Tentative detection of clear-air turbulence using a ground-based Rayleigh lidar.

Atmospheric gravity waves and turbulence generate small-scale fluctuations of wind, pressure, density, and temperature in the atmosphere. These fluctuations represent a real hazard for commercial aircraft and are known by the generic name of clear-air turbulence (CAT). Numerical weather prediction models do not resolve CAT and therefore provide only a probability of occurrence.

Using stellar scintillation for studies of turbulence in the Earth's atmosphere.

Stellar scintillation observed through the Earth's atmosphere is the result of interaction of light waves and the turbulent atmosphere. This review is dedicated to using stellar scintillation measurements for studies of turbulence in the Earth's atmosphere. We present an overview of ground-based, air-borne and satellite stellar scintillation measurements, discuss the approaches to data analyses and give an overview of the main geophysical results.

Measurement of Stratospheric Chromatic Scintillation with the AMON-RA Balloonborne Spectrometer.

The balloonborne instrument AMON (which is a French acronym for Absorption par les Minoritaires Ozone et NO(x)) has been modified to record chromatic scintillation during stellar occultation by the Earth's atmosphere. A 14-channel spectrophotometer with a sampling rate of 10 Hz was added, and the modified instrument, AMON-RA, performed successful measurements of the setting star Alnilam during the third European Stratospheric Experiment on Ozone (THESEO) project. Unambiguous records of the chromatic scintillation were obtained, to our knowledge for the first time from above the atmosphere, and some of its basic properties are reported.

Chromatic Refraction with Global Ozone Monitoring by Occultation of Stars. II. Statistical Properties of Scintillations.

The statistical properties of stellar scintillations are discussed with special attention to correcting the atmospheric transmittance data for scintillations in measurements made with the Global Ozone Monitoring by Occultation of Stars (GOMOS) instrument. Both anisotropic and isotropic turbulent inhomogeneities are taken into account. Calculated rms scintillation reaches several percent for altitudes of 30-35 km, an amplitude comparable with the expected absorbing features.

Chromatic refraction with global ozone monitoring by occultation of stars. I. Description and scintillation correction.

We describe refractive and chromatic effects, both regular and random, that occur during star occultations by the Earth's atmosphere. The scintillation that results from random density fluctuations, as well as the consequences of regular chromatic refraction, is qualitatively described. The resultant chromatic scintillation will produce random features on the Global Ozone Monitoring by Occultation of Stars (GOMOS) spectrometer, with an amplitude comparable with that of some of the real absorbing features that result from atmospheric constituents.