排序方式: 共有17条查询结果,搜索用时 15 毫秒
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Cutten DR Rothermel J Jarzembski MA Hardesty RM Howell JN Tratt DM Srivastava V 《Applied optics》2002,41(18):3530-3537
Radiometric calibration of an airborne CO2 pulsed Doppler lidar has been accomplished with surface retroreflection signals from the White Sands National Monument, New Mexico. Two circular passes were made at altitudes of 6.3 and 9.3 km. The computed calibration factors for both altitudes are in excellent agreement with the value derived from standard ground-based measurements involving a fixed sandpaper target of known reflectance. This finding corroborates a previous study that successfully calibrated an airborne cw Doppler lidar with a variety of natural Earth surfaces. The present results indicate that relatively uniform Earth surface targets can be used for in-flight calibration of CO2 pulsed airborne and, in principal, other infrared lidars. 相似文献
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Airborne CO(2) coherent lidar for measurements of atmospheric aerosol and cloud backscatter 总被引:1,自引:0,他引:1
An airborne CO(2) coherent lidar has been developed and flown on over 30 flights of the NASA DC-8 research aircraft to obtain aerosol and cloud backscatter and extinction data at a wavelength near 9μm. Designed to operate in either zenith- or nadir-directed modes, the lidar can be used to measure vertical profiles of backscatter throughout the vertical extent of the troposphere and the lower stratosphere. Backscatter measurements in absolute units are obtained through a hard-target calibration methodology. The use of coherent detection results in high sensitivity and narrow field of view, the latter property greatly reducing multiple-scattering effects. Aerosol backscatter profile intercomparisons with other airborne and ground-based CO(2) lidars were conducted during instrument checkout flights over the NASA Ames Research Center before extended depolyment over the Pacific Ocean. Selected results from data taken during the flights over the Pacific Ocean are presented, emphasizing intercom arisons with backscatter profile data obtained at 1.06 μm with a NASA Goddard Space Flight Center Nd:YAG lidar on the same flights. 相似文献
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Lidar in-space technology experiment measurements of sea surface directional reflectance and the link to surface wind speed 总被引:2,自引:0,他引:2
The dependence of sea surface directional reflectance on surface wind stress suggests a method for deriving surface wind speed from space-based lidar measurements of sea surface backscatter. In particular, lidar measurements in the nadir angle range from 10 degrees to 30 degrees appear to be most sensitive to surface wind-speed variability in the regime below 10 m/s. The Lidar In-space Technology Experiment (LITE) shuttle lidar mission of September 1994 provided a unique opportunity to measure directional backscatter at selected locations by use of the landmark track maneuver and to measure fixed-angle backscatter from the ocean surfaces on a global scale. During the landmark track maneuver the shuttle orbiter orientation and roll axis are adjusted continuously to maintain the lidar footprint at a fixed location for a duration of ~1 min. Several data sets were converted to calibrated reflectance units and compared with a surface reflectance model to deduce surface wind speeds. Comparisons were made with ERS-1 scatterometer data and surface measurements. 相似文献
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Laurence Tratt 《Software and Systems Modeling》2005,4(2):112-122
Model transformations are increasingly recognised as being of significant importance to many areas of software development and integration. Recent attention on model transformations has particularly focused on the OMGs Queries/Views/Transformations (QVT) Request for Proposals (RFP). In this paper I motivate the need for dedicated approaches to model transformations, particularly for the data involved in tool integration, outline the challenges involved, and then present a number of technologies and techniques which allow the construction of flexible, powerful and practical model transformations. 相似文献
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Tratt DM Menzies RT Chiao MP Cutten DR Rothermel J Hardesty RM Howell JN Durden SL 《Applied optics》2002,41(33):6941-6949
Concurrent measurements of sea-surface retroreflectance and associated wind velocity acquired with an airborne CO2 Doppler lidar are described. These observations provide further insight into thermal infrared optical phenomenology of air-sea interface processes, contribute to a greater understanding of radiation transfer between the atmosphere and the hydrosphere, and enable improved models of wind-driven ocean-surface stress applicable to other remote sensing applications. In particular, we present lidar measurements of azimuthally anisotropic reflectance behavior and discuss the implications to current understanding of sea-surface optical properties. 相似文献
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Electron-plasma-induced chirping phenomena are incorporated into a quantitative theoretical treatment of an injection-locked compact TEA CO2 laser. For the first time, inferred estimates of both the magnitude and sense of the single mode detuning range asymmetry about resonance are shown to agree with experimentally derived data. Conditions for chirp-free operation are discussed and demonstrated. 相似文献