Vertical remote sensing of the Earth's surface using GPS signals

GPS satellite grouping as a source of external radiation for remote sensing of the Earth's surface is very attractive at first glance since it allows to exclude radars and other satellite systems from consideration. The facts mentioned above are especially useful for measuring ocean surface level to detect the occurrence of a tsunami from space. The latter requires high accuracy and speed of measurement and should not include the time averaging function. These circumstances are the main difficulties of remote sensing since they are related to the interaction of satellite signals with their propagation medium [1–3], as demonstrated in experiments [4]. Speaking about the accuracy of measurements, we should refer to the work of the Montenbruck group with employees to determine the water surface level of the mountain lake Walchen in Bavaria (Germany), which was carried out under the GORS (GPS Occultation, Reflectometry, and Scatterometry) program [5–7]. This paper provides a detailed discussion of their measurements based on the resonant quantum properties of the D and E layers of the ionosphere at 60-110 km [8]. These properties are due to the settlement of orbitally degenerate states of Rydberg complexes in a non-equilibrium two-temperature plasma, the transitions between which include a decimeter range of wavelengths without changing the main quantum number Δn=0 [9]. These states lead to the spontaneous behavior of the signal-to-noise ratio at the specified altitudes [4] and are responsible for the delay of satellite signals [3].