Raman-shifted eye-safe aerosol lidar

Mayor, Satyajit; Spuler, Scott M.

doi:10.1364/ao.43.003915

Cited by 72 publications

(37 citation statements)

References 15 publications

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“…Additionally, by pointing a laser beam in various directions at various angles (scanning) with respect to the surface, a ground-based aerosol LiDAR system can provide a description of the three-dimensional distribution of aerosols in the atmosphere [60][61][62][63]. Range height indicator (RHI) scanning measurements can help obtain low z i starting from a distance where complete overlap is reached [56].…”

Section: Theoretical and Experimental Approaches To Correct Lidar Sigmentioning

confidence: 99%

“…The RHI scanning measurements were used only within some feasibility studies and/or case studies using data obtained during field campaigns. Notwithstanding, all range eye-safety in the transmitted laser beam needs to be maintained for these LiDAR systems (e.g., [62,63]), otherwise they cannot be deployed in urbanized areas. Additionally, scanning LiDAR systems usually require high-power laser transmitters to achieve useful SNR in the off-zenith profiles due to the trade-off in range/height relationships with scanner elevation angles in the RHI mode (e.g., [47]).…”

Section: Theoretical and Experimental Approaches To Correct Lidar Sigmentioning

confidence: 99%

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Monitoring Depth of Shallow Atmospheric Boundary Layer to Complement LiDAR Measurements Affected by Partial Overlap

Pal

2014

Remote Sensing

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Abstract:There is compelling evidence that the incomplete laser beam receiver field-of-view overlap (i.e., partial overlap) of ground-based vertically-pointing aerosol LiDAR restricts the observational range for detecting aerosol layer boundaries to a certain height above the LiDAR. This height varies from one to few hundreds of meters, depending on the transceiver geometry. The range, or height of full overlap, is defined as the minimum distance at which the laser beam is completely imaged onto the detector through the field stop in the receiver optics. Thus, the LiDAR signal below the height of full overlap remains erroneous. In effect, it is not possible to derive the atmospheric boundary layer (ABL) top (z i ) below the height of full overlap using lidar measurements alone. This problem makes determination of the nocturnal z i almost impossible, as the nocturnal z i is often lower than the minimum possible retrieved height due to incomplete overlap of lidar. Detailed studies of the nocturnal boundary layer or of variability of low z i would require changes in the LiDAR configuration such that a complete transceiver overlap could be achieved at a much lower height. Otherwise, improvements in the system configuration or deployment (e.g., scanning LiDAR) are needed. However, these improvements are challenging due to the instrument configuration and the need for Raman channel signal, eye-safe laser transmitter for scanning deployment, etc. This paper presents a brief review of some of the challenges and opportunities in overcoming the partial overlap of the LiDAR transceiver to determine z i below the height of full-overlap using complementary approaches to derive low z i . A comprehensive discussion focusing on four different techniques is presented. These are based on the combined (1) ceilometer and LiDAR; (2) tower-based trace gas (e.g., CO 2 ) concentration profiles and LiDAR measurements; (3) 222 Rn budget approach and LiDAR-derived results; and (4) encroachment model and LiDAR observations.

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Section: Theoretical and Experimental Approaches To Correct Lidar Sigmentioning

confidence: 99%

Section: Theoretical and Experimental Approaches To Correct Lidar Sigmentioning

confidence: 99%

Monitoring Depth of Shallow Atmospheric Boundary Layer to Complement LiDAR Measurements Affected by Partial Overlap

Pal

2014

Remote Sensing

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“…Raman-shifted Eye-safe Aerosol Lidar)) system [12] of National Center for Atmospheric Research (NCAR) at Boulder, CO, was used for atmospheric testing by integrating newly developed phototransistors (HPT) into REAL system. The REAL system has a 16" telescope, two 200-micron APD detector channels, and operates at 1.543-micron wavelength.…”

Section: The Co 2 Dial Profiling Systemmentioning

confidence: 99%

Development of Laser, Detector, and Receiver Systems for an Atmospheric CO<inf>2</inf> Lidar Profiling System

Ismail

Koch

Abedin

et al. 2008

2008 IEEE Aerospace Conference

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Abstract-Technology developments are in progress towards the development of a Differential Absorption Lidar (DIAL) to measure range-resolved and column amounts of atmospheric CO 2 . This system is also capable of providing high-resolution aerosol profiles and cloud distributions. It is being developed as part of the NASA ESTO Instrument Incubator Program (IIP). The long-term goal of this work is the development of a space-based DIAL system. The IIP effort involves the design, development, evaluation, and fielding of a ground-based CO 2 profiling system. A successful outcome of this development will be an instrument capable of making measurements in the lower troposphere and boundary layer where the sources and sinks of CO 2 are located. It will also be a valuable tool for contributing to the validation of space-based measurements of column CO 2 from NASA's Orbiting Carbon Observatory (OCO) and for participation in the North American Carbon Program (NACP) regional intensive field campaigns. The system can also be used as a test-bed for the evaluation of lidar technologies for space-application. This DIAL system leverages 2-micron laser technology developed under a number of NASA programs to develop new solid-state laser technology that provides high pulse energy, tunable, wavelength-stabilized, and double-pulsed lasers that are operable over pre-selected temperature insensitive strong CO 2 absorption lines suitable for profiling of lower tropospheric CO 2 . It also incorporates new high quantum efficiency, high gain, and high signal-tonoise ratio phototransistors, and a new receiver/signal processor system to achieve high precision DIAL measurements. In situ sensor system calibration is in progress at Pennsylvania State University for field evaluation of the DIAL system in 2008. High-resolution laser spectroscopic measurements are being conducted at the Jet Propulsion Laboratory to characterize line parameters of the temperature insensitive line to be used for DIAL measurements.Atmospheric tests of the laser have been conducted by operating it locked to the CO 2 absorption line center, with offset locking in the side-line mode, and in the off-line position. The reference laser is locked to center of absorption line within 390 kHz. This improves the level of stabilization improved by factor of 10 compared to earlier configuration. The detector has been characterized in the laboratory and has been evaluated by conducting atmospheric tests at NCAR, Boulder, Colorado. The receiver uses an F2.2 all aluminum 16" diameter telescope and optical design focuses light onto a 200-micron detector. Design, development, atmospheric testing, and performance evaluation associated with the development of this DIAL system are presented in this paper.

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“…Because potential airborne hazards include particulate matter (such as bacteria related to anthrax, tularemia, and other infectious diseases) whose detection would be important to a building protection system, the Pentagon Shield field program was used as an opportunity to test a new aerosol lidar developed at NCAR (Mayor and Spuler 2004;Spuler and Mayor 2005). This 1.54-^m elastic backscatter lidar was located just to the east of the CTI Windtracer system on the hill of the Pentagon Annex ("R" in Fig.…”

Section: Raman-shifted Eye-safe Aerosol Lidar (Real)mentioning

confidence: 99%