A brief review of the current state of studies of long-term trends in the middle and upper atmosphere and ionosphere is presented. It is shown that the present trends in the density and temperature ...of the upper atmosphere and parameters of the ionospheric layers may lead to changes in the aforementioned spheres. It would be necessary to take into account these trends in applied problems related to planning space vehicle orbits, propagation of radio waves, measurements at low-orbiting satellites, and so on. It is emphasized that the Helio–Geophysical Service of the State Committee of Hydrometeorology, which supplies customers with information on the state of the upper atmosphere, ionosphere, and near-Earth space, should develop information products related to possible changes in atmospheric and ionospheric parameters caused by the presence of the long-term trends.
The satellite ionosondes in highly elliptical orbits are proposed to be used for the task of continuous monitoring of the Arctic ionosphere. The monitoring scheme with the ionosonde location aboard ...the
Arktika-M
satellites is presented. The calculations of the vertical topside and transionospheric sounding using the SIMP1 ionospheric model are performed, which show the feasibility of continuous monitoring.
We present maximum usable frequency (MUF) calculation results when a radiowave, radiated at a zero angle, is reflected from the ionosphere along direct and reverse paths when the latitudinal ...variability of the medium is significant. As an example, we consider the Novorossiysk-California path. Calculations were carried out using a “two-point” method and data of the Monthly MUF Prediction for May 1980 and May 1991. The “two-point” method is validated based on a new way of approximated representation of the Watson integral, which is an exact solution of the benchmark problem related to the point source field in a spherically layered medium. It is shown that MUFs along a reverse path are several MHz higher than MUFs along a direct path during the whole day.
