Structure of Air Density Irregularities in the Stratosphere from Spacecraft Observations of Stellar Scintillation: 2. Characteristic Scales, Structure Characteristics, and Kinetic Energy Dissipation

• Published in: Izvestiya. Atmospheric and oceanic physics 2003-05, Vol.39 (3)
• Main Authors: Gurvich, A S, Kan, V
• Format: Article
• Language: English
• ISSN: 0001-4338

This work is the second part of the studies of the fine structure of air density irregularities at heights of 25 to 70 km on the basis of star observations through the Earth's atmosphere from space. The results presented refer to the region between 40 degree S and 50 degree N. The observations of occulations of stars with different positions with respect to the observer's orbit plane allowed one to study the isotropic and anisotropic components of the spatial spectra of air density fluctuations with a spatial resolution of up to a few decimeters. The basic notions of the Kolmogorov turbulence in combination with an ensemble of saturated internal waves formed the basis for a model to retrieve the parameters of the three-dimensional spectra of air density irregularities in the stratosphere. These problems are discussed in the first part of this work Three-Dimensional Spectrum Model and Retrieval of Its Parameters published also in this issue of the journal. The spatial resolution achieved in retrieving the parameters allowed one to determine the height behaviors of the Kolmogorov scale (27-67 km) and the buoyancy scale (27-53 km). Between these scales, there is a gap whose width increases monotonically with height. The values obtained for the structure characteristics of the anisotropic component are in good agreement with the predictions based on the assumption that the regime of saturated internal waves exists. The structure characteristics of relative-temperature and air-density fluctuations for the isotropic component increase almost exponentially with height within the entire height range. The values of the rate of kinetic-energy dissipation are calculated from the measured values of the Kolmogorov scale. The height dependence of the rate of smoothing temperature irregularities is estimated from the combined measurements of the scales and structure characteristics.