) technology visit: http://ngom.usgs.gov/dsp/.

  9. 75 FR 33821 - Section 8 Random Digit Dialing Fair Market Rent Surveys

    2010-06-15

    ... URBAN DEVELOPMENT Section 8 Random Digit Dialing Fair Market Rent Surveys AGENCY: Office of the Chief... incorrect. The Department has used this random digit dialing (RDD) survey methodology for 15 years, as... lists the following information: Title of Proposal: Section 8 Random Digit Dialing Fair Market...

  10. Development of ground-based lidars for measuring H2O and O3 profiles in the troposphere

    Sakai, T.; Abo, M.; Pham, L. H. P.; Uchino, O.; Nagai, T.; Izumi, T.; Morino, I.; Ohyama, H.; Nagasawa, C.

    2015-12-01

    Water vapor is the strongest natural greenhouse gas and a highly variable atmospheric constituent. It plays an important role of the energy transfer and the meteorological phenomena such as evaporation, vapor transport, cloud formation, and rainfall in the troposphere. Ozone is an important air pollutant that at high concentrations impacts on human health and ecosystem including crops and also a greenhouse gas that plays an important role in climate change. Aerosol is an important climate parameter and also one of the largest error sources (causes) in retrieval from solar reflected short wavelength infrared radiances observed with greenhouse gases observing satellites such as the GOSAT and OCO-2. Therefore, we have been developing ground-based differential absorption lidars (DIALs) for measuring the tropospheric water vapor, ozone and aerosols.The water vapor DIAL employs two distributed Bragg reflector (DBR) lasers operating at 829.054 nm for the online wavelength and 829.124 nm for the offline wavelength with tapered semiconductor optical amplifier (TSOA) in a master oscillator power amplifier (MOPA) configuration, and utilizes pseudorandom coded pulse modulation technique.It has started to measure the vertical distribution of lower tropospheric water vapor in order to improve accuracy and lead time of numerical weather prediction of local heavy rainfalls. Well-organized and regularly spaced convective cells of which vertical thickness were 200 m and the periods were 10 minutes were observed in the top of planetary boundary layer at 2.5 km altitude over Tokyo (35.66°N, 139.37°E) on 22 June 2015.The ozone DIAL employs a Nd:YAG laser and a 2 m long Raman cell filled with CO2 gas which generates four Stokes lines (276.2, 287.2, 299.1, and 312.0 nm) of stimulated Raman scattering, and two receiving telescopes with diameters of 49 and 10 cm.It has started to measure the vertical distributions of the tropospheric ozone as well as aerosols and thin cirrus cloud in

  11. Calculation of optimal parameters of an NH3-CO2 lidar

    Vasil'ev, BI; Mannoun, OM

    2005-01-01

    The basic parameters (range, signal-to-noise ratio, and sensitivity) of a lidar using NH3 and CO2 lasers are calculated. The principle of lidar operation is based on the differential absorption recording. Absorption spectra of all known Freons are considered in the spectral range 9-13.5 mu m and opt

  12. Hardness of Preemptive Finite Capacity Dial-a-Ride

    Gørtz, Inge Li

    2006-01-01

    In the Finite Capacity Dial-a-Ride problem the input is a metric space, a set of objects, each specifying a source and a destination, and an integer k---the capacity of the vehicle used for making the deliveries. The goal is to compute a shortest tour for the vehicle in which all objects can be...

  13. Development of a Portable, Ground-based Ozone Lidar Instrument for Tropospheric Ozone Research and Educational Training

    Chyba, Thomas; Zemker, Thomas; Fishman, Jack (Technical Monitor)

    1999-01-01

    The objective of this research project is to develop a portable, eye-safe, ground-based ozone lidar instrument specialized for ozone differential absorption lidar (DIAL) measurements in the troposphere. This research project directly supports the goal of NASA's Earth Science Enterprise to understand the distribution and budget of tropospheric ozone (objective 1.5 of the Earth Science Strategic Enterprise Plan, 1998-2002). It can participate in ground validation experiments for TES, a tropospheric ozone satellite mission due to be launched in 2002. It can also be utilized for correlative ground measurements in future GTE (Global Tropospheric Experiment) and space-based ozone lidar missions, such as ORACLE. Multiple ground-based ozone lidar systems would improve the data obtained through current ozone-sonde networks. This prototype instrument could to serve as the basic unit for these and other future monitoring projects requiring multi-instrument networks, such as that proposed for the Global Tropospheric Ozone Project (GTOP). GTOP is currently being formulated by a scientific panel of the International Global Atmospheric Chemistry Project to meet its goal to better understand the processes that control the global distribution of tropospheric ozone. In order for the lidar to be widely deployed in networks, it must be fairly easy to use and maintain as well as being cost-competitive with a ground station launching ozonesondes several times a day. A second 2-year grant to continue this effort with students participating in ground tests and system improvements has been awarded by the Office of Equal Employment Opportunities (OEOP). This project also supports existing NASA lidar missions through its development of advanced, compact lidar technology. Innovations in both transmitters and receivers have been made in this project. Finally, this system could be modified in the future to probe more deeply into the stratosphere. This could be accomplished by increasing the

  14. Wind Measurement LIDAR Project

    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. Sobre o transcendental prático e a dialética da sociabilidade

    Luiz Henrique Lopes dos Santos

    2011-07-01

    Full Text Available Ao escrever Apresentação do mundo: considerações sobre o pensamento de Ludwig Wittgenstein, as intenções de José Arthur Giannotti não eram principalmente exegéticas. Ele pretendia trilhar alguns caminhos abertos por Ludwig Wittgenstein no intuito de lidar com suas próprias obsessões filosóficas. Neste artigo, mostro por que e como algumas das linhas de pensamento de Wittgenstein ajudaram Giannotti a clarear logicamente alguns de seus próprios temas filosóficos obsessivos: o transcendental prático e a dialética da sociabilidade.In writing Presentation of the World: considerations on the thought of Ludwig Wittgenstein, Giannotti's intentions were not primarily exegetical. He aimed to follow some of Wittgenstein's conceptual pathways in order to deal with his own philosophical obsessions. In this paper, I show why and how some of Wittgenstein's lines of thought helped Giannotti to logically clarify a couple of his own obsessive philosophical themes: the practical transcendental and the dialectic of sociability.

  16. Space-borne clear air lidar measurements in the presence of broken cloud

    I. Astin

    Full Text Available A number of proposed lidar systems, such as ESA’s AEOLUS (formerly ADM and DIAL missions (e.g. WALES are to make use of lidar returns in clear air. However, on average, two-thirds of the globe is covered in cloud. Hence, there is a strong likelihood that data from these instruments may be contaminated by cloud. Similarly, optically thick cloud may not be penetrated by a lidar pulse, resulting in unobservable regions that are overshadowed by the cloud. To address this, it is suggested, for example, in AEOLUS, that a number of consecutive short sections of lidar data (between 1 and 3.5 km in length be tested for cloud contamination or for overshadowing and only those that are unaffected by cloud be used to derive atmospheric profiles. The prob-ability of obtaining profiles to near ground level using this technique is investigated both analytically and using UV air-borne lidar data recorded during the CLARE’98 campaign. These data were measured in the presence of broken cloud on a number of flights over southern England over a four-day period and were chosen because the lidar used has the same wavelength, footprint and could match the along-track spacing of the proposed AEOLUS lidar.

    Key words. Atmospheric composition and structure (aerosols and particles Meteorology and atmospheric dynamics (instruments and techniques; general circulation

  17. Lidar base specification

    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.

  18. SunDial: embodied informal science education using GPS

    Megan K. Halpern

    2010-12-01

    Full Text Available Science centers serve a number of goals for visitors, ideally providing experiences that are educational, social, and meaningful. This paper describes SunDial, a handheld application developed for families to use at a science center. Inspired by the idea of geocaching, the high-tech treasure hunting game that utilizes GPS technologies, SunDial asks families to use a single handheld device to locate and participate in a series of learning modules around the museum. Observations of 10 families suggest that it supports rich informal science education experiences, provides insights about families’ interaction patterns around and with single handheld devices, and demonstrates the value of navigation as an educational experience. Further, using recently released guidelines for Informal Science Education (ISE experiences to inform the design process proved valuable, tying features of the technology to educational and social goals, and giving evidence that explicit reference to these guidelines can improve ISE experiences and technologies.

  19. Liderazgo dialógico en Comunidades de Aprendizaje

    Gisela Redondo-Sama

    2015-09-01

    Full Text Available Objeto: El objetivo de este artículo es presentar y discutir los resultados obtenidos en tres Comunidades de Aprendizaje en relación a los procesos de creación, promoción y consolidación del liderazgo dialógico. En el análisis, se incorpora el papel de los diferentes miembros de la comunidad en la organización escolar. Diseño/metodología: Se realiza una revisión de literatura científica sobre los conceptos de liderazgo, liderazgo educativo y liderazgo dialógico. Las contribuciones se han seleccionado principalmente del Journal Citation Report, SCOUPS y ERIH, entre otras bases científicas. El trabajo empírico se ha desarrollado en base a la metodología comunicativa, que pone el énfasis en el diálogo igualitario entre investigadores e investigadoras y sujetos implicados en la realidad social objeto de estudio. Se han seleccionado tres centros que se transforman en Comunidad de Aprendizaje en muy diferentes momentos (1978, 2001 y 2013. Las personas entrevistadas se han seleccionado considerango la diversidad de perfiles de participación en los centros, concretamente profesorado, familiares y voluntariado. Aportaciones y resultados: Los resultados obtenidos contribuyen a la comprensión de las formas en que en estas tres Comunidades de Aprendizaje se desarrolla el liderazgo dialógico y cómo se consolida con la comunidad. En base a los resultados obtenidos en las entrevistas, se destacan aspectos vinculados a los procesos de aprendizaje a través de la implementación de las actuaciones educativas de éxito. Limitaciones: El liderazgo dialógico en Comunidades de Aprendizaje se desarrolla en contextos escolares muy diversos, estando este artículo centrado en tres centros. Implicaciones prácticas: La participación de toda la comunidad en el liderazgo dialógico en Comunidades de Aprendizaje tiene implicaciones que pueden ir más allá del centro escolar. Implicaciones sociales: Comunidades de Aprendizaje ha demostrado mejorar

  20. Feasibility testing for dial-a-ride problems

    Haugland, Dag; Ho, Sin C.

    Hunsaker and Savelsbergh have proposed an algorithm for testing feasibility of a route in the solution to the dial-a-ride problem. The constraints that are checked are load capacity constraints, time windows, ride time bounds and wait time bounds. The algorithm has linear running time. By virtue ...... a simple example, we show in this work that their algorithm is incorrect. We also prove that by increasing the time complexity by only a logarithmic factor, a correct algorithm is obtained....

  1. Feasibility Testing for Dial-a-Ride Problems

    Haugland, Dag; Ho, Sin C.

    2010-01-01

    Hunsaker and Savelsbergh have proposed an algorithm for testing feasibility of a route in the solution to the dial-a-ride problem. The constraints that are checked are load capacity constraints, time windows, ride time bounds and wait time bounds. The algorithm has linear running time. By virtue ...... a simple example, we show in this work that their algorithm is incorrect. We also prove that by increasing the time complexity by only a logarithmic factor, a correct algorithm is obtained....

  2. Feasibility Checking for Dial-a-Ride Problems

    Haugland, Dag; Ho, Sin C.

    Hunsaker and Savelsbergh have proposed an algorithm for testing feasibility of a route in the solution to the dial-a-ride problem. The constraints that are checked are load capacity constraints, time windows, ride time bounds and wait time bounds. The algorithm has linear running time. By virtue ...... a simple example, we show in this work that their algorithm is incorrect. We also prove that by increasing the time complexity by only a logarithmic factor, a correct algorithm is obtained....

  3. A semi-automation procedure for dial comparators calibration

    Garcia Benadí, Albert; Shariat Panahi, Shahram; Río Fernandez, Joaquín del; Manuel Lázaro, Antonio

    2009-01-01

    In this article an improvement of a calibration process of measurement equipment in the field of dimensional metrology is presented. Devices under calibration process are dial comparators. The semi-automated process is focused on the acquisition and treatment of the calibration data. The aim of the semi-automated implementation is the improvement of the process performance for error minimization produced by human factors and a reduction of time. We have implemented semi-automated process i...

  4. Efficient 1.6 Micron Laser Source for Methane DIAL

    Shuman, Timothy; Burnham, Ralph; Nehrir, Amin R.; Ismail, Syed; Hair, Johnathan W.

    2013-01-01

    Methane is a potent greenhouse gas and on a per molecule basis has a warming influence 72 times that of carbon dioxide over a 20 year horizon. Therefore, it is important to look at near term radiative effects due to methane to develop mitigation strategies to counteract global warming trends via ground and airborne based measurements systems. These systems require the development of a time-resolved DIAL capability using a narrow-line laser source allowing observation of atmospheric methane on local, regional and global scales. In this work, a demonstrated and efficient nonlinear conversion scheme meeting the performance requirements of a deployable methane DIAL system is presented. By combining a single frequency 1064 nm pump source and a seeded KTP OPO more than 5 mJ of 1.6 µm pulse energy is generated with conversion efficiencies in excess of 20%. Even without active cavity control instrument limited linewidths (50 pm) were achieved with an estimated spectral purity of 95%. Tunable operation over 400 pm (limited by the tuning range of the seed laser) was also demonstrated. This source demonstrated the critical needs for a methane DIAL system motivating additional development of the technology.

  5. Ozone profiles obtained by DIAL technique at Maïdo Observatory in La Reunion Island: comparisons with ECC ozone-sondes, ground-based FTIR spectrometer and microwave radiometer measurements

    Portafaix, T.; Godin-Beekmann, S.; Payen, G.; de Mazière, M.; Langerock, B.; Fernandez, S.; Posny, F.; Cammas, J. P.; Metzger, J. M.; Bencherif, H.; Vigouroux, C.; Marquestaut, N.

    2016-06-01

    A DIAL lidar system performing stratospheric ozone profile measurements from 15 to 45 km is installed at Reunion Island (southwest of Indian Ocean). The purpose of this communication is to present this DIAL system mounted now at the new Maïdo Observatory since February 2013, and the ozone profile retrieval. The first stratospheric ozone profiles obtained during 2013 and 2014 will be presented and discussed. Inter-comparison and differences observed with other high vertical resolution ozone profiles performed by ECC ozonesonde will be shown. Finally, comparisons with low vertical resolution ozone profiles retrieved from microwave and FTIR remote sensing measurements performed at Maïdo will be carried out, making appropriate use of the associated averaging kernels

  6. 2015 Lowndes County (GA) Lidar

    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...

  7. Lidar Calibration Centre

    Pappalardo, Gelsomina; Freudenthaler, Volker; Nicolae, Doina; Mona, Lucia; Belegante, Livio; D'Amico, Giuseppe

    2016-06-01

    This paper presents the newly established Lidar Calibration Centre, a distributed infrastructure in Europe, whose goal is to offer services for complete characterization and calibration of lidars and ceilometers. Mobile reference lidars, laboratories for testing and characterization of optics and electronics, facilities for inspection and debugging of instruments, as well as for training in good practices are open to users from the scientific community, operational services and private sector. The Lidar Calibration Centre offers support for trans-national access through the EC HORIZON2020 project ACTRIS-2.

  8. First-time lidar measurement of water vapor flux in a volcanic plume

    Fiorani, L.; Colao, F.; A. PALUCCI; Poreh, D.; Aiuppa, A.; Giudice, G.

    2011-01-01

    The CO2 laser-based lidar ATLAS has been used to study the Stromboli volcano plume. ATLAS measured water vapor concentration in cross-sections of the plume and wind speed at the crater. Water vapor concentration and wind speed were retrieved by differential absorption lidar and correlation technique, respectively. Lidar returns were obtained up to a range of 3 km. The spatial resolution was 15 mand the temporal resolution was 20 s. By combining these measurements, the water vapor ...

  9. Dimensionless parameterization of lidar for laser remote sensing of the atmosphere and its application to systems with SiPM and PMT detectors.

    Agishev, Ravil; Comerón, Adolfo; Rodriguez, Alejandro; Sicard, Michaël

    2014-05-20

    In this paper, we show a renewed approach to the generalized methodology for atmospheric lidar assessment, which uses the dimensionless parameterization as a core component. It is based on a series of our previous works where the problem of universal parameterization over many lidar technologies were described and analyzed from different points of view. The modernized dimensionless parameterization concept applied to relatively new silicon photomultiplier detectors (SiPMs) and traditional photomultiplier (PMT) detectors for remote-sensing instruments allowed predicting the lidar receiver performance with sky background available. The renewed approach can be widely used to evaluate a broad range of lidar system capabilities for a variety of lidar remote-sensing applications as well as to serve as a basis for selection of appropriate lidar system parameters for a specific application. Such a modernized methodology provides a generalized, uniform, and objective approach for evaluation of a broad range of lidar types and systems (aerosol, Raman, DIAL) operating on different targets (backscatter or topographic) and under intense sky background conditions. It can be used within the lidar community to compare different lidar instruments. PMID:24922200

  10. Simultaneous and Independent Measurement of Atmospheric Water Vapor and Carbon Dioxide using a Triple-Pulsed, 2-micron Airborne IPDA Lidar - A Feasibility Study

    Singh, U. N.; Refaat, T. F.; Yu, J.; Petros, M.

    2013-12-01

    Water vapor (H2O) and carbon dioxide (CO2) are dominant greenhouse gases that are critical for Earth's radiation budget and global warming through the eco-system and the carbon cycle. NASA Langley Research Center (LaRC) has a strong heritage in atmospheric remote sensing of both gases using several instruments adopting various DIAL techniques. This communication presents a feasibility study for measuring both H2O and CO2 simultaneously and independently using a single instrument. This instrument utilizes the Integrated Path Differential Absorption (IPDA) lidar technique to measure the weighted-average column dry-air mixing ratios of CO2 (XCO2) and H2O (XH2O) independently and simultaneously from an airborne platform. The key component of this instrument is a tunable triple-pulse 2-micron laser. The three laser pulses are transmitted sequentially within a short time interval of 200 microsec. The wavelength of each of the laser pulses can be tuned separately. The IPDA receiver design is based on low-risk, commercially available components, including 300-micron diameter InGaAs 2-micron pin detector, a low-noise, high speed trans-impedance amplifier (TIA) and 12-bit 400 MHz digitizer.

  11. Lidar calibration experiments

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

    1997-01-01

    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. The...

  12. Airborne 2-Micron Double Pulsed Direct Detection IPDA Lidar for Atmospheric CO2 Measurement

    Yu, Jirong; Petros, Mulugeta; Refaat, Tamer; Reithmaier, Karl; Remus, Ruben; Singh, Upendra; Johnson, Will; Boyer, Charlie; Fay, James; Johnston, Susan; Murchison, Luke

    2016-06-01

    An airborne 2-micron double-pulsed Integrated Path Differential Absorption (IPDA) lidar has been developed for atmospheric CO2 measurements. This new instrument has been flown in spring of 2014 for a total of ten flights with 27 flight hours. This IPDA lidar provides high precision measurement capability by unambiguously eliminating contamination from aerosols and clouds that can bias the results.

  13. Calculus, Radio Dials and the Straight-Line Frequency Variable Capacitor

    Boyadzhiev, Khristo N.

    2010-01-01

    Most often radio dials of analogue radios are not uniformly graded; the frequencies are cramped on the left side or on the right side. This makes tuning more difficult. Why are dials made this way? We shall see here that simple calculus can help understand this problem and solve it. (Contains 7 figures.)

  14. Lidar User’s Manual

    Peterson, Lance William

    2011-01-01

    This is intended to be a user’s manual for the upgraded USU Rayleigh lidar. As such, it begins with a discussion of the purpose of a lidar. This is followed by a brief explanation of the fundamentals of Rayleigh scatter lidar. Next the reasons for and benefits of upgrading the lidar are discussed and as well as how the upgrade was accomplished. After establishing this basis, instructions are provided for operating the lidar, performing basic maintenance, and aligning various components.

  15. DIAL-meettechniek toegepast op NO2-detectie

    Salemink; H.; Valk; P.de*

    1985-01-01

    Verslag van experimenteel onderzoek naar haalbaarheid van meting van NO2 m.b.v. lidar remote sensing. Aangetoond wordt de mogelijkheid tot detectie van NO2 over 1.0 km padlengte. Verbeteringen van de techniek, om tot een acceptabele detectielimiet voor stedelijke omgeving te komen, worden aangeg

  16. DIAL-meettechniek toegepast op NO2-detectie

    Salemink; H.;; Valk, van der, G.G.M.; P.

    1985-01-01

    Verslag van experimenteel onderzoek naar haalbaarheid van meting van NO2 m.b.v. lidar remote sensing. Aangetoond wordt de mogelijkheid tot detectie van NO2 over 1.0 km padlengte. Verbeteringen van de techniek, om tot een acceptabele detectielimiet voor stedelijke omgeving te komen, worden aangegeven. Het onderzoek is gebaseerd op de huidige operationele ervaring met lidarsystemen.

  17. Lidar techniques for environmental and ecological monitoring

    Svanberg, Sune

    2015-04-01

    An overview of optical probing of the atmosphere will be given, where mostly active remote- sensing techniques of the laser-radar type will be covered, but also some passive techniques employing ambient radiation. Atmospheric objects of quite varying sizes can be studied. Mercury is the only pollutant in atomic form in the atmosphere, while other pollutants are either molecular or in particle form. Light detection and ranging (Lidar) techniques allow three-dimensional mapping of such constituents, and examples from atmospheric lidar work in Lund and in Guangzhou will be given. Recently, much larger lidar targets have been studied. Monitoring of flying insects and birds is of considerable ecological interest, and several projects have been pursued in collaboration with biologists. Mostly, elastic backscattering and fluorescence techniques are employed. Some references to recent activities by the author and his colleagues are given below. [1] Z.G. Guan, L. Mei, P. Lundin, G. Somesfalean, and S. Svanberg, Vertical Lidar Sounding of Air Pollutants in a Major Chinese City, Appl. Phys. B 101, 465 (2010) [2] L. Mei, G.Y. Zhou and S. Svanberg, Differential Absorption Lidar System Employed for Background Atomic Mercury Vertical Profiling in South China, Lasers Opt. Eng. 55, 128 (2013) [3] Z.G. Guan, M. Brydegaard, P. Lundin, M. Wellenreuther, E. Svensson, and S. Svanberg, Insect Monitoring with Fluorescence LIDAR techniques - Field experiments, Appl. Optics 48, 5668 (2010) [4] A. Runemark, M. Wellereuther, H. Jayaweera, S. Svanberg and M. Brydegaard, Rare Events in Remote Dark Field Spectroscopy: An Ecological Case study of Insects, IEEE JSTQE 18, 1573 (2011) [5] L. Mei, Z.G. Guan, H.J. Zhou, J. Lv, Z.R. Zhu, J.A. Cheng, F.J. Chen, C. Löfstedt, S. Svanberg, and G. Somesfalean, Agricultural Pest Monitoring using Fluorescence Lidar Techniques, Applied Physics B 106, 733 (2011) [6] P. Lundin, P. Samuelsson, S. Svanberg, A. Runemark, S. Åkesson, and M. Brydegaard, Remote

  18. 2004 Connecticut Lidar

    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...

  19. LIDAR: Malheur NWR

    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...

  20. Lidar 2009 - All Returns

    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...

  1. 2003 Oahu Coastline Lidar

    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...

  2. LIDAR: Malheur NWR

    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...

  3. 2006 FEMA Hawaii Lidar

    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.

  4. LIDAR Thomson scattering

    This collection contains 21 papers on the application and development of LIDAR (Light Detection and Ranging) Thomson scattering techniques for the determination of spatially resolved electron temperature and density in magnetic confinement experiments, particularly tokamaks. Refs, figs and tabs

  5. 2004 Maine Lidar

    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...

  6. Phoenix Lidar Operation Animation

    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.

  7. Minimum Makespan Multi-vehicle Dial-a-Ride

    Gørtz, Inge Li; Nagarajan, Viswanath; Ravi, R.

    -vehicle Dial-a-Ride problem, there are q vehicles each having capacity k and where each vehicle j is an element of [q] has its own depot-vertex r(j) is an element of V. A feasible schedule consists of a capacitated route for each vehicle (where vehicle j originates and ends at its depot r(j)) that together...... move all objects from their sources to destinations. The objective is to find a feasible schedule that minimizes the maximum completion time (i.e. makespan) of vehicles, where the completion time of vehicle j is the time when it returns to its depot r(j) at the end of its route. We consider the...

  8. A psicoterapia dialógica de Martin Buber

    Ramón, Saturnino Pesquero

    2010-01-01

    Full Text Available A doutrina buberiana sobre os efeitos humanizadores do seu principio dialógico, que define o genuíno diálogo, estabelece a base para se alcançar tanto uma realização pessoal plena quanto uma sociedade construída sobre as relações interpessoais. Num primeiro momento, sua elaboração teórica e aplicação prática estiveram mais voltadas para o campo da sociologia e da educação. A partir da década dos anos 50, no entanto, privilegia seu viés psicológico e psicoterápico. O presente artigo objetiva expor os principais conceitos e postulados de seu modelo psicoterápico assim como a convergência do mesmo com o da Psicoterapia Centrada na Pessoa de C. Rogers.

  9. Solving the Dial-a-Ride Problem using Genetic algorithms

    Bergvinsdottir, Kristin Berg; Larsen, Jesper; Jørgensen, Rene Munk

    In the Dial-a-Ride problem (DARP) customers send transportation requests to an operator. A request consists of a specified pickup location and destination location along with a desired departure or arrival time and demand. The aim of DARP is to minimize transportation cost while satisfying custom...... routing problems for the vehicles using a routing heuristic. The algorithm is implemented in Java and tested on publicly available data sets....... service level constraints (Quality of Service). In this paper we present a genetic algorithm for solving the DARP. The algorithm is based on the classical cluster-first route-second approach, where it alternates between assigning customers to vehicles using a genetic algorithm and solving independent...

  10. Solving the Dial-a-Ride Problem using Genetic Algorithms

    Jørgensen, Rene Munk; Larsen, Jesper; Bergvinsdottir, Kristin Berg

    2007-01-01

    In the Dial-a-Ride problem (DARP), customers request transportation from an operator. A request consists of a specified pickup location and destination location along with a desired departure or arrival time and capacity demand. The aim of DARP is to minimize transportation cost while satisfying ...... routing problems for the vehicles using a routing heuristic. The algorithm is implemented in Java and tested on publicly available data sets. The new solution method has achieved solutions comparable with the current state-of-the-art methods....... customer service level constraints (Quality of Service). In this paper, we present a genetic algorithm (GA) for solving the DARP. The algorithm is based on the classical cluster-first, route-second approach, where it alternates between assigning customers to vehicles using a GA and solving independent...

  11. Comparison of Efficacy of Dial Flow Microdrip Sets for Hyperviscous Fluids

    Shiraboina Madanmohan

    2012-04-01

    Full Text Available The current study was conducted with an objective to compare efficacy of dial flow microdrip sets for hyperviscous fluids. Four different sets and two hyperviscous fluids were used to eliminate bias. The study was done by suspending buret sets which was attached with microdrip dial flow sets and set rate was 100 ml/min. we noted the time to flow 100ml. 3 sets were delivered fluid as per set rate with insignificant p value. Micro drip dial flow sets can be used for hyperviscous fluids. [National J of Med Res 2012; 2(2.000: 232-233

  12. Comparison of Efficacy of Dial Flow Microdrip Sets for Hyperviscous Fluids

    Shiraboina Madanmohan; Ramachandran Gopinath

    2012-01-01

    The current study was conducted with an objective to compare efficacy of dial flow microdrip sets for hyperviscous fluids. Four different sets and two hyperviscous fluids were used to eliminate bias. The study was done by suspending buret sets which was attached with microdrip dial flow sets and set rate was 100 ml/min. we noted the time to flow 100ml. 3 sets were delivered fluid as per set rate with insignificant p value. Micro drip dial flow sets can be used for hyperviscous fluids. [Nation...

  13. Novel solid state lasers for Lidar applications at 2 μm

    Della Valle, G.; Galzerano, G.; Toncelli, A.; Tonelli, M.; Laporta, P.

    2005-09-01

    A review on the results achieved by our group in the development of novel solid-state lasers for Lidar applications at 2 μm is presented. These lasers, based on fluoride crystals (YLF4, BaY2F8, and KYF4) doped with Tm and Ho ions, are characterized by high-efficiency and wide wavelength tunability around 2 μm. Single crystals of LiYF4, BaY2F8, and KYF4 codoped with the same Tm3+ and Ho3+ concentrations were successfully grown by the Czochralski method. The full spectroscopic characterization of the different laser crystals and the comparison between the laser performance are presented. Continuous wave operation was efficiently demonstrated by means of a CW diode-pumping. These oscillators find interesting applications in the field of remote sensing (Lidar and Dial systems) as well as in high-resolution molecular spectroscopy, frequency metrology, and biomedical applications.

  14. LIDAR Thomson scattering

    This report on the IAEA Technical Committee Meeting on LIDAR (LIght Detection And Ranging) Thomson Scattering, held at the JET Joint Undertaking, Abingdon, Oxfordshire, United Kingdom, 8-10 April 1991, summarizes reviews of (1) the existing JET LIDAR system; (2) developments in solid state, visible and near IR lasers that are of potential interest for LIDAR applications; (3) possible laser sources, including Excimer and CO2 for their interesting pulse duration and repetition rate if suitable detectors can be found; (4) a compact design for a Nd phosphate glass system; (5) short pulse length (30-50 ps) laser requirements to obtain improved spatial resolution needed for the divertor region plasma in tokamaks; (6) a more advanced laser design using a so-called light boiler and wave front reversal (WFR) cells; (7) possibilities to use Nd:YAG laser wavelengths in a LIDAR system; a session on detectors and analysis methods describing (8) the new Scancross streaking intensifier; (9) detectors for LIDAR Thomson scattering (advantages of streak cameras, photomultipliers, and gated intensifiers); (10) results of investigations into the use of an AGAT streak camera as a possible LIDAR detector; (11) assessment experiments on a Hamamatsu streak camera planned for use on the Large Helical Device (heliotron); (12) studies on the usefulness of microchannel plate photomultipliers as detectors in the JET LIDAR system; (13) conventional Thomson scattering application of microchannel photomultipliers on the reversed-field pinch RFX; (14) a description of the Nd:YLF 10 Hz laser based scattering system for FTU; (15) the feasibility of a 8-10 Hz LIDAR system; (16) some aspects of Raman calibration of scattering systems; (17) use of statistical analysis of data for recovering calibrations of a data set; and, finally, a session on LIDAR systems for future devices, especially (18) ITER and BPX, with ITER requiring development of radiation hard optics capable of withstanding both thermal

  15. The Zugspitze Raman Lidar: System Testing

    Höveler, Katharina; Klanner, Lisa; Trickl, Thomas; Vogelmann, Hannes

    2016-06-01

    A high-power Raman lidar system has been installed at the high-altitude research station Schneefernerhaus (Garmisch-Partenkirchen, Germany) at 2675 m a.s.l., at the side of the existing wide-range differrential-absorption lidar. An industrial XeCl laser was modified for polarized single-line operation at an average power of about 175 W. This high power and a 1.5-m-diameter receiver are expected to allow us to extend the operating range for water-vapour sounding to more than 25 km, at an accuracy level of the order of 10 %. In addition, temperature measurements in the free troposphere and to altitudes beyond 80 km are planned. The system is currently thoroughly tested and exhibits an excellent performance up to the lowermost stratosphere. We expect that results for higher altitudes can be presented at the meeting.

  16. Sonoma County, CA, 2013 Lidar

    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...

  17. 2012 USGS Lidar: Juneau (AK)

    National Oceanic and Atmospheric Administration, Department of Commerce — This task order is for planning, acquisition, processing, and derivative products of LiDAR data to be collected for Juneau, Alaska. LiDAR data, and derivative...

  18. Solid State Transmitters for Water Vapor and Ozone DIAL Systems Project

    National Aeronautics and Space Administration — The focus of this Select Phase II program is to build and deliver laser components both for airborne water vapor and ozone DIAL systems. Specifically, Fibertek...

  19. Calling for Help? Considering Function and Meaning when Patients Drunk-Dial Psychotherapists

    Kelly Serafini; Donna LaPaglia; Matthew Steinfeld

    2013-01-01

    Drunk-dialing is a term documented in both popular culture and academic literatures to describe a behavior in which a person contacts another individual by phone while intoxicated. In our collective clinical experience we have found that clients drunk-dial their clinicians too, particularly while in substance use treatment, and yet there is a noticeable absence of research on the topic to guide clinical decision-making within a process-based understanding of these events. As the parameters wi...

  20. Operational Effects of Service Level Variations for the Dial-a-Ride Problem

    MOLENBRUCH, Yves; Braekers, Kris; CARIS, An

    2015-01-01

    The dial-a-ride problem consists of designing a number of minimum-cost vehicle routes in a system of demand-dependent, collective people transportation. Quality is ensured by taking into account service level requirements. However, little research has been performed regarding the effect of simultaneous service level variations on operational costs incurred by dial-a-ride service providers. By investigating 78 different quality scenarios, being a combination of a maximum deviation from the use...

  1. Survival times of pre-1950 US women radium dial workers

    Survival times of US women radium dial workers to the end of 1989 were examined by life table methods. Included were 1301 women rust employed before 1930 and 1242 first employed in 1930-1949. Expected numbers of deaths were estimated from age- and time-specific death rates for US white females. In the early group, 85 deaths from the well-known radium-induced cancers - bone sarcomas and head carcinomas - were observed, but only 724 deaths from aH other causes were observed vs 755 expected. Life shortening (±S.E.) of 1.8 ±0.5 y compared to the general population of US white females was calculated from the time distribution of all deaths in the pre-1930 group. In the 1930--1949 group, 350 deaths were observed vs 343 expected and no bone sarcomas or head carcinomas occurred. Among women who survived at least 2 y after rust measurement of body radium, a significant excess of observed vs expected deaths was found only for radium intakes greater than 1.85 MBq of 226Ra + 228Ra, and no trend of deaths or reduction of life expectancy was found with length of employment

  2. Micropulse Lidar (MPL) Handbook

    Mendoza, A; Flynn, C

    2006-05-01

    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 the same as for radar. Pulses of energy are transmitted into the atmosphere; the energy scattered back to the transceiver is collected and measured as a time-resolved signal. From the time delay between each outgoing transmitted pulse and the backscattered signal, the distance to the scatterer is infered. Besides real-time detection of clouds, post-processing of the lidar return can also characterize the extent and properties of aerosol or other particle-laden regions.

  3. Ozone lidar monitoring

    An ozone lidar system was installed at the National Institute for Environmental Studies (36 deg. N, 140 deg. E) in March, 1988 and observation of ozone profiles commenced from August 1988. The lidar system consists of XeCl, XeF and KrF excimer lasers, 2 m and 56 cm telescope optics and data processing systems. Since the Ozone Lidar Monitoring Program of the Center for the Environmental Research started in October 1990, frequent measurements (more than 50 times per year) have been made. After checking the statistical and systematic errors, the ozone profiles were archived. Comparisons between the lidar data and SAGE II satellite data were done for mutual validation and gave good results. Seventy four vertical profiles of ozone archived for the period from August 1990 through December 1991 are presented in this report. The seasonal and altitudinal variations of stratospheric ozone distribution can be explained by generally understood transport and photochemical reaction processes. Longer term monitoring is required to detect trends in the vertical profile of ozone

  4. Calibrating nacelle lidars

    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)

  5. Lidar 2009 - IMG

    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...

  6. 2004 Alaska Lidar Mapping

    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...

  7. Nacelle lidar power curve

    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...

  8. Dose-response relationships for female radium dial workers

    Among 1474 women employed in the United States radium dial-painting industry before 1930, there are 61 known cases of bone sarcoma and 21 cases of carcinoma of the paranasal sinuses or the mastoid air cells (''head carcinomas''). The relative effectiveness of 226Ra and 228Ra and dose-incidence relationships were examined for the 759 of these women whose radium body burden has been determined; there are 38 cases of bone sarcoma and 17 cases of head carcinoma in this group. Incidence (I) was expressed as tumor cases per person-year and the dose parameter (D) was the quantity (microcuries) of radium that entered the blood during the period of exposure. To the observed data for each type of tumor were fitted equations that can be formulated from the general form I = (C + alpha dD+ βD2)e-γ/sup D/, where C, the natural incidence for this population, was about 10-5 per person-year. For each equation, the best values of the dose coefficients were found by a least-squares fitting procedure. An equation of the form I = (C + BD2)e-/sup γD/ provided the best fit for the bone sarcomas, when the dose was expressed as microcuries of 226Ra plus 2.5 times microcuries of 228Ra. An acceptable fit to the head carcinoma data was provided by the linear equation I = C + d alpha γ with D equal to microcuries of 226Ra. As a test of bias due to selection of cases with known symptoms of malignancy, the analyses were repeated after removal of all cases for whom radium was determined only after exhumation, and no significant changes in the fitted coefficients were found. The dose-incidence equations obtained when the dose was expressed as average skeletal dose in rad are also given

  9. Dose-effect relationships for the US radium dial painters

    Dose-response data are presented from a large percentage of the US workers who were exposed to radium through the painting of luminous dials. The data in this paper are only from females, because very few males worked in this occupation. Log-normal analyses were done for radium-induced bone sarcomas and head carcinomas after the populations of the respective doses were first determined to be log-normally distributed. These populations included luminisers who expressed no radium-related cancerous condition. In this study of the female radium luminisers, the most important data concerning radiation protection are probably from workers who were exposed to radium but showed no cancer incidence. A total of 1391 subjects with average measured skeletal doses below 10 Gy are in this category. A primary purpose is to illustrate the strong case that 226,228Ra is representative of those radionuclides that exemplify in humans a 'threshold' dose, a dose below which there has been no observed health effects on the exposed individual. Application of a threshold dose for radium deposited in the skeleton does not mean to imply that any other source of skeletal irradiation should be considered to follow a similar pattern. Second, a policy issue that begs for attention is the economic consequence of forcing radiation to appear as a highly toxic insult. It is time to evaluate the data objectively instead of formatting the extrapolation scheme beforehand and forcing the data to fit a preconceived pattern such as linearity through the dose-effect origin. In addition, it is time to re-evaluate (again) variations in background radiation levels throughout the world and to cease being concerned with, and regulating against, miniscule doses for which no biomedical effects on humans have ever been satisfactorily identified or quantified. (author)

  10. Calculation of optimal parameters of an NH3-CO2 lidar

    The basic parameters (range, signal-to-noise ratio, and sensitivity) of a lidar using NH3 and CO2 lasers are calculated. The principle of lidar operation is based on the differential absorption recording. Absorption spectra of all known Freons are considered in the spectral range 9-13.5 μm and optimal wavelengths suitable for sensing them are determined. It is shown that the NH3-CO2 lidar can sense Freons at distances up to 10 km at a signal-to-noise ratio exceeding 10. Sensitivities of the lidar for sensing Freon-11 using various lines of the ammonia laser are calculated. It is shown that remote sensing of Freon-11 at concentrations of the order of 5x10-6% is possible at distances up to 8.5 km. (laser applications and other topics in quantum electronics)

  11. 2006 MDEQ Camp Shelby, MS Lidar Survey

    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. Lidar detection of carbon dioxide in volcanic plumes

    Fiorani, Luca; Santoro, Simone; Parracino, Stefano; Maio, Giovanni; Del Franco, Mario; Aiuppa, Alessandro

    2015-06-01

    Volcanic gases give information on magmatic processes. In particular, anomalous releases of carbon dioxide precede volcanic eruptions. Up to now, this gas has been measured in volcanic plumes with conventional measurements that imply the severe risks of local sampling and can last many hours. For these reasons and for the great advantages of laser sensing, the thorough development of volcanic lidar has been undertaken at the Diagnostics and Metrology Laboratory (UTAPRAD-DIM) of the Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA). In fact, lidar profiling allows one to scan remotely volcanic plumes in a fast and continuous way, and with high spatial and temporal resolution. Two differential absorption lidar instruments will be presented in this paper: BILLI (BrIdge voLcanic LIdar), based on injection seeded Nd:YAG laser, double grating dye laser, difference frequency mixing (DFM) and optical parametric amplifier (OPA), and VULLI (VULcamed Lidar), based on injection seeded Nd:YAG laser and optical parametric oscillator (OPO). The first one is funded by the ERC (European Research Council) project BRIDGE and the second one by the ERDF (European Regional Development Fund) project VULCAMED. While VULLI has not yet been tested in a volcanic site, BILLI scanned the gas emitted by Pozzuoli Solfatara (Campi Flegrei volcanic area, Naples, Italy) during a field campaign carried out from 13 to 17 October 2014. Carbon dioxide concentration maps were retrieved remotely in few minutes in the crater area. Lidar measurements were in good agreement with well-established techniques, based on different operating principles. To our knowledge, it is the first time that carbon dioxide in a volcanic plume is retrieved by lidar, representing the first direct measurement of this kind ever performed on an active volcano and showing the high potential of laser remote sensing in geophysical research.

  13. Remote Sensing of Greenhouse Gases by Combining Lidar and Optical Correlation Spectroscopy

    Anselmo C.; Thomas B; Miffre A.; Francis M; Cariou J.P.; Rairoux P.

    2016-01-01

    In this contribution, we present recent work on the ability to achieve range-resolved greenhouse gases concentration measurements in the Earth’s atmosphere (CH4, H2O) by combining broadband optical correlation spectroscopy (OCS) with lidar. We show that OCS-Lidar is a robust methodology, allowing trace gases remote sensing with a low dependence on the temperature and pressure-variation absorption cross section. Moreover, we evaluate, as an experimental proof, the water vapor profile in the pl...

  14. Airborne high spectral resolution lidar for measuring aerosol extinction and backscatter coefficients

    Esselborn, Michael; Wirth, Martin; Fix, Andreas; Tesche, Matthias; Gerhard, Ehret

    2008-01-01

    An airborne high spectral resolution lidar (HSRL) based on an iodine absorption filter and a high--power frequency--doubled Nd:YAG laser has been developed to measure backscatter and extinction coefficients of aerosols and clouds. The instrument was operated aboard the DLR Falcon 20 research aircraft during the Saharan Mineral Dust Experiment (SAMUM) in May/June 2006 to measure optical properties of Saharan dust. A detailed description of the lidar system, the analysis of...

  15. LIDAR mapping of ozone-episode dynamics in Paris and intercomparaison with spot analysers

    Thomasson, Alexandre; Geffroy, Sylvain; Frejafon, Emeric; Weidauer, Derk; Fabian, R.; Godet, Yves; Nomine, Michel; Menard, Tamara; Rairoux, Pierre; Moeller, D.; Wolf, Jean-Pierre

    2002-01-01

    International audience Continuous mapping of an ozone episode in Paris in June 1999 has been performed using a differential absorption lidar system. The 2D ozone concentration vertical maps recorded over 33 h at the Champ de Mars are compiled in a video clip that gives access to local photochemical dynamics with unprecedented precision. The lidar data are compared over the whole period with point monitors located at 0-, 50- and 300-m altitudes on the Eiffel Tower. Very good agreement is fo...

  16. A semianalytic Monte Carlo code for modelling LIDAR measurements

    Palazzi, Elisa; Kostadinov, Ivan; Petritoli, Andrea; Ravegnani, Fabrizio; Bortoli, Daniele; Masieri, Samuele; Premuda, Margherita; Giovanelli, Giorgio

    2007-10-01

    LIDAR (LIght Detection and Ranging) is an optical active remote sensing technology with many applications in atmospheric physics. Modelling of LIDAR measurements appears useful approach for evaluating the effects of various environmental variables and scenarios as well as of different measurement geometries and instrumental characteristics. In this regard a Monte Carlo simulation model can provide a reliable answer to these important requirements. A semianalytic Monte Carlo code for modelling LIDAR measurements has been developed at ISAC-CNR. The backscattered laser signal detected by the LIDAR system is calculated in the code taking into account the contributions due to the main atmospheric molecular constituents and aerosol particles through processes of single and multiple scattering. The contributions by molecular absorption, ground and clouds reflection are evaluated too. The code can perform simulations of both monostatic and bistatic LIDAR systems. To enhance the efficiency of the Monte Carlo simulation, analytical estimates and expected value calculations are performed. Artificial devices (such as forced collision, local forced collision, splitting and russian roulette) are moreover foreseen by the code, which can enable the user to drastically reduce the variance of the calculation.

  17. Simulating full-waveform LIDAR

    Kim, Angela M.

    2009-01-01

    LIDAR (LIght Detection And Ranging) is used to remotely measure the threedimensional shapes and arrangements of objects with high efficiency and accuracy by making precise measurements of time-of-flight of pulses of light. Discrete return LIDAR systems provide a discrete series of elevation points corresponding to reflections from objects in the scene. Full-waveform LIDAR systems measure the intensity of light returned to the sensor continuously over a period of time. Relatively little r...

  18. Advanced Photodetectors for Space Lidar

    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

  19. Complex Terrain and Wind Lidars

    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...

  20. Improved CO [lidar detector

    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.

  1. NASA/GSFC Scanning Raman Lidar Measurements of Water Vapor and Cirrus Clouds during WVIOP2000 and AFWEX

    Whiteman, D. N.; Evans, K. D.; DiGirolamo, P.; Demoz, B. B.; Turner, D.; Comstock, J.; Ismail, S.; Ferrare, R. A.; Browell, E. V.; Goldsmith, J. E. M.; Abshire, James B. (Technical Monitor)

    2002-01-01

    The NASA/GSFC Scanning Raman Lidar (SRL) was deployed to the Southern Great Plains CART site from September - December, 2000 and participated in two field campaigns devoted to comparisons of various water vapor measurement technologies and calibrations. These campaigns were the Water Vapor Intensive Operations Period 2000 (WVIOP2000) and the ARM FIRE Water Vapor Experiment (AFWEX). WVIOP2000 was devoted to validating water vapor measurements in the lower atmosphere while AFWEX had similar goals but for measurements in the upper troposphere. The SRL was significantly upgraded both optically and electronically prior to these field campaigns. These upgrades enabled the SRL to demonstrate the highest resolution lidar measurements of water vapor ever acquired during the nighttime and the highest S/N Raman lidar measurements of water vapor in the daytime; more than a factor of 2 increase in S/N versus the DOE CARL Raman Lidar. Examples of these new measurement capabilities along with comparisons of SRL and CARL, LASE, MPI-DIAL, in-situ sensors, radiosonde, and others will be presented. The profile comparisons of the SRL and CARL have revealed what appears to be an overlap correction or countrate correction problem in CARL. This may be involved in an overall dry bias in the precipitable water calibration of CARL with respect to the MWR of approx. 4%. Preliminary analysis indicates that the application of a temperature dependent correction to the narrowband Raman lidar measurements of water vapor improves the lidar/Vaisala radiosonde comparisons of upper tropospheric water vapor. Other results including the comparison of the first-ever simultaneous measurements from four water vapor lidar systems, a bore-wave event captured at high resolution by the SRL and cirrus cloud optical depth studies using the SRL and CARL will be presented at the meeting.

  2. Lectura dialógica: interacciones que mejoran y aceleran la lectura

    Valls, Rosa; Soler Gallart, Marta; Flecha, Ramón

    2008-01-01

    En este trabajo se aborda el estudio de la lectura dialógica enmarcada en una más amplia concepción de aprendizaje que tiene sus fundamentos en las prácticas (comunidades de aprendizaje), teorías (Freire, Habermas, Searle) e investigaciones (includ-ed) más relevantes de la actual sociedad de la información, situando en este nuevo contexto las aportaciones dialógicas anteriores. Esto permite entenderla como una instancia coordinante de las actividades de aprendizaje que realizan todas las pers...

  3. Henri Walon: por uma teoria dialética na educação

    Maria Inês Naujorks

    2000-04-01

    Full Text Available O texto aborda as principais idéias desenvolvidas por Henri Wallon. Tendo como método o materialismo dialético, seu projeto foi o de formular uma "ciência do homem". Para o autor o desenvolvimento é a síntese dialética do biológico e do social e só pode ser entendido à luz das contradições de um processo que se estende por toda vida toda.

  4. Henri Walon: por uma teoria dialética na educação

    Maria Inês Naujorks

    2000-01-01

    O texto aborda as principais idéias desenvolvidas por Henri Wallon. Tendo como método o materialismo dialético, seu projeto foi o de formular uma "ciência do homem". Para o autor o desenvolvimento é a síntese dialética do biológico e do social e só pode ser entendido à luz das contradições de um processo que se estende por toda vida toda.

  5. The Client Program of WLAN Dialing%WLAN拨号客户端方案

    肖宏

    2011-01-01

    随着中国电信WLAN业务开放和深入推进,客户对WLAN业务体验飞速增长,本文就WLAN业务拨号方式进行多方位的分析,并提出WLAN专用拨号客户端的建议和发展思路。%With the opening up of China Telecom and further promote the WLAN business,customer service experience rapid growth of WLAN,the WLAN business dialing this multi-faceted analysis,and proposed WLAN dedicated dialing client's suggestions and development ideas.

  6. La Biblioteca Tutorizada: Una Experiencia de Aprendizaje Dialógico desde una Comunidad de Aprendizaje

    Reca Fernández, María Henar

    2013-01-01

    Desde el proyecto comunidades de aprendizaje se pretende dar respuesta a las desigualdades imperantes en la sociedad de la información transformando las prácticas educativas tradicionales de la sociedad industrial a través de un planteamiento dialógico que utiliza como herramienta principal el aprendizaje dialógico. Dentro de las medidas de éxito educativo avaladas por la comunidad científica internacional desarrolladas en las comunidades de aprendizaje encontramos la biblioteca tutorizada. E...

  7. To LiDAR or Not to LiDAR

    Niemeyer, Grant; Kelly, Rodney

    2015-01-01

    This session provides an overview and discussion of the different methods of preparing a topographic survey, from conventional to mobile Lidar. The presentation will include discussion of the pros and cons for each method in different situations. Three case studies will be presented in which Lidar was used to prepare the topographic survey: an airport, an interstate, and an urban area.

  8. High Spectral Resolution Lidar: System Calibration

    Vivek Vivekanandan, J.; Morley, Bruce; Spuler, Scott; Eloranta, Edwin

    2015-04-01

    One of the unique features of the high spectral resolution lidar (HSRL) is simultaneous measurements of backscatter and extinction of atmosphere. It separates molecular scattering from aerosol and cloud particle backscatter based on their Doppler spectrum width. Scattering from aerosol and cloud particle are referred as Mie scattering. Molecular or Rayleigh scattering is used as a reference for estimating aerosol extinction and backscatter cross-section. Absolute accuracy of the backscattered signals and their separation into Rayleigh and Mie scattering depends on spectral purity of the transmitted signals, accurate measurement of transmit power, and precise performance of filters. Internal calibration is used to characterize optical subsystems Descriptions of high spectral resolution lidar system and its measurement technique can be found in Eloronta (2005) and Hair et al.(2001). Four photon counting detectors are used to measure the backscatter from the combined Rayleigh and molecular scattering (high and low gain), molecular scattering and cross-polarized signal. All of the detectors are sensitive to crosstalk or leakage through the optical filters used to separate the received signals and special data files are used to remove these effects as much as possible. Received signals are normalized with respect to the combined channel response to Mie and Rayleigh scattering. The laser transmit frequency is continually monitored and tuned to the 1109 Iodine absorption line. Aerosol backscatter cross-section is measured by referencing the aerosol return signal to the molecular return signal. Extinction measurements are calculated based on the differences between the expected (theoretical) and actual change in the molecular return. In this paper an overview of calibration of the HSRL is presented. References: Eloranta, E. W., High Spectral Resolution Lidar in Lidar: Range-Resolved Optical Remote Sensing of the Atmosphere, Klaus Weitkamp editor, Springer Series in Optical

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

    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).

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

    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.