Investigations of Atmospheric Waves in the Earth Lower Ionosphere by Means of the Method of the Creation of the Artificial Periodic Irregularities of the Ionospheric Plasma

Abstract

We present results of the studies of internal gravity waves based on altitude-time dependences of the temperature and the density of the neutral component and the velocity of the vertical plasma motion at altitudes of the lower ionosphere (60–130 km). The vertical plasma velocity, which in the specified altitude range is equal to the velocity of the neutral component, the temperature, and the density of the neutral atmosphere are determined by the method of the resonant scattering of radio waves by artificial periodic irregularities (APIs) of the ionosphere plasma. We have developed an API technique and now we are evolving it for studying the ionosphere and the neutral atmosphere using the Sura heating facility (56.1 N; 46.1 E), Nizhny Novgorod, Russia. An advantage of the API technique is the opportunity to determine the parameters of the undisturbed natural environment under a disturbance of the ionosphere by a field of powerful high frequency radio waves. Analysis of altitude-time variations of the neutral temperature, the density, and the vertical plasma velocity allows one to estimate periods of atmospheric waves propagation. Wavelike variations with a period from 5 min to 3 h and more are clearly determined.

Acoustic–gravity waves and their role in ionosphere–lower thermosphere coupling

“…Horizontal wavelengths for these waves are in the range of 115 km< λ p < 161 km. This is consistent with the results known from the scientific literature (Fritts et al , 2014;Bakhmetieva et al , 2019), which emphasize that gravity waves with periods as short as 10 minutes (i.e. Ω < 0.24, or ω < 0.01s −1 ) can carry significant momentum flux vertically.…”

“…These waves have lower vertical phase velocities than high-frequency gravity waves with ω ≈ ω BV which travel faster through the ionospheric D layer towards the lower thermosphere. The reflection coefficient is the smallest for the gravity waves with the frequencies ω < 0.0087s −1 , horizontal phase velocities 159m/s < v h < 222m/s, and horizontal wavelengths 115 km< λ p <161 km, which is in accordance with the results known in the scientific literature (Lizunov and Hayakawa , 2004;Fritts et al , 2014;Bakhmetieva et al , 2019). These waves can generate the middle-scale TIDs and cause temperature rise in the lower ionosphere.…”

Artificial Periodic Irregularities and Temperature of the Lower Thermosphere

“…Our long-term studies of the ionosphere by the API technique have shown that the relaxation time of the scattered signal fluctuates in height and in time [23,32,39,41]. Altitude profiles of the relaxation time τ(h) for 30 min of measurements are shown in Figure 2c.…”

Study of a Gas Disturbance Mode Content Based on the Measurement of Atmospheric Parameters at the Heights of the Mesosphere and Lower Thermosphere

“…The atmospheric temperature and density are determined from the API relaxation time, which is inversely proportional to the ambipolar diffusion coefficient. Many results of studying the altitude-temporal variations of temperature and density in different geo-and helio-physical conditions are presented in Reference [23][24][25][26][27][28].…”