The algorithms for transformation of the Reanalysis NCEP/NCAR data from their standard system to grid domains of variable structure are described. These data are used in basis models of hydrothermodynamics and admixture transfer in the atmosphere. To reconstruct the detailed spatiotemporal structure of fields, the algorithm for assimilation of data is developed. The algorithm provides for "hydrothermodynamic" interpolation with the basis models. Different versions of data reconstruction for the direct and inverse simulation are considered.