Reconstruction of regional distributions of electron density in the ionosphere from heterogeneous remote sensing data

A new iterative algorithm has been developed for solving the problem of reconstructing regional distributions of electron density in the ionosphere based on heterogeneous data from low-orbit satellite radio sounding at a pair of coherent frequencies VHF/UHF and UV spectrometry of the upper atmosphere's airglow at 135.6 nm. It allows us to use complementary probing geometries. Each iteration of the algorithm is split into two, in which problems concerning the electron concentration and its square are sequentially solved with diffusion smoothing between steps. In addition, the algorithm implements the possibility of taking into account the absorption of the intrinsic UV radiation of the thermosphere by molecular oxygen, which makes it possible to include low perigee rays, the absorption of which plays a significant role, into consideration. The developed algorithm was tested on synthetic observational data obtained on the basis of the NRLMSISE00 and NeQuick2 models for real operation modes of the CERTO and SSUSI/SSULI equipment. It is shown that the proposed algorithm provides better spatial resolution compared to the traditional RT approach, and also removes the problem of correctly specifying the initial approximation, due to the presence of quasi-horizontal rays in the sounding geometry.