Atmospheric sounding by ground-based and space-based systems

The possibilities of reconstruction of various atmospheric structures and i nfluence of localized atmospheric and ionospheric irregularities on the rec onstructed atmospheric profiles are discussed. In the case of vast atmosphe ric structures (above 400-600 km long), the radiooccultation method of atmo spheric studies makes it possible to reconstruct the vertical profiles of m eteorological 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 hori zontal dimensions up to 300-400 km leads to significant reconstruction erro rs, the fact being related to the 'spreading' of the disturbance to the ent ire region of the sounding ray intersection of the troposphere. Therefore, near such structures as secondary typo atmospheric fronts and developing cy clones, the profiles are reconstructed with strong distortions reaching 1-1 0%. 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 irreg ularities by the tomographic method, using a network of ground-based receiv ers, are considered. (C) 2001 Elsevier Science Ltd. All rights reserved.