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Abstract
During 13 nights of Rayleigh lidar measurements at Urbana Illinois in 1984–86, thirty-six quasi-monochromatic gravity waves were observed in the 35–50 km altitude region of the stratosphere. The characteristics of the waves are compared with other lidar and radar measurements of gravity waves and with theoretical models of wave saturation and dissipation phenomena. The measured vertical wavelengths (λ2) ranged from 2 to 11.5 km and the measured vertical phase velocities (c z) ranged from 10 to 85 cm s−1. The vertical wavelengths and vertical phase velocities were used to infer observed wave periods (T ob) which ranged from 100 to 1000 min and horizontal wavelengths (λx) which ranged firm 70 to 2000 km. There may be errors, in the inferred values of the horizontal wavelengths because they were calculated by assuming that the observed period inferred the intrinsic period. Dominant wave activity was found at vertical wavelengths between 2–4 km and 7–10 km. No significant seasonal variations were evident in the observed parameters. Vertical and horizontal wavelengths showed a clear tendency to increase with T ob, which is consistent with recent sodium lidar studies of quasi-monochromatic waves near the mesopause. An average amplitude growth length of 20.9 km for the rms wind perturbations was estimated from the data. Kinetic energy density associated with the waves decreased with height, suggesting that waves in this altitude region were subject to dissipation or saturation effects.
Abstract
During 13 nights of Rayleigh lidar measurements at Urbana Illinois in 1984–86, thirty-six quasi-monochromatic gravity waves were observed in the 35–50 km altitude region of the stratosphere. The characteristics of the waves are compared with other lidar and radar measurements of gravity waves and with theoretical models of wave saturation and dissipation phenomena. The measured vertical wavelengths (λ2) ranged from 2 to 11.5 km and the measured vertical phase velocities (c z) ranged from 10 to 85 cm s−1. The vertical wavelengths and vertical phase velocities were used to infer observed wave periods (T ob) which ranged from 100 to 1000 min and horizontal wavelengths (λx) which ranged firm 70 to 2000 km. There may be errors, in the inferred values of the horizontal wavelengths because they were calculated by assuming that the observed period inferred the intrinsic period. Dominant wave activity was found at vertical wavelengths between 2–4 km and 7–10 km. No significant seasonal variations were evident in the observed parameters. Vertical and horizontal wavelengths showed a clear tendency to increase with T ob, which is consistent with recent sodium lidar studies of quasi-monochromatic waves near the mesopause. An average amplitude growth length of 20.9 km for the rms wind perturbations was estimated from the data. Kinetic energy density associated with the waves decreased with height, suggesting that waves in this altitude region were subject to dissipation or saturation effects.
The Lidar In-Space Technology Experiment (LITE) is being developed by NASA/Langley Research Center for a series of flights on the space shuttle beginning in 1994. Employing a three-wavelength Nd:YAG laser and a 1-m-diameter telescope, the system is a test-bed for the development of technology required for future operational spaceborne lidars. The system has been designed to observe clouds, tropospheric and stratospheric aerosols, characteristics of the planetary boundary layer, and stratospheric density and temperature perturbations with much greater resolution than is available from current orbiting sensors. In addition to providing unique datasets on these phenomena, the data obtained will be useful in improving retrieval algorithms currently in use. Observations of clouds and the planetary boundary layer will aid in the development of global climate model (GCM) parameterizations. This article briefly describes the LITE program and discusses the types of scientific investigations planned for the first flight.
The Lidar In-Space Technology Experiment (LITE) is being developed by NASA/Langley Research Center for a series of flights on the space shuttle beginning in 1994. Employing a three-wavelength Nd:YAG laser and a 1-m-diameter telescope, the system is a test-bed for the development of technology required for future operational spaceborne lidars. The system has been designed to observe clouds, tropospheric and stratospheric aerosols, characteristics of the planetary boundary layer, and stratospheric density and temperature perturbations with much greater resolution than is available from current orbiting sensors. In addition to providing unique datasets on these phenomena, the data obtained will be useful in improving retrieval algorithms currently in use. Observations of clouds and the planetary boundary layer will aid in the development of global climate model (GCM) parameterizations. This article briefly describes the LITE program and discusses the types of scientific investigations planned for the first flight.
