Atmospheric sounding by ground-based and space-based systems

The possibilities of reconstruction of various atmospheric structures and influence of localized atmospheric and ionospheric irregularities on the reconstructed atmospheric profiles are discussed. In the case of vast atmospheric structures (above 400-600 km long), the radiooccultation method of atmospheric studies makes it possible to reconstruct the vertical profiles of meteorological parameters with the accuracy acceptable for applications (the errors in the refractive index profile are 0.5-1% for the altitude region 8-40 km). However, the presence of the atmospheric irregularities with horizontal dimensions up to 300-400 km leads to significant reconstruction errors, the fact being related to the 'spreading' of the disturbance to the entire region of the sounding ray intersection of the troposphere. Therefore, near such structures as secondary typo atmospheric fronts and developing cyclones, the profiles are reconstructed with strong distortions reaching 1-10%. The impact of the irregularities in the radio signal propagation media (atmosphere, ionosphere, and protonosphere) on the accuracy of the profiles reconstructed is studied. Possibilities to study various atmospheric irregularities by the tomographic method, using a network of ground-based receivers, are considered. (C) 2001 Elsevier Science Ltd. All rights reserved.