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  • 1
    Electronic Resource
    Electronic Resource
    Rotational collisional narrowing in an infrared CO2 Q branch studied with a tunable-diode laser (1986)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 84 (1986), S. 1149-1156 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Rotational collisional narrowing, or line mixing, has been observed in the infrared absorption spectrum of the Q branch of the (1110,0310)II – 0000 band of CO2 at 1932.47 cm−1 using a tunable diode laser. Spectra were recorded at pressures ranging from 100 to 745 Torr both inside the Q branch and below the band origin. The observed absorption coefficients below the band origin were up to 80% less than those calculated using an isolated Lorentz line approximation. A simple fitting law for the state-to-state rotationally inelastic rate constants is determined using the known line broadening coefficients. A calculation of line mixing using these rates agrees with the observed absorption coefficients to within several percent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.450504
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    Paper (German National Licenses)
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  • 2
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    Rotational collisional narrowing in an infrared CO2Qbranch studied with a tunable‐diode laser (1986)
    American Institute of Physics
    Details
    Publication Date: 1986-02-01
    Print ISSN: 0021-9606
    Electronic ISSN: 1089-7690
    Topics: Chemistry and Pharmacology , Physics
    Published by American Institute of Physics
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  • 3
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    An Atmospheric Soliton Observed with Doppler Radar, Differential Absorption Lidar, and a Molecular Doppler Lidar (2008)
    American Meteorological Society
    Details
    Publication Date: 2008-08-01
    Description: Airborne Leandre II differential absorption lidar (DIAL), S-band dual-polarization Doppler radar (S-Pol), and Goddard Lidar Observatory for Winds (GLOW) Doppler lidar data are used, in conjunction with surface mesonet and special sounding data, to derive the structure and dynamics of a bore and associated solitary wave train (soliton) that were generated in southwestern Kansas during the International H20 Project (IHOP_2002). Vertical cross sections of S-Pol reflectivity, S-Pol radial velocity, and DIAL water vapor mixing ratio show a stunning amplitude-ordered train of trapped solitary waves. DIAL data reveal that the leading wave in the soliton increasingly flattened with time as the soliton dissipated. A method is developed for using the GLOW Doppler winds to obtain the complex two-dimensional vertical circulation accompanying the dissipating soliton. The results show multiple circulations identical in number to the oscillations seen in the S-Pol and DIAL data. The leading updraft occurred precisely at the time that the bore passed over the GLOW facility, as well as when the photon count values suddenly ramped up (suggesting lifting of the low-level inversion by the bore). Additional evidence in support of the validity of the results is provided by the fact that layer displacements computed using the derived vertical motions agree well with those implied by the changes in height of the DIAL mixing ratio surfaces. The depth and speed of propagation of the bore seen in the DIAL and surface mesoanalyses were shown to be consistent with the predictions from bore hydraulic theory. Analysis of National Center for Atmospheric Research (NCAR) Integrated Sounding System (ISS) data shows that a highly pronounced curvature in the profile of bore-relative winds, related to the existence of a very strong low-level jet, effectively trapped the upward leakage of solitary wave energy below 3 km. This finding explains the trapped lee wave–type structures seen in the DIAL, GLOW, and S-Pol data.
    Print ISSN: 0739-0572
    Electronic ISSN: 1520-0426
    Topics: Geography , Geosciences , Physics
    Published by American Meteorological Society
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  • 4
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    Lidar-Measured Wind Profiles: The Missing Link in the Global Observing System (2014)
    American Meteorological Society
    Details
    Publication Date: 2014-04-01
    Print ISSN: 0003-0007
    Electronic ISSN: 1520-0477
    Topics: Geography , Physics
    Published by American Meteorological Society
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  • 5
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    Infrared lidar windshear detection for commercial aircraft and the edge technique, a new method for atmospheric wind measurement (1991)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: The edge technique, a new method for measuring small frequency shifts, is described. The technique allows high-accuracy measurement of atmospheric winds (0.2-1 m/s) with a high vertical resolution (10 m) using currently available technology. With the edge technique, a lidar system can be used to obtain range resolved measurements of the wind in the atmosphere from the ground, aircraft, or spaceborne platforms. The edge technique can be used with different lasers over a broad range of wavelengths.
    Keywords: AIRCRAFT INSTRUMENTATION
    Type: In: Image understanding for aerospace applications; Proceedings of the Meeting, Munich, Germany, June 13, 14, 1991 (A93-33082 12-35); p. 144-157.
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  • 6
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    High spatial resolution atmospheric wind measurements with the edge technique (1995)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: The edge technique is a new and powerful method for measuring small frequency shifts such as the Doppler shift of an atmospheric backscattered signal from a pulsed laser. The edge technique can be used for high spatial resolution, high accuracy ground and airborne wind measurements as well as high accuracy spaceborne wind measurements. We have recently made our first ground based wind measurements. These have a spatial resolution of 15 m and an accuracy of 25 cm/s and these measurements are presented in this paper. This is a unique capability and provides valuable information for studies of turbulent processes in the lower atmosphere. It could also be used for high sensitivity detection of wind shear and microbursts in the vicinity of airports. In addition, global wind measurements can be made with the edge technique from space with an accuracy of 1 m/s and a vertical resolution as high as 150 m in the boundary layer and 1 km through the troposphere. Such a system could make eyesafe wind measurements using well developed diode pumped solid state laser technology at 1.06 micron. Multi-pulse averaging would provide a spatially representative wind measurement.
    Keywords: Meteorology and Climatology
    Type: ; 59-61
    Format: text
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  • 7
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    Edge technique - Theory and application to the lidar measurement of atmospheric wind (1992)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: The paper describes the theory of the edge technique, a powerful method for the detection and measurement of small frequency shifts. It can be employed with a lidar to obtain range-resolved measurements of wind with high accuracy and high vertical resolution. The technique can be applied to measure wind with a lidar by using either the aerosol or molecular backscattered signal. Simulations for a ground-based lidar at 1.06 micron using reasonable instrumental parameters show an accuracy of the vector components of the wind which is better than 0.5 m/s from the ground to an altitude of 20 km for a 100-m vertical resolution and a 100-shot average.
    Keywords: LASERS AND MASERS
    Type: Applied Optics (ISSN 0003-6935); 31; 21, J
    Format: text
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  • 8
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    Capacitively Stabilized Etalon Technology for Spaceborne Wind Lidar Application (1998)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: Global monitoring by satellites is important for many types of environmental studies. Among these, the wind field is the single most important atmospheric state variable required for understanding atmospheric motion and predicting weather. Studies indicate that a global determination of the tropospheric wind field to an accuracy of 1-5 m/sec is critical for improved numerical weather forecasting. This measurement could be carried out with a spaceborne lidar system sensing the Doppler shift of a laser signal backscattered from the atmosphere. Over the past four years we have developed a ground-based Edge Technique lidar system and demonstrated wind measurements through the troposphere with high accuracy (1-6 m/s) and high spatial resolution. Recently, we began the design of a shuttle based wind measurement system for technology demonstration as part of the Zephyr program. In this paper, we present the characteristics of the high spectral resolution etalon filter technology for lidar wind measurement with the Edge Technique. In conclusion, a spacecraft motion compensation method has been discussed. We demonstrated experimentally that the etalon can be tuned to compensate for any satellite induced Doppler shift to an accuracy of better than 0.6 m/s over a time period of 2.5 ms.
    Keywords: Instrumentation and Photography
    Type: Nineteenth International Laser Radar Conference; Part 2; 915-918; NASA/CP-1998-207671/PT2
    Format: text
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  • 9
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    The Double Edge Technique for Doppler lidar wind measurement (1998)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: The edge technique utilizes the edge of a high spectral resolution filter for high accuracy wind measurement using direct detection lidar. The signal is split between an edge filter channel and a broadband energy monitor channel. The energy monitor channel is used for signal normalization. The edge measurement is made as a differential frequency measurement between the outgoing laser signal and the atmospheric backscattered return for each pulse. As a result, the measurement is insensitive to laser and edge filter frequency jitter and drift at a level less than a few parts in 10(exp 10). We will discuss the methodology of the technique in detail, present a broad range of simulation results, and provide preprints of a journal article currently in press.
    Keywords: Meteorology and Climatology
    Type: Nineteenth International Laser Radar Conference; Part 2; 691-694; NASA/CP-1998-207671/PT2
    Format: text
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  • 10
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    Lidar Measurements of Tropospheric Wind Profiles with the Double Edge Technique (1998)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: Research has established the importance of global tropospheric wind measurements for large scale improvements in numerical weather prediction. In addition, global wind measurements provide data that are fundamental to the understanding and prediction of global climate change. These tasks are closely linked with the goals of the NASA Earth Science Enterprise and Global Climate Change programs. NASA Goddard has been actively involved in the development of direct detection Doppler lidar methods and technologies to meet the wind observing needs of the atmospheric science community. A variety of direct detection Doppler wind lidar measurements have recently been reported indicating the growing interest in this area. Our program at Goddard has concentrated on the development of the edge technique for lidar wind measurements. Implementations of the edge technique using either the aerosol or molecular backscatter for the Doppler wind measurement have been described. The basic principles have been verified in lab and atmospheric lidar wind experiments. The lidar measurements were obtained with an aerosol edge technique lidar operating at 1064 nm. These measurements demonstrated high spatial resolution (22 m) and high velocity sensitivity (rms variances of 0.1 m/s) in the planetary boundary layer (PBL). The aerosol backscatter is typically high in the PBL and the effects of the molecular backscatter can often be neglected. However, as was discussed in the original edge technique paper, the molecular contribution to the signal is significant above the boundary layer and a correction for the effects of molecular backscatter is required to make wind measurements. In addition, the molecular signal is a dominant source of noise in regions where the molecular to aerosol ratio is large since the energy monitor channel used in the single edge technique measures the sum of the aerosol and molecular signals. To extend the operation of the edge technique into the free troposphere we have developed a variation of the edge technique called the double edge technique. In this paper a ground based aerosol double edge lidar is described and the first measurements of wind profiles in the free troposphere obtained with this lidar will be presented.
    Keywords: Geophysics
    Type: Nineteenth International Laser Radar Conference; Part 2; 587-590; NASA/CP-1998-207671/PT2
    Format: text
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